Suppression of Highly Pathogenic Avian Influenza A/H5N1 Infection Using Migratory Antibody Passed from Mother to Chick

Mammals are equipped with an immune system in which antibodies from mothers transfer to children through the placenta and breast milk. These antibodies are called migratory antibodies and are responsible for protecting young children with an incomplete immune function against infection. In egg-laying animals, such as birds, migratory antibodies can be transferred from mothers to their eggs, thereby protecting their offspring. Even in domestic chickens, migratory antibodies from mothers are useful for defense against various infectious diseases, and the mother’s immune status determines the susceptibility of chicks to infection.

Highly pathogenic avian influenza is the most feared infectious disease in poultry, and in recent years, a number of infectious and death cases have been reported in humans as well, mainly in Southeast Asia. In avian flu-free countries, vaccination is not conducted, and if infection occurs, all suspected infected chickens must be disposed, which causes a large economic loss.

In this study, the authors investigated the presence of anti-avian influenza virus antibody in chickens hatched on a poultry farm in Indonesia and examined the involvement of migratory antibodies in protecting against virus infection by infectious experiments of highly pathogenic avian influenza in chickens.

Thirty newly-hatched chicks were collected from poultry farms selected at random in Indonesia. The authors confirmed that these birds had no history of vaccination with avian influenza vaccine. In addition, specific-pathogen-free (SPF) chicks were purchased and used for experiments as controls. Blood was sampled at 10 days of age. The serum titer of antibodies against A/H5N1 antigens was measured by an enzyme-linked immunosorbent assay (ELISA). Antibodies against avian influenza virus were evaluated in all birds.

Since these young birds had no history of vaccination, the antibodies were deemed to have been transferred from the mother birds. The enzyme-linked immunosorbent assay antibody titer in each bird varied. Infection of these birds with highly pathogenic avian influenza virus A/H5N1 intra-nasally resulted in a high mortality rate in chicks with low antibody titers but a low mortality rate in chicks with high antibody titers.

In conclusion, the findings suggest that the transfer of antibodies from mother birds to their chicks may be a way to prevent avian influenza infection in the offspring. Maternal antibodies migration to chicks is considered effective for preventing virus infection, but the development of a good-quality vaccine and improvements in existing vaccination programs are required.

Article by Kazuhide Adachi, et al, from Japan and Indonesia.

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