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Background: Zika virus (ZIKV) and Dengue virus (DENV) are often co-endemic. The high protein-sequence homology of flaviviruses renders IgG induced by and directed against them highly cross-reactive against their antigen(s), as observed on a large set of sera, leading to poorly reliable sero-diagnosis. Methods: We selected Domain III of the ZIKV Envelope (ZEDIII) sequence, which is virus specific. This recombinant domain was expressed and purified for the specific detection of ZEDIII-induced IgG by ELISA from ZIKV-RT-PCR-positive, ZIKV-IgM-positive, flavivirus-positive but ZIKV-negative, or flavivirus-negative sera. We also assessed the reactivity of ZEDIII-specific human antibodies against EDIII of DENV serotype 4 (D4EDIII) as a specific control. Sera from ZEDIII-immunized mice were also tested. Results: Cross-reactivity of IgG from 5,600 sera against total inactivated DENV or ZIKV was high (71.0% [69.1; 72.2]), whereas the specificity and sensitivity calculated using a representative cohort (242 sera) reached 90% [84.0; 95.8] and 92% [84.5; 99.5], respectively, using a ZEDIII-based ELISA. Moreover, purified human IgG against D2EDIII or D4EDIII did not bind to ZEDIII and we observed no D4EDIII reactivity with ZIKV-induced mouse polyclonal IgGs. Conclusions: We developed a ZEDIII-based ELISA that can discriminate between past or current DENV and ZIKV infections, allowing the detection of a serological scar from other flaviviruses. This could be used to confirm exposure of pregnant women or to follow the spread of an endemic disease. [ABSTRACT FROM AUTHOR]

Zika virus infection is associated with the development of Guillain-Barré syndrome (GBS), a neurological autoimmune disorder caused by immune recognition of gangliosides and other components at nerve membranes. Using a high-throughput ELISA, we have analyzed the anti-glycolipid antibody profile, including gangliosides, of plasma samples from patients with Zika infections associated or not with GBS in Salvador, Brazil. We have observed that Zika patients that develop GBS present higher levels of anti-ganglioside antibodies when compared to Zika patients without GBS. We also observed that a broad repertoire of gangliosides was targeted by both IgM and IgG anti-self antibodies in these patients. Since Zika virus infects neurons, which contain membrane gangliosides, antigen presentation of these infected cells may trigger the observed autoimmune anti-ganglioside antibodies suggesting direct infection-induced autoantibodies as a cause leading to GBS development. Collectively, our results establish a link between anti-ganglioside antibodies and Zika-associated GBS in patients. [ABSTRACT FROM AUTHOR]

Mother-to-child-transmission (MTCT) of human T-cell lymphotropic virus type-1(HTLV-1) contributes disproportionately to the burden of HTLV-1 associated diseases. All preventive measures to avoid MTCT rely on the identification of infected mothers. However, the impact of pregnancy on HTLV-1 diagnosis has not been clearly assessed. Paired samples from 21 HTLV-1 infected women taken during pregnancy and while not pregnant were analysed by CMIA and PCR. The signal-to-cut-off values (S/CO) were higher during pregnancy than in the paired non-pregnant samples. HTLV-1 proviral load did not alter significantly by pregnant state. S/CO positively correlated with HTLV proviral load. Pregnancy does not impair the diagnosis of HTLV-1/2, by either immunological (CMIA) or molecular (qPCR/nPCR) tests. [ABSTRACT FROM AUTHOR]

Background: Rift Valley fever (RVF) is one of the main vector borne zoonotic diseases that affects a wide range of ruminants and human beings in Africa and the Arabian Peninsula. A rapid and specific test for RVF diagnosis at the site of a suspected outbreak is crucial for the implementation of control measures. Methodology/Principal findings: A first-line lateral flow immunochromatographic strip test (LFT) was developed for the detection of the nucleoprotein (N) of the RVF virus (RVFV). Its diagnostic performance characteristics were evaluated using reference stocks isolates recovered from different hosts and in geographic regions mimicking clinical specimens and from known RVF negative serum samples. A high level of diagnostic accuracy (DSe (35/35), DSp (167/169)) was observed, including the absence of cross-reactivity with viruses belonging to different genera. Conclusion/Significance: The fact no specialized reagents and laboratory equipment are needed, make this assay a valuable, first-line diagnostic tool in resource-poor diagnostic territories for on-site RVFV detection, however the staff require training. [ABSTRACT FROM AUTHOR]

Background: Pathogens causing acute fever, with the exception of malaria, remain largely unidentified in sub-Saharan Africa, given the local unavailability of diagnostic tests and the broad differential diagnosis. Methodology: We conducted a cross-sectional study including outpatient acute undifferentiated fever in both children and adults, between November 2015 and June 2016 in Kinshasa, Democratic Republic of Congo. Serological and molecular diagnostic tests for selected arboviral infections were performed on blood, including PCR, NS1-RDT, ELISA and IFA for acute, and ELISA and IFA for past infections. Results: Investigation among 342 patients, aged 2 to 68 years (mean age of 21 years), with acute undifferentiated fever (having no clear focus of infection) revealed 19 (8.1%) acute dengue–caused by DENV-1 and/or DENV-2 –and 2 (0.9%) acute chikungunya infections. Furthermore, 30.2% and 26.4% of participants had been infected in the past with dengue and chikungunya, respectively. We found no evidence of acute Zika nor yellow fever virus infections. 45.3% of patients tested positive on malaria Rapid Diagnostic Test, 87.7% received antimalarial treatment and 64.3% received antibacterial treatment. Discussion: Chikungunya outbreaks have been reported in the study area in the past, so the high seroprevalence is not surprising. However, scarce evidence exists on dengue transmission in Kinshasa and based on our data, circulation is more important than previously reported. Furthermore, our study shows that the prescription of antibiotics, both antibacterial and antimalarial drugs, is rampant. Studies like this one, elucidating the causes of acute fever, may lead to a more considerate and rigorous use of antibiotics. This will not only stem the ever-increasing problem of antimicrobial resistance, but will–ultimately and hopefully–improve the clinical care of outpatients in low-resource settings. Trial registration: ClinicalTrials.gov . [ABSTRACT FROM AUTHOR]

Background: Evaluation of therapeutic response in chronic Chagas disease is a major challenge, due to prolonged persistence of Trypanosoma cruzi-specific antibodies, lack of sensitivity of parasitological tests, and need for long-term follow-up to observe negative seroconversion of conventional serological tests (CS). The objective of this study was to evaluate F2/3-ELISA serology, a promising early biomarker of therapeutic response, and T.cruzi Polymerase chain reaction (PCR) for T. cruzi Deoxyribonucleic acid (DNA), for neonatal diagnosis and evaluation of parasitemia after treatment. Methods: Prospective cohort study, with three-year clinical, serological and parasitological follow-up of pediatric Chagas disease patients treated with benznidazole. Serology was evaluated by Enzyme-Linked ImmunoSorbent Assay (ELISA), Indirect hemagglutination (IHA) and F2/3-ELISA; Parasitemia by microhematocrit (MH) and PCR. Results: A cohort of 107 pediatric patients treated with benznidazole was enrolled in the study. ELISA and IHA were initially reactive in 100% of patients, F2/3-ELISA serology was reactive in 80% (86/107) and 91% (97/107) had detectable parasitemia. Seventy-six (71%) patients completed at least 36 months of serological follow up after treatment. Although a similar decreasing linear trend was observed for all serological tests, F2/3-ELISA presented earlier, age dependent, negative seroconversion compared to CS. All patients reaching undetectable CS titers had previously seroreverted by F2/3-ELISA. All patients with persistently decreasing antibody titers had negative PCRs throughout the follow up period. No new cardiological lesions were observed during the 3 years follow-up period. Conclusions: The data reported here, using CS, F2/3 ELISA and PCR provide support for the efficacy of benznidazole in congenital Chagas diseases. These results provide support for scaling up of screening, diagnosis and access to benznidazole treatment. Trial registration: ClinicalTrials.gov 0028/04 in the Research Council, Secretary of Health Buenos Aires city Goberment. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) is a newly-identified infectious cause of congenital disease. Transplacental transfer of maternal IgG to the fetus plays an important role in preventing many neonatal infections. However, antibody transfer may also have negative consequences, such as mediating enhancement of flavivirus infections in early life, or trafficking of virus immune complexes to the fetal compartment. ZIKV infection produces placental pathology which could lead to impaired IgG transfer efficiency as occurs in other maternal infections, such as HIV-1 and malaria. In this study, we asked whether ZIKV infection during pregnancy impairs transplacental transfer of IgG. We enrolled pregnant women with fever or rash in a prospective cohort in Vitoria, Brazil during the recent ZIKV epidemic. ZIKV and dengue virus (DENV)-specific IgG, ZIKV and DENV neutralizing antibodies, and routine vaccine antigen-specific IgG were measured in maternal samples collected around delivery and 20 paired cord blood samples. We concluded that 8 of these mothers were infected with ZIKV during pregnancy and 12 were ZIKV-uninfected. The magnitude of flavivirus-specific IgG, neutralizing antibody, and vaccine-elicited IgG were highly correlated between maternal plasma and infant cord blood in both ZIKV-infected and -uninfected mother-infant pairs. Moreover, there was no difference in the magnitude of plasma flavivirus-specific IgG levels between mothers and infants regardless of ZIKV infection status. Our data suggests that maternal ZIKV infection during pregnancy does not impair the efficiency of placental transfer of flavivirus-specific, functional, and vaccine-elicited IgG. These findings have implications for the neonatal outomes of maternal ZIKV infection and optimal administration of antibody-based ZIKV vaccines and therapeutics. [ABSTRACT FROM AUTHOR]

