Host range of influenza A virus H1 to H16 in Eurasian ducks based on tissue and receptor binding studies

Dabbling and diving ducks partly occupy shared habitats, but have been reported to play different roles in wildlife infectious disease dynamics. Influenza A virus (IAV) epidemiology in wild birds has primarily been based on surveillance programs focused on dabbling duck species, particularly mallard (Anas platyrhynchos). Surveillance in Eurasia has shown that in mallards some subtypes are commonly (H1–H7, and H10), intermediately (H8, H9, H11, and H12), or rarely detected (H13–H16), contributing to discussions on virus host range and reservoir competence. An alternative to surveillance in determining IAV host range is to study virus attachment as a determinant for infection. Here we investigated the attachment patterns of all avian IAV subtypes (H1–H16) to the respiratory and intestinal tracts of four dabbling (Mareca and Anas spp.), two diving duck species (Aythya spp.) and chicken, as well as to a panel of 65 synthetic glycan structures. We found that IAV subtypes generally showed abundant attachment to colon of the Anas duck species, mallard and Eurasian teal (Anas crecca), supporting the fecal–oral transmission route in these species. The reported glycan attachment profile did not explain the virus attachment patterns to tissues, however showed significant attachment of duck-originated viruses to fucosylated glycan structures and H7 virus tropism for Neu5Gc-LN. Our results suggest Anas ducks to play an important role in the ecology and epidemiology of IAV. Further knowledge on virus tissue attachment, receptor distribution and receptor binding specificity is necessary to understand the mechanisms underlying host range and epidemiology of IAV. Importance Influenza A viruses (IAVs) circulate in wild birds worldwide. From wild birds the viruses can cause outbreaks in poultry, and sporadically and indirectly infect humans. A high IAV diversity has been found in mallards (Anas platyrhynchos)—that are most often sampled as part of surveillance programs—meanwhile little is known about the role of other duck species in IAV ecology and epidemiology. In this study, we investigated the attachment of all avian IAV HA subtypes (H1–H16) to tissues of six different duck species and chicken as an indicator of virus host range. We demonstrated that the observed virus attachment patterns partially explained reported field prevalence. This study demonstrates that dabbling ducks of the Anas genus are potential hosts for most IAV subtypes, including those infecting poultry. This knowledge is useful to target the sampling of wild birds in nature, and to further study the interaction between IAVs and birds.

Novel Flu Viruses in Bats and Cattle: “Pushing the Envelope” of Influenza Infection

Influenza viruses are among the major infectious disease threats of animal and human health. This review examines the recent discovery of novel influenza viruses in bats and cattle, the evolving complexity of influenza virus host range including the ability to cross species barriers and geographic boundaries, and implications to animal and human health.

Twenty five new viruses associated with the Drosophilidae (Diptera)

Drosophila melanogasteris an important laboratory model for studies of antiviral immunity in invertebrates, andDrosophilaspecies provide a valuable system to study virus host range and host switching. Here we use metagenomic RNA sequencing ofca. 1600 adult flies to discover 25 new RNA viruses associated with six different drosophilid hosts in the wild. We also provide a comprehensive listing of viruses previously reported from the Drosophilidae. The new viruses include Iflaviruses, Rhabdoviruses, Nodaviruses, and Reoviruses, and members of unclassified lineages distantly related to Negeviruses, Sobemoviruses and Poleroviruses, Flaviviridae, and Tombusviridae. Among these are close relatives ofDrosophila X virusandFlock House virus, which we find in association with wildDrosophila immigrans. These two viruses are widely used in experimental studies but have not previously been reported to naturally infectDrosophila. Although we detect no new DNA viruses, inD. immigransandD. obscurawe identify sequences very closely related toArmadillidium vulgareIridescent virus (Invertebrate Iridescent virus 31), bringing the total number of DNA viruses found in the Drosophilidae to three.