Search

This study evaluated whether IgG avidity measured by chemiluminescent microparticle immunoassay (CMIA) compared with enzyme-linked immunosorbent assay (ELISA) was useful to detect primary T. gondii infection during pregnancy and to estimate the risk for congenital T. gondii infection. One hundred six women with positive tests for T. gondii IgG and T. gondii IgM, comprising 21 women (19.8%) with low (<30%), 6 (5.7%) with borderline (30%–35%), and 79 (74.5%) with high (>35%) IgG avidity measured by ELISA were selected. Their stored sera were used for T. gondii IgG avidity measurements by CMIA. In CMIA, 72 (67.9%) women had low (<50%), 12 (11.3%) had borderline (50%–59.9%), and 22 (20.8%) had high (≥60%) IgG avidity. The ratio of low T. gondii IgG avidity index in CMIA was more than three-fold than that in ELISA. Eighteen (85.7%) of 21 women with ELISA low avidity also had CMIA low avidity, and 26 (96.3%) of 27 women with ELISA low or borderline avidity corresponded to CMIA low or borderline avidity, whereas 21 (26.6%) of 79 women with ELISA high avidity were diagnosed with CMIA low avidity. All three cases with congenital T. gondii infection showed coincidentally low IgG avidity in both methods. A positive correlation in IgG avidity indices was found between of ELISA and CMIA. CMIA for T. gondii avidity measurements compared with ELISA was clinically useful to detect pregnant women at a high risk of developing congenital T. gondii infection. [ABSTRACT FROM AUTHOR]

Fasciola hepatica , a worldwide distributed helminth, has a robust immunoregulatory effect in the host, increasing the susceptibility to secondary infections. Foot and mouth disease (FMD) is a highly contagious acute vesicular viral disease effectively controlled by vaccination in endemic regions. Despite the evidence of immunoregulatory effects, the impact of fasciolosis on the immune response induced by FMD vaccination in cattle has never been assessed. Our objective was to evaluate whether the infection by F. hepatica in cattle influences the long-term immunity elicited by the currently used commercial FMD-inactivated vaccines. Aberdeen Angus steers negative for F. hepatica were vaccinated twice against FMD virus (FMDV) during the first 6 months of age using a commercial oil vaccine formulated with A24/Cruzeiro and O1/Campos strains. When maternal antibodies against F. hepatica were weaned (18––20 months of age) animals were divided into groups of 12 and infected or mock-infected with 500 metacercariae/animal. Individual serum samples were collected at 0-, 28-, 59-, 87- and 157-days post-infection (dpi). Indirect ELISAs were used to detect A24/Cruzeiro specific bovine IgG and IgG subtypes. The total IgG antibody levels and avidity against FMDV did not show significant differences between all the groups. The commercial vaccine induced higher IgG2 than IgG1 titers in vaccinated animals. Anti-FMDV IgG1 levels significantly decreased in the infected group at 28 dpi. In addition, the avidity of IgG1 FMDV-specific antibodies at day 28 in the infected group was reduced compared to the control. These results show that F. hepatica infection modified anamnestic responses against FMDV, reducing serum IgG1 titers and avidity. To our knowledge, this is the first report of immune-regulation of F. hepatica altering the immune response of FMD vaccines, one of the most globally used animal vaccines. [ABSTRACT FROM AUTHOR]

In regions where the endemic measles virus has been eliminated, early detection of contagious patients is important for preventing the spread of measles and sustaining elimination. To investigate whether serological assays can be used for the estimation of highly infectious patients with measles, we performed a seroepidemiologic study of a measles outbreak in Yamagata Prefecture, Japan, in 2017. We tested plaque reduction neutralization (PRN), IgG avidity, and gelatin particle agglutination (PA) assays in 31 patients with measles, subdivided into two super-spreaders, three spreaders, and 26 non-spreaders. Simultaneously, these results were compared with the cycle threshold (Ct) of a semi-quantitative real-time reverse transcription PCR for the measles virus from throat swab specimens. In the PRN assay, one super-spreader and two spreaders lacked protective antibodies. The IgG avidity assay showed that two super-spreaders and one spreader had low avidity. The PA assay indicated that two super-spreaders and two spreaders lacked protective antibodies. Comparison of the results of the three serological assays and Ct revealed that patients whose antibody titers were judged as low in the IgG avidity and PA assays showed low Ct (i.e., high viral load), whereas non-spreaders tended to show low viral load. Our preliminary seroepidemiologic analysis of a population of 31 patients with measles suggests that PA and IgG avidity assays may be used for the identification of super-spreader/spreader candidates. However, further investigations are necessary to validate the robustness of these serological assays in detecting contagious measles cases. [ABSTRACT FROM AUTHOR]

