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A fter spilling over from an unknown animal host to humans, a novel betacoronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 (1,2) and induced a global pandemic. This virus, which causes coronavirus disease, was first identified in humans in Wuhan, China (3). The role of livestock and wildlife species at the human-animal interface in disease emergence and dynamics was extensively discussed, focusing on the identification of susceptible species, potential reservoirs, and intermediate hosts. Natural or experimental infections have demonstrated the susceptibility of fruit bats (Rousettus aegyptiacus), ferrets, felids, dogs, and minks to the virus; however, pigs, chicken, and ducks are not susceptible (4-6). Besides ducks, chicken, and pigs, other major livestock species, including >1.5 billion cattle (Bos taurus), live with close contact with humans. Non-SARS-CoV-2 betacoronaviruses are widespread in bovines (7); seroprevalences reach up to 90% (8), but these infections are usually subclinical (7). However, whether any ruminant species are susceptible to SARS-CoV-2 infection or whether there is any cross-reactivity of antibodies against bovine coronaviruses (BCoVs) and SARS-CoV-2 is unknown. We examined the susceptibility of cattle to SARS-CoV-2 infection and characterized the course of infection.

Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths.

During the evolution of SARS-CoV-2 in humans a D614G substitution in the spike (S) protein emerged and became the predominant circulating variant (S-614G) of the COVID-19 pandemic. However, whether the increasing prevalence of the S-614G variant represents a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains elusive. Here, we generated isogenic SARS-CoV-2 variants and demonstrate that the S-614G variant has (i) enhanced binding to human ACE2, (ii) increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a novel human ACE2 knock-in mouse model, and (iii) markedly increased replication and transmissibility in hamster and ferret models of SARS-CoV-2 infection. Collectively, our data show that while the S-614G substitution results in subtle increases in binding and replication in vitro, it provides a real competitive advantage in vivo, particularly during the transmission bottle neck, providing an explanation for the global predominance of S-614G variant among the SARS-CoV-2 viruses currently circulating.