The explosive spread of Zika virus (ZIKV) and associated complications in flavivirus-endemic regions underscore the need for sensitive and specific serodiagnostic tests to distinguish ZIKV, dengue virus (DENV) and other flavivirus infections. Compared with traditional envelope protein-based assays, several nonstructural protein 1 (NS1)-based assays showed improved specificity, however, none can detect and discriminate three flaviviruses in a single assay. Moreover, secondary DENV infection and ZIKV infection with previous DENV infection, both common in endemic regions, cannot be discriminated. In this study, we developed a high-throughput and multiplex IgG microsphere immunoassay (MIA) using the NS1 proteins of DENV1-DENV4, ZIKV and West Nile virus (WNV) to test samples from reverse-transcription-polymerase-chain reaction-confirmed cases, including primary DENV1, DENV2, DENV3, WNV and ZIKV infections, secondary DENV infection, and ZIKV infection with previous DENV infection. Combination of four DENV NS1 IgG MIAs revealed a sensitivity of 94.3% and specificity of 97.2% to detect DENV infection. The ZIKV and WNV NS1 IgG MIAs had a sensitivity/specificity of 100%/87.9% and 86.1%/78.4%, respectively. A positive correlation was found between the readouts of enzyme-linked immunosorbent assay and MIA for different NS1 tested. Based on the ratio of relative median fluorescence intensity of ZIKV NS1 to DENV1 NS1, the IgG MIA can distinguish ZIKV infection with previous DENV infection and secondary DENV infection with a sensitivity of 88.9–90.0% and specificity of 91.7–100.0%. The multiplex and high-throughput assay could be applied to serodiagnosis and serosurveillance of DENV, ZIKV and WNV infections in endemic regions. [ABSTRACT FROM AUTHOR]

Bacillus anthracis and Yersinia pestis are zoonotic bacteria capable of causing severe and sometimes fatal infections in animals and humans. Although considered as diseases of antiquity in industrialized countries due to animal and public health improvements, they remain endemic in vast regions of the world disproportionally affecting the poor. These pathogens also remain a serious threat if deployed in biological warfare. A single vaccine capable of stimulating rapid protection against both pathogens would be an extremely advantageous public health tool. We produced multiple-antigen fusion proteins (MaF1 and MaF2) containing protective regions from B. anthracis protective antigen (PA) and lethal factor (LF), and from Y. pestis V antigen (LcrV) and fraction 1 (F1) capsule. The MaF2 sequence was also expressed from a plasmid construct (pDNA-MaF2). Immunogenicity and protective efficacy were investigated in mice following homologous and heterologous prime-boost immunization. Antibody responses were determined by ELISA and anthrax toxin neutralization assay. Vaccine efficacy was determined against lethal challenge with either anthrax toxin or Y. pestis. Both constructs elicited LcrV and LF-specific serum IgG, and MaF2 elicited toxin-neutralizing antibodies. Immunizations with MaF2 conferred 100% and 88% protection against Y. pestis and anthrax toxin, respectively. In contrast, pDNA-MaF2 conferred only 63% protection against Y. pestis and no protection against anthrax toxin challenge. pDNA-MaF2-prime MaF2-boost induced 75% protection against Y. pestis and 25% protection against anthrax toxin. Protection was increased by the molecular adjuvant CARDif. In conclusion, MaF2 is a promising multi-antigen vaccine candidate against anthrax and plague that warrants further investigation. [ABSTRACT FROM AUTHOR]

Background: To be transmitted to vertebrate hosts via the saliva of their vectors, arthropod-borne viruses have to cross several barriers in the mosquito body, including the midgut infection and escape barriers. Yellow fever virus (YFV) belongs to the genus Flavivirus, which includes human viruses transmitted by Aedes mosquitoes, such as dengue and Zika viruses. The live-attenuated YFV-17D vaccine has been used safely and efficiently on a large scale since the end of World War II. Early studies have shown, using viral titration from salivary glands of infected mosquitoes, that YFV-17D can infect Aedes aegypti midgut, but does not disseminate to other tissues. Methodology/Principal findings: Here, we re-visited this issue using a panel of techniques, such as RT-qPCR, Western blot, immunofluorescence and titration assays. We showed that YFV-17D replication was not efficient in Aedes aegypti midgut, as compared to the clinical isolate YFV-Dakar. Viruses that replicated in the midgut failed to disseminate to secondary organs. When injected into the thorax of mosquitoes, viruses succeeded in replicating into midgut-associated tissues, suggesting that, during natural infection, the block for YFV-17D replication occurs at the basal membrane of the midgut. Conclusions/Significance: The two barriers associated with Ae. aegypti midgut prevent YFV-17D replication. Our study contributes to our basic understanding of vector–pathogen interactions and may also aid in the development of non-transmissible live virus vaccines. [ABSTRACT FROM AUTHOR]

The 2013–2016 Ebola virus outbreak in West Africa was the largest and deadliest outbreak to date. Here we conducted a serological study to examine the antibody levels in survivors and the seroconversion in close contacts who took care of Ebola-infected individuals, but did not develop symptoms of Ebola virus disease. In March 2017, we collected blood samples from 481 individuals in Makeni, Sierra Leone: 214 survivors and 267 close contacts. Using commercial, quantitative ELISAs, we tested the plasma for IgG-specific antibodies against three major viral antigens: GP, the only viral glycoprotein expressed on the virus surface; NP, the most abundant viral protein; and VP40, a major structural protein of Zaire ebolavirus. We also determined neutralizing antibody titers. In the cohort of Ebola survivors, 97.7% of samples (209/214) had measurable antibody levels against GP, NP, and/or VP40. Of these positive samples, all but one had measurable neutralizing antibody titers against Ebola virus. For the close contacts, up to 12.7% (34/267) may have experienced a subclinical virus infection as indicated by detectable antibodies against GP. Further investigation is warranted to determine whether these close contacts truly experienced subclinical infections and whether these asymptomatic infections played a role in the dynamics of transmission. [ABSTRACT FROM AUTHOR]

Background: Oral cholera vaccine (OCV) containing killed Vibrio cholerae O1 and O139 organisms (Bivalent-OCV; Biv-OCV) are playing a central role in global cholera control strategies. OCV is currently administered in a 2-dose regimen (day 0 and 14). There is a growing body of evidence that immune responses targeting the O-specific polysaccharide (OSP) of V. cholerae mediate protection against cholera. There are limited data on anti-OSP responses in recipients of Biv-OCV. We assessed serum antibody responses against O1 OSP, as well as antibody secreting cell (ASC) responses (a surrogate marker for mucosal immunity) and memory B cell responses in blood of adult recipients of Biv-OCV in Dhaka, Bangladesh. Methodology/Principal findings: We enrolled 30 healthy adults in this study and administered two doses of OCV (Shanchol) at days 0 and 14. Blood samples were collected before vaccination (day 0) and 7 days after each vaccination (day 7 and day 21), as well as on day 44. Serum responses were largely IgA with minimal IgG and IgM responses in this population. There was no appreciable boosting following day 14 vaccination. There were significant anti-OSP IgA ASC responses on day 7 following the first vaccination, but none after the second immunization. Anti-OSP IgA memory B cell responses were detectable 30 days after completion of the vaccination series, with no evident induction of IgG memory responses. In this population, anti-Ogawa OSP responses were more prominent than anti-Inaba responses, perhaps reflecting impact of previous exposure. Serum anti-OSP responses returned to baseline within 30 days of completing the vaccine series. Conclusion: Our results call into question the utility of the 2-dose regimen separated by 14 days in adults in cholera endemic areas, and also suggest that Biv-OCV-induced immune responses targeting OSP are largely IgA in this highly endemic cholera area. Studies in children in cholera-endemic areas need to be performed. Protective efficacy that extends for more than a month after vaccination presumably is mediated by direct mucosal immune response which is not assessed in this study. Our results suggest a single dose of OCV in adults in a cholera endemic zone may be sufficient to mediate at least short-term protection. [ABSTRACT FROM AUTHOR]

Background: Although the tprK gene of Treponema pallidum are thought to play a critical role in the pathogenesis of syphilis, the profile of variations in tprK during the development of human syphilis infection have remained unclear. Methods/Principal findings: Through next-generation sequencing, we compared the tprK gene of 14 secondary syphilis patients with that of 14 primary syphilis patients, and the results showed an increased number of variants within the seven V regions of the tprK gene in the secondary syphilis samples. The length of the sequences within each V region also presented a 3-bp changing pattern. Interestingly, the frequencies of predominant sequences within the V regions in the secondary syphilis samples were generally decreased compared with those found in the primary syphilis samples, particularly in the V7 region, where a frequency below 60% was found in up to 57% (8/14) of all secondary samples compared with 7% (1/14) of all primary samples. Moreover, the number of minor variants distributed between frequencies of 10 and 49.9% was increased. The alignment of all amino acid sequences within each V region of the primary and secondary syphilis samples revealed that some amino acid sequences, particularly the amino acid sequences IASDGGAIKH and IASEDGSAGNLKH in V1, were highly stable. Additionally, the amino acid sequences in V6 also exhibited notable intrastrain heterogeneity and were likely to form a strain-specific pattern at the interstrain level. Conclusions: The identification of different profiles of the tprK gene in primary and secondary syphilis patients indicated that the tprK gene of T. pallidum undergoes constant variation to result in the best adaptation to the host. The highly stable peptides found in V1 are likely promising potential vaccine components. The highly heterogenetic regions (e.g., V6) could help to understand the role of tprK in immune evasion. [ABSTRACT FROM AUTHOR]

