ABSTRACT
Outbreaks of hemorrhagic syndrome-like disease with high mortality rates have frequently occurred in Pelodiscus sinensis farms. The purpose of this study was to investigate the pathogen through challenge infection assays and partial sequencing of the genome of the pathogen. A 453-bp amplicon was obtained by random PCR using the nucleic acid extracted from the tissue homogenate filtrate and showed 32% identity at the amino acid level with the replicase polyprotein of the porcine reproductive and respiratory syndrome virus by Blastx. Multiple alignments indicated the putative protein sequence has some similarities to the replicase polyprotein of Arteriviridae, and the phylogenetic tree showed it was closely related to equine arteritis virus. This sequence was found in the lung of the diseased P. sinensis by in situ hybridization. Dot blot hybridization and quantitative RT-PCR showed that the lung had the highest content of virus. The peak replication of P. sinensis hemorrhagic syndrome virus (TSHSV) in the lung occurred 4 days after infection. The ribonucleic nature of the viral genome was confirmed by RNase A or DNase I treatments. We named the virus TSHSV in this study as P. sinensis is also known as Trionyx sinensis. These results provide a fundamental basis for further understanding the biology and the molecular mechanisms of TSHSV.
