Influenza A Virus on Oceanic Islands: Host and Viral Diversity in Seabirds in the Western Indian Ocean

Abstract

Ducks and seabirds are natural hosts for influenza A viruses (IAV). On oceanic islands, the ecology of IAV could be affected by the relative diversity, abundance and density of seabirds and ducks. Seabirds are the most abundant and widespread avifauna in the Western Indian Ocean and, in this region, oceanic islands represent major breeding sites for a large diversity of potential IAV host species. Based on serological assays, we assessed the host range of IAV and the virus subtype diversity in terns of the islands of the Western Indian Ocean. We further investigated the spatial variation in virus transmission patterns between islands and identified the origin of circulating viruses using a molecular approach. Our findings indicate that terns represent a major host for IAV on oceanic islands, not only for seabird-related virus subtypes such as H16, but also for those commonly isolated in wild and domestic ducks (H3, H6, H9, H12 subtypes). We also identified strong species-associated variation in virus exposure that may be associated to differences in the ecology and behaviour of terns. We discuss the role of tern migrations in the spread of viruses to and between oceanic islands, in particular for the H2 and H9 IAV subtypes.

Interpreting ELISA analyses from wild animal samples: Some recurrent issues and solutions

“…An ELISA targeting the nucleoprotein, an antigen known to be shared by all the subtypes of the virus, is generally used to first screen efficiently all the samples. In a second step, the ELISA positive samples can be analysed using inhibition of haemagglutination assays specific to each viral subtype (Lebarbenchon et al., ) or increasingly available multiplex assays (Freidl et al., ). Another example deals with the circulation of flaviviruses in bird populations: ELISA screening using an assay specific for a broad range of flaviviruses has been efficiently implemented to detect populations with positive samples that have then been analysed using more specific virus neutralization assays (Arnal et al., ).…”

Parasites of seabirds: A survey of effects and ecological implications

“…molecular biology, virus isolation) in sometimes high security laboratories such as for highly pathogenic avian influenza and West Nile viruses is needed, and certain biological safety precautions are required by law in some regions (e.g. Allison et al, 2015;Lebarbenchon et al, 2010Lebarbenchon et al, , 2015.…”

“…This supports the idea that bird age is an important factor involved in influenza virus infection. Investigations of virus transmission on tropical oceanic islands have also shown that terns could be involved in the introduction and maintenance of avian influenza viruses in these remote locations (Lebarbenchon et al, 2015).…”

Serological evidence for the circulation of flaviviruses in seabird populations of the western Indian Ocean

“…These islands are uninhabited or host small human communities (these islands are mainly nature reserves, military camps, or privately owned), except for Réunion island (800 000 inhabitants). The same sampling strategy was performed as in a previous investigation on influenza A virus infection in seabirds performed on the same bird communities and islands [32]. The most abundant and diverse bird species were sampled on each island by taking into account geographical, safety, ethical and sample conservation constraints.…”