Persistence of maternal antibodies to influenza A virus among captivemallards (Anas platyrhynchos)

AbstractWild waterfowl are maintenance hosts of most influenza A virus (IAV) subtypes and are often the subjects of IAV surveillanceand transmission models. While maternal antibodies have been detected in yolks and in nestlings for a variety of wildbird species and pathogens, the persistence of maternal antibodies to IAVs in mallard ducklings (Anas platyrhynchos) hasnot been previously investigated. Nonetheless, this information is important for a full understanding of IAV transmissiondynamics because ducklings protected by maternal antibodies may not be susceptible to infection. In this study, we examinedthe transfer of IAV-specific maternal antibodies to ducklings. Blood samples were collected approximately every five daysfrom ducklings hatched from hens previously infected with an H6 strain of IAV. Serum samples were tested for antibodiesto IAV by an enzyme-linked immunosorbent assay. The median persistence of maternal antibodies in ducklings was 12.5days (range: 4-33 days) post-hatch. The majority of ducklings (71%) had detectable maternal antibodies from 4 to 17 dayspost-hatch, while a small subset of individuals (29%) had detectable maternal antibodies for up to 21-33 days post-hatch.Antibody concentrations in hens near the time of egg laying were correlated with maternal antibody concentrations in theinitial blood sample collected from ducklings (0-4 days post-hatch). Knowledge of the duration of maternal antibodies inducklings will aid in the interpretation of IAV serological surveillance results and in the modeling of IAV transmissiondynamics in waterfowl