CLONING AND CHARACTERIZATION OF CDNA CLONES ENCODING 2 BABESIA-BOVIS PROTEINS WITH HOMOLOGOUS AMINO-TERMINAL AND CARBOXY-TERMINAL DOMAINS

A dextran sulphate protein (DSP) fraction derived from Babesia bovis h as previously been shown to induce a protective immune response in cat tle. A B. bovis cDNA library was screened with both the complete anti- DSP serum and a subfraction of the anti-DSP serum affinity purified on a native B. bovis protein of approx. 80 kDa. cDNA clones encoding two different B. bovis proteins were identified. The product of one gene, Bv80, has a single divergent copy of a sequence of 149 amino acids (a pprox. 30% amino acid identity) in both the amino- and carboxy-termina l domains. These domains are separated by an array of short variant re peat sequences rich in proline and glutamic acid. The product of the o ther gene, BvVA1 (homologous to the previously described 225-kDa B. bo vis protein [191, is predicted to have a single divergent copy of a se quence of 170-171 amino acids (approx. 35% amino acid identity) in bot h the amino- and carboxy-terminal domains. These domains are also sepa rated by an array of repeats. The 73-amino acid repeat unit of this ar ray is composed of a number of variant derivatives of shorter repeat u nits. Detailed analysis of genomic clones flanking two alleles of the gene encoding BvVA 1 /225 kDa identified further members of a multi-ge ne family. This region of the genome of B. bovis has been subject to a large number of amplification processes.