Bovine-like coronaviruses in domestic and wild ruminants

Abstract

Coronaviruses (CoVs) produce a wide spectrum of disease syndromes in different mammalian and avian host species. These viruses are well-recognized for their ability to change tissue tropism, to hurdle the interspecies barriers and to adapt ecological variations. It is predicted that the inherent genetic diversity of CoVs caused by accumulation of point mutations and high frequency of homologous recombination is the principal determinant of these competences. Several CoVs (e.g. Severe acute respiratory syndrome-CoV, Middle East respiratory syndrome-CoV) have been recorded to cross the interspecies barrier, inducing different disease conditions in variable animal hosts. Bovine CoV (BCoV) is a primary cause of gastroenteritis and respiratory disease in cattle calves, winter dysentery in lactating cows and shipping fever pneumonia in feedlot cattle. Although it has long been known as a restrictive cattle pathogen, CoVs that are closely related to BCoV have been recognized in dogs, humans and in other ruminant species. Biologic, antigenic and genetic analyses of the so-called 'bovine-like CoVs' proposed classification of these viruses as host-range variants rather than distinct virus species. In this review, the different bovine-like CoVs that have been identified in domesticated ruminants (water buffalo, sheep, goat, dromedary camel, llama and alpaca) and wild ruminants (deer, wild cattle, antelopes, giraffes and wild goats) are discussed in terms of epidemiology, transmission and virus characteristics. The presented data denote the importance of these viruses in the persistence of BCoV in nature, spread to new geographical zones, and continuous emergence of disease epidemics in cattle farms.

Keywords: Bovine-like coronavirus; host-range variant; interspecies transmission; ruminant species; wildlife.

Fig. 1.

Phylogenetic analysis of bovine-like coronaviruses based on the sequence of (a) nucleocapsid gene and (b) spike gene. Reference bovine coronaviruses were included for comparison purposes. Sequences were downloaded from GenBank (Table 3) and aligned together using Clustal W algorithm of MegAlign program, Lasergene software, version 3.18 (DNAStar, Madison, WI). Phylograms were constructed by MEGA 7.0 software using the maximum likelihood method. The strength of the tree was evaluated by bootstrapping of 1000 replicates. Bootstrap values are shown at the branch nodes of the tree. Bovine-like coronaviruses are grouped according to the type of animal(s), state or country of origin, and year of identification as indicated in the brackets at the right side. The scale bar at the bottom indicates the number of nucleotide changes per site.