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Gaining more appreciation on the protective/damaging aspects of anti-SARS-CoV-2 immunity associated with disease severity is of great importance. This study aimed to evaluate the avidity of serum IgG antibodies against SARS-CoV-2 spike (S) and nucleocapsid (N) in hospitalized symptomatic COVID-19 patients and asymptomatic RT-PCR-confirmed SARS-CoV-2 carriers as well as to compare antibody avidities with respect to vaccination status, vaccination dose and reinfection status. Serum levels of anti-S and anti-N IgG were determined using specific ELISA kits. Antibody avidity was determined by urea dissociation assay and expressed as avidity index (AI) value. Despite higher IgG levels in the symptomatic group, AI values of both anti-S and anti-N IgG were significantly lower in this group compared to asymptomatic individuals. In both groups, anti-S AI values were elevated in one-dose and two-dose vaccinees versus unvaccinated subjects, although significant differences were only detected in the symptomatic group. However, anti-N avidity showed no significant difference between the vaccinated and unvaccinated subgroups. Almost all vaccinated patients of different subgroups (based on vaccine type) had higher anti-S IgG avidity, while the statistical significance was detected only between those receiving Sinopharm compared to the unvaccinated subgroup. Also, statistically significant differences in antibody AIs were only found between primarily infected individuals of the two groups. Our findings indicate a key role for anti-SARS-CoV-2 IgG avidity in protection from symptomatic COVID-19 and calls for the incorporation of antibody avidity measurement into the current diagnostic tests to predict effective immunity toward SARS-CoV-2 infection or even for prognostic purposes. [ABSTRACT FROM AUTHOR]

Toxoplasmosis, one of the most common parasitic infections, can cause abortions in human. The purpose of this study was to determine seroprevalence of toxoplasmosis and acute form of toxoplasmosis in pregnant women. 208 pregnant women who referred to health centers in south-eastern Iran were taken under study after signing the informed consent forms and filling out the checklists. For those with high levels of IgG or IgM antibody titers, IgG Avidity test was performed to determine the acute infection. High level of IgG anti-body were found in sera of 81 pregnant women and 7 persons had borderline titer. IgM antibody results were positive in 33 and borderline in 4 cases. Then, the samples with positive and borderline results for IgM and IgG were evaluated by IgG avidity test. In this study, approximately 60% of pregnant women were not immune to risks posed by Toxoplasma gondii. Therefore, this group are at risk of acquiring primary infection of toxoplasmosis during gestation. [ABSTRACT FROM AUTHOR]

Proper diagnosis of toxoplasmosis is very important for proper treatment in manifested cases and to prevent congenital toxoplasmosis in case of pregnancy. Screening of 180 pregnant females by automated immune assay for Toxoplasma IgG and IgM Abs was done first then positive cases and some of negative cases were evaluated for the Toxoplasma IgG avidity test versus Toxoplasma IgM and IgA Abs using ELISA technique for the detection of active toxoplasmosis during gestation using IHA rising titer as reference test. Assessment of Toxoplasma IgM by ELISA compared with rising titer of IHA as a reference test revealed that the sensitivity, specificity, PPV, and NPP of IgM by ELISA were 66.67, 88.73, 42.86, and 95.45%, respectively. Assessment of Toxoplasma IgA Abs by ELISA compared with rising titer IHA as a reference test showed that the sensitivity, specificity, PPV, and NPP of IgA Abs by ELISA were 44.4, 92.96, 44.4, and 92.96%, respectively. Additionally, by assessment of Toxoplasma IgG avidity compared with rising titer of IHA as a reference test, the sensitivity, specificity, PPV, and NPP of Toxoplasma IgG avidity were 100, 98.59, 90%, and 100%, respectively. Detection of specific Toxoplasma IgM by ELISA is not always sufficient in the diagnosis of early and late during pregnancy, because Toxoplasma-specific IgM antibodies may persist as long as 18 months after acute acquired infection. Thus, the specific IgG avidity test should be used as more or less low cost tool to detect acute . [ABSTRACT FROM AUTHOR]