Immunoglobulins of the Australian brush-tailed opossum, Trichosurus vulpecula

Using standard methods IgG, IgM and (s) IgA were isolated from the serum or intestinal fluid of the Australian brush-tailed opossum, Trichosurus vulpecula. The molecular weights of the intact immunoglobulin molecules and their heavy and light chains were established. Two forms of IgG were seen which differed in their abilities to bind to insoluble matrices and also in their molecular weights. No antigenic differences were seen between them on analysis by agar diffusion. The molecular weights of opossum IgM and the two forms of IgG were similar to those of the corresponding immunoglobulins of man and other marsupials. However, the molecular weight of the IgA seen in intestinal fluid and results from its analysis by agar diffusion suggest that the molecule may lack secretory component.