oa Molecular Diagnosis and Vaccines - VP4 and VP7 genotyping of human rotavirus: relationship between genetic variation and severity of infantile gastroenteritis
Specific and sensitive tests for detection and typing of group A rotavirus strains are needed for a more comprehensive knowledge of the epidemiology of rotaviral infection. In this study 30 stool specimens from infants with acute gastroenteritis with age ranging from 2-12 months were examined. Group A rotavirus was unequivocally demonstrated in 60% of samples by latex agglutination test, in 40% by enzyme linked immunosorbant assay (ELISA) and in 36.3% by polymerase chain reaction (PCR). The infection was common among males and with artificial feeding than breast feeding. G and P typing of rotavirus was carried out by RT-PCR by amplification of VP7 and VP4 genes. Results showed the presence of VP4 in 16.7% of cases, VP7 in 13.3% and mixed VP4 and VP7 in 6.7% of cases. VP7 genotype was associated with the most severe symptoms followed by mixed VP4 and VP7 then VP4 gene. Detection of faecal rotavirus specific IgM and IgA antibodies in stool samples demonstrated that IgA antibodies are present in 33.3% of positive cases and in 11.1% of negative cases where virus shedding was no longer observed, while IgM was detected in 25% of positive cases and in 5.6% of negative cases. When RT-PCR was considered as the gold standard method for the detection of rotavirus in stool samples, ELISA and Latex assays sensitivity was found to be 90.4% and 72.3%, specificity 89.5% and 47.4% and accuracy 90% and 56.7% respectively. It is concluded that RT-PCR is a convenient method for genotyping of rotavirus strains. VP7 genotype correlates with the severity of infantile gastroenteritis. ELISA technique is a rapid, sensitive and inexpensive procedure for the direct detection of rotavirus antigen in clinical pecimens. However, detection of IgM and IgA antibodies is a useful supplement for diagnosis recent infection.
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