Objective: Toxoplasmosis acquired in early pregnancy is a potentially severe complication for the fetus. Evaluating the risk of transplacental infection in pregnant women accessing the Tuscany Reference Center for Infectious Diseases in Pregnancy during the last 20 years with suspected or confirmed toxoplasmosis acquired in early pregnancy was the aim of the study.Study Design: We retrospectively enrolled all pregnant women undergoing amniocentesis for toxoplasmosis acquired in the first 16 gestational weeks in the period 1999-2019, comparing patients with certain acute infection (seroconversion occurred in pregnancy, CAIP) with those with suspected acute infection (IgG positive with low/intermediate IgG avidity index, SAIP).Results: 237 patients were enrolled, 187 (78.9%) with SAIP and 50 (21.1%) with CAIP. Specific IgM was detected in 47.5% and 76.7% (p-value 0.001), and the mean IgG avidity index was 22.7% and 7.1% (p-value < 0.001) in the SAIP and in the CAIP group, respectively. The mean delay from diagnosis to antibiotic initiation was 14.6 in SAIP and 11 days in CAIP group. Toxoplasma DNA was detected in the amniotic fluid in one case in a patient with CAIP. Excluding 24 newborns with not available data, prevalence of congenital infection was 0.47% [1/213 (95% CI 0.08%-2.61%)], 0% [0/178 (95% CI 0%-2.11%)] in SAIP and 2.8% [1/35 (95% CI 0.51%-14.53%)] in CAIP group.Conclusions: Toxoplasmosis acquired in early pregnancy has a low risk of fetal infection. Actively discussing case-by-case amniocentesis indication with patients, especially when a recent toxoplasmosis is not properly confirmed, is desirable. [ABSTRACT FROM AUTHOR]

Juvenile Idiopathic Arthritis (JIA) patients living in areas with high prevalence of tick-borne-encephalitis-virus-(TBEV)-infection are recommended for administration of inactivated TBE-vaccination. However, there are serious concerns regarding protective vaccine-induced immune responses against TBEV in immunocompromised patients. The present study aimed to analyze the humoral and cellular immune response to TBE-vaccination in previously TBE-vaccinated JIA patients compared to healthy controls (HC) including investigation of IgG-anti-TBEV avidity, neutralization capacity, cellular reactivity by IFNgamma-ELISPOT and cytokine secretion assays. Similar IgG-anti-TBEV antibody concentrations, neutralization titers and cellular reactivity were found between JIA and HC. The number and the early timing of booster vaccinations after primary vaccination had the most prominent effect on neutralizing antibodies in JIA and on IgG-anti-TBEV concentrations in both JIA and HC. Administration of booster vaccinations made it more likely for JIA patients to have IgG-anti-TBEV concentrations ≥165 VIEU/ml and avidities >60%. TNF-alpha inhibitors had a positive and MTX administration a negative effect on humoral immune responses. In conclusion, irrespective of having JIA or not, vaccinated children showed similar humoral and cellular immunity against TBEV several years after primary TBE-vaccination. However, in JIA, booster vaccinations mounted a significantly higher humoral immune response than in JIA without boosters. Our results highlight the need for timely administration of boosters particularly in JIA. Although immunosuppressive treatment at vaccinations in diagnosed JIA had a negative effect mainly on TBEV-specific cellular immunity, most JIA patients mounted a favorable humoral immune response which was maintained over time. Thus, successful TBE-vaccination seems highly feasible in JIA patients with immunosuppressive regimens. [ABSTRACT FROM AUTHOR]

