一株猪繁殖与呼吸综合征病毒变异株的分离与鉴定

试验旨在分离并鉴定从发病猪场分离的一株疑似猪繁殖与呼吸综合征病毒毒株。从某疫情猪场病猪体内分离到一株猪繁殖与呼吸综合征病毒(PRRSV)变异株，经细胞传代培育成功增殖性能稳定的新毒株，命名为PRRSV-CHD。该毒株接种细胞后能够产生细胞病变(CPE)，病毒滴度达10^-6 TCID50/0.1 mL，在Vero与BHK-21细胞上不出现细胞病变。采用间接免疫荧光法(IFA)检测病毒抗原分布在细胞浆中。与VR2332、CH-1a、HUN4序列比对及系统进化树分析结果表明，该分离株属于美洲型PRRSV；与PRRSV VR2332、CH-1a等比对，Nsp2基因序列在2780—2782 nt有3个核苷酸小缺失和2933—3019 nt的87个核苷酸大缺失，属PRRSV变异株。

Isolation and Identification of a Variant of Porcine Reproductive and Respiratory Syndrome Virus

A porcine reproductive and respiratory syndrome virus (PRRSV) strain was isolated from visceral organs of a dead piglet obtained from a large-scale breeding farm and designated as PRRSV-CHD. It became cell-adapted and stable after several passages in Marc-145 cell line. The results showed that PRRSV-CHD could cause cytopathic effect (CPE) in Marc-145 cell line and the titer was 10^-6 TCID50/0.1 mL, while no CPE appeared in Vero cell line and BHK-21 cell line. The results of indirect immunofluorescent assay (IFA) tests indicated that the specific fluorescence could be detected in cytoplasm of infected cells. The strain we isolated was proved to be American genotype of PRRSV by sequence analysis and phylogenetic tree analysis with VR2332, CH-1a, HUN4 sequences. There were two non-continued deletions in the Nsp2 region of viral genome, that were 3 nucleotides deletions between 2780 and 2782 nt and 87 nucleotides deletions between 2933 and 3019 nt compared with VR2332, CH-1a, and so on, which proved the strain to be a variant PRRSV strain.