Abstract: To understand the molecular epidemiological and genetic variation characteristics of feline infectious peritonitis virus (FIPV) in China, the N gene of FIPV AH1905 strain was cloned by PCR, and the bioinformatics softwares were used to predict the N protein. Then, N gene was cloned into a prokaryotic vector pGEX-4T-1 and was successfully expressed. The expressed protein was purified, and identified by SDS-PAGE and Western blot. The results showed that the N gene of FIPV, 1 134 bp, encodes 377 amino acids. The molecular bioinformatics analysis showed that the nucleotide homology and the amino acid homology between FIPV AH1905 strain and the reported FIPV reference strains were 90.2%-92.4% and 91.8%-93.9%, respectively. The phylogenetic analysis showed that FIPV AH1905 belongs to the FIPV gene type Ⅰ, the same as other isolates in China. The prediction of the secondary structure of the N protein showed that the protein was a hydrophilic stable protein with 14.06% α-helix (h), 15.12% extended chain (e), 3.71% β turn (t) and 67.11% random spiral (c). There were no signal peptide region and transmembrane domain. It may have 48 phosphorylation sites. Moreover, there may exist six B cell epitopes, two CTL epitopes and two Th epitopes. The molecular weight of expressed protein is approximately 68 ku, mainly expressed in inclusion body form with good reactogenicity. In conclusion, the present study has successfully expressed the N protein of FIPV, and prepared the multi-antiserum, which laid the foundation for further research on epidemiology and molecular biology of FIPV.

Key words: feline infectious peritonitis virus (FIPV), N gene, prokaryotic expression, bioinformatics