We have identified circulation of 3 genogroups of enterovirus (EV) A71 in India. A new genogroup (proposed designation G) was discovered during this study. We isolated genogroups D and G in wide geographic areas but detected subgenogroup C1 only in 1 focus in western India. A systematic nationwide search for EV-A71 is warranted.

Sensitive, reliable, and rapid methods of virus culture are essential for wild poliovirus isolation and identification from stool specimens collected from cases of acute flaccid paralysis. Recently, recombinant murine cell lines expressing human poliovirus receptor (CD155) on the cell surface have become available. These cells are sensitive selectively to poliovirus because the poliovirus receptor is not used by other enteroviruses. In early field studies non-polio enteroviruses were not isolated from stool samples of cases of acute flaccid paralysis using L20B cells. For the past 3 years, L20B cells were used extensively in our laboratory for virus culture. The objective of the present study was to identify non-polio enteroviruses causing cytopathic changes in L20B cells. Stool specimens collected from 1,153 cases of acute flaccid paralysis and 2,670 apparently healthy children were tested for enteroviruses using RD and L20B cell lines. A small number of viruses other than poliovirus causing cytopathic effect in L20B cells were isolated. Such isolates detected in other polio network laboratories in India were also included. The virus isolates were typed using partial VP1 nucleotide sequence analysis and virus neutralization tests. Of the 111 viruses studied, 8 were non-enteroviruses. Among the 103 non-polio enteroviruses, 73 were identified as group A coxsackieviruses. Of the 30 isolates that could not be characterized, 1 remained unidentified even by sequence analysis and 29 did not reach high titers in L20B as well as RD cells. In conclusion, coxsackie A viruses multiply in L20B cells causing cytopathic effect. Coxsackievirus A8 and coxsackievirus A10 were predominant among the eight coxsackie A virus types so far identified.

A prospective study enrolling 50 mother-infant pairs was undertaken to determine the effect of maternal antibodies on poliovirus antibody titres and seroconversion rates in infants and to determine the difference in titres and seroconversion rates following three and five doses of oral poliovaccine (OPV). Cord blood samples and samples collected 4 weeks after 3rd and 5th doses of trivalent oral poliovaccine were processed for estimation of anti-poliovirus antibody titres. These were expressed as geometric mean titres (GMT). Significance was analyzed using unpaired 't' test. The relationship between maternal antibody titres and seroconversion was determined by correlation coefficient test. Post OPV5 titres were significantly higher than post OPV3 titres for type 1 and type 2 polioviruses. Seroconversion rates against type 1, 2 and 3 polioviruses were 92.9%, 100.0% and 92.9% following OPV3 and 100.0%, 100.0% and 93.2% following OPV5. The cord blood titres did not have any relation to post-OPV3 or post-OPV5 titres. Although there is significant passive transfer of poliovirus antibodies across the placenta, this does not affect titres achieved after immunization. Post-OPV5 titres against type 1 and type 2 viruses are significantly higher than post-OPV3 titres. The seroconversion rates following OPV5 are higher than those obtained post-OPV3 but this difference is not statistically significant.