Development of specific enzyme-linked immunosorbent assays to evaluate the duck immune response after experimental infection with H5N1 and H7N1 low pathogenic avian influenza viruses.

The role of wild ducks as vectors of avian influenza viruses (AIVs) is well known but the immune response induced by AIV has different patterns according to the species of duck. The local antibody produced on the mucosal surface may play an important role not only in protection but also in limitation of the primary replication at the portal of entry and shedding of the virus. With this aim, specific enzyme-linked immunosorbent assays (ELISAs) for duck IgY, Ig light chain, IgY (heavy chain), IgA, and IgM were developed and used to evaluate the systemic and mucosal response induced in ducks after low pathogenic avian influenza (LPAI) infections. Two different species of ducks (Mule and Pekin), ages (1 wk and 3 wk), and virus strains (H7N1 and H5N1 low pathogenic viruses) were tested in two studies to evaluate the developed tools. In the two studies, systemic and mucosal AIV-specific duck IgY, Ig (light chain), IgY (heavy chain), IgA, and IgM were detected and followed. Therefore, the developed ELISAs proved to be efficient tools allowing the follow-up of the systemic and mucosal responses induced by LPAI infection in ducklings. These tools can be very helpful for the development and evaluation of AI vaccines for ducks.