Characterisation of enteric viruses in dogs

Abstract

Human noroviruses (HuNoV) are a significant cause of viral gastroenteritis in man worldwide. Noroviruses are also associated with intestinal disease in multiple species, including dogs. Canine norovirus (CNV) was initially discovered in 2007 and the first aim of this thesis was to determine the prevalence of CNV in the UK dog population. qPCR screening of canine stool samples did not identify CNV RNA, but canine astroviruses (CaAstV) were serendipitously identified and subsequently characterized according to the second aim of this work. For serological screening, CNV virus-like particles (VLPs) to three CNV strains were produced. CNV circulation in the UK was confirmed by identification of CNV-specific antibodies in 60% of canine serum samples collected in 2012-2013.

The third aim of this thesis was investigate to CNV interactions with host cells by identifying the cellular attachment factor for CNV. Synthetic carbohydrates and canine tissue samples were used to assess the binding specificity of CNV VLPs, and it was shown that antigens of the HBGA family were recognized. Phenotyping studies then demonstrated expression of HBGAs in dogs. As HuNoV also uses HBGAs to attach to cells, this raised concerns that dogs may be susceptible to HuNoV.

Evaluating the zoonotic risk of enteric viruses in dogs was the final aim of this thesis. The susceptibility of dogs to HuNoV and hepatitis E virus (HEV) was determined by screening canine samples for the presence of HuNoV or HEV RNA and HuNoV or HEV-specific antibodies. Antibodies to both HuNoV and HEV were identified in dogs, and results confirmed HuNoV VLPs can bind to canine gastrointestinal samples. This data indicates that dogs are susceptible to HuNoV and HEV infections.

In conclusion, this thesis has provided epidemiological and molecular characterization of CNV and CaAstV, in addition to highlighting the zoonotic potential for CNV, HuNoV and HEV in dogs.