Low-Pathogenic Avian Influenza Viruses in Wild House Mice

Abstract

Background Avian influenza viruses are known to productively infect a number of mammal species, several of which are commonly found on or near poultry and gamebird farms. While control of rodent species is often used to limit avian influenza virus transmission within and among outbreak sites, few studies have investigated the potential role of these species in outbreak dynamics. Methodology/Principal Findings We trapped and sampled synanthropic mammals on a gamebird farm in Idaho, USA that had recently experienced a low pathogenic avian influenza outbreak. Six of six house mice ( Mus musculus ) caught on the outbreak farm were presumptively positive for antibodies to type A influenza. Consequently, we experimentally infected groups of naïve wild-caught house mice with five different low pathogenic avian influenza viruses that included three viruses derived from wild birds and two viruses derived from chickens. Virus replication was efficient in house mice inoculated with viruses derived from wild birds and more moderate for chicken-derived viruses. Mean titers (EID 50 equivalents/mL) across all lung samples from seven days of sampling (three mice/day) ranged from 10 3.89 (H3N6) to 10 5.06 (H4N6) for the wild bird viruses and 10 2.08 (H6N2) to 10 2.85 (H4N8) for the chicken-derived viruses. Interestingly, multiple regression models indicated differential replication between sexes, with significantly (p<0.05) higher concentrations of avian influenza RNA found in females compared with males. Conclusions/Significance Avian influenza viruses replicated efficiently in wild-caught house mice without adaptation, indicating mice may be a risk pathway for movement of avian influenza viruses on poultry and gamebird farms. Differential virus replication between males and females warrants further investigation to determine the generality of this result in avian influenza disease dynamics.

The role of rodents in avian influenza outbreaks in poultry farms: a review

“…Virus was not isolated from these animals, but haemagglutination inhibiting activity was detected in some rat sera (Shortridge et al 2000). Virus was also undetectable by PCR in oral swabs of rodents captured around a game bird farm infected with LPAIV H5N8, H4N7 and H11N7 in Idaho in 2008 (Shriner et al 2012). However, in all of the examined (n = 6) house mice an indirect ELISA showed IAV antibodies.…”

“…This emphasizes the need for surveillance studies in a variety of avian and mammalian species to understand their possible role in dissemination of AIV. However, care must be taken when applying serological tests, as these are often not specifically validated for the species examined (VanDalen et al 2009;Shriner et al 2012) and may not provide consistent results between assays and laboratories (Poen et al 2016).…”

“…In an infection study using wild-caught house mice, na€ ıve mice were inoculated with LPAIV H3N8, H3N6, H4N6, H4N8 and H6N2 and showed efficient replication of wild bird-derived viruses and more moderate replication for chicken-derived isolates (Shriner et al 2012). Most viruses replicated more efficiently in lungs than in nasal turbinates.…”

“…Faecal samples remained negative. As these viruses replicated so efficiently (and more so in females than in males) without adaptation resulting in high viral titres, it is likely that wild house mice can play a role in virus dissemination as mechanical vectors, by contaminating water sources and to other animals as a result of scavenging or predation (Shriner et al 2012).…”

Transmission of H6N2 wild bird-origin influenza A virus among multiple bird species in a stacked-cage setting

“…Daily sampling consisted of an oral swab, a cloacal swab, a fecal swab (from each cage, when present), and a water sample (from each cage, when present). All swab samples were stored in 1 mL of BA-1 viral transport media [15]. Animal procedures were approved by the Animal Care and Use Committee of the National Wildlife Research Center (NWRC).…”