Experimental Hendra virus infection of dogs: virus replication, shedding and potential for transmission

Abstract

Objective Characterisation of experimental Hendra virus (HeV) infection in dogs and assessment of associated transmission risk. Methods Beagle dogs were exposed oronasally to Hendra virus/Australia/Horse/2008/Redlands or to blood collected from HeV‐infected ferrets. Ferrets were exposed to oral fluids collected from dogs after canine exposure to HeV. Observations made and samples tested post‐exposure were used to assess the clinical course and replication sites of HeV in dogs, the infectivity for ferrets of canine oral fluids and features of HeV infection in dogs following contact with infective blood. Results Dogs were reliably infected with HeV and were generally asymptomatic. HeV was re‐isolated from the oral cavity and virus clearance was associated with development of virus neutralising antibody. Major sites of HeV replication in dogs were the tonsils, lower respiratory tract and associated lymph nodes. Virus replication was documented in canine kidney and spleen, confirming a viraemic phase for canine HeV infection and suggesting that urine may be a source of infectious virus. Infection was transmitted to ferrets via canine oral secretions, with copy numbers for the HeV N gene in canine oral swabs comparable to those reported for nasal swabs of experimentally infected horses. Conclusion HeV is not highly pathogenic for dogs, but their oral secretions pose a potential transmission risk to people. The time‐window for transmission risk is circumscribed and corresponds to the period of acute infection before establishment of an adaptive immune response. The likelihood of central nervous system involvement in canine HeV infection is unclear, as is any long‐term consequence.

Drivers and Distribution of Henipavirus-Induced Syncytia: What Do We Know?

“…In particular, syncytia were observed at the epithelium of the nasal cavity and the lungs [99][100][101][102]. Syncytia were also observed, although more rarely, among epithelial cells of the tonsil [103] and the uterus [42]. More anecdotally, syncytia were reported from smooth muscle cells of blood vessels and macrophages [104].…”

Viral glycoproteomes: technologies for characterization and outlook for vaccine design

“…Horse vaccination by recombinant soluble Hendra glycoprotein G has been implemented in Australia to reduce the risk of Hendra virus spread to humans . However, lack of compliancy by horse owners and the potential for dog transmission argue for the need of developing a human vaccine . Effect of expression system was investigated for recombinant soluble attachment glycoprotein G of Hendra virus, revealing different N‐glycosite occupancy dependent on expression cell line.…”

In this issue – January/February 2017

“…Our first paper, on experimental Hendra virus (HeV) infection of dogs, concludes that that the virus is not highly pathogenic in that species. However, the authors suggest that an infected dog's oral secretions may be a potential risk for transmission of the virus to humans during the acute stages of the disease before they have established an adaptive immune response …”

“…I find it interesting that we have two studies using immunohistochemistry for viral antigen identification that have come to opposite conclusions about intracytoplasmic staining of macrophages. Middelton et al make the point that identification of the antigen is not regarded as sufficient evidence that a particular tissue is the site of virus replication, as this may simply reflect sequestration of virus or fragments in phagocytes or cellular debris . However, Barigye et al are more confident that their positive staining does demonstrate virus survival and replication in macrophages …”