Analysis of the VP19 and VP28 genes of white spot syndrome virus in Korea and comparison with strains from other countries.

The results of our DNA analysis showed that there was 100% homology of the VP28 and VP19 genes of white spot syndrome virus (WSSV) among the samples collected from different shrimp farms in Korea. Comparing with an earlier isolated Korean strain, Korea01, the genes nucleotide sequences had only a single base difference which was observed in both VP19 and VP28. This resulted in a single amino acid substitution at position 40 of the latter. This implies that a single genetic strain of WSSV has been circulating in Korea and that its mutation rate is very low. In comparison with known sequences of VP19 and VP28 genes of WSSV isolates from other countries, the Korean strains had more than 99% sequence homology with those in gene and protein. Based on our sequence analysis of VP19 and VP28 of WSSV from various shrimp farms in Korea, the WSSV strains circulating in the region were genetically identical and similar to the strain identified two years ago. In addition, the Korean strain had close genetic identity with strains circulating in other Asian countries as well as other continents.