Measles is a highly infectious illness requiring herd immunity of 95% to interrupt transmission. China has not reached elimination goals despite high vaccination coverage. We estimated the population susceptibility against measles in Tianjin, China and to tailor awareness raising activities in the measles elimination plan. Age-specific measles seroprevalence was evaluated by Enzyme-Linked Immunosorbent Assay (ELISA) on 12,164 individual aged 0–44 years in 2009–2018. Measles IgG avidity testing was performed to confirm the relationship of the waning immunity after vaccination and secondary vaccination failures (SVF) on 324 confirmed measles cases in 2013–2018. 11,108 samples (91.32%) tested positive for measles IgG, 239 (1.96%) tested as equivocal and 817 (6.72%) were negative. The age distribution of measles cases in Tianjin followed a U-shaped curve and was highest for those at <8 months and again at 20–39 years which correlated closely with the age distribution of measles susceptibility based on measles IgG antibody status (r = 0.72, P < 0.001). The seropositivity rate and antibody geometric mean concentration (GMC) for the 2018 study population were significantly lower (χ 2 = 7.45, P = 0.006 and t = 12.01, P < 0.001) compared to 2009. The multivariate stepwise logistic regression analysis showed that age and region were the risk factors for both measles seropositivity rate and GMC after vaccination. The proportion of high avidity cases increased with age, being significantly higher in 75.31% of cases in patients aged 30–34 years (χ 2 = 18.04, P = 0.003). High immunization coverage in children alone will not be adequate to realizing sufficient levels of population herd immunity, particularly given that the potential susceptibility window in adult. Implementation of supplemental immunization activity (SIA) targeted to appropriate group aged 30–34 years is recommended. [ABSTRACT FROM AUTHOR]

• IgM and IgG avidity are not always reliable for diagnosis of primary HCMV infections. • Anti-p52 IgM and anti-gB IgG provide additional tools in dating HCMV infections. • Combination of different assays improves diagnosis and dating of HCMV infections. Dating of primary human cytomegalovirus (HCMV) infection in pregnancy is crucial to define whether infection occurred before or during pregnancy and at which gestational age. The aim of this study was to identify a diagnostic strategy for determination of early, intermediate and late phase of HCMV primary infection during pregnancy. Sequential serum samples from 40 pregnant women with defined onset of HCMV primary infection were tested retrospectively for IgM, IgG and IgG avidity against whole HCMV lysate, along with anti-p52 IgM and anti-gB IgG (Euroimmun AG). Anti-HCMV IgM were positive in all samples collected within the first 2 months, then decreased remaining weakly positive in about 40% of samples collected within 6–12 months after infection. Anti-p52 IgM followed similar kinetics but decreased earlier, remaining weakly positive only in 20% of late samples. Anti-HCMV IgG were positive in all samples and showed variable kinetics. Their avidity increased from low levels, observed within 2 months, to intermediate/high levels from 4 months onwards. Anti-gB IgG increased over time following kinetics similar to anti-HCMV IgG avidity. By combining results of anti-HCMV IgM plus IgG avidity, and confirming them with anti-p52 IgM plus anti-gB IgG as second-line assays, the early (within 2–3 months) and late (after 3 months) phases of HCMV infection were satisfactorily defined, whereas the intermediate phase overlapped with the beginning of the late phase. Anti-p52 IgM and anti-gB IgG provide additional tools besides classical anti-HCMV IgM, IgG and IgG avidity in dating HCMV primary infections. [ABSTRACT FROM AUTHOR]

Primary infection with Toxoplasma gondii (T. gondii) during pregnancy may cause congenital infection of the infant. This study evaluated whether screening using IgG avidity and multiplex-nested polymerase chain reaction (PCR) methods was effective for detecting a high-risk pregnancy for congenital T. gondii infection. In a prospective cohort study serum T. gondii IgG avidity was measured in 469 pregnant women who had a positive test for T. gondii antibody plus a positive or equivocal test for IgM. Multiplex-nested PCR for T. gondii DNA on amniotic fluid, maternal blood, and neonatal blood was performed with informed consent. Low (<30%), borderline (30–35%), and high (>35%) IgG avidity indices were found in 104 (22.2%), 30 (6.4%), and 305 (71.4%), respectively. A total of 12 cases had a positive PCR test for amniotic fluids of the prenatal amniocentesis or at birth, or neonatal blood. Seven of the 12 cases were diagnosed as having congenital T. gondii infection, and they had low IgG avidity indices. Congenital T. gondii infection screening using of IgG avidity and multiplex-nested PCR methods for pregnant women with a positive test for T. gondii antibody plus a positive or equivocal test for T. gondii IgM was useful for detecting a high-risk pregnancy and diagnosing congenital T. gondii infection. [ABSTRACT FROM AUTHOR]

