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Brazil's COVID-19 response has faced challenges due to the continuous emergence of variants of concern (VOCs), emphasizing the need for ongoing genomic surveillance and retrospective analyses of past epidemic waves to reassess and fine tune containment protocols. Rio Grande do Sul (RS), Brazil's southernmost state, has international borders and trades with Argentina and Uruguay, along with significant domestic connections within Brazil. The identification of source and sink transmission chains at national and international scales can identify main hubs and pathways to target future interventions. In this study we investigated the RS state role in the national and international SARS-CoV-2 transmission chains, which has not been fully explored. Nasopharyngeal samples from various municipalities in RS were collected between June 2020 and July 2022. SARS-CoV-2 whole genome amplification and sequencing were performed using high-throughput Illumina sequencing. Bioinformatics analysis encompassed the development of scripts and tools to perform subsampling taking into account epidemiological information to reduce sequencing disparities bias among the regions/countries, genome assembly, and large-scale alignment and phylogenetic reconstruction. We sequenced a total of 1,480 SARS-CoV-2 genomes from RS, covering all major regions. Sequences predominantly represented Gamma (April-June 2021) and Omicron (January-July 2022) lineages. Phylogenetic analysis revealed a regional pattern for transmission dynamics, particularly with Southeast Brazil for Gamma, and a range of inter-regional connections for Delta and Omicron within the country. On the other hand, international and cross-border transmission with Argentina and Uruguay was rather limited. We evaluated the three VOCs circulation over two years in RS using a new subsampling strategy based on the number of cases in each state during the circulation of each VOC. In summary, the retrospective analysis of genomic surveillance data demonstrated that virus transmission was less intense between country borders than within the country. These findings suggest that while non-pharmacological interventions were effective to mitigate transmission across international RS land borders, they were insufficient to contain transmission at the domestic level., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The multiplex molecular diagnostic assays described for severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), influenza A (IAV) and B (IBV) viruses have been mainly based on real-time reaction, which limits their access to many laboratories or diagnostic institutions. To contribute to available strategies and expand access to differential diagnosis, we describe an end-point multiplex RT-PCR targeting SARS-CoV-2, IAV and IBV with simultaneous endogenous control amplification. Initially, we looked for well-established primers sets for SARS-CoV-2, IAV, IBV and RNAse P whose amplicons could be distinguished on agarose gel. The multiplex assay was then standardized by optimizing the reaction mix and cycle conditions. The limit of detection (LoD) was determined using titrated viruses (for SARS-CoV-2 and IAV) and by dilution from a pool of IBV-positive samples. The diagnostic performance of the multiplex was evaluated by testing samples with different RNAse P and viral loads, previously identified as positive or negative for the target viruses. The amplicons of IAV (146 bp), SARS-CoV-2 (113 bp), IBV (103 bp) and RNAse P (65 bp) were adequately distinguished in our multiplex. The LoD for SARS-CoV-2, IAV and IBV was 0.02 TCID 50 /ml, 0.07 TCID 50 /ml and 10 -3 from a pool of positive samples, respectively. All samples positive for SARS-CoV-2 ( n =70, Ct 17.2-36.9), IAV ( n =53, Ct 14-34.9) and IBV ( n =12, Ct 23.9-31.9) remained positive in our multiplex assay. RNAse P from negative samples ( n =40, Ct 25.2-30.2) was also amplified in the multiplex. Overall, our assay is a timely and alternative tool for detecting SARS-CoV-2 and influenza viruses in laboratories with limited access to supplies/equipment.

