Characterization of Amblyomma variegatum tick saliva and salivary gland antigens inducing anti-tick immunity in boran cattle

Abstract

The sequence of proteins synthesized during the feeding of Amblyomma variegatum and humoral resistance acquired by Boran cattle when exposed to A. variegatum infestations were studied. Resistance was induced by repeatedly infested cattle with all stages of the tick. Salivary gland proteins possibly responsible for the acquired immunity were studied by analysing homogenates of salivary glands (SGA) on 5-20% gradient Sodium dodecylsulphate Polyacrylamide gel electrophoresis (SDS-PAGE) and comparing them to those in the tick saliva (SA) and nymph homogenates (NH). The proteins with Mr 18, 49.5, 55, 67.5 and 160 kDs were found unique for the tick saliva. On the other hand the proteins with molecular weights of about 17, 33, 27 and 66 kDs, which seemed to have been synthesized at different times during the feeding process, were only found in SGA. When SDS-PAGE was followed with immunobloting, IgG1 subclass isolated from infestation sera recognized prominently two SGA proteins with Mr of about 58 and 53 kD and a third high molecular weight protein, less prominently. Apart from the high molecular weight protein, the rest were not recognized by the IgG2 also from the same infestation sera.