Molecular epidemiological investigation of infectious hypodermal and hematopoietic necrosis virus and Taura syndrome virus in Penaeus Vannamei cultured in China

The Infectious hypodermal and hematopoietic necrosis virus (IHHNV) and Taura syndrome virus (TSV) are two important shrimp viruses in cultured shrimp in America. These two viruses were transmitted to China at the beginning of the 21^st century. In this study, 214 shrimp samples of Penaeus vannamei were collected from seven different areas of China and tested by PCR for IHHNV and TSV infection. The results showed that there were a high prevalence of IHHNV (65.42%) and low prevalence of TSV (3.27%) in the tested samples. Several samples were found to be co-infected with these two viruses. A 3 kb fragment of 7 positive IHHNV samples and a structure protein region (ORF2) of three TSV positive samples were amplified and sequenced. The sequence comparison indicated that both IHHNV and TSV sequenced in China have a low genetic variations compared with the prototype IHHNV and TSV from Hawaii. Phylogenetic analysis showed that TSV isolates were clustered into two groups, Asia and America group, which was genetically correlated to geographic distribution. Foundation item: This work was supported by 973 project (2006CB101801)