Mycetoma is a persistent, progressive granulomatous inflammatory disease caused either by fungi or by bacteria. Characteristic of this disease is that the causative agents organise themselves in macroscopic structures called grains. These grains are surrounded by a massive inflammatory reaction. The processes leading to this host tissue reaction and the immunophenotypic characteristics of the mycetoma granuloma are not known. Due to the massive immune reaction and the tissue remodeling involved, we hypothesised that the expression levels of interleukin-17 (IL-17) and matrix metalloprotease-9 (MMP-9) in the mycetoma granuloma formation were correlated to the severity of the disease and that this correlation was independent of the causative agent responsible for the granuloma reaction. To determine the expression of IL-17 and MMP-9 in mycetoma lesions, the present study was conducted at the Mycetoma Research Centre, Sudan. Surgical biopsies from 100 patients with confirmed mycetoma were obtained, and IL-17 and MMP-9 expression in the mycetoma granuloma were evaluated immunohistochemically. IL-17 was mainly expressed in Zones I and II, and far less in Zone III. MMP-9 was detected mainly in Zones II and III, and the least expression was in Zone I. MMP-9 was more highly expressed in Actinomadura pelletierii and Streptomyces somaliensis biopsies compared to Madurella mycetomatis biopsies. MMP-9 levels were directly proportional to the levels of IL-17 (p = 0.001). The only significant association between MMP9 and the patients’ characteristics was the disease duration (p<0.001). There was an insignificant correlation between the IL-17 levels and the patients’ demographic characteristics. [ABSTRACT FROM AUTHOR]

Background: Plasmodium vivax and Hepatitis B virus (HBV) are globally outspread in similar geographic regions. The concurrence of both infections and its association with some degree of protection against symptomatic and/or severe vivax malaria has been already described. Nevertheless, data on how host response to both pathogens undermines the natural progression of the malarial infection are scarce. Here, a large cohort of vivax malaria and HBV patients is retrospectively analyzed in an attempt to depict how inflammatory characteristics could be potentially related to the protection to severe malaria in coinfection. Methods: A retrospective analysis of a databank containing 601 individuals from the Brazilian Amazon, including 179 symptomatic P. vivax monoinfected patients, 145 individuals with asymptomatic P. vivax monoinfection, 28 P. vivax-HBV coinfected patients, 29 HBV monoinfected subjects and 165 healthy controls, was performed. Data on plasma levels of multiple chemokines, cytokines, acute phase proteins, hepatic enzymes, bilirubin and creatinine were analyzed to describe and compare biochemical profiles associated to each type of infection. Results: Coinfected individuals predominantly presented asymptomatic malaria, referred increased number of previous malaria episodes than symptomatic vivax-monoinfected patients, and were predominantly younger than asymptomatic vivax-monoinfected individuals. Coinfection was hallmarked by substantially elevated concentrations of interleukin (IL)-10 and heightened levels of C-C motif chemokine ligand (CCL)2. Correlation matrices showed that coinfected individuals presented a distinct biomarker profile when compared to asymptomatic or symptomatic P. vivax patients, or HBV-monoinfected individuals. Parasitemia could distinguish coinfected from symptomatic or asymptomatic P. vivax-monoinfected patients. HBV viremia was associated to distinct inflammatory profiles in HBV-monoinfected and coinfected patients. Conclusion: The findings demonstrate a distinct inflammatory profile in coinfected patients, with characteristics associated with immune responses to both pathogens. These host responses to P. vivax and HBV, in conjunction, could then be potentially associated, if not mainly responsible, for the protection against symptomatic vivax malaria. [ABSTRACT FROM AUTHOR]

Oral cholera vaccines (OCVs) are being increasingly employed, but current killed formulations generally require multiple doses and lack efficacy in young children. We recently developed a new live-attenuated OCV candidate (HaitiV) derived from a Vibrio cholerae strain isolated during the 2010 Haiti cholera epidemic. HaitiV exhibited an unexpected probiotic-like activity in infant rabbits, preventing intestinal colonization and disease by wild-type V. cholerae before the onset of adaptive immunity. However, it remained unknown whether HaitiV would behave similarly to other OCVs to stimulate adaptive immunity against V. cholerae. Here, we orally immunized adult germ-free female mice to test HaitiV’s immunogenicity. HaitiV safely and stably colonized vaccinated mice and induced known adaptive immune correlates of cholera protection within 14 days of administration. Pups born to immunized mice were protected against lethal challenges of both homologous and heterologous V. cholerae strains. Cross-fostering experiments revealed that protection was not dependent on vaccine colonization in or transmission to the pups. These findings demonstrate the protective immunogenicity of HaitiV and support its development as a new tool for limiting cholera. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that is caused by a novel bunyavirus SFTSV. Currently our knowledge of the host-related factors that influence the pathogenesis of disease is inadequate to allow prediction of fatal outcome. Here we conducted a prospective study of the largest database on the SFTS patients, to identify the presence of comorbidities in SFTS, and estimate their effect on the fatal outcome. Among 2096 patients eligible for inclusion, we identified nine kinds of comorbidities, from which hyperlipidemia (12.2%; 95% CI: 10.8%–13.6%), hypertension (11.0%; 95% CI: 9.6%–12.3%), chronic viral hepatitis (CVH) (9.3%; 95% CI: 8.1%–10.5%), and diabetes mellitus (DM) (6.8%; 95% CI: 5.7%–7.9%) were prevalent. Higher risk of death was found in patients with DM (adjusted OR = 2.304; 95% CI: 1.520–3.492; P<0.001), CVH (adjusted OR = 1.551; 95% CI: 1.053–2.285; P = 0.026) and chronic obstructive pulmonary diseases (COPD) (adjusted OR = 2.170; 95% CI: 1.215–3.872; P = 0.009) after adjusting for age, sex, delay from disease onset to admission and treatment regimens. When analyzing the comorbidities separately, we found that the high serum glucose could augment diseases severity. Compared to the group with max glucose < 7.0 mmol/L, patients with glucose between 7.0–11.1 mmol/L and glucose ≥11.1 mmol/L conferred higher death risk, with the adjusted OR to be 1.467 (95% CI: 1.081–1.989; P = 0.014) and 3.443 (95% CI: 2.427–4.884; P<0.001). Insulin therapy could effectively reduce the risk of severe outcome in DM patients with the adjusted OR 0.146 (95% CI: 0.058–0.365; P<0.001). For CVH patients, severe damage of liver and prolongation of blood coagulation time, as well as high prevalence of bleeding phenotype were observed. These data supported the provocative hypothesis that treating SFTS related complications can attain potentially beneficial effects on SFTS. [ABSTRACT FROM AUTHOR]

Infections of humans and livestock with African trypanosomes are treated with drugs introduced decades ago that are not always fully effective and often have severe side effects. Here, the trypanosome haptoglobin-haemoglobin receptor (HpHbR) has been exploited as a route of uptake for an antibody-drug conjugate (ADC) that is completely effective against Trypanosoma brucei in the standard mouse model of infection. Recombinant human anti-HpHbR monoclonal antibodies were isolated and shown to be internalised in a receptor-dependent manner. Antibodies were conjugated to a pyrrolobenzodiazepine (PBD) toxin and killed T. brucei in vitro at picomolar concentrations. A single therapeutic dose (0.25 mg/kg) of a HpHbR antibody-PBD conjugate completely cured a T. brucei mouse infection within 2 days with no re-emergence of infection over a subsequent time course of 77 days. These experiments provide a demonstration of how ADCs can be exploited to treat protozoal diseases that desperately require new therapeutics. [ABSTRACT FROM AUTHOR]

Fever is a regulated increase of the body temperature resulting from both infectious and non-infectious causes. Fever is known to play a role in modulating immune responses to infection, but the potential of febrile temperatures in regulating antigen binding affinity to antibodies has not been explored. Here we investigated this process under in vitro conditions using Isothermal titration calorimetry and ELISA. We used selected malarial and dengue antigens against specific monoclonal antibodies, and observed a marked increase in the affinity of these antibody-antigen complexes at 40°C, compared to physiological (37°C) or pathophysiological temperatures (42°C). Induced thermal equilibration of the protein partners at these temperatures in vitro, prior to measurements, further increased their binding affinity. These results suggest another positive and adaptive role for fever in vivo, and highlight the favourable role of thermal priming in enhancing protein-protein affinity for samples with limited availability. [ABSTRACT FROM AUTHOR]

Laboratory confirmation of Zika virus (ZIKV) infection during pregnancy is challenging due to cross-reactivity with dengue virus (DENV) and limited knowledge about the kinetics of anti-Zika antibody responses during pregnancy. We described ZIKV and DENV serological markers and the maternal-fetal transfer of antibodies among mothers and neonates after the ZIKV microcephaly outbreak in Northeast Brazil (2016). We included 89 microcephaly cases and 173 neonate controls at time of birth and their mothers. Microcephaly cases were defined as newborns with a particular head circumference (2 SD below the mean). Two controls without microcephaly were matched by the expected date of delivery and area of residence. We tested maternal serum for recent (ZIKV genome, IgM and IgG3 anti-NS1) and previous (ZIKV and DENV neutralizing antibodies [NAbs]) markers of infection. Multiple markers of recent or previous ZIKV and DENV infection in mothers were analyzed using principal component analysis (PCA). At delivery, 5.6% of microcephaly case mothers and 1.7% of control mothers were positive for ZIKV IgM. Positivity for ZIKV IgG3 anti-NS1 was 8.0% for case mothers and 3.5% for control mothers. ZIKV NAbs was slightly higher among mothers of cases (69.6%) than that of mothers of controls (57.2%; p = 0.054). DENV exposure was detected in 85.8% of all mothers. PCA discriminated two distinct components related to recent or previous ZIKV infection and DENV exposure. ZIKV NAbs were higher in newborns than in their corresponding mothers (p<0.001). We detected a high frequency of ZIKV exposure among mothers after the first wave of the ZIKV outbreak in Northeast Brazil. However, we found low sensitivity of the serological markers to recent infection (IgM and IgG3 anti-NS1) in perinatal samples of mothers of microcephaly cases. Since the neutralization test cannot precisely determine the time of infection, testing for ZIKV immune status should be performed as early as possible and throughout pregnancy to monitor acute Zika infection in endemic areas. [ABSTRACT FROM AUTHOR]

