Immunoglobulin G binding proteins in male Rhipicephalus appendiculatus ticks

Three abundant immunoglobulin G binding proteins (IGBPs) of 29 kDa (IGBP-MA), 25 kDa (IGBP-MB), and 21 kDa (IGBP-MC) were isolated from partly fed male Rhipicephalus appendiculatus ticks using an agarose-IgG column. After separating the proteins by SDS-PAGE, each individual IGBP band was cut out from the gel and used to raise antiserum in guinea pigs. Using immunoblotting, each of the three IGBPs was shown to be antigenically distinct, and specific for feeding male R. appendiculatus ticks. They were detected in the salivary glands of male ticks that had been feeding in either the presence of absence of female ticks, and appeared to be glycoproteins. The smallest protein, IGBP-MC, bound to guinea pig IgG (on which species the ticks were fed) and also bound to human and bovine IgG, whereas IGBP-MA and possibly IGBP-MB only bound to guinea pig IgG. The function of IGBPs in tick salivary glands and their significance in male ticks are discussed.