Prevalence, phylogenetic and evolutionary analysis of porcine deltacoronavirus in Henan province, China

Porcine deltacoronavirus (PDCoV) is a novel porcine enteric coronavirus that causes diarrhea, vomiting and dehydration in piglets. This newly virus has spread rapidly and has caused serious economic losses for pig industry since the outbreak in USA in 2014. In this study, 430 faecal and intestinal samples (143 faecal samples and 287 intestinal samples) were collected from individual pigs with diarrhea and 211 serum samples were also collected from the sows with mild diarrhea in 17 regions in Henan province, China from April 2015 to March 2018. The RT-PCR detection indicated that the infection of PDCoV was high up to 23.49% (101/430), and co-infection with PEDV were common (60.40%, 61/101) in Henan pigs. The prevalence of PDCoV in suckling piglets was the highest (36.43%, 94/258). We also found that PDCoV could be detected in sows faeces and sera while the sows showed mild, self-limited diarrhea in clinic. The complete genomes of 4 PDCoV Henan strains (CH-01, HNZK-02, HNZK-04, HNZK-06) were sequenced and analyzed. Phylogenetic analysis based on the complete genome, spike and nucleocapsid gene sequences revealed that the PDCoV Henan strains were closely related to other PDCoV reference strains that located in the Chinese clade. Furthermore, the phylogenetic analysis showed PDCoV CH-01 strain was closely related to CHN-HB-2014 strain and HKU15-44 strain, while the other PDCoV Henan strains were more related to PDCoV CHJXNI2 and CH-SXD1-2015 strains, indicating that the ancestor of these sequenced strains may different. These results would support the understanding of the prevalence and evolution characteristics of PDCoV in China.