Coral snakes of the genus Micrurus have a high diversity and a wide distribution in the Americas. Despite envenomings by these animals are uncommon, accidents are often severe and may result in death. Producing an antivenom to treat these envenomings has been challenging since coral snakes are difficult to catch, produce small amounts of venom, and the antivenoms produced have shown limited cross neutralization. Here we present data of cross neutralization among monovalent antivenoms raised against M. dumerilii, M. isozonus, M. mipartitus and M. surinamensis and the development of a new polyvalent coral snake antivenom, resulting from the mix of monovalent antivenoms. Our results, show that this coral snake antivenom has high neutralizing potency and wide taxonomic coverage, constituting a possible alternative for a long sought Pan-American coral snake antivenom. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) is a mosquito-borne positive sense RNA virus. Recently, ZIKV emerged into the Western hemisphere as a human health threat, with severe disease associated with developmental and neurological complications. The structural envelope protein of ZIKV and other neurotropic flaviviruses contains an extended CD-loop relative to non-neurotropic flaviviruses, and has been shown to augment ZIKV stability and pathogenesis. Here we show that shortening the CD-loop in ZIKV attenuates the virus in mice, by reducing the ability to invade and replicate in the central nervous system. The CD-loop mutation was genetically stable following infection in mice, though secondary site mutations arise adjacent to the CD-loop. Importantly, while shortening of the CD-loop attenuates the virus, the CD-loop mutant maintains antigenicity in immunocompetent mice, eliciting an antibody response that similarly neutralizes both the mutant and wildtype ZIKV. These findings suggest that the extended CD-loop in ZIKV is a determinant of neurotropism and may be a target in live-attenuated vaccine design, for not only ZIKV, but for other neurotropic flaviviruses. [ABSTRACT FROM AUTHOR]

Diffuse cutaneous leishmaniasis (DCL) is a rare form of leishmaniasis where parasites grow uncontrolled in diffuse lesions across the skin. Meta-transcriptomic analysis of biopsies from DCL patients infected with Leishmania amazonensis demonstrated an infiltration of atypical B cells producing a surprising preponderance of the IgG4 isotype. DCL lesions contained minimal CD8+ T cell transcripts and no evidence of persistent TH2 responses. Whereas localized disease exhibited activated (so-called M1) macrophage presence, transcripts in DCL suggested a regulatory macrophage (R-Mϕ) phenotype with higher levels of ABCB5, DCSTAMP, SPP1, SLAMF9, PPARG, MMPs, and TM4SF19. The high levels of parasite transcripts in DCL and the remarkable uniformity among patients afforded a unique opportunity to study parasite gene expression in this disease. Patterns of parasite gene expression in DCL more closely resembled in vitro parasite growth in resting macrophages, in the absence of T cells. In contrast, parasite gene expression in LCL revealed 336 parasite genes that were differently upregulated, relative to DCL and in vitro macrophage growth, and these transcripts may represent transcripts that are produced by the parasite in response to host immune pressure. [ABSTRACT FROM AUTHOR]

Background: The burden of scrub typhus in endemic areas is poorly understood. This study aimed at estimating the proportion of hospitalisations and outpatient visits for undifferentiated fever in the community that may be attributable to scrub typhus. Methodology and principal findings: The study was a retrospective cohort with a nested case-control study conducted in the South Indian state of Tamil Nadu. We conducted house-to-house screening in 48 villages (42965 people, 11964 households) to identify hospitalised or outpatient cases due to undifferentiated fever during the preceding scrub typhus season. We used scrub typhus IgG to determine past infection. We calculated adjusted odds ratios for the association between IgG positivity and case status. Odds ratios were used to estimate population attributable fractions (PAF) indicating the proportion of hospitalised and outpatient fever cases attributable to scrub typhus. We identified 58 cases of hospitalisation and 236 outpatient treatments. 562 people were enrolled as control group to estimate the background IgG sero-prevalence. IgG prevalence was 20.3% in controls, 26.3% in outpatient cases and 43.1% in hospitalised cases. The PAFs suggested that 29.5% of hospitalisations and 6.1% of outpatient cases may have been due to scrub typhus. In villages with a high IgG prevalence (defined as ≥15% among controls), the corresponding PAFs were 43.4% for hospitalisations and 5.6% for outpatients. The estimated annual incidence of scrub typhus was 0.8/1000 people (0.3/1000 in low, and 1.3/1000 in high prevalence villages). Evidence for recall error suggested that the true incidences may be about twice as high as these figures. Conclusions: The study suggests scrub typhus as an important cause for febrile hospitalisations in the community. The results confirm the adequacy of empirical treatment for scrub typhus in hospitalised cases with undifferentiated fever. Since scrub typhus may be rare among stable outpatients, the use of empirical treatment remains doubtful in these. [ABSTRACT FROM AUTHOR]

Background: Mammarenaviruses are associated with human hemorrhagic fever diseases in Africa and America. Recently, a rodent mammarenavirus, Wēnzhōu virus (WENV) and related viruses, have been reported in China, Cambodia, and Thailand. Moreover, in Cambodia, these viruses were suspected to be associated with human disease. In China, Yunnan Province is famous for its abundant animal and plant diversity and is adjacent to several South-eastern Asia countries. Therefore, it is necessary to know whether WENV-related viruses, or other mammarenaviruses, are prevalent in this province. Methodology/Principal findings: Small mammals were trapped, euthanized, and sampled. Mammarenavirus RNA was detected using a nested reverse transcription polymerase chain reaction (RT-PCR) and quantified by real-time RT-PCR. A total of 1040 small mammals belonging to 13 genera and 26 species were trapped in Yunnan Province. WENV-related mammarenaviruses were detected in 41 rodent liver samples, mainly in brown rats (Rattus norvegicus) and oriental house rats (R. tanezumi).Viral nucleocapsid protein was detected in liver sections by indirect immunofluorescence assay. Full-length-genomes were amplified by RT-PCR and used for phylogenetic analysis with the MEGA package. Recombination analysis was performed using the SimPlot and Recombination Detection Program. Conclusions/Significance: WENV related viruses circulated in small mammals in Yunnan Province. Whole genome sequence analysis of five selected viral strains showed that these viruses are closely related to WENVs discovered in Asia and form an independent branch in the phylogenetic tree in the WENV clade. Paying attention to investigate the influence of these viruses to public health is essential in the epidemic regions. [ABSTRACT FROM AUTHOR]

Background: Lonomia obliqua venom is nephrotoxic and acute kidney injury (AKI) is the main cause of death among envenomed victims. Mechanism underlying L. obliqua-induced AKI involves renal hypoperfusion, inflammation, tubular necrosis and loss of glomerular filtration and tubular reabsorption capacities. In the present study, we aimed to investigate the contribution of kallikrein to the hemodynamic instability, inflammation and consequent renal and vascular impairment Methodology/Principal findings: Addition of L. obliqua venom to purified prekallikrein and human plasma in vitro or to vascular smooth muscle cells (VSMC) in culture, was able to generate kallikrein in a dose-dependent manner. Injected in rats, the venom induced AKI and increased kallikrein levels in plasma and kidney. Kallikrein inhibition by aprotinin prevented glomerular injury and the decrease in glomerular filtration rate, restoring fluid and electrolyte homeostasis. The mechanism underlying these effects was associated to lowering renal inflammation, with decrease in pro-inflammatory cytokines and matrix metalloproteinase expression, reduced tubular degeneration, and protection against oxidative stress. Supporting the key role of kallikrein, we demonstrated that aprotinin inhibited effects directly associated with vascular injury, such as the generation of intracellular reactive oxygen species (ROS) and migration of VSMC induced by L. obliqua venom or by diluted plasma obtained from envenomed rats. In addition, kallikrein inhibition also ameliorated venom-induced blood incoagulability and decreased kidney tissue factor expression Conclusions/Significance: These data indicated that kallikrein and consequently kinin release have a key role in kidney injury and vascular remodeling. Thus, blocking kallikrein may be a therapeutic alternative to control the progression of venom-induced AKI and vascular disturbances. [ABSTRACT FROM AUTHOR]

