Deltacoronaviruses

Deltacoronaviruses are a genus of enveloped, positive-sense single-stranded RNA viruses within the subfamily Orthocoronavirinae, family Coronaviridae. They are one of the four coronavirus genera, alongside alphacoronaviruses, betacoronaviruses and gammacoronaviruses. Members of this genus have a genome of roughly 26 to 28 kilobases and share the general coronavirus genome organization, including replicase genes in ORF1a/1b and downstream structural genes for spike (S), envelope (E), membrane (M) and nucleocapsid (N), with additional accessory genes.

The host range of deltacoronaviruses is broad, with numerous avian deltacoronaviruses detected in ducks, cranes and other birds, often associated with enteric infections. In mammals, deltacoronaviruses include porcine deltacoronavirus (PDCoV), which causes diarrhoea, vomiting, and dehydration in piglets and can contribute to enteric disease in swine herds. Another deltacoronavirus, Swine Acute Diarrhea Syndrome coronavirus (SADS-CoV), emerged in China in 2017 and caused severe piglet mortality; its origin is linked to bat reservoirs with cross-species spillover to pigs. These viruses are typically transmitted via the fecal–oral route and can circulate in farmed and wild populations, occasionally spreading between regions.

Diagnosis relies on molecular methods such as RT-PCR and genome sequencing to detect deltacoronavirus RNA. Surveillance and biosecurity measures in poultry and swine operations focus on reducing exposure to wildlife reservoirs and contaminated materials, as no broadly used vaccines for deltacoronaviruses are available in swine, and control mainly involves management practices.

Human infections by deltacoronaviruses have not been established as sustained or widely reported, though ongoing surveillance assesses any potential zoonotic risk associated with these viruses.