Highlights • Biomarkers of clinical disease are useful in prophylaxis and therapeutics CVL. • Multivariate regression identified important markers, especially the avidity index. • IgG avidity index was also strongly correlated with the number of clinical signs. Abstract Canine visceral leishmaniosis (CVL), a parasitic disease caused by Leishmania infantum , may evolve to a chronic condition and lead to death. Evaluation of infected dogs is important to establish the clinical and laboratory parameters involved in the evolution of the disease. The objectives of the present study were to discriminate a canine population (n = 52) into sub-clinical and clinically affected dogs based on signs and scores, to evaluate the hematological, biochemical, histopathological and parasitological parameters of the two dog groups, and to analyze the results by multivariate regression analysis with the aim of establishing biomarkers of CVL clinical disease. The most common signs observed in the clinically affected dogs (n = 29) were hyperkeratosis, weight loss, onychogryphosis, pale mucosa and lymphadenomegaly. In the multivariate analysis, animals presenting high IgG avidity index and low red blood, lymphocyte and eosinophil counts, and low serum urea concentration had an increased probability of being classified as clinically affected (p < 0.05). All five parameters were considered to be strong biomarkers for monitoring the clinical disease, while IgG avidity percentage was strongly correlated with the number of clinical signs and could function as an indicator of the duration of infection. This is the first report on the application of IgG avidity and of multivariate regression analysis in establishing associations between the clinical signs of CVL and host biomarkers. Since avidity index (AI) percentages were strongly correlated with the number of clinical signs, it could be useful in clinical practice for auxiliary diagnosis of CVL and monitoring disease progression. A limitation of this study is the lack of information on co-infections by Anaplasma platys , Babesia canis vogeli , Ehrlichia canis and Hepatozoon canis. Therefore future studies should evaluate the influence of such co-infections on the associations studied using multivariate methods with larger samples. [ABSTRACT FROM AUTHOR]

Primary Toxoplasma gondii (T. gondii) infection during pregnancy could result in congenital disease with severe clinical complications. IgM antibodies are one of the indices of primary infection. The IgG avidity index (AI) is also known to remain low for at least 3 months after primary infection. Here, we evaluated and compared the performance of T. gondii IgG avidity assays as confirmed by T. gondii IgM serostatus and number of days post-exposure. Four assays preferentially used in Japan were employed to measure the T. gondii IgG AI. Results for the T. gondii IgG AI showed good concordance, particularly in cases with a low IgG AI. This study confirms that the combination of T. gondii IgM and IgG AI tests is a reliable and suitable method for identifying T. gondii primary infections. Our study proposes the necessity of measuring the T. gondii IgG AI as an additional indicator of T. gondii primary infection. [ABSTRACT FROM AUTHOR]

Background and objectives The mechanisms leading to low effectiveness of the humoral immune response against P. aeruginosa in cystic fibrosis (CF) are poorly understood. The aim of the present study was to assess the avidity maturation of specific antipseudomonal IgG before and during the development of chronic lung infection in a cohort of Danish CF patients. Methods Avidity maturation was assessed against a pooled P. aeruginosa antigen (St-Ag) and against P. aeruginosa alginate in 10 CF patients who developed chronic lung infection and 10 patients who developed intermittent lung colonization, using an ELISA technique with the thiocyanate elution method. Avidity was quantitatively determined by calculating the avidity Constant (Kav). Results IgG avidity to St-Ag significantly increased at the onset (Median Kav = 2.47) and one year after the onset of chronic infection (Median Kav = 3.27), but did not significantly changed in patients who developed intermittent colonization. IgG avidity against alginate did not significantly change over the years neither in patients who developed chronic lung infection (Median Kav = 3.84 at the onset of chronic infection), nor in patients who developed intermittent colonization. Conclusion IgG avidity to P. aeruginosa alginate does not significantly enhance as chronic lung infection progresses. This probably plays a role in the difficulty to mount an effective opsonophagocytic killing to clear mucoid P. aeruginosa infection in CF. [ABSTRACT FROM AUTHOR]

