Isolation and Characterization of Porcine Deltacoronavirus from Pigs with Diarrhea in the United States

March 18, 2015 — 

Porcine deltacoronavirus (PDCoV) is a novel coronavirus that causes diarrhea in nursing piglets. Following its first detection in the United States (US) in February 2014, additional PDCoV strains have been identified in the US and Canada. Currently no treatments or vaccines for PDCoV are available. In this study, the US PDCoV OH-FD22 strain from intestinal contents of a diarrheic pig from Ohio was isolated in swine testicular (ST) and LLC-porcine kidney (LLC-PK) cell cultures using various media additives. We also isolated PDCoV [OH-FD22 (DC44) strain] in LLC-PK cells from intestinal contents of the PDCoV OH-FD22 strain inoculated into gnotobiotic (Gn) pigs. Cell culture isolation and propagation were optimized, and the isolates have been serially propagated in cell culture for >20 passages. The full-length S and N genes were sequenced to study PDCoV genetic changes after passage in Gn pigs and cell culture (P11 and P20). Genetically, the S and N genes of PDCoV isolates were relatively stable during the first 20 passages in cell culture with only five nucleotide changes, each corresponding to an amino acid change. The S and N genes of our sequenced strains were genetically closely related to each other and other US PDCoV strains, with the highest sequence similarity to South Korean KNU14-04 strain. This is the first report describing the cell culture isolation, serial propagation, biologic and genetic characterization of the cell adapted PDCoV strains. The information presented in this study is important for the development of diagnostic reagents, assays and potential vaccines against the emergent PDCoV strains.

Hu H, Jung K, Vlasova AN, Chepngeno J, Lu Z, Wang Q, Saif LJ; Isolation and Characterization of Porcine Deltacoronavirus from Pigs with Diarrhea in the United States; J Clin Microbiol. 2015 Mar 4. pii: JCM.00031-15. [Epub ahead of print]