Background: Cholera remains a substantial health burden in Asia and Africa particularly in resource poor settings. The standard procedures to identify the etiological organism V. cholerae are isolation from microbiological culture from stool as well as Polymerase Chain Reaction (PCR). Both the processes are highly lab oriented, labor extensive, time consuming, and expensive. In an effort to control for outbreaks and epidemics; an effective, convenient, quick and relatively less expensive detection method is imperative, without compromising the sensitivity and specificity that exists at present. The objective of this component of the study was to evaluate the effectiveness of a locally produced rapid diagnostic test (RDT) for cholera diagnosis. Methods: In Bangladesh, nationwide cholera surveillance is ongoing in 22 hospitals covering all 8 divisions of the country since June, 2016. In the surveillance, stool samples have been collected from patients presenting to hospitals with acute watery diarrhea. Crystal VCTM (Span diagnostics, India) and Cholkit (locally produced RDT) have been used to detect V. cholerae from stool samples. Samples have also been sent to the main laboratory at icddr,b where the culture based isolation is routinely performed. All the tests were carried out for both direct and enriched stool samples. RDT sensitivity and specificity were calculated using stool culture as the gold standard. Results: A total of 7720 samples were tested. Among these, 5865 samples were solely tested with Crystal VC and 1355 samples with Cholkit whereas 381 samples were tested with both the RDTs. In comparison with culture, direct testing with Crystal VC showed a sensitivity of 72% (95% CI: 50.6% to 87.9%) and specificity of 86.8% (95% CI: 82.8% to 90.1%). After enrichment the sensitivity and specificity was 68% (95% CI: 46.5% to 85.1%) and 97.5% (95% CI: 95.3% to 98.8%) respectively. The direct Cholkit test showed sensitivity of 76% (95% CI: 54.9% to 90.6%) and specificity of 90.2% (95% CI: 86.6% to 93.1%). Conclusion: This evaluation has demonstrated that the sensitivity and specificity of Cholkit is similar to the commercially available test, Crystal VC when used in field settings for detecting V. cholerae from stool specimens. The findings from this study suggest that the Cholkit could be a possible alternative for cholera endemic regions where V. cholerae O1 is the major causative organism causing cholera. [ABSTRACT FROM AUTHOR]

The bivalent killed whole-cell oral cholera vaccine (BivWC) is being increasingly used to prevent cholera. The presence of O-antigen-specific memory B cells (MBC) has been associated with protective immunity against cholera, yet MBC responses have not been evaluated after BivWC vaccination. To address this knowledge gap, we measured V. cholerae O1-antigen MBC responses following BivWC vaccination. Adults in St. Marc, Haiti, received 2 doses of the BivWC vaccine, Shanchol, two weeks apart. Participants were invited to return at days 7, 21, 44, 90, 180 and 360 after the initial vaccination. Serum antibody and MBC responses were assessed at each time-point before and following vaccination. We observed that vaccination with BivWC resulted in significant O-antigen specific MBC responses to both Ogawa and Inaba serotypes that were detected by day 21 and remained significantly elevated over baseline for up to 12 months following vaccination. The BivWC oral cholera vaccine induces durable MBC responses to the V. cholerae O1-antigen. This suggests that long-term protection observed following vaccination with BivWC could be mediated or maintained by MBC responses. [ABSTRACT FROM AUTHOR]

Background: Early ante-mortem laboratory confirmation of human rabies is essential to aid patient management and institute public health measures. Few studies have highlighted the diagnostic value of antibody detection in CSF/serum in rabies, and its utility is usually undermined owing to the late seroconversion and short survival in infected patients. This study was undertaken to examine the ante-mortem diagnostic utility and prognostic value of antibody detection by rapid fluorescent focus inhibition test (RFFIT) in cerebrospinal fluid (CSF)/serum samples received from clinically suspected human rabies cases from January 2015 to December 2017. Methodology/Principal findings: Samples collected ante-mortem and post-mortem from 130 and 6 patients with clinically suspected rabies respectively, were received in the laboratory during the study period. Ante-mortem laboratory confirmation was achieved in 55/130 (42.3%) cases. Real time PCR for detection of viral nucleic acid performed on saliva, nuchal skin, brain tissue and CSF samples could confirm the diagnosis in 15 (27.2%) of the 55 laboratory confirmed cases. Ante-mortem diagnosis could be achieved by RFFIT (in CSF and/or serum) in 45 (34.6%) of the 130 clinically suspected cases, accounting for 81.8% of the total 55 laboratory confirmed cases. The sensitivity of CSF RFFIT increased with the day of sample collection (post-onset of symptoms) and was found to be 100% after 12 days of illness. Patients who had received prior vaccination had an increased probability of a positive RFFIT and negative PCR result. Patients who were positive by RFFIT alone at initial diagnosis had longer survival (albeit with neurological sequelae) than patients who were positive by PCR alone or both RFFIT and PCR. Conclusions/Significance: Detection of antibodies in the CSF/serum is a valuable ante-mortem diagnostic tool in human rabies, especially in patients who survive beyond a week. It was also found to have a limited role as a prognostic marker to predict outcomes in patients. [ABSTRACT FROM AUTHOR]

Background: Program decision-making for trachoma elimination currently relies on conjunctival clinical signs. Antibody tests may provide additional information on the epidemiology of trachoma, particularly in regions where it is disappearing or elimination targets have been met. Methods: A cluster-randomized trial of mass azithromycin distribution strategies for trachoma elimination was conducted over three years in a mesoendemic region of Niger. Dried blood spots were collected from a random sample of children aged 1–5 years in each of 24 study communities at 36 months after initiation of the intervention. A multiplex bead assay was used to test for antibodies to two Chlamydia trachomatis antigens, Pgp3 and CT694. We compared seropositivity to either antigen to clinical signs of active trachoma (trachomatous inflammation—follicular [TF] and trachomatous inflammation—intense [TI]) at the individual and cluster level, and to ocular chlamydia prevalence at the community level. Results: Of 988 children with antibody data, TF prevalence was 7.8% (95% CI 6.1 to 9.5) and TI prevalence was 1.6% (95% CI 0.9 to 2.6). The overall prevalence of antibody positivity to Pgp3 was 27.2% (95% CI 24.5 to 30), and to CT694 was 23.7% (95% CI 21 to 26.2). Ocular chlamydia infection prevalence was 5.2% (95% CI 2.8 to 7.6). Seropositivity to Pgp3 and/or CT694 was significantly associated with TF at the individual and community level and with ocular chlamydia infection and TI at the community level. Older children were more likely to be seropositive than younger children. Conclusion: Seropositivity to Pgp3 and CT694 correlates with clinical signs and ocular chlamydia infection in a mesoendemic region of Niger. Trial registration: ClinicalTrials.gov . [ABSTRACT FROM AUTHOR]

Background: Leprosy is a treatable infectious disease caused by Mycobacterium leprae. However, there is additional morbidity from leprosy-associated pathologic immune reactions, reversal reaction (RR) and erythema nodosum leprosum (ENL), which occur in 1 in 3 people with leprosy, even with effective treatment of M. leprae. There is currently no predictive marker in use to indicate which people with leprosy will develop these debilitating immune reactions. Our peripheral blood mononuclear cell (PBMC) transcriptome analysis revealed that activation of the classical complement pathway is common to both RR and ENL. Additionally, differential expression of immunoglobulin receptors and B cell receptors during RR and ENL support a role for the antibody-mediated immune response during both RR and ENL. In this study, we investigated B-cell immunophenotypes, total and M. leprae-specific antibodies, and complement levels in leprosy patients with and without RR or ENL. The objective was to determine the role of these immune mediators in pathogenesis and assess their potential as biomarkers of risk for immune reactions in people with leprosy. Methodology/findings: We followed newly diagnosed multibacillary leprosy cases (n = 96) for two years for development of RR or ENL. They were compared with active RR (n = 35), active ENL (n = 29), and healthy household contacts (n = 14). People with leprosy who subsequently developed ENL had increased IgM, IgG1, and C3d-associated immune complexes with decreased complement 4 (C4) at leprosy diagnosis. People who developed RR also had decreased C4 at leprosy diagnosis. Additionally, elevated anti-M. leprae antibody levels were associated with subsequent RR or ENL. Conclusions: Differential co-receptor expression and immunoglobulin levels before and during immune reactions intimate a central role for humoral immunity in RR and ENL. Decreased C4 and elevated anti-M. leprae antibodies in people with new diagnosis of leprosy may be risk factors for subsequent development of leprosy immune reactions. [ABSTRACT FROM AUTHOR]

Background: Naja annulifera is a medically important venomous snake occurring in some of the countries in Sub-Saharan Africa. Accidental bites result in severe coagulation disturbances, systemic inflammation and heart damage, as reported in dogs, and death, by respiratory arrest, in humans. Despite the medical importance of N. annulifera, little is known about its venom composition and the pathogenesis of envenomation. In this paper, the toxic, inflammatory and immunogenic properties of N. annulifera venom were analyzed. Methodology/Principal findings: Venom proteomic analysis identified 79 different proteins, including Three Finger Toxins, Cysteine Rich Secretory Proteins, Metalloproteinases, Phospholipases A2 (PLA2), Hyaluronidase, L-amino-acid oxidase, Cobra Venom Factor and Serine Proteinase. The presence of PLA2, hyaluronidase, fibrinogenolytic and anticoagulant activities was detected using functional assays. The venom was cytotoxic to human keratinocytes. In an experimental murine model of envenomation, it was found that the venom induced local changes, such as swelling, which was controlled by anti-inflammatory drugs. Moreover, the venom caused death, which was preceded by systemic inflammation and pulmonary hemorrhage. The venom was shown to be immunogenic, inducing a strong humoral immune response, with the production of antibodies able to recognize venom components with high molecular weight and to neutralize its lethal activity. Conclusions/Significance: The results obtained in this study demonstrate that N. annulifera venom contains toxins able to induce local and systemic inflammation, which can contribute to lung damage and death. Moreover, the venom is immunogenic, an important feature that must be considered during the production of a therapeutic anti-N. annulifera antivenom. [ABSTRACT FROM AUTHOR]