Objectives Current serological methods cannot distinguish active from past infection with Borrelia burgdorferi sensu lato. The aim of this study was to develop an IgG avidity Western blot and assess its potential to differentiate patients with early and late Lyme borreliosis (LB) i.e. active disease, from those infected in the past. Methods An IgG avidity Western blot was developed. Penalized linear discriminant analysis (PLDA) was employed to compare the Western blot/avidity Western blot profiles of an evaluation panel consisting of 75 sera from patients with early ( n  = 26) and late ( n  = 24) LB and past infection ( n  = 25). The PLDA models produced were used to predict infection stage for 20 well characterised sera from the Centers for Disease Control and Prevention (CDC) Lyme disease serum repository and 112 routine seropositive sera (disease stage unknown), to validate and assess the usefulness of the avidity Western blot/avidity Western blot and PLDA approach. Results PLDA correctly classified 40/51 (78%) of patients when early LB and past infection groups in the evaluation panel were compared. Likewise, when late LB and past infection groups were compared, 34/49 (69%) were correct. The resultant PLDA models correctly predicted infection stage for 18/20 (90%) of the CDC sera, validating the use of the avidity Western blot/avidity Western blot and PLDA approach. When tested with the routine sera, 21/29 (72%) tested with the early LB vs. past infection model were correct but only 32/83 (39%) with the late LB vs. past infection model. Past infection was predicted for 40/112 (35%) of the routine sera, 80% of which correlated with the clinical picture. Conclusion The Western blot/avidity Western blot with PLDA approach shows exciting potential for being able to predict disease stage in some patients with LB, which could improve patient management. [ABSTRACT FROM AUTHOR]

Background The immunoglobulin (Ig) G avidity index (AI) is useful to detect primary cytomegalovirus (CMV) infection. However, because IgG matures with time, this index is not useful to detect a primary infection, unless measured at an appropriate time. Objectives We aimed to clarify the difference between using IgG AI and IgM positivity according to the stage of pregnancy to identify congenital CMV infection risk. Study design We collected the serum samples from 1115 pregnant women who underwent maternal screening for primary infection (n = 956) and were referred to our hospital because of CMV IgM positivity (n = 155) or had abnormal fetal ultrasonography findings (n = 4). The same sera samples were used to measure CMV IgM, IgG, and IgG AI. An IgG AI of <35% was defined as low. Neonatal urine collected within 5 days after birth was examined by polymerase chain reaction to confirm congenital infection. Results Fourteen mothers gave birth to infected neonates. The sensitivity, specificity, and negative predictive values of the low IgG AI group with IgM-positive samples to discriminate between women with congenital infection at ≤14 weeks of gestation were 83.3, 83.8, and 99.1, respectively, which were higher than those of other subjects. Uni- and multivariate analyses revealed that IgM positivity and low IgG AI were independent variables associated with congenital infection at any stage of pregnancy, except low IgG AI at ≥15 weeks of gestation. Conclusion Low IgG AI with IgM positivity at ≤14 weeks of gestation was a good indicator of congenital infection, which should prove useful in obstetric practice. [ABSTRACT FROM AUTHOR]

In this study we showed that complement factors are responsible for assay interference in the VIDAS cytomegalovirus (CMV) immunoglobulin G (IgG) assay. Three different serum treatments were applied to show the cause of interference: heat treatment (56 °C), adding cobra venom factor, and adding EDTA. Elimination of complement interference by EDTA treatment of serum was prospectively evaluated on 215 CMV IgM positive samples and a sensitivity increase of the VIDAS CMV IgG assay was noticed. On average the CMV IgG level increased 100% after EDTA treatment of the serum. In paired serum samples from 38 patients we could show that serum treatment with EDTA can make the CMV IgG level changes more obvious in recent CMV infections. Since the CMV IgG avidity II assay on VIDAS depends on the determination of CMV IgG, the CMV IgG avidity was also evaluated in this study but only a limited effect of the complement interference was observed. [ABSTRACT FROM AUTHOR]

Background Human Cytomegalovirus (CMV) is the virus most frequently responsible for severe diseases of the fetus and newborn. The reported intrauterine transmission rate of CMV following primary maternal infection is approximately 40%. Invasive techniques are needed for the prenatal diagnosis of congenital CMV infection. Objectives The aim of this study was to evaluate whether the rapidity of change in the CMV IgG avidity index (AI) is associated with the presence of congenital CMV infection among mothers with suspected primary CMV infection. Study design The serum CMV IgG AI was repeatedly measured in 17 pregnant women with positive or borderline test results for CMV IgM together with an initial IgG AI value of <40%. Their neonates underwent polymerase chain reaction analyses for the presence of CMV DNA in the urine. The rapidity of change in the IgG AI per 4 weeks was defined as the ΔAI (%). The ΔAI of women with congenital CMV infection was compared with that of women with no infection. Results The ΔAI of nine mothers with congenital CMV infection (median,15.7%; range,7.8–42.8%) was significantly higher than that of eight mothers with no infection (median, 6.5%, range, 2.0–8.8%; p < 0.001). The incidences of congenital CMV infection were 100.0%, 16.7%, and 0.0% among mothers with a ΔAI of >10, 5–10, and <5%, respectively. Conclusions Measurement of the ΔAI in pregnant women might be useful for estimating the risk of mother-to-neonate CMV transmission. [ABSTRACT FROM AUTHOR]

