Antiserum to the egg coats of the fat-tailed dunnart (Marsupialia, Dasyuridae) cross-reacts with egg coats of other marsupial and eutherian species

We are examining the extracellular coats of the brush-tailed possum as a possible target for an immunocontraceptive vaccine for biocontrol of this pest species in New Zealand. In this study we have compared the composition of the extracellular coats of the fat-tailed and stripe-faced dunnarts, brush-tailed possum, domestic rabbit, and laboratory mouse using histochemistry, immunocytochemistry, and immunofluorescence. The histochemistry of the luminal epithelium of the oviduct and mucoid coats of the marsupials and rabbit indicated that they contain acidic glycoproteins. Immunofluorescence showed that polyclonal antiserum raised against the extracellular coats of the oocyte and early embryo of the fat-tailed dunnart, cross-reacted with the extracellular coats of the oocytes of all five species. These results suggest that there are common epitopes on the extracellular coats of oocytes and early embryos of distinctly related therian species. Further work to characterise these proteins is required to determine whether there is close homology between the oviductal glycoproteins of these species.