GENETIC-ANALYSIS OF WILD-TYPE-1 POLIOVIRUS ISOLATES IN CHINA, 1985-1993

We examined the genomic variability of 26 wild-type 1 polioviruses iso lated from 12 provinces in China from 1985-1993, The poliovirus genome region that encodes the N-terminal portion of the VP1 protein was amp lified by the polymerase chain reaction (PCR), The PCR product of each isolate was analysed by restriction fragment length polymorphism (PCR -RFLP) and by direct sequencing. Several groups of viruses with differ ent PCR-RFLP patterns were found to cause outbreaks in China during th is period. Viruses with identical PCR-RFLP profiles were dominantly is olated in 11 provinces from 1991 to 1993 and were considered to be the major epidemic strain in China. On the other hand, in the GuangDong p rovince, a different group was responsible for each year's outbreak, w hile in the XinJiang autonomous prefecture, a single strain was consis tently isolated from 1990 to 1993, Understanding of the nationwide dis tribution of wild poliovirus is very important for interrupting its tr ansmission during the final stage of the eradication program in China.