Abstract: The preliminary diagnostic utility of two mixtures of Toxoplasma gondii recombinant antigens (rROP1+rSAG2 and rROP1+rGRA6) in IgG ELISA and IgG avidity test has been evaluated. A total of 173 serum samples from patients with toxoplasmosis and seronegative people were examined. The sensitivity of IgG ELISA for rROP1+rSAG2 and rROP1+rGRA6 was 91.1% and 76.7%, respectively, while the reactivity for sera from patients where acute toxoplasmosis was suspected was higher, at 100% and 95.4%, respectively, than for people with chronic infection, at 88.2% and 70.6%. In this study a different trend in avidity maturation of IgG antibodies for two mixtures of proteins in comparison with native antigen was observed. The results suggest that a new IgG avidity test using the mixtures of recombinant antigens may be useful for the diagnosis of difficult-to-identify phases of toxoplasmosis. For this reason, selected mixtures after the additional tests on groups of sera with well-defined dates of infection could be used as a better alternative to the native antigens of the parasite in the serodiagnosis of human T. gondii infection. [Copyright &y& Elsevier]

Abstract: A search for specific IgM antibodies was used for the detection of primary human cytomegalovirus (HCMV) infections, but the significance of the results is limited by the possible persistence of specific IgM over time, the fact that they are also produced during episodes of reactivation or reinfection, and possible cross-reactions with other viruses. Anti-HCMV antibody screening was carried out to assess the positive predictive value of detecting specific IgM antibodies using IgG and IgM enzyme-linked immunosorbent assays (ELISAs) in 6990 patients examined during the period 2005–2007. In comparison with IgG avidity, the positive predictive value of screening by IgM ELISA alone was 49.3%, which increased to 73% when the presence of IgM was confirmed by an enzyme-linked fluorescent assay (ELFA). The predictive values of highly or weakly positive IgM ELISA alone were respectively 68.8% and 16.4%, but increased to 83.1% and 39.1% if IgM was confirmed by ELFA. The positive predictive value of the IgM/IgG ratio ranged from 26.7% for a low ratio and the detection of IgM by ELISA alone, to 90.7% for a high ratio and ELFA-confirmed IgM detection. These findings indicate that a specimen in which highly positive IgM ELISA values are confirmed by ELFA, or which shows a high IgM/IgG ratio, is a good indicator of infection occurring within the previous three months. [Copyright &y& Elsevier]

Abstract: Background: The interpretation of a positive IgM antibody result to human cytomegalovirus (HCMV) in a pregnant woman is of major importance for the correct management of the pregnancy. Determination of HCMV-specific IgG avidity is considered an useful approach for distinguishing IgM antibody due to primary HCMV infection from IgM antibody elicited during non-primary infection. Objective: Comparative evaluation of eight commercial HCMV IgG avidity assays currently available in Europe. Study design: A panel of 198 sequential samples collected from 65 pregnant women at 0–90, 91–180, and >180 days after the onset of primary HCMV infection was retrospectively tested by Abbott, BioMérieux, Bio-Rad, DiaSorin, Diesse, Euroimmun, Radim, and Technogenetics HCMV IgG avidity assays according to the manufacturer''s instructions. Results: None of the 198 samples tested yielded identical scores by the kits under evaluation. The Euroimmun and Radim assays showed the best correlation with expected results in terms of low (0–90 days), intermediate (90–180 days) and high (>180 days) avidity results, respectively. The best accuracy in diagnosing a recent (<90 days after the onset) or non-recent (>180 days after the onset) primary HCMV infection was shown by Radim followed by Euroimmun and Diesse. The best correlation with a well established in-house developed HCMV IgG avidity assay was shown by Radim. Conclusions: HCMV IgG avidity kits need to be improved and standardized. In the meantime, highly specific IgM assays are preferable for screening purposes in pregnant women. [Copyright &y& Elsevier]

Abstract: The objective of this work was to carry out a study on caprine toxoplasmosis in the state of Minas Gerais, Brazil. To determine the prevalence of toxoplasmosis in goats in Minas Gerais, 767 sera from goats were tested by ELISA (enzyme-linked immunosorbent assay) and IFAT (indirect fluorescence antibody test). The prevalence of antibodies to Toxoplasma gondii was 43.0% and 46.0% by ELISA and IFAT, respectively. It was observed that 26.8% of the goats show low-avidity IgG to T. gondii. These results suggest the presence of animals in recent phase of toxoplasmosis in Minas Gerais. The risk factors for toxoplasmosis in goats were: age over 36 months (OR=1.21; IC 95% 1.02–1.44), use of pen (OR=1.83; IC 95%1.01–3.31) and pure breed animals (OR=2.49; IC 95% 1.11–5.59). [Copyright &y& Elsevier]