Chikungunya fever (CHIKF) is an emerging infectious disease caused by an alphavirus transmitted by Aedes spp. mosquitoes. Because mosquito control programs are not highly efficient for outbreak containment, vaccines are essential to reduce the burden of disease. Although no licensed vaccine against CHIKF is yet available, many highly promising candidates are undergoing preclinical studies, and a few of them have been tested in human trials of phase 1 or 2. Here, we review recent findings regarding the need for a CHIKF vaccine and provide an update on vaccines nearing or having entered clinical trials. We also address needs to tackle bottlenecks to vaccine development—including scientific and financial barriers—and to accelerate the development of vaccines; several actions should be taken: (i) design efficacy trials to be conducted during the course of outbreaks; (ii) evaluate the opportunity for adopting the “animal rule”for demonstration of efficacy for regulatory purposes; (iii) strengthen the collective commitment of nations, international organizations, potential donors and industry; (iv) stimulate public and/or private partnerships to invest in vaccine development and licensure; and (v) identify potential markets for an effective and safe CHIKF vaccine. [ABSTRACT FROM AUTHOR]

Human rabies is an encephalitic disease transmitted by animals infected with lyssaviruses. The most common lyssavirus that causes human infection is rabies virus (RABV), the prototypic member of the genus. The incubation period of RABV in humans varies from few weeks to several months in some instances. During this prodromal period, neither antibodies nor virus is detected. Antibodies, antigen and nucleic acids are detectable only after the onset of encephalitic symptoms, at which point the outcome of the disease is nearly 100% fatal. Hence, the primary intervention for human RABV exposure and subsequent post-exposure prophylaxis relies on testing animals suspected of having rabies. The most widely used diagnostic tests in animals focus on antigen detection, RABV-encoded nucleoprotein (N protein) in brain tissues. N protein accumulates in the cytoplasm of infected cells as large and granular inclusions, which are visualized in infected brain tissues by immuno-microscopy using anti-N protein antibodies. In this study, we explored a mass spectrometry (MS) based method for N protein detection without the need for any specific antibody reagents or microscopy. The MS-based method described here is unbiased, label-free, requires no amplification and determines any previously sequenced N protein available in the database. The results demonstrate the ability of MS/MS based method for N protein detection and amino acid sequence determination in animal diagnostic samples to obtain RABV variant information. This study demonstrates a potential for future developments of rabies diagnostic tests based on MS platforms. [ABSTRACT FROM AUTHOR]

The effectiveness of rabies vaccination in both humans and animals is determined by the presence of virus neutralizing antibodies (VNAs). The Rapid Fluorescent Focus Inhibition Test (RFFIT) is the method traditionally used for detection and quantification of VNAs. It is a functional in vitro test for assessing the ability of antibodies in serum to bind and prevent infection of cultured cells with rabies virus (RABV). The RFFIT is a labor intensive, low throughput and semi-quantitative assay performed by trained laboratorians. It requires staining of RABV-infected cells by rabies specific fluorescent antibodies and manual quantification of fluorescent fields for titer determination. Although the quantification of fluorescent fields observed in each sample is recorded, the corresponding images are not stored or captured to be used for future analysis. To circumvent several of these disadvantages, we have developed an alternative, automated high throughput neutralization test (HTNT) for determination of rabies VNAs based on green fluorescent protein (GFP) expression by a recombinant RABV and compared with the RFFIT. The HTNT assay utilizes the recombinant RABV ERA variant expressing GFP with a nuclear localization signal (NLS) for efficient quantification. The HTNT is a quantitative method where the number of RABV-infected cells are determined and the images are stored for future analysis. Both RFFIT and HTNT results correlated 100% for a panel of human and animal positive and negative rabies serum samples. Although, the VNA titer values are generally agreeable, HTNT titers tend to be lower than that of RFFIT, probably due to the differences in quantification methods. Our data demonstrates the potential for HTNT assays in determination of rabies VNA titers. [ABSTRACT FROM AUTHOR]

Background: Validation of elimination of trachoma as a public health problem is based on clinical indicators, using the WHO simplified grading system. Chlamydia trachomatis (Ct) infection and anti-Ct antibody responses (anti-Pgp3) have both been evaluated as alternative indicators in settings with varying levels of trachoma. There is a need to evaluate the feasibility of using tests for Ct infection and anti-Pgp3 antibodies at scale in a trachoma-endemic country and to establish the added value of the data generated for understanding transmission dynamics in the peri-elimination setting. Methodology/Principal findings: Dried blood spots for serological testing and ocular swabs for Ct infection testing (taken from children aged 1–9 years) were integrated into the pre-validation trachoma surveys conducted in the Northern and Upper West regions of Ghana in 2015 and 2016. Ct infection was detected using the GeneXpert PCR platform and the presence of anti-Pgp3 antibodies was detected using both the ELISA assay and multiplex bead array (MBA). The overall mean cluster-summarised TF prevalence (the clinical indicator) was 0.8% (95% CI: 0.6–1.0) and Ct infection prevalence was 0.04% (95%CI: 0.00–0.12). Anti-Pgp3 seroprevalence using the ELISA was 5.5% (95% CI: 4.8–6.3) compared to 4.3% (95%CI: 3.7–4.9) using the MBA. There was strong evidence from both assays that seropositivity increased with age (p<0.001), although the seroconversion rate was estimated to be very low (between 1.2 to 1.3 yearly events per 100 children). Conclusions/Significance: Infection and serological data provide useful information to aid in understanding Ct transmission dynamics. Elimination of trachoma as a public health problem does not equate to the absence of ocular Ct infection nor cessation in acquisition of anti-Ct antibodies. [ABSTRACT FROM AUTHOR]

Background: We examined relationships between schistosome infection, HIV transmission or acquisition, and all-cause death. Methods: We retrospectively tested baseline sera from a heterosexual HIV-discordant couple cohort in Lusaka, Zambia with follow-up from 1994–2012 in a nested case-control design. Schistosome-specific antibody levels were measured by ELISA. Associations between baseline antibody response to schistosome antigens and incident HIV transmission, acquisition, and all-cause death stratified by gender and HIV status were assessed. In a subset of HIV- women and HIV+ men, we performed immunoblots to evaluate associations between Schistosoma haematobium or Schistosoma mansoni infection history and HIV incidence. Results: Of 2,145 individuals, 59% had positive baseline schistosome-specific antibody responses. In HIV+ women and men, baseline schistosome-specific antibodies were associated with HIV transmission to partners (adjusted hazard ratio [aHR] = 1.8, p<0.005 and aHR = 1.4, p<0.05, respectively) and death in HIV+ women (aHR = 2.2, p<0.001). In 250 HIV- women, presence of S. haematobium-specific antibodies was associated with increased risk of HIV acquisition (aHR = 1.4, p<0.05). Conclusion: Schistosome infections were associated with increased transmission of HIV from both sexes, acquisition of HIV in women, and increased progression to death in HIV+ women. Establishing effective prevention and treatment strategies for schistosomiasis, including in urban adults, may reduce HIV incidence and death in HIV+ persons living in endemic areas. [ABSTRACT FROM AUTHOR]

Background: Age patterns in asymptomatic and symptomatic infection with Leishmania donovani, the causative agent of visceral leishmaniasis (VL) in the Indian subcontinent (ISC), are currently poorly understood. Age-stratified serology and infection incidence have been used to assess transmission levels of other diseases, which suggests that they may also be of use for monitoring and targeting control programmes to achieve elimination of VL and should be included in VL transmission dynamic models. We therefore analysed available age-stratified data on both disease incidence and prevalence of immune markers with the aim of collating the currently available data, estimating rates of infection, and informing modelling and future data collection. Methodology/Principal findings: A systematic literature search yielded 13 infection prevalence and 7 VL incidence studies meeting the inclusion criteria. Statistical tests were performed to identify trends by age, and according to diagnostic cut-off. Simple reversible catalytic models with age-independent and age-dependent infection rates were fitted to the prevalence data to estimate infection and reversion rates, and to test different hypotheses about the origin of variation in these rates. Most of the studies showed an increase in infection prevalence with age: from ≲10% seroprevalence (<20% Leishmanin skin test (LST) positivity) for 0-10-year-olds to >10% seroprevalence (>20% LST-positivity) for 30-40-year-olds, but overall prevalence varied considerably between studies. VL incidence was lower amongst 0-5-year-olds than older age groups in most studies; most showing a peak in incidence between ages 5 and 20. The age-independent catalytic model provided the best overall fit to the infection prevalence data, but the estimated rates for the less parsimonious age-dependent model were much closer to estimates from longitudinal studies, suggesting that infection rates may increase with age. Conclusions/Significance: Age patterns in asymptomatic infection prevalence and VL incidence in the ISC vary considerably with geographical location and time period. The increase in infection prevalence with age and peaked age-VL-incidence distribution may be due to lower exposure to infectious sandfly bites in young children, but also suggest that acquired immunity to the parasite increases with age. However, poor standardisation of serological tests makes it difficult to compare data from different studies and draw firm conclusions about drivers of variation in observed age patterns. [ABSTRACT FROM AUTHOR]

Background: Scavenger Receptors (SRs) from the host’s innate immune system are known to bind multiple ligands to promote the removal of non-self or altered-self targets. CD5 and CD6 are two highly homologous class I SRs mainly expressed on all T cells and the B1a cell subset, and involved in the fine tuning of activation and differentiation signals delivered by the antigen-specific receptors (TCR and BCR, respectively), to which they physically associate. Additionally, CD5 and CD6 have been shown to interact with and sense the presence of conserved pathogen-associated structures from bacteria, fungi and/or viruses. Methodology/Principal findings: We report herein the interaction of CD5 and CD6 lymphocyte surface receptors with Echinococcus granulosus sensu lato (s.l.). Binding studies show that both soluble and membrane-bound forms of CD5 and CD6 bind to intact viable protoscoleces from E. granulosus s.l. through recognition of metaperiodate-resistant tegumental components. Proteomic analyses allowed identification of thioredoxin peroxidase for CD5, and peptidyl-prolyl cis-trans isomerase (cyclophilin) and endophilin B1 (antigen P-29) for CD6, as their potential interactors. Further in vitro assays demonstrate that membrane-bound or soluble CD5 and CD6 forms differentially modulate the pro- and anti-inflammatory cytokine release induced following peritoneal cells exposure to E. granulosus s.l. tegumental components. Importantly, prophylactic infusion of soluble CD5 or CD6 significantly ameliorated the infection outcome in the mouse model of secondary cystic echinococcosis. Conclusions/Significance: Taken together, the results expand the pathogen binding properties of CD5 and CD6 and provide novel evidence for their therapeutic potential in human cystic echinococcosis. [ABSTRACT FROM AUTHOR]

