Résumé
To understand the genetic diversity of porcine deltacoronavirus(PDCo V) in Guangxi Province, clinical diarrhea samples were collected from suspected piglets in Guangxi Province from2017 to 2019, detected by RT-PCR for PDCoV, and the positive samples were used for amplification and sequence of S, M, N genes. Finally, 16 S, M and N gene sequences of PDCoV were obtained. Homology analysis showed that the S, M, N gene nucleotide identity among Guangxi strains were 95.8% -99.9%, 95.9%-100% and 97.9%-99.9%, respectively. The nucleotide identity of S, M and N genes among Guangxi strains and other reference strains were 95.1%-100%, 95.0%-100%and 96.3%-99.9%, respectively. Sequence alignment showed that S1 protein existed amino acid mutations and insertions, and there were some variations among different epidemic strains. Phylogenetic trees based on S, M and N genes obtained similar topological diagram and all strains could be divided into Group I, Group II and GroupIII, of which Group I came from USA, Japan and Korea, Group II came from China, and Group III came from China, Vietnam, Laos and Thailand. Most strains from Guangxi Province distributed in Group II, individual strain distributed in Group III and some strains formed a single small branch. The evolutionary rates of S, M and N genes of Guangxi strains and other reference strains were 2.57 x 10-4, 2.07 x 10-4, 1.70 x 10-4 substitutions/site/year, respectively, showing that the evolutionary rate of S gene was the fastest. The results indicated that the S, M, N genes of PDCo V strains from Guangxi Province had some variations and existed genetic diversity.