猪瘟病毒石门株NS2-3基因片段的序列测定及比较

A couple of CSFV specific primer (PF 5648 and PR 6604) was designed with the aid of computer primer designation software and synthesized based upon the relative conserved regions of published sequences of C strain. NS2-3 gene (p125 gene) fragment of CSFV Shimen strain was amplified successfully by RT-PCR from the anticoagulant blood of infected pig. The product length is 957 bp, located in the central of NS3, a putative NTPase and helicase domain. The obtained PCR product was cloned and then sequenced. The sequence showed that this fragment contained all of seven typical conserved segments of helicase superfamily, including two common NTP-binding motifs, namely, “A” site (GXGKT/S) and “B” site (3hy, 2x) D. Sequence homology analysis revealed that Shimen strain had the highest homology with Japanese strains (ALD and GPE^-), and slightly lower homology with other three CSFV strains (C, BresciaandAlfort). Shimen strain had also significant homology with two BVDV strains (NADL and SD-1). The deduced amino acid sequence homology of Shimen strain with five CSFV and two BVDV strains was all upper than 90%. It is further confirmed that this fragment is the most conserved in pestivirus amino acid sequence. It is consistent with its essential function in replication and translation of virus genome and in processing of polyprotein precursor.

Sequencing and Comparison of NS2-3 Gene Fragment of Classical Swine Fever Virus Shimen Strain