Molecular analysis of the immunoglobulin genes in goose

• We identified three Ig heavy chain classes: IgM, IgA, IgY and the λ light chain in the goose.
• In addition to the full length of IgY, goose can also express a truncated isoform of IgY (IgY(ΔFc)).
• The generation of antibody diversity in goose mainly depends on gene conversion.

Immunoglobulins play an important role in adaptive immune system as defense molecules against pathogens. However, our knowledge on avian immunoglobulin genes has been limited to a few species. In this study, we analyzed goose (Anser cygnoides orientalis) immunoglobulin genes. Three IgH classes including IgM, IgA, IgY and λ light chain were identified. The IgM and IgA heavy chain constant regions are characteristically similar to their counterparts described in other vertebrates. In addition to the classic Ig isotypes, we also detected a transcript that encoded a truncated form of IgY (IgY(ΔFc)) in goose. Similar to duck, the IgY(ΔFc) in goose was generated by using different transcriptional termination signal of the same υ gene. Limited variability and only one leader peptide were observed in VH and VL domains, which suggested that gene conversion was the primary mechanism involved in goose antibody diversity. Our study provides more insights into the immunoglobulin genes in goose that had not been fully explored before.