Background The accuracy of IgG avidity assays is crucial for the diagnosis of primary CMV infection in pregnancy. Objective To compare the performance of the second generation avidity assays LIAISON ® CMV IgG Avidity II and VIDAS ® CMV IgG Avidity II for the diagnosis of primary infection in pregnant women. Study design In our laboratory, in sera of pregnant women presenting with positive CMV IgG and positive CMV IgM, the two avidity assays were run in parallel from January 2013 to April 2015. Results The results of the 2 avidity assays were analyzed in 280 sera. The correlation between the second generation LIAISON ® and VIDAS ® avidity results was significantly higher than between the results of the first generation assays (77% versus 49%, p < 0.001). Discrepant results were mainly explained by the difficulty of the VIDAS ® assay to reach intermediate and high avidity status over time, suggesting the superiority of the LIAISON ® assay to achieve high avidity levels. In 4 sera from 3 pregnant women (1.4%) with documented primary infection the LIAISON ® avidity was falsely high. In these cases the level of CMV IgG was low (<50 U/mL). Conclusion The LIAISON ® CMV IgG Avidity II assay reached more rapidly higher avidity status than the VIDAS ® CMV IgG Avidity II. However, with the LIAISON ® CMV IgG Avidity II, we identified rare sera with high positive avidity values in documented recent seroconversion. The advantages and drawbacks of each assay must be known for a sound interpretation of the results. [ABSTRACT FROM AUTHOR]

Abstract: Sheep are important domestic animals in the Northeast region of Brazil due to their minimal rearing and maintenance costs, and to their production of both meat and milk. In animals, Toxoplasma gondii infection results in significant reproductive and economic losses. The epidemiology of toxoplasmosis in sheep in the Northeast of Brazil has been little studied; particularly in Rio Grande do Norte State. Sera from 102 sheep intended for consumption in Lajes were subjected to the Toxoplasma-ELISA test to detect anti-T. gondii specific IgG confirming a past infection. Of the total tested, 30 (29.41%) sera were positive for IgG with an increasing number of positive animals with advancing age. We used IgG avidity ELISA in 30 positive samples and observed that 6 (20%) had low avidity antibodies and 24 (80%) had high avidity antibodies. Epidemiological studies are required in order to identify sources of infection for these hosts as well as their impact on animal breeding in the region and risk of transmission to humans. [Copyright &y& Elsevier]

Abstract: Avidity tests can be used to discriminate between cattle that are acutely and chronically infected with the intracellular parasite Neospora caninum. The aim of this study was to compare the IgG avidity ELISA tests being used in four European laboratories. A coded panel of 200 bovine sera from well documented naturally and experimentally N. caninum infected animals were analysed at the participating laboratories by their respective assay systems and laboratory protocols. Comparing the numeric test results, the concordance correlation coefficients were between 0.479 and 0.776. The laboratories categorize the avidity results into the classes “low” and “high” which are considered indicative of recent and chronic infection, respectively. Three laboratories also use an “intermediate” class. When the categorized data were analysed by Kappa statistics there was moderate to substantial agreements between the laboratories. There was an overall better agreement for dichotomized results than when an intermediate class was also used. Taken together, this first ring test for N. caninum IgG avidity assays showed a moderate agreement between the assays used by the different laboratories to estimate the IgG avidity. Our experience suggests that avidity tests are sometimes less robust than conventional ELISAs. Therefore, it is essential that they are carefully standardised and their performance continuously evaluated. [Copyright &y& Elsevier]

A Neospora caninum IgG avidity ELISA was carried out on the basis of a somatic N. caninum tachyzoite antigen. The test was validated using experimentally infected calves, where a clear maturation of the IgG avidity over time could be demonstrated. At a maximum of 82 days after infection (d.p.i.), all animals showed antibody avidities ranging above 35%, and respective sera were thus defined as highly avid.Sera of 103 naturally infected seropositive cows with abortion (N. caninum association was provided by a N. caninum PCR-positivity of the fetus in 40 cases) and 139 seropositive animals without abortion history were concurrently examined. Significantly lower avidities were observed in aborting cows when compared to animals without abortion problems (P<0.01). While the avidity of sera collected before abortion remained practically constant until abortion, a significant increase of avidity could be observed in samples collected weeks to months after abortion (P<0.01).The avidities of non-aborting animals from farms with or without abortion problems did not differ significantly with time and were mainly located in the high avidity area. These data indicate that low avidities are not necessarily linked to recent N. caninum infection but can also be an indicator for increased abortion risk in cattle. [Copyright &y& Elsevier]

