Recombinant murine L20B cell line supports multiplication of group A coxsackieviruses

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.