Molecular Epidemiology Of Infectious Hypodermal And Hematopoietic Necrosis Virus And Taura Syndrome Virus In Penaeus Vannamei Cultured In China

Penaeus vannamei is one of the most important shrirnp species cultured inChina. Infectious hypodermal and hematopoietic necrosis virus (IHHNV) and taurasyndrome virus (TSV) are two of the major causes of shrimp disease which result insevere economic losses for shrimp culture industry.In this study, 214 shrimp samples of Penaeus vannamei were collected fromseven different areas of China and detected for IHHNV and TSV infection by PCR.The results showed that there were a high prevalence of IHHNV (65.42%) and lowprevalence TSV (3.27%) in tested samples. Several samples were found co-infectedwith these two viruses.A 3 kb fragment containing the putative non-structure and capsid proteins ofIHHNV were amplified and sequenced from IHHNV positive samples from sevendifferent areas of China. The sequence comparison indicate that these seven isolateshas very low sequence variations compared with the IHHNV from Hawaii, with anucleotide similarity between 99.3ï¼…to 99.9ï¼…. The percentage of substitution washigher in putative capsid proteins (1.92ï¼…) than in putative non-structure proteins(1.00ï¼…). And the mutation sites are dispersive and seem irregular in the genome ofIHHNV.The structure protein region (ORF2) of TSV were amplified and sequenced from TSV positive samples from three different areas of China. Sequence analysisshowed that these isolates were clustered into two groups (Asia group and Americagroup) which are correlated to geographic origins based on ORF2 sequences. Themutation sites were concentrated in the VP1 region of ORF2 and some of them can beused as the genetic markers to differentiate the Asia TSV isolates from others.