Porcine deltacoronavirus (PDCoV) strain OH-FD22 infects poultry and shares high nucleotide identity with sparrow-origin deltacoronaviruses (SpDCoV) ISU73347 and HKU17 strains. We hypothesized that the spike (S) protein or receptor-binding domain (RBD) from these SpDCoVs would alter the host and tissue tropism of PDCoV. First, an infectious cDNA clone of PDCoV OH-FD22 strain (icPDCoV) was generated and used to construct chimeric icPDCoVs harboring the S protein of HKU17 (icPDCoV-S HKU17 ) or the RBD of ISU73347 (icPDCoV-RBD ISU ). To evaluate their pathogenesis, neonatal gnotobiotic pigs were inoculated orally/oronasally with the recombinant viruses or PDCoV OH-FD22. All pigs inoculated with icPDCoV or OH-FD22 developed severe diarrhea and shed viral RNA at moderate-high levels (7.62–10.56 log 10 copies/mL) in feces, and low-moderate levels in nasal swabs (4.92–8.48 log 10 copies/mL). No pigs in the icPDCoV-S HKU17 and icPDCoV-RBD ISU groups showed clinical signs. Interestingly, low-moderate levels (5.07–7.06 log 10 copies/mL) of nasal but not fecal viral RNA shedding were detected transiently at 1–4 days post-inoculation in 40% (2/5) of icPDCoV-S HKU17 – and 50% (1/2) of icPDCoV-RBD ISU -inoculated pigs. These results confirm that PDCoV infected both the upper respiratory and intestinal tracts of pigs. The chimeric viruses displayed an attenuated phenotype with the loss of tropism for the pig intestine. The SpDCoV S protein and RBD reduced viral replication in pigs, suggesting limited potential for cross-species spillover upon initial passage.
【저자키워드】 S protein, spillover, reverse genetics, tissue tropism, Porcine deltacoronavirus, 【초록키워드】 Pathogenesis, nasal, diarrhea, virus, Protein, RBD, viral replication, intestine, phenotype, Clinical signs, Viral RNA, nasal swab, group, Strains, nucleotide, fecal, Neonatal, chimeric, cDNA, identity, Viral RNA shedding, domain, intestinal tract, clone, infect, Host, Alter, initial, upper respiratory, log, evaluate, inoculated, reduced, the RBD, the S protein, gnotobiotic, 【제목키워드】 spike, tropism, pig, Sparrow,