猪瘟病毒低毒力毒株FJFQ株的分离鉴定

从福建某猪场分离到 1 株病毒,其在PK 15细胞上的毒价为 106.5 TCID50/mL,该病毒能被猪瘟病毒高免血清所中和(效价为1∶8)。通过 RT -PCR 扩增出猪瘟病毒约250 bp的E2蛋白主要抗原编码区序列,其与几株已发表毒株序列的核苷酸及氨基酸同源性分别为79.9%~87.9%,77.7%~86.6%,与Alfort 株同属于基因二群。经本动物传3代均不表现明显的临床症状。用猪瘟兔化弱毒疫苗免疫后以此分离毒作强攻进行免疫保护相关实验,结果免疫组猪在攻毒前及攻毒后扁桃体 HCFA检测均为阴性,对照组猪扁桃体HCFA于攻毒后1周开始出现阳性结果,且一直持续到试验结束。用分离株免疫本动物后再攻石门毒, 2 头试验猪中 1 头死亡,1头出现临床症状。初步说明,所分离的病毒为猪瘟病毒(命名为CSFV- FJFQ株),可能是一株低毒力毒株,且其免疫原性不好。

Isolation and Identification of a Low Virulence Strain of Classical swine fever virus

A classical swine fever virus strain,named FJFQ strain,was isolated from suckling pig in Fujian.The titer of the virus was 10~(6.5)TCID_(50)/mL in PK15 cell.Virus neutralization(VN) test showed that the isolate could be neutralized by CSFV positive serum.The neutralization titer was 1:8.With the special primer,the major antigen coding region sequences of E2 gene about 250 bp was obtained by RT-PCR.The identity of nucleotide sequence and amino acid sequences of the major antigen coding region sequences of E2 gene of the isolated strains was 79.9%~87.9% and 77.7%~86.6%.comparied with the published sequence of CSFV.The phylogenetic tree was divided into 2 groups. The isolate strain and Alfort strain were distributed in 2 group.The generation of the isolate strain was done by pigs.The results showed that the pigs of 3 different generation had not apperently sign.Immunization with attenuated hog cholera virus chinese C strain can protect pigs successfully against challenge with the isolate strain.But immunization with the isolate strain could not protect pigs successfully against challenge with virulent shimen strain.According to the results above,it was suggested that the virus isolate might be a low virulence CSFV with weak protection against virulent strain of CSFV.