Vaccination of cattle against the Boophilus microplus using a mucin-like membrane glycoprotein

An antigen, BMA7, which induced partial immunity against tick infestation h as been isolated from Boophilus microplus using two different protein fract ionation protocols, accompanied by vaccination and parasite challenge trial s. The antigen is a 63 kDa glycoprotein isolated from semi-engorged adult f emale ticks. Though significant, the induced immunity is less striking than that previously reported for antigen Bm86 from the same parasite. However covaccination with Bm86 and BMA7 cart enhance immunity over that seen with a commercial vaccine based on Bm86 alone. Limited peptide sequence informat ion shows significant variation in the BMA7 protein occurs. The antigen has approximately 36 kDa of glycosylation, in both N-linked and O-linked oligo saccharides. There is evidence that both polypeptide and oligosaccharide ar e antigenic, but the chemical nature of the protective antigenic sites is n ot clear. There is little or no immunological response to the antigen durin g natural infestation with parasites, suggesting the antigen is 'concealed' and protective immunity dependent on artificial vaccination The antigen ha s some similarities with the vertebrate mucins. It is widely distributed in tick tissues and membrane bound but its function is currently unknown.