Papillomaviruses (PVs) have been identified in several animal species, including dogs (canine papillomaviruses, CPVs) and cattle (bovine papillomaviruses, BPVs). Although some BPVs may occasionally infect species other than cattle, to the best of our knowledge, BPVs have not been reported in dogs to date. Herein, we carried out a retrospective phylogenetic study of PVs circulating in dogs from southern Brazil between 2017 and 2022, also investigating possible mixed infections and spillover events. For this, we screened 32 canine papilloma samples by PCR using the degenerate primers FAP59/64 and/or MY09/11, which amplify different regions of the L1 gene; the genomic target often used for PV classification/typing. Out these, 23 PV DNA samples were successfully amplified and sequenced. All PVs amplified by FAP59/64 (n = 22) were classified as CPV-1. On the other hand, PVs amplified by MY09/11 (n = 4) were classified as putative BPV-1. Among these, three samples showed mixed infection by CPV-1 and putative BPV-1. One of the putative BPV-1 detected in co-infected samples had the L1 gene full-sequenced, confirming the gene identity. Furthermore, the phylogenetic classifications from the FAP59/64 and/or MY09/11 amplicons were supported by a careful in silico analysis, which demonstrated that the analysis based on them matches to the classification from the complete L1 gene. Overall, we described CPV-1 circulation in southern Brazil over the years and the potencial BPV infection in dogs (potential spillover event), as well as possible CPV/1/BPV-1 co-infections. Finally, we suggest the analysis of the complete genome of the putative BPVs detected in dogs in order to deepen the knowledge about the PV-host interactions., (© 2024. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Canine distemper virus (CDV) is a major threat to domestic dogs and wildlife worldwide. Molecular assays are the most sensitive and specific tests to diagnose the disease, however, the high CDV genetic variability may compromise laboratory diagnosis. Herein, we designed a high-coverage primer set for end-point (RT-PCR) and real-time (RT-qPCR) for CDV detection. Initially, we collected 194 complete/near-complete CDV genomes (GenBank) and analyzed them for highly conserved regions for primer design. We then assessed the in silico coverage, analytical sensitivity, specificity and diagnostic performance of RT-PCR/RT-qPCR reactions based on our primers. Furthermore, the coverage of our primers, as well as their analytical sensitivity and diagnostic performance, were compared to a commonly used primer set for CDV detection (named PP-I). Our forward (F) and reverse (R) primers fully matched 100 % (194/194) and 99 % (192/194) of the analyzed sequences, whereas the PP-I F and R primers fully matched 15 % (29/194) and 9 % (18/194) sequences, respectively. The detection limit of our RT-PCR and RT-qPCR was equivalent to that of PP-I primers (0.001 TCID 50 /mL). Out of 70 clinical samples tested, 38 were positive by our RT-PCR/RT-qPCR assays, whereas reactions with primers PP-I failed to detect 9/28 (32 %) positive samples selected for comparison purposes. In addition, our assays did not amplify other canine viruses associated with respiratory and neurological diseases: canine adenovirus 2, canine parainfluenza virus 2, canine herpesvirus 1 and rabies virus. Overall, we describe a high-coverage primer set for CDV detection, which represents an attractive tool for laboratory diagnosis of canine distemper., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The overwhelming majority of SARS-CoV-2 epidemiological studies cover a narrow time period, making general knowledge about the COVID-19 pandemic difficult. To assess COVID-19-related host aspects in the overall pandemic, we analyzed COVID-19 cases during the first two years of SARS-CoV-2 circulation in southern Brazil. Herein, 390 patients admitted in 2020-2022 to a Brazilian public referral hospital were allocated into two groups according to the COVID-19 outcome: hospital discharge (n=237) or death (n=153). In the univariate analysis, several variables, including sociodemographic, clinical and laboratory aspects (primary data), were significantly different between the analyzed groups. In multivariate logistic regression, eight of these factors remained associated with the COVID-19 outcome. In particular, we report oxygen supplementation and the need