The purpose of this paper is to investigate the high rate of seroconversion for Neospora caninum in a dairy herd. Forty-five of 95 (47%) of the seronegative animals seroconverted within a period of 6 months. Seropositive animals were not equally distributed among age-groups. A high seroprevalence age-group of 8–30 months was housed together during a period of 4 months, indicating a point source infection within this period. A lack of association between the serological status of daughters and mothers also indicated horizontal transmission of the infection. Low avidity indices in the seroconverted animals confirmed a recent infection in this herd. However, there was no increased abortion rate in connection with the seroconversion, which indicates that mass seroconversions in dairy herds may remain unnoticed. There was circumstantial evidence that the farm dog played a role in the transmission of the infection to the cattle. However, also evidence was found for an unexplained ongoing horizontal transmission after the initial point source exposure. [Copyright &y& Elsevier]

• The IgG ZIKV Avidity test DIA.PRO® is currently the only commercial kit available. • This assay offered poor discrimination between recent and past infections. • Sensitivity and specificity to identify recent infection were poor (67.3 % and 4.5 %). • By using a modified protocol, a better discrimination was observed. ZIKV infection has potentially severe consequences particularly in fetuses/newborns born to mothers that were infected early in pregnancy. Diagnosis relies on the detection of ZIKV IgM that can also be detected due to cross reactivity or to nonspecific polyclonal activation of the immune system. Therefore, in case of ZIKV IgM detection, identification of a recent infection can be of major importance for the optimal management of pregnant women. This study evaluates the performances of a commercially available assay to measure ZIKV-IgG avidity. A total of 110 serum or plasma samples collected from symptomatic or asymptomatic patients living or returning from a ZIKV endemic area were classified according to epidemiological and clinical information, and to serology and molecular assays' results. Samples were tested with the IgG ZIKV Avidity Test (DIA.PRO®) according to manufacturer's instruction and with a modified protocol. By using the manufacturer's Avidity Index cut-off, distinction between recent and past infection was unclear with similar AIs in the two situations (p = 0.8872). Sensitivity and specificity in identifying recent infection were poor, 67.3 % and 4.5 % respectively. By using a modified protocol, a better discrimination was observed with significant differences between mean AIs (p = 0.0318), and with higher sensitivity and specificity, respectively 87.8 % and 100 %. Our results highlight that IgG ZIKV Avidity Test DIA.PRO® assay is not reliable enough to be used in clinical practice without modifications. [ABSTRACT FROM AUTHOR]

Congenital toxoplasmosis (CT) affects one to ten fetuses per 10 000 live newborns in western countries. Without knowing pre-conception serostatus, it is hard to date the infection when anti- Toxoplasma IgG and IgM antibodies are positive at first screening. Although a high IgG avidity index (AI) in the first trimester excludes CT, the same cannot be said of intermediate and low AI. The aim of this study was to estimate the risk of CT when intermediate or low AI is detected in the first trimester of pregnancy. Our observational retrospective study enrolled women with positive anti- Toxoplasma IgG and IgM, and low/intermediate AI in the first trimester of gestation seen at two reference centres in northern Italy between 2006 and 2015. All women received spiramycin. When requested by women, a sample of fluid obtained through amniocentesis was tested with a commercial real-time PCR. CT was defined by positive PCR result confirmed on aborted materials or by newborn follow up. Overall, 778 first-trimester pregnant women were included; AI was low in 532/778 (68%) and intermediate in 246/778 (32%). Amniocenteses were performed in 528/778 (67.9%), with no fetal loss. In all, 19/778 (2.4%) miscarriages and 15/778 (1.9%) pregnancy terminations were recorded; 9/778 (1.6%) were lost to follow up. In two women, PCR on amniotic fluid was positive, but CT was confirmed in only 1/747 cases (0.13%, 95% CI 0.02%–0.75%). In our study, the risk of CT was much lower than anticipated. These data must be considered when counselling these women. [ABSTRACT FROM AUTHOR]