[Studies on the molecular epidemiology of poliovirus type 1 in China]

A strain of poliovirus type 1 isolated from an endemic in Shandong Province in 1988 and three strains of poliovirus type 1 isolated from an endemic in Xinjiang in 1990 were analysed by dot blot hybridization with Sabin I specific probe and PCR amplification with Sabin I specific primers. They were proved to be non-Sabin-like poliovirus. The nucleotide sequences of VP1-2A junction region of four poliovirus type 1 isolates were analysed. It was found that the nucleotide diversity of four isolates with Sabin I was equal to or greater than 16.7%. This finding proved that they were wild polioviruses and greatly different fromSabin I. It was also found that the nucleotide sequence diversity among three strains from Xinjiang was very small (less than 2.6%) with identical amino acid sequences. This indicated that the three Xinjiang strains belonged to the same genotype. While the difference of Shandong strain from the three Xinjiang strains was between 14. 0% to 15.33% in nucleotide sequence and 2.0% to 4.0% in amino acids. This indicated that Shandong strain was apparently different from three Xinjiang strains and it belonged to another wild genotype which had a different history of evolution.