Susceptibility to and transmission of H5N1 and H7N1 highly pathogenic avian influenza viruses in bank voles (Myodes glareolus)

Abstract

The study of influenza type A (IA) infections in wild mammals populations is a critical gap in our knowledge of how IA viruses evolve in novel hosts that could be in close contact with avian reservoir species and other wild animals. The aim of this study was to evaluate the susceptibility to infection, the nasal shedding and the transmissibility of the H7N1 and H5N1 highly pathogenic avian influenza (HPAI) viruses in the bank vole (Myodes glareolus), a wild rodent common throughout Europe and Asia. Two out of 24 H5N1-infected voles displayed evident respiratory distress, while H7N1-infected voles remained asymptomatic. Viable virus was isolated from nasal washes collected from animals infected with both HPAI viruses, and extra-pulmonary infection was confirmed in both experimental groups. Histopathological lesions were evident in the respiratory tract of infected animals, although immunohistochemistry positivity was only detected in lungs and trachea of two H7N1-infected voles. Both HPAI viruses were transmitted by direct contact, and seroconversion was confirmed in 50% and 12.5% of the asymptomatic sentinels in the H7N1 and H5N1 groups, respectively. Interestingly, viable virus was isolated from lungs and nasal washes collected from contact sentinels of both groups. The present study demonstrated that two non-rodent adapted HPAI viruses caused asymptomatic infection in bank voles, which shed high amounts of the viruses and were able to infect contact voles. Further investigations are needed to determine whether bank voles could be involved as silent hosts in the transmission of HPAI viruses to other mammals and domestic poultry.

Caprine herpesvirus 2-associated malignant catarrhal fever of captive sika deer (Cervus nippon) in an intensive management system

“…In this scenario, 1.0 km is far from a safe distance for sika deer to prevent CpHV-2 associated MCF. However, we could not rule out the possibilities of CpHV-2 transmission through harmful fauna, given the proximity between the farms, as has been described for other viruses [ 28 ]. Wild rodents, ticks or bats could serve as vectors in this situation.…”

Surveillance for highly pathogenic H5 avian influenza virus in synanthropic wildlife associated with poultry farms during an acute outbreak

“…While wild aquatic birds have long been considered the natural maintenance hosts of avian IAV8, increasing attention has been focused on synanthropic wildlife as spillover hosts that could act as bridge hosts, potentially capable of moving these viruses from natural maintenance hosts to poultry or between poultry farms. Previous studies of peridomestic mammals91011121314151617 and birds16181920212223242526272829303132 have provided strong evidence that a number of these species are able to shed high levels of some IAVs. Nonetheless, only a few studies101331 have examined the potential of any of these species to transmit influenza A viruses to poultry species.…”

Bacterial and viral rodent-borne infections on poultry farms. An attempt at a systematic review

“…On the other hand, HPAIV infection of laboratory Sprague Dawley rats was asymptomatic and the animals shed only a small quantity of the virus (57). Similarly, infection of bank voles with the H5 and H7 subtypes of HPAIV caused no disease symptoms, but in this case resulted in shedding of high amounts of the virus (53). It is reasonable to assume that whether the outcome of infection is the disease state depends on the species, subspecies, genetic line, age and general health status of the infected organism, but also on the virus itself -its subtypes, lineage of haemagglutinin (HA), dose or route of infection.…”