Variation in viral shedding patterns between different wild bird species infected experimentally with low-pathogenicity avian influenza viruses that originated from wild birds

Abstract

The prevalence of infection with avian influenza (AI) virus varies significantly between taxonomic Orders and even between species within the same Order. The current understanding of AI infection and virus shedding parameters in wild birds is limited and largely based on trials conducted in mallards (Anas platyrhynchos). The objective of the present study was to provide experimental data to examine species-related differences in susceptibility and viral shedding associated with wild bird-origin low-pathogenicity avian influenza (LPAI) viruses in multiple duck species and gulls. Thus mallards, redheads (Aythya americana), wood ducks (Aix sponsa), and laughing gulls (Leucophaeus atricilla) were inoculated experimentally with three wild mallard-origin LPAI viruses representing multiple subtypes. Variation in susceptibility and patterns of viral shedding associated with LPAI virus infection was evident between the duck and gull species. Consistent with the literature, mallards excreted virus predominantly via the gastrointestinal tract. In wood ducks, redheads, and laughing gulls, AI virus was detected more often in oropharyngeal swabs than cloacal swabs. The results of this study suggest that LPAI shedding varies between taxonomically related avian species. Such differences may be important for understanding the potential role of individual species in the transmission and maintenance of LPAI viruses and may have implications for improving sampling strategies for LPAI detection. Additional comparative studies, which include LPAI viruses originating from non-mallard species, are necessary to further characterize these infections in wild avian species other than mallards and provide a mechanism to explain these differences in viral excretion.

Wood ducks (Aix sponsa) as potential reservoirs for avian influenza and avian paramyxoviruses

“…As a comparison, antibody prevalence in mallards (Anas platyrhynchos) and Canada geese (Branta canadensis) sampled during these same time periods can exceed 50% and 20%, respectively (Brown et al, 2010;Kistler et al, 2012). Although, the duration of the detectable IAV antibody response is not well defined for wood ducks, and may partially explain the low prevalence, antibodies to IAV nucleoprotein have been detected for more than 1 year in naturally exposed mallards (Fereidouni et al, 2010) and for 21 days in experimentally infected wood ducks and mallards (Costa et al, 2011). These results suggest that wood ducks are probably spillover hosts of IAVs, and it is possible that previously reported isolations of IAV from this species reflect such spillover Hinshaw et al, 1985;Wilcox et al, 2011).…”

“…Finally, most of these studies only tested cloacal swabs. However, it has since been reported that wood ducks predominantly shed IAVs via the oropharyngeal route (Costa et al, 2011), indicating that the role wood ducks play in the epidemiology of infections with IAVs may be spatially dependent or poorly defined due to sampling focused on cloacal swabs.…”

“…One of these studies only tested serum from three wood ducks using a blocking ELISA (Brown et al, 2010), and the other study did not report sample size, but sera were tested by the agar gel immunodiffusion assay, which has been shown to perform poorly in waterfowl species (Bahl et al, 1975;Brown et al, 2009). Experimentally infected wood ducks have developed an antibody response that has been detected up to 21 days after exposure to IAVs (Brown et al, 2009;Costa et al, 2011).…”

Reassortant influenza A viruses in wild duck populations: effects on viral shedding and persistence in water

“…The absence of variation between virus genotypes contrasts with host-related effects that can significantly affect the outcome of virus shedding. Recent studies have for instance highlighted the effect of bird host species [40], age [38,41], body condition [42] and preexposure to other IAV [43,44], in the CL shedding duration and viral load. Such host-related variations may have direct implications in the transmission dynamics of IAV in wild duck populations.…”

Pathogenicity and Transmission of H5 and H7 Highly Pathogenic Avian Influenza Viruses in Mallards

“…In ducks, the naturally occurring endemic LPAI viruses are typically enterotropic and are shed primarily through feces (62)(63)(64). a Two-week-old mallard ducks were i.n.…”