for hemodialysis as predictors of hospital discharge and death from COVID-19, respectively. To the best of our knowledge, none of these findings have been previously reported in the Brazilian or world population. In conclusion, our results contribute to current knowledge by demonstrating that factors described at different times may remain associated with COVID-19 over the pandemic and by identifying novel predictors of COVID-19 outcome., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: The severity and distribution of dengue virus (DENV) infections have been attributed to a complex interaction among viral, host and environmental factors. Herein, we investigated the influence of chikungunya (CHIKV) and Zika (ZIKV) viruses on the epidemiological profile of dengue cases, using Recife, Pernambuco state, Brazil, as a study model. In addition, we described and compared the epidemiological profile related to each arbovirus (DENV vs. CHIKV vs. ZIKV)., Methods: All cases of dengue, chikungunya and Zika reported to the Pernambuco Health Department in 2011-2013 (DENV circulation) and 2016-2018 (DENV, CHIKV and ZIKV co-circulation) were included in our study. The cases were classified by sex, age and race/color and their distribution was analyzed by the χ 2 test. Furthermore, the data were also analyzed for co-infections. Temperature, humidity and rainfall data were analyzed using one-way ANOVA and paired t-test., Results: During 2011-2013, 15,315 dengue cases were diagnosed, most of them female, brown and 20-29 age group. Between 2016 and 2018, 15,870 dengue cases were described, which presented the same profile described above. In the two triennia, the female/male dengue ratio fluctuated significantly, ranging from 1.07 to 1.52. Regarding chikungunya, 7076 cases were reported, most of them female and brown. The female/male ratio also fluctuated significantly, ranging from 1.62 to 2.1. Two main age groups were observed in chikungunya: ≤ 19 years (minority of diagnoses) and ≥ 20 years (majority of diagnoses). In the same triennium, 266 Zika cases were reported to the Pernambuco Health Department, mainly in females and in the 0-9 and 20-39 age groups. In general, 119 co-infections were identified: 117 DENV-CHIKV, 1 CHIKV-ZIKV and 1 DENV-CHIKV-ZIKV. Concerning climate data, only the humidity in 2011 was significantly different from the other years., Conclusion: The epidemiological profile of dengue cases did not change after the introduction of CHIKV and ZIKV. Females were the most diagnosed with dengue, chikungunya or Zika, however we found important differences in the age profile of these arboviruses, which should be considered by public health policies, as well as investigated in future studies of virus-host interaction., (© 2023. The Author(s).)

Infection is one of the main complications that hinder wound healing. Currently, antibiotic-resistant bacteria, such as Methicilin-resistant Staphylococcus aureus (MRSA), are a concern worldwide for both humans and animals. Maggot therapy is re-emerging as an alternative to intractable wounds and may be an option to the traditional antibiotic treatment. Although the species of choice is Lucilia sericata, reports of clinical use have led us to evaluate the efficacy and safety of using Lucilia cuprina larvae on induced infected wounds in Wistar rats. In short, 32 male Wistar rats were divided into 4 groups: Group I - saline solution treated; Group II - antibiotic-treated; Group III - treated with larval debridement, and Group IV - without wound and treatment. Skin wounds were induced in groups I, II and III. All treatments were performed once and held for 48 h. Clinical, microbiological, histopathological, hematological, and biochemical analyses were done. Significant wound area contraction was found (>95%) in group III on day 9 compared to day 15 in group II. Complete elimination (0.0 ± 0.0 CFU/mL) of bioburden was achieved after the second treatment (day 6) in both the II and III groups, compared to an increase in Group I (6.51 ± 0.37 CFU/mL). A cleaner wound was also observed in the histopathological evaluation of group III, with adequate collagen formation and re-epithelialization on day 15. Furthermore, larvae increased blood platelet levels after the first treatment. L. cuprina larvae have proven safe and effective in accelerating wound treatment and eliminating MRSA., (Copyright © 2022. Published by Elsevier Inc.)

