Porcine Deltacoronavirus-Related Viruses in House Sparrows

Porcine deltacoronavirus (PDCoV) is an emerging enteric pathogen in pigs and a newly recognized zoonotic coronavirus in humans. Genetic analyses suggest that PDCoV origi-nated from avian deltacoronaviruses, with sparrow deltacoronaviruses (SpDCoVs) being the most closely related. House sparrows (Passer domesticus) frequently visit farms and in-teract directly with pigs in barns, raising the possibility of interspecies transmission. We hypothesized that PDCoV can be transmitted between pigs and house sparrows. To inves-tigate this, 200 house sparrows near Ohio swine farms were sampled and screened for gamma- and deltacoronaviruses using RT-PCR targeting the conserved RNA polymerase region. Deltacoronaviruses and gammacoronaviruses were detected in 18.0% (36/200) and 5.5% (11/200) of fecal samples, respectively. Genomic sequence analysis of representative samples revealed that SpDCoVs are closely related to, but not the direct ancestors of, PDCoVs. These SpDCoVs appear to be widespread in the U.S. Midwest and may contrib-ute to PDCoV evolution. Attempts to isolate SpDCoV from these samples in embryonated chicken eggs and four cell lines were unsuccessful. Because coronaviruses frequently cross species barriers to cause epidemics and/or pandemics in humans and livestock, these findings underscore the need for ongoing surveillance of deltacoronaviruses in diverse wild animals, livestock, and humans to safeguard public health.