The specificity of the antibody response against Zika virus (ZIKV) is not well-characterized. This is due, in part, to the antigenic similarity between ZIKV and closely related dengue virus (DENV) serotypes. Since these and other similar viruses co-circulate, are spread by the same mosquito species, and can cause similar acute clinical syndromes, it is difficult to disentangle ZIKV-specific antibody responses from responses to closely-related arboviruses in humans. Here we use high-density peptide microarrays to profile anti-ZIKV antibody reactivity in pregnant and non-pregnant macaque monkeys with known exposure histories and compare these results to reactivity following DENV infection. We also compare cross-reactive binding of ZIKV-immune sera to the full proteomes of 28 arboviruses. We independently confirm a purported ZIKV-specific IgG antibody response targeting ZIKV nonstructural protein 2B (NS2B) that was recently reported in ZIKV-infected people and we show that antibody reactivity in pregnant animals can be detected as late as 127 days post-infection (dpi). However, we also show that these responses wane over time, sometimes rapidly, and in one case the response was elicited following DENV infection in a previously ZIKV-exposed animal. These results suggest epidemiologic studies assessing seroprevalence of ZIKV immunity using linear epitope-based strategies will remain challenging to interpret due to susceptibility to false positive results. However, the method used here demonstrates the potential for rapid profiling of proteome-wide antibody responses to a myriad of neglected diseases simultaneously and may be especially useful for distinguishing antibody reactivity among closely related pathogens. [ABSTRACT FROM AUTHOR]

Background: Tanzania is among the Rift Valley fever (RVF) epizootic/endemic countries in sub Saharan Africa, where RVF disease outbreaks occur within a range of 3 to 17-year intervals. Detection of Rift Valley fever virus (RVFV) antibodies in animals in regions with no previous history of outbreaks raises the question of whether the disease is overlooked due to lack-of effective surveillance systems, or if there are strains of RVFV with low pathogenicity. Furthermore, which vertebrate hosts are involved in the inter-epidemic and inter-epizootic maintenance of RVFV? In our study region, the Kyela and Morogoro districts in Tanzania, no previous RVF outbreaks have been reported. Methodology: The study was conducted from June 2014 to October 2015 in the Kyela and Morogoro districts, Tanzania. Samples (n = 356) were retrieved from both the local breed of zebu cattle (Bos indicus) and Bos indicus/Bos Taurus cross breed. RVFV antibodies were analyzed by two enzyme-linked immunosorbent assay (ELISA) approaches. Initially, samples were analyzed by a RVFV multi-species competition ELISA (cELISA), which detected both RVFV IgG and IgM antibodies. All serum samples that were positive with the cELISA method were specifically analysed for the presence of RVFV IgM antibodies to trace recent infection. A plaque reduction neutralization assay (PRNT80) was performed to determine presence of RVFV neutralizing antibodies in all cELISA positive samples. Findings: Overall RVFV seroprevalence rate in cattle by cELISA in both districts was 29.2% (104 of 356) with seroprevalence rates of 33% (47/147) in the Kyela district and 27% (57/209) in the Morogoro district. In total, 8.4% (30/356) of all cattle sampled had RVFV IgM antibodies, indicating current disease transmission. When segregated by districts, the IgM antibody seroprevalence was 2.0% (3/147) and 12.9% (27/209) in Kyela and Morogoro districts respectively. When the 104 cELISA positive samples were analyzed by PRNT80 to confirm that RVFV-specific antibodies were present, the majority (89%, 93/104) had RVFV neutralising antibodies. Conclusion: The results provided evidence of widespread prevalence of RVFV antibody among cattle during an inter-epizootic/inter-epidemic period in Tanzania in regions with no previous history of outbreaks. There is a need for further investigations of RVFV maintenance and transmission in vertebrates and vectors during the long inter-epizootic/inter-epidemic periods. [ABSTRACT FROM AUTHOR]

Background: Estimates of current global rabies mortality range from 26,000 to 59,000 deaths per annum. Although pre-exposure prophylaxis using inactivated rabies virus vaccines (IRVs) is effective, it requires two to three doses and is regarded as being too expensive and impractical for inclusion in routine childhood immunization programmes. Methodology/ Principal findings: Here we report the development of a simian-adenovirus-vectored rabies vaccine intended to enable cost-effective population-wide pre-exposure prophylaxis against rabies. ChAdOx2 RabG uses the chimpanzee adenovirus serotype 68 (AdC68) backbone previously shown to achieve pre-exposure protection against rabies in non-human primates. ChAdOx2 differs from AdC68 in that it contains the human adenovirus serotype 5 (AdHu5) E4 orf6/7 region in place of the AdC68 equivalents, enhancing ease of manufacturing in cell lines which provide AdHu5 E1 proteins in trans. We show that immunogenicity of ChAdOx2 RabG in mice is comparable to that of AdC68 RabG and other adenovirus serotypes expressing rabies virus glycoprotein. High titers of rabies virus neutralizing antibody (VNA) are elicited after a single dose. The relationship between levels of VNA activity and rabies virus glycoprotein monomer-binding antibody differs after immunization with adenovirus-vectored vaccines and IRV vaccines, suggesting routes to further enhancement of the efficacy of the adenovirus-vectored candidates. We also demonstrate that ChAdOx2 RabG can be thermostabilised using a low-cost method suitable for clinical bio-manufacture and ambient-temperature distribution in tropical climates. Finally, we show that a dose-sparing effect can be achieved by formulating ChAdOx2 RabG with a simple chemical adjuvant. This approach could lower the cost of ChAdOx2 RabG and other adenovirus-vectored vaccines. Conclusions/ Significance: ChAdOx2 RabG may prove to be a useful tool to reduce the human rabies death toll. We have secured funding for Good Manufacturing Practice- compliant bio-manufacture and Phase I clinical trial of this candidate. [ABSTRACT FROM AUTHOR]

The gold-standard method for quantifying neutralizing antibody responses to many viruses, including dengue virus (DENV), is the plaque reduction neutralization test (PRNT, also called the immunofocus reduction neutralization test). The PRNT conducted on 96-well plates is high-throughput and requires a smaller volume of antiserum than on 6- or 24-well plates, but manual plaque counting is challenging and existing automated plaque counters are expensive or difficult to optimize. We have developed Viridot (Viridot package), a program for R with a user interface in shiny, that counts viral plaques of a variety of phenotypes, estimates neutralizing antibody titers, and performs other calculations of use to virologists. The Viridot plaque counter includes an automatic parameter identification mode (misses <10 plaques/well for 87% of diverse DENV strains [n = 1521]) and a mode that allows the user to fine-tune the parameters used for counting plaques. We compared standardized manual and Viridot plaque counting methods applied to the same wells by two analyses and found that Viridot plaque counts were as similar to the same analyst's manual count (Lin’s concordance correlation coefficient, ρc = 0.99 [95% confidence interval: 0.99–1.00]) as manual counts between analysts (ρc = 0.99 [95% CI: 0.98–0.99]). The average ratio of neutralizing antibody titers based on manual counted plaques to Viridot counted plaques was 1.05 (95% CI: 0.98–1.14), similar to the average ratio of antibody titers based on manual plaque counts by the two analysts (1.06 [95% CI: 0.84–1.34]). Across diverse DENV and ZIKV strains (n = 14), manual and Viridot plaque counts were mostly consistent (range of ρc = 0.74 to 1.00) and the average ratio of antibody titers based on manual and Viridot counted plaques was close to 1 (0.94 [0.86–1.02]). Thus, Viridot can be used for plaque counting and neutralizing antibody titer estimation of diverse DENV strains and potentially other viruses on 96-well plates as well as for formalization of plaque-counting rules for standardization across experiments and analysts. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is the causative agent of dengue fever and dengue hemorrhagic shock syndrome. Dengue vaccine development is challenging because of the need to induce protection against four antigenically distinct DENV serotypes. Recent studies indicate that tetravalent DENV vaccines must induce balanced, serotype-specific neutralizing antibodies to achieve durable protective immunity against all 4 serotypes. With the leading live attenuated tetravalent DENV vaccines, it has been difficult to achieve balanced and type-specific responses to each serotype, most likely because of unbalanced replication of vaccine viral strains. Here we evaluate a tetravalent DENV protein subunit vaccine, based on recombinant envelope protein (rE) adsorbed to the surface of poly (lactic-co-glycolic acid) (PLGA) nanoparticles for immunogenicity in mice. In monovalent and tetravalent formulations, we show that particulate rE induced higher neutralizing antibody titers compared to the soluble rE antigen alone. Importantly, we show the trend that tetravalent rE adsorbed to nanoparticles stimulated a more balanced serotype specific antibody response to each DENV serotype compared to soluble antigens. Our results demonstrate that tetravalent DENV subunit vaccines displayed on nanoparticles have the potential to overcome unbalanced immunity observed for leading live-attenuated vaccine candidates. [ABSTRACT FROM AUTHOR]