Introduction: Human T-lymphotropic virus (HTLV) 1 and 2 infections can lead to neurological diseases, mainly in HIV/HTLV 1 coinfected. Furthermore, HTLV 1 infection in HIV/AIDS patients has also been associated with AIDS progression. Despite this, HTLV 1/2 infections are not of mandatory notification in Brazil. Here, we describe the prevalence of HTLV 1/2 in HIV/AIDS patients from Paraíba state, Brazil, as well as the sociodemographic characteristics of the coinfected individuals., Methodology: Information about HIV viral load and TCD4 lymphocyte count were obtained from patients' records. Data on the patients' sociodemographic characteristics were obtained by interview conducted after signing the informed consent form. The serological diagnosis for HTLV 1/2 was performed by Enzyme-Linked Immunosorbent Assay (ELISA) and Western Blot (WB)., Results: A total of 401 HIV/AIDS patients participated in the study, of whom about 1.5% (6/401) were positive for antibodies against HTLV, specifically for HTLV 1, evaluated by both ELISA and WB. No risk factors were found associated with HIV/HTLV 1/2 coinfection., Conclusions: We report a 1.5% prevalence of HTLV 1 infection in HIV/AIDS patients from Paraíba state. Although we have not identified risk factors associated with HTLV 1, we describe the most observed sociodemographic characteristics in HIV/HTLV 1 coinfection., Competing Interests: No Conflict of Interest is declared, (Copyright (c) 2021 Marcela Santos de Souza, Juliana Prado Goncales, Viviane Martha Santos deMorais, Jose Valter Joaquim Silva Junior, Thaisa Regina Rocha Lopes, Joanne Elizabeth Ferraz da Costa, Maria Rosangela Cunha Duarte Coelho.)

Imbalance in the immune response is one of the main pathogenic mechanisms of diseases related with human immunodeficiency virus (HIV)/human gammaherpesvirus 8 (HHV-8) coinfection, such as Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman disease (MCD) and the Kaposi's sarcoma-associated herpesvirus inflammatory cytokine syndrome (KICS). However, significant changes in pro- and anti-inflammatory cytokine levels may be observed in HIV/HHV-8 individuals who are negative for KS, PEL, MCD, and/or KICS. In this study, serum levels of interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor nucrosis factor α (TNF-α) and interferon γ (IFN-γ) were assessed in 69 HIV and 48 HIV/HHV-8 individuals, all negatives for HHV-8-related diseases. The cytokines were measured by flow cytometry and analyzed by the Mann-Whitney test. The p < .05 and 95% confidence interval were considered in all analyzes. IL-4 (p = .0155), IL-6 (p = .0036), and IL-10 (p = .0036) levels were significantly higher in HIV/HHV-8 patients than in the HIV group. On the other hand, IL-2 (p = .2295), TNF-α (p = .1216) and IFN-γ (p = .1178) did not differ between the groups analyzed. To our knowledge, to date, this is the first report on significant differences in the levels of IL-4 and IL-6 in HIV versus HIV/HHV-8 individuals. Finally, these early findings are important as a prognostic tool and contribute to clarifying the HHV-8-host interaction., (© 2020 Wiley Periodicals LLC.)

Background: The spread of Dengue virus (DENV) infections, as well as their signs and symptoms, are the result of a complex interaction between several factors. In Brazil, especially in the Northeastern, dengue is an important public health problem. Here, we report an epidemiological analysis of dengue cases in Pernambuco state, Northeastern Brazil, during 2015-2017., Methods: This work is a retrospective cross-sectional observational study on the epidemiological profile of all dengue cases confirmed and reported to the Health Secretary of Pernambuco between 2015 and 2017. These data cover all municipalities of Pernambuco, except Fernando de Noronha. DENV-positive individuals were classified according to the dengue type (without and with warning signs, or severe dengue), age, gender, ethnicity and intermediate geographic region of residence (Recife, Caruaru, Serra Talhada or Petrolina). The distribution of cases over the years was assessed by χ2 test. Temperature and rainfall data were evaluated by Unpaired t-test. p-value < 0.05 and CI 95% were considered in all analyses., Results: Most dengue cases was without warning signs. The most observed characteristics in the less severe dengue phenotypes were: female, mulatto ethnicity and age between 20 and 39 years old; this profile was more clearly observed in 2015. In 2016 and 2017, however, the numbers of dengue without and with warning signs were more evenly distributed and the difference in cases within groups decreased significantly. Regarding severe dengue, mulattoes were the most affected, but it is possible to note a trend towards a more uniform distribution between the genders and ages. Recife was the region with the highest numbers of both total cases and incidence rates and the highest rainfall levels. Overall, over the years, there has been a decrease in dengue cases in all regions of Pernambuco., Conclusions: We identified the epidemiological profile of dengue in Pernambuco, Brazil, reporting the gender, age, ethnicity and regions most affected by different dengue types. In addition, we observed that these cases were probably more influenced by rainfall than by temperature. Finally, we believe that this epidemiological knowledge is important to direct public health policies to the reality of each population.

