In a South Indian study, an 'in-house' enzyme-linked immunosorbent assay (ELISA) was developed to evaluate the potential of herpes simplex virus (HSV)-specific tear secretory IgA (sIgA) in the diagnosis of herpes simplex keratitis (HSK). The presence of HSV-specific tear sIgA was found to be diagnostic in 20.28% of cases. The usefulness of the sIgA ELISA system was evaluated against HSV isolation, which is the 'gold standard' and HSV antigen detection, a more sensitive, commonly employed method. Analysis of HSV-specific IgG and IgM results showed their failure as reliable indicators of active or ongoing infection. Comparison of sIgA ELISA with culture as 'gold standard' showed its sensitivity, specificity, and positive and negative predictive values to be 60% (95% CI 36.4-80), 93.2% (95% CI 86.7-96.8), 60% (95% CI 36.4-80), and 93.2% (95% CI 86.7-96. 8), respectively. This study is the first report on the complete evaluation of the usefulness of tear anti-HSV sIgA in the laboratory diagnosis of HSK, taking into account both epithelial and stromal keratitis cases.
Hepatitis B virus (HBV) surface antigen mutations may lead to immune escape and eventually cause failure of immunization. In this report, we identified immune escape variants in immunized babies born to hepatitis B surface antigen (HBsAg) carrier mothers. A total of 68 babies were followed up for 2 years after the full course of vaccination; 2.9% (2/68) of babies were found to be infected with the variant HBV in spite of preexisting antibody to surface antigen (anti-HBs) at 24 months post immunization. Both infants were positive for HBV-DNA; sequencing results of the "a" determinant region of the surface gene revealed that both babies had point mutations at a different nucleotide position resulting in various amino acid substitutions. In addition, an intriguing variant having an addition-deletion mutation was observed in one of the babies. This is the first report to show the addition-deletion variant of HBV in India. However, the immunological significance of the above HBV variants needs to be further elucidated.
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