Serological prevalence of canine respiratory coronavirus

Abstract

Canine respiratory coronavirus (CRCoV) has recently been detected in dogs; it is a group 2 coronavirus showing similarity to bovine coronavirus (BCoV) but is distinct from canine enteric coronavirus (CECoV). CRCoV may play an important role in canine infectious respiratory disease (CIRD) either by predisposing to further and potentially more serious viral and bacterial infections or possibly as a primary pathogen. The prevalence of serum antibodies to CRCoV, in a population of dogs in the south east of England, has been shown previously to be 30.1% on the first day of entry to a rehoming kennel [Erles, K., Toomey, C., Brooks, H.W., Brownlie, J., 2003. Detection of a group 2 coronavirus in dogs with canine infectious respiratory disease. Virology 310, 216-223]. The purpose of this study was to establish the prevalence of CRCoV in the general canine population within as well as outside the UK. An ELISA, used to test for the presence of antibodies to CRCoV in canine serum samples, identified seropositive dogs in UK, USA, Canada, Republic of Ireland and Greece. The development of an ELISA based on CRCoV antigen and immunofluorescence assay are described here. 54.7% (547/1000) of North American and 36.0% (297/824) of United Kingdom dogs were seropositive for CRCoV. The age and geographical distribution of seropositive dogs was also assessed. The cross-reactivity demonstrated between CRCoV antibodies from different countries and a UK viral isolate suggests immunological similarity. The overall prevalence of this virus in both North America and the UK suggests that CRCoV has international significance and that further epidemiological studies are required.

Fig. 1

Diagrammatic representation of states with CRCoV seropositive dogs. Grey states have one or more CRCoV seropositive dogs and white states have either no seropositive dogs or no data.

Fig. 2

Relationship of CRCoV antibody status to age in canine samples from North America (n = 943). Numbers indicate the quantity of samples associated with each data point. Each data point represents the average age within an age range, i.e., 0–6 months: 0.25, 6 months–1 year: 0.75, 1–2 years: 1.5 and so on until 10–12 years: 11, 12–14 years: 13 and 14–16 years: 15.

Fig. 3

Diagrammatic representation of counties with CRCoV seropositive dogs. Scotland, Northern Ireland and the Republic of Ireland were omitted since low sample numbers prohibited meaningful representation. Grey counties have one or more CRCoV seropositive dogs and white counties have either no seropositive dogs or no data.

Fig. 4

Relationship of CRCoV antibody status to age in canine samples from UK, Republic of Ireland, Greece and Malta (n = 887). Numbers indicate the quantity of samples associated with each data point.

Fig. 5

Immunofluorescence assay—human rectal tumour (HRT-18) cells infected with CRCoV (UK isolate 4182). (A) ELISA negative serum, (B) and (C) ELISA positive serum.