Human gammaherpesvirus 8 (HHV-8) replication is influenced by a complex interaction between viral and host elements. Here, we evaluated the expression of NFκB and TNF-α in B (CD19 +) and T (CD3 +) lymphocytes, and the serum concentration of IL-1β and IL-12 cytokines in people living with HIV/AIDS (PLHA), negative for HHV-8-related diseases, and who presented antibodies to latent or lytic antigens from HHV-8. In addition, we also evaluated the correlation of HHV-8 viral load with NFκB, TNF-α, IL-1β and IL-12 levels. The expression of NFκB (p < 0.0001) or TNF-α (p < 0.0001) in B lymphocytes (CD19 +) and the IL-1β (p < 0.0266) and IL-12 (p < 0.0001) concentrations were associated with the presence of antibodies to HHV-8 lytic antigens. The CD19 + NFκB + TNF-α + and CD3 + NFκB + TNF-α + cells were also associated with the presence of antibodies to lytic infection (p < 0.0001). Among all PLHA evaluated, only individuals with the highest titers of lytic antibodies, i.e., 1:320, had detectable HHV-8 viral load. In these, HHV-8 viral load was correlated to NFκB (r = 0.6, p = 0.003) and TNF-α (r = 0.5, p = 0.01) (both in CD19 + lymphocytes) and with IL-1β (r = 0.5, p = 0.01) and IL-12 (r = 0.6, p = 0.006) levels. We believe that viral replication and/or reactivation, in addition to being associated with the development of lytic antibodies against HHV-8, may be associated with inflammatory response via NFκB. Finally, although immune response imbalance has been previously related to HHV-8-associated diseases, our results indicate that important changes in immunity, mainly in the inflammatory response, may be clearly observed in individuals with HHV-8, but who have not yet presented clinical manifestations.

Human gammaherpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma (KS), one of the most common cancers in people living with HIV/AIDS. It is believe that the course of both HIV and HHV-8 infection is associated with the imbalance of anti- and/or pro-inflammatory cytokines. Here, we evaluated the IL-6, TNF-α, IL-10, CCL2 and CXCL10 serum concentrations in HIV- and HIV/HHV-8 (without KS) individuals, and in patients with cutaneous or visceral AIDS-KS. Serum concentrations of IL-6, IL-10 and CXCL10 were significantly higher in the AIDS-KS group compared to HIV and HIV/HHV-8 individuals. Similarly, the concentrations of theses cytokines were higher in patients with visceral than in those with cutaneous AIDS-KS. The TNF-α concentration was significantly higher in the HIV group compared to HIV/HHV-8 (with and without KS) individuals, and CCL2 levels did not present significant difference among the groups. The HIV viral load was undetectable in all patients from the HIV and HIV/HHV-8 groups. On the other hand, in the AIDS-KS group, most patients had detectable HIV viral load. In this context, we believe that the cytokine levels in AIDS-KS may be result of a complex interaction between HIV, HHV-8 and immunity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Human gammaherpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma, multicentric Castleman's disease and primary effusion lymphoma. Like other herpesviruses, the HHV-8 may exhibit latent or lytic cycle, both regulated by viral and host factors. Regarding host factors, we analysed the association of polymorphisms in NFkB1 promoter (NFkB1-94 ins/del ATTG) and NFκBIA gene (NFκBIA 3'UTR A→G) with the development of antibodies against latent or lytic antigens from HHV-8. The ins/del [OR 7.9 (95% CI 3.3-19.1), p < 0.001], AG [OR 12.3 (95% CI 4.3-34.9) p < 0.001], GG [OR 9.4 (95% CI 3.2-27.9), p < 0.001], ins/del + AG [OR 94.5 (95% CI 9.6-924.4), <0.0001], ins/del + GG [OR 50.4 (95% CI 5.2-482.2, p < 0.0001] and G allele [OR 3.3 (95% CI 2.0-5.6), p < 0.001] were strongly related with the presence of antibodies to lytic antigens. This is the first association of polymorphisms in NFκB1 promoter and NFκBIA gene with the development of antibodies against HHV-8., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Chikungunya fever is a mosquito-borne viral illness characterized by a sudden onset of fever associated with joint pains. It was first described in the 1950s during a Chikungunya virus (CHIKV) outbreak in southern Tanzania and has since (re-) emerged and spread to several other geographical