Molecular phylogeny of coronaviruses and host receptors among domestic and close-contact animals reveals subgenome-level conservation, crossover, and divergence.

BACKGROUND: Coronaviruses have the potential to cross species barriers. To learn the molecular intersections among the most common coronaviruses of domestic and close-contact animals, we analyzed representative coronavirus genera infecting mouse, rat, rabbit, dog, cat, cattle, white-tailed deer, swine, ferret, mink, alpaca, Rhinolophus bat, dolphin, whale, chicken, duck and turkey hosts; reference or complete genome sequences were available for most of these coronavirus genera. Protein sequence alignments and phylogenetic trees were built for the spike (S), envelope (E), membrane (M) and nucleocapsid (N) proteins. The host receptors and enzymes aminopeptidase N (APN), angiotensin converting enzyme 2 (ACE2), sialic acid synthase (SAS), transmembrane serine protease 2 (TMPRSS2), dipeptidyl peptidase 4 (DPP4), cathepsin L (and its analogs) and furin were also compared. RESULTS: Overall, the S, E, M, and N proteins segregated according to their viral genera (α, ß, or γ), but the S proteins of alphacoronaviruses lacked conservation of phylogeny. Interestingly, the unique polybasic furin cleavage motif found in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) but not in severe acute respiratory syndrome coronavirus (SARS-CoV) or Middle East respiratory syndrome coronavirus (MERS-CoV) exists in several ß-coronaviruses and a few α- or γ-coronaviruses. Receptors and enzymes retained host species-dependent relationships with one another. Among the hosts, critical ACE2 residues essential for SARS-CoV-2 spike protein binding were most conserved in white-tailed deer and cattle. CONCLUSION: The polybasic furin cleavage motif found in several ß- and other coronaviruses of animals points to the existence of an intermediate host for SARS-CoV-2, and it also offers a counternarrative to the theory of a laboratory-engineered virus. Generally, the S proteins of coronaviruses show crossovers of phylogenies indicative of recombination events. Additionally, the consistency in the segregation of viral proteins of the MERS-like coronavirus (NC_034440.1) from pipistrelle bat supports its classification as a ß-coronavirus. Finally, similarities in host enzymes and receptors did not always explain natural cross-infections. More studies are therefore needed to identify factors that determine the cross-species infectivity of coronaviruses.

Molecular-based cross-species evaluation of bovine coronavirus infection in cattle, sheep and goats in Ghana.

BACKGROUND: Apart from the huge worldwide economic losses often occasioned by bovine coronavirus (BCoV) to the livestock industry, particularly with respect to cattle rearing, continuous surveillance of the virus in cattle and small ruminants is essential in monitoring variations in the virus that could enhance host switching. In this study, we collected rectal swabs from a total of 1,498 cattle, sheep and goats. BCoV detection was based on reverse transcriptase polymerase chain reaction. Sanger sequencing of the partial RNA-dependent RNA polymerase (RdRp) region for postive samples were done and nucleotide sequences were compared with homologous sequences from the GenBank. RESULTS: The study reports a BCoV prevalence of 0.3%, consisting of 4 positive cases; 3 goats and 1 cattle. Less than 10% of all the animals sampled showed clinical signs such as diarrhea and respiratory distress except for high temperature which occurred in > 1000 of the animals. However, none of the 4 BCoV positive animals manifested any clinical signs of the infection at the time of sample collection. Bayesian majority-rule cladogram comparing partial and full length BCoV RdRp genes obtained in the study to data from the GenBank revealed that the sequences obtained from this study formed one large monophyletic group with those from different species and countries. The goat sequences were similar to each other and clustered within the same clade. No major variations were thus observed between our isolates and those from elsewhere. CONCLUSIONS: Given that Ghana predominantly practices the extensive and semi-intensive systems of animal rearing, our study highlights the potential for spillover of BCoV to small ruminants in settings with mixed husbandry and limited separation between species.

Sero-prevalence, cross-species infection and serological determinants of prevalence of Bovine Coronavirus in Cattle, Sheep and Goats in Ghana.

Cattle, goats and sheep are dominant livestock species in sub-Saharan Africa, with sometimes limited information on the prevalence of major infectious diseases. Restrictions due to notifiable epizootics complicate the exchange of samples in surveillance studies and suggest that laboratory capacities should be established domestically. Bovine Coronavirus (BCoV) causes mainly enteric disease in cattle. Spillover to small ruminants is possible. Here we established BCoV serology based on a recombinant immunofluorescence assay for cattle, goats and sheep, and studied the seroprevalence of BCoV in these species in four different locations in the Greater Accra, Volta, Upper East, and Northern provinces of Ghana. The whole sampling and testing was organized and conducted by a veterinary school in Kumasi, Ashanti Region of Ghana. Among sampled sheep (n = 102), goats (n = 66), and cattle (n = 1495), the seroprevalence rates were 25.8 %, 43.1 % and 55.8 %. For cattle, seroprevalence was significantly higher on larger farms (82.2 % vs 17.8 %, comparing farms with >50 or <50 animals; p = 0.027). Highest prevalence was seen in the Northern province with dry climate, but no significant trend following the north-south gradient of sampling sites was detected. Our study identifies a considerable seroprevalence for BCoV in Ghana and provides further support for the spillover of BCoV to small ruminants in settings with mixed husbandry and limited separation between species.