Swine acute diarrhoea syndrome coronavirus (SADS-CoV) Nsp5 antagonizes type I interferon signaling by cleaving DCP1A.

Swine acute diarrhoea syndrome coronavirus (SADS-CoV), which is a recently discovered enteric coronavirus, is the major aetiological agent that causes severe clinical diarrhoea and intestinal pathological damage in pigs, and it has caused significant economic losses to the swine industry. Nonstructural protein 5, also called 3C-like protease, cleaves viral polypeptides and host immune-related molecules to facilitate viral replication and immune evasion. Here, we demonstrated that SADS-CoV nsp5 significantly inhibits the Sendai virus (SEV)-induced production of IFN-ß and inflammatory cytokines. SADS-CoV nsp5 targets and cleaves mRNA-decapping enzyme 1a (DCP1A) via its protease activity to inhibit the IRF3 and NF-κB signaling pathways in order to decrease IFN-ß and inflammatory cytokine production. We found that the histidine 41 and cystine 144 residues of SADS-CoV nsp5 are critical for its cleavage activity. Additionally, a form of DCP1A with a mutation in the glutamine 343 residue is resistant to nsp5-mediated cleavage and has a stronger ability to inhibit SADS-CoV infection than wild-type DCP1A. In conclusion, our findings reveal that SADS-CoV nsp5 is an important interferon antagonist and enhance the understanding of immune evasion by alpha coronaviruses.

SARS-CoV-2 was not detected in 383 samples from birds

Since December 2019, an outbreak of pneumonia (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-Z) has been widespread in the world. Investigation of Virus spread is a constant research focus. At present, SARS-CoV-Z has not been detected in livestock, poultry, or fur animals. This study focused on the traceability of SARS-CoV-Z in rare and endangered migratory birds. A total of 383 samples (throat swabs, anal swabs and fecal samples) were collected from 10 types of rare or endangered migratory bird, including mallard, white duck, pheasant, swan goose and white swan, in Jilin Province, China, between September 2019 and April 2020. Real-time RT-PCR, as recommended by the World Health Organization, was used to detect SARS-CoV-Z in these samples. SARS-CoV-Z was not detected in any of the samples.

Genetic characterization and phylogenetic analysis of porcine deltacoronavirus (PDCoV) in Shandong Province, China.

Porcine deltacoronavirus (PDCoV) is the etiological agent of acute diarrhoea and vomiting in pigs, threatening the swine industry worldwide. Although several PDCoV studies have been conducted in China, more sequence information is needed to understand the molecular characterization of PDCoV. In this study, the partial ORF1a, spike protein (S) and nucleocapsid protein (N) were sequenced from Shandong Province between 2017 and 2018. The sequencing results for the S protein from 10 PDCoV strains showed 96.7 %-99.7 % nucleotide sequence identity with the China lineage strains, while sharing a lower level of nucleotide sequence identity, ranging from 95.7 to 96.8%, with the Vietnam/Laos/Thailand lineage strains. N protein sequencing analysis showed that these strains showed nucleotide homologies of 97.3%-99.3% with the reference strains. Phylogenetic analyses based on S protein sequences showed that these PDCoV strains were classified into the China lineage. The discontinuous 2 + 3 aa deletions at 400-401 and 758-760 were found in the Nsp2 and Nsp3 coding region in five strains, respectively, with similar deletions having been identified in Vietnam, Thailand, and Laos. Three novel patterns of deletion were observed for the first time in the Nsp2 and Nsp3 regions. Importantly, those findings suggest that PDCoV may have undergone a high degree of variation since PDCoV was first detected in China.