Cystic echinococcosis (CE) is one of the most widespread helminthic zoonoses and is caused by the tapeworm Echinococcus granulosus complex. CE diagnosis and monitoring primarily rely on imaging techniques, complemented by serology. This is usually approached by the detection of IgG antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture results in a variable percentage of false positive and negative results, and has shown to be useless for follow-up due to the long persistence of anti-HF antibodies in cured patients. To improve test performances and standardization, a number of recombinant antigens mainly derived from HF have been described, among them the B2t and 2B2t antigens. The performance of these antigens in the diagnosis and follow up of patients with CE has been so far evaluated on a limited number of samples. Here, we evaluated the performances of tests based on B2t and 2B2t recombinant antigens compared to HF in IgG-ELISA and immunochromatography (IC) for the diagnosis and follow-up of patients with CE in a retrospective cohort study. A total of 721 serum samples were collected: 587 from 253 patients with CE diagnosed by ultrasonography (US), 42 from patients with alveolar echinococcosis and 92 from healthy donors from Salamanca (Spain). The highest overall sensitivity was obtained with HF in ELISA (85.5%), followed by IC containing HF and 2B2t-HF (83.0% and 78.2%, respectively). The lowest sensitivity was obtained with B2t and 2B2t in ELISA (51.8%). The highest specificity was obtained with IC containing 2B2t-HF (100%), and the lowest with HF-ELISA (78.0%). The lowest cross-reactivity with sera from patients with alveolar echinococcosis was detected with the recombinant antigens in ELISA (9.5% - 16.7%) and the highest with the HF-IC (64.3%). The results of B2t and 2B2t-ELISA were influenced by cyst stage, as classified by US according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE), with low sensitivity for inactive (CE4 and CE5) cysts, and by the drug treatment, with higher sensitivity in patients after drug treatment compared with patients not subjected to drug treatment. The two recombinant antigens in ELISA provided promising results for monitoring patients in follow-up, although their use is limited to patients with positive serology against them at the beginning of the follow-up. Potential biological reasons behind the low sensitivity of the recombinant antigens and possible strategies to enhance the performance of CE serology are discussed. [ABSTRACT FROM AUTHOR]

Background: In India, dengue disease is emerging as the most important vector borne public health problem due to rapid and unplanned urbanization, high human density and week management of the disease. Clinical cases are grossly underreported and not much information is available on prevalence and incidence of the disease. Methodology: A cross sectional, stratified, facility based, multistage cluster sampling was conducted between May 4 and June 27, 2017 in Pune city. A total of 1,434 participants were enrolled. The serum samples were tested for detection of historical dengue IgG antibodies by ELISA using the commercial Panbio Dengue IgG Indirect ELISA kit. Anti-dengue IgG-capture Panbio ELISA was used for detection of high titered antibodies to detect recent secondary infection. We used this data to estimate key transmission parameters like force of infection and basic reproductive number. A subset of 120 indirect ELISA positive samples was also tested for Plaque Reduction Neutralizing Antibodies for determining serotype-specific prevalence. Findings: Overall, 81% participants were infected with dengue virus (DENV) at least once if not more. The positivity was significantly different in different age groups. All the adults above 70 years were positive for DENV antibodies. Over 69% participants were positive for neutralizing antibodies against all 4 serotypes suggesting intense transmission of all DENV serotypes in Pune. Age-specific seroprevalence was consistent with long-term, endemic circulation of DENV. There was an increasing trend with age, from 21.6% among <36 months to 59.4% in age group 10–12 years. We estimate that 8.68% of the susceptible population gets infected by DENV each year resulting into more than 3,00,000 infections and about 47,000 to 59,000 cases per year. This transmission intensity is similar to that reported from other known hyper-endemic settings in Southeast Asia and the Americas but significantly lower than report from Chennai. Conclusions: Our study suggests that Pune city has high disease burden, all 4 serotypes are circulating, significant spatial heterogeneity in seroprevalence and suboptimal immunity in younger age groups. This would allow informed decisions to be made on management of dengue and introduction of upcoming dengue vaccines in the city. [ABSTRACT FROM AUTHOR]

Background: Chikungunya virus (CHIKV) is the most common alphavirus infecting humans worldwide, causing acute and chronically debilitating arthralgia at a great economic expense. Methodology/Principal findings: To facilitate our study of CHIKV, we generated a mCherry tagged replication-competent chimeric virus, CHIKV 37997-mCherry. Single particle cryoEM demonstrated icosahedral organization of the chimeric virus and the display of mCherry proteins on virus surface. CHIKV 37997-mCherry is attenuated in both IFNαR knockout and wild-type mice. Strong anti-CHIKV and anti-mCherry antibody responses were induced in CHIKV 37997-mCherry infected mice. Conclusions/Significance: Our work suggests that chimeric alphaviruses displaying foreign antigen can serve as vaccines against both aphaviruses and other pathogens and diseases. [ABSTRACT FROM AUTHOR]

Chronic chagasic cardiomyopathy (CCC) is observed in 30% to 50% of the individuals infected by Trypanosoma cruzi and heart failure is the important cause of death among patients in the chronic phase of Chagas disease. Although some studies have elucidated the role of adaptive immune responses involving T and B lymphocytes in cardiac pathogenesis, the role of innate immunity receptors such as Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in CCC pathophysiology has not yet been determined. In this study, we evaluated the association among innate immune receptors (TLR1-9 and nucleotide-binding domain-like receptor protein 3/NLRP3), its adapter molecules (Myd88, TRIF, ASC and caspase-1) and cytokines (IL-1β, IL-6, IL-12, IL-18, IL-23, TNF-α, and IFN-β) with clinical manifestation, digestive and cardiac function in patients with different clinical forms of chronic Chagas disease. The TLR8 mRNA expression levels were enhanced in the peripheral blood mononuclear cells (PBMC) from digestive and cardiodigestive patients compared to indeterminate and cardiac patients. Furthermore, mRNA expression of IFN-β (cytokine produced after TLR8 activation) was higher in digestive and cardiodigestive patients when compared to indeterminate. Moreover, there was a positive correlation between TLR8 and IFN-β mRNA expression with sigmoid and rectum size. Cardiac and cardiodigestive patients presented higher TLR2, IL-12 and TNF-α mRNA expression than indeterminate and digestive patients. Moreover, cardiac patients also expressed higher levels of NLRP3, ASC and IL-1β mRNAs than indeterminate patients. In addition, we showed a negative correlation among TLR2, IL-1β, IL-12 and TNF-α levels with left ventricular ejection fraction, and positive correlation between NLRP3 with cardiothoracic index, and TLR2, IL-1β and IL-12 with left ventricular mass index. Together, our data suggest that high expression of innate immune receptors in cardiac and digestive patients may induce an enhancement of cytokine expression and participate of cardiac and digestive dysfunction. [ABSTRACT FROM AUTHOR]

Crimean-Congo hemorrhagic fever virus (CCHFV) causes severe acute human disease with lethal outcome. The knowledge about the immune response for this human health threat is highly limited. In this study, we have screened the glycoprotein of CCHFV for novel linear B-cell epitopic regions using a microarray approach. The peptide library consisted of 168 synthesized 20mer peptides with 10 amino acid overlap covering the entire glycoprotein. Using both pooled and individual human sera from survivors of CCHF disease in Turkey five peptide epitopes situated in the mucin-like region and GP 38 (G15-515) and GN G516-1037 region of the glycoprotein were identified as epitopes for a CCHF immune response. An epitope walk of the five peptides revealed a peptide sequence located in the GN region with high specificity and sensitivity. This peptide sequence, and a sequence downstream, reacted also against sera from survivors of CCHF disease in South Africa. The cross reactivity of these peptides with samples from a geographically distinct region where genetically diverse strains of the virus circulate, enabled the identification of unique peptide epitopes from the CCHF glycoprotein that could have application in development of diagnostic tools. In this study clinical samples from geographically distinct regions were used to identify conserved linear epitopic regions of the glycoprotein of CCHF. [ABSTRACT FROM AUTHOR]

Background: Dengue is a febrile illness transmitted by mosquitoes, causing disease across the tropical and sub-tropical world. Antibody prevalence data and serotype distributions describe population-level risk and inform public health decision-making. Methodology/Principal findings: In this cross-sectional study we used data from a pediatric dengue seroprevalence study to describe historical dengue serotype circulation, according to age and geographic location. A sub-sample of 780 dengue IgG-positive sera, collected from 30 sites across urban Indonesia in 2014, were tested by the plaque reduction neutralization test (PRNT) to measure the prevalence and concentration of serotype-specific neutralizing antibodies according to subject age and geography. PRNT results were obtained from 776 subjects with mean age of 9.6 years. 765 (98.6%) neutralized one or more dengue serotype at a threshold of >10 (1/dil). Multitypic profiles were observed in 50.9% of the samples; a proportion which increased to 63.1% in subjects aged 15–18 years. Amongst monotypic samples, the highest proportion was reactive against DENV-2, followed by DENV-1, and DENV-3, with some variation across the country. DENV-4 was the least common serotype. The highest anti-dengue antibody titers were recorded against DENV-2, and increased with age to a geometric mean of 516.5 [1/dil] in the oldest age group. Conclusions/Significance: We found that all four dengue serotypes have been widely circulating in most of urban Indonesia, and more than half of children had already been exposed to >1 dengue serotype, demonstrating intense transmission often associated with more severe clinical episodes. These data will help inform policymakers and highlight the importance of dengue surveillance, prevention and control. [ABSTRACT FROM AUTHOR]