Biologic, Antigenic, and Full-Length Genomic Characterization of a Bovine-Like Coronavirus Isolated from a Giraffe

Abstract

Coronaviruses (CoVs) possess large RNA genomes and exist as quasispecies, which increases the possibility of adaptive mutations and interspecies transmission. Recently, CoVs were recognized as important pathogens in captive wild ruminants. This is the first report of the isolation and detailed genetic, biologic, and antigenic characterization of a bovine-like CoV from a giraffe (Giraffa camelopardalis) in a wild-animal park in the United States. CoV particles were detected by immune electron microscopy in fecal samples from three giraffes with mild-to-severe diarrhea. From one of the three giraffe samples, a CoV (GiCoV-OH3) was isolated and successfully adapted to serial passage in human rectal tumor 18 cell cultures. Hemagglutination assays, receptordestroying enzyme activity, hemagglutination inhibition, and fluorescence focus neutralization tests revealed close biological and antigenic relationships between the GiCoV-OH3 isolate and selected respiratory and enteric bovine CoV (BCoV) strains. When orally inoculated into a BCoV-seronegative gnotobiotic calf, GiCoV-OH3 caused severe diarrhea and virus shedding within 2 to 3 days. Sequence comparisons and phylogenetic analyses were performed to assess its genetic relatedness to other CoVs. Molecular characterization confirmed that the new isolate belongs to group 2a of the mammalian CoVs and revealed closer genetic relatedness between GiCoV-OH3 and the enteric BCoVs BCoV-ENT and BCoV-DB2, whereas BCoV-Mebus was more distantly related. Detailed sequence analysis of the GiCoV-OH3 spike gene demonstrated the presence of a deletion in the variable region of the S1 subunit (from amino acid 543 to amino acid 547), which is a region associated with pathogenicity and tissue tropism for other CoVs. The point mutations identified in the structural proteins (by comparing GiCoV-OH3, BCoV-ENT, BCoV-DB2, and BCoV-Mebus) were most conserved among GiCoV-OH3, BCoV-ENT, and BCoV-DB2, whereas most of the point mutations in the nonstructural proteins were unique to GiCoV-OH3. Our results confirm the existence of a bovine-like CoV transmissible to cattle from wild ruminants, namely, giraffes, but with certain genetic properties different from those of BCoVs.

Coronavirus Host Range Expansion and Middle East Respiratory Syndrome Coronavirus Emergence: Biochemical Mechanisms and Evolutionary Perspectives

“…Some coronaviruses appear to be generalists, capable of infecting many different orders of mammals. For example, Betacoronavirus 1 has been detected in dogs, humans, and numerous ungulate species (21)(22)(23). Other coronaviruses have been detected in only a single mammalian order, such as the many SARS-like coronaviruses that have been found only in bats (24,25).…”

An update on canine coronaviruses: Viral evolution and pathobiology

“…There is multiple genetic and antigenic evidence that several subgroup 2a CoVs, such as HCoV-OC43, HECV-4408 and PHEV, have arisen as consequence of transspecies infections caused by BCoV (Zhang et al, 1994;Vijgen et al, 2005Vijgen et al, , 2006Erles et al, 2006). Recently, bovine-like CoVs were identified in wild or domesticated ruminants, including several species of deer, waterbuck antelope (Tsunemitsu et al, 1995), giraffe (Giraffa camelopardalis) (Hasoksuz et al, 2007), alpaca (Lama pacos) (Jin et al, 2007), sable antelope (Hippotragus niger) (Spiro et al, unpublished) and water buffalo (Bubalus bubalis) (Decaro et al, 2008b) (Fig. 1), but the genetic determinants that may have caused the interspecies transmission from cattle have not been identified so far.…”

Development of a Panel of Multiplex Real-Time Polymerase Chain Reaction Assays for Simultaneous Detection of Major Agents Causing Calf Diarrhea in Feces

“…1,23,24,26 Bovine coronavirus is an enveloped virus with positive-sense, single-stranded RNA genome and is classified into genus Betacoronavirus as species Betacoronavirus 1 along with Mouse hepatitis virus, Human coronavirus OC43, Rat sialodacryoadenitis virus, Porcine hemagglutinating encephalomyelitis virus, Canine respiratory coronavirus, and Equine coronavirus. 9,14 Besides causing calf diarrhea, BCoV infection is also associated with winter dysentery in adult cattle as well as respiratory disease in all ages of cattle. 7,18 Group A BRV is a nonenveloped virus and possesses 11 double-stranded RNA segments.…”