The Immune Response of the Quokka (Setonix brachyurus).

The quokka (Setonix brachyurus) a macropod marsupial endemic to Western Australia forms circulating antibodies to bacteriophage ΦX174, Salmonella adelaide flagella, sheep erythrocytes and bovine serum albumin. The kinetics of antibody production in the primary and secondary responses suggest that the immunological capacity of the quokka is between that of eutherians and the lower vertebrates. Three classes of antibody, macroglobulin, IgG and a low molecular weight antibody (80,000 daltons) were produced. However, the production of low molecular weight antibody was dependent upon the nature of the antigen. Evidence is presented to suggest that while the IgG and low molecular weight classes of antibody share common antigenic determinants on the heavy chains, they are independent entities. A low molecular weight degradation product of IgG accumulated in immune sera but the low molecular weight antibody is neither a degradation nor an anabolic byproduct of IgG immunoglobulin. [ABSTRACT FROM AUTHOR]