areas, reaching large populations and causing massive epidemics. In recent years, CHIKV has gained considerable attention due to its quick spread to the Caribbean and then in the Americas, with many cases reported between 2014 and 2017. CHIKV has further garnered attention due to the clinical diagnostic difficulties when Zika (ZIKV) and dengue (DENV) viruses are simultaneously present. In this review, topical CHIKV-related issues, such as epidemiology and transmission, are examined. The different manifestations of infection (acute, chronic and atypical) are described and a particular focus is placed upon the diagnostic handling in the case of ZIKV and DENV co-circulating. Natural and synthetic compounds under evaluation for treatment of chikungunya disease, including drugs already licensed for other purposes, are also discussed. Finally, previous and current vaccine strategies, as well as the control of the CHIKV transmission through an integrated vector management, are reviewed in some detail., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Host genetic factors such as MBL2 gene polymorphisms cause defects in the polymerization of MBL protein and result in a functional deficiency and/or in low serum levels that can influence susceptibility to various viral infections. The aim of this study was to estimate the frequency of alleles, genotypes and haplotypes related to -550, -221 and exon 1 polymorphisms of the MBL2 gene and investigate their association with HHV-8 in people living with HIV/AIDS (PLWHA), as well as the impacts on CD4 cell count and HIV viral load in HIV/HHV-8 coinfected and HIV monoinfected patients., Results: A cross sectional study in PLWHA, with and without HHV-8 infection, exploring associations between different factors, was performed in the outpatient infectious and parasitic diseases clinic at a referral hospital. Genomic DNA extractions from leukocytes were performed using a commercial Wizard ® Genomic DNA Purification kit (Promega, Madison, WI). The promoter region (-550 and -221) was genotyped with the TaqMan system (Applied TaqMan Biosystems ® genotyping Assays), and the structural region (exon1) was genotyped with Express Sybr Greener Supermix kit (Invitrogen, USA). In total, 124 HIV/HHV-8 coinfected and 213 HIV monoinfected patients were analysed. Median TCD4 counts were significantly lower in HIV/HHV-8 coinfected patients, whereas the mean of the first and last viral load of HIV did not present significant difference. There was no difference in frequency between the LL, YY and AA genotypes between the HIV/HHV-8 coinfected or HIV monoinfected patients. However, in a multivariate analysis, coinfected patients with the intermediate expression haplotype of the MBL2 gene had an odds ratio of 3.1-fold (CI = 1.2-7.6) of their last CD4 cell count being below 350 cells/mm 3 . Among the coinfected individuals, four developed KS and presented the intermediate expression MBL haplotype, with three being HYA/LXA and one being LYA/LYO., Conclusions: Host genetic factors, such as -550, -221 and exon 1 polymorphisms, can be related to the may modify coinfections and/or to the development clinical manifestations caused by HHV-8, especially in HIV/HHV-8 coinfected patients who present the intermediate expression haplotypes of MBL.

Emerging and re-emerging viral infections transmitted by insect vectors (arthopode-borne viruses, arbovirus) are a serious threat to global public health. Among them, yellow fever (YFV), dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses are particularly important in tropical and subtropical regions. Although vector control is one of the most used prophylactic measures against arboviruses, it often faces obstacles, such as vector diversity, uncontrolled urbanization and increasing resistance to insecticides. In this context, vaccines may be the best control strategy for arboviral diseases. Here, we provide a general overview about licensed vaccines and the most advanced vaccine candidates against YFV, DENV, CHIKV and ZIKV. In particular, we highlight vaccine difficulties, the current status of the most advanced strategies and discuss how the molecular characteristics of each virus can influence the choice of the different vaccine formulations., (Copyright © 2018 Elsevier B.V. All rights reserved.)