Molecular characterization and B cell membrane expression analysis of Fc fragment gene of goose IgY

• IgY is an avian version of IgG that is the major systemic antibody produced after IgM in the primary antibody response and the main isotype produced in the secondary response.
• Fc fragment gene is the main difference between the IgY and IgY (ΔFc).
• The Fc fragment of goose IgY was first cloned here by RT-PCR.
• The characterization of the Fc fragment of goose IgY was analyzed.
• A surface membrane-bound (sIg) receptor form IgY that can be expressed on the surface of B lymphocytes is found in goose.

A novel goose immunoglobulin υ chain (Igυ) Fc fragment gene was cloned from splenic tissue mRNA using RT-PCR. Deduced amino acid sequence data from different vertebrates revealed high similarity to IgY-Fc fragments of duck (91%) and chicken (64%). Molecular characterization showed that the goose IgY-Fc fragment was consistent with the definition of immunoglobulin, and had the same antigenicity to natural IgY. Flow cytometry and laser scanning confocal microscopy showed that the polyclonal antibody against GoυFc reacted with the membrane surface of B lymphocytes in peripheral blood, which indicates that IgY was expressed on the surface of B cells. Analyses of the gene sequence of the goose IgY-Fc fragment and expression of B cell membrane may provide insight into the evolution of the Ig heavy chain gene family and benefit future studies on the avian immune system.