Marsupial and monotreme serum immunoglobulin binding by proteins A, G and L and anti-kangaroo antibody

• Binding of four Ig-binding reagents to sera from 17 marsupial or monotreme species was studied.
• Evolutionary distance between host species did not accurately predict Ig binding capacity.
• Monotreme sera reacted strongly with protein A.
• Marsupial sera reacted with protein A, protein L and polyclonal anti-kangaroo antibody.
• The results can be used to inform the selection of appropriate serological reagents.

Serological studies are often conducted to examine exposure to infectious agents in wildlife populations. However, specific immunological reagents for wildlife species are seldom available and can limit the study of infectious diseases in these animals. This study examined the ability of four commercially available immunoglobulin-binding reagents to bind serum immunoglobulins from 17 species within the Marsupialia and Monotremata. Serum samples were assessed for binding, using immunoblots and ELISAs (Enzyme-linked immunosorbent assays), to three microbially-derived proteins — staphylococcal protein A, streptococcal protein G and peptostreptococcal protein L. Additionally, an anti-kangaroo antibody was included for comparison. The inter- and intra-familial binding patterns of the reagents to serum immunoglobulins varied and evolutionary distance between animal species was not an accurate predictor of the ability of reagents to bind immunoglobulins. Results from this study can be used to inform the selection of appropriate immunological reagents in future serological studies in these clades.

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