Abstract
Background Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, the most common neoplastic disease of cattle. BLV is closely related to human T cell leukemia virus. B cell epitopes are important for the use of antibodies as therapeutic agents, the epitope-driven vaccine design, and immunological assays. A common B cell epitope for BLV has not yet been found due to individual differences in disease susceptibility.ResultsWe used a peptide microarray with 156 synthetic 15-mer peptides covering the envelope glycoprotein gp51 and the Gag proteins p15, p24, and p12 to map B cell epitope and one B cell epitope, gp51p16, was recognized by all four cattle experimentally infected with BLV. A newly developed high-throughput peptide ELISA system revealed 590 (91.2 %) of 647 cattle naturally infected with BLV, carrying 25 different bovine leukocyte antigen class II DRB3 (BoLA-DRB3) alleles, responded to a 20-mer gp51p16-C peptide containing a C-terminal cysteine and gp51p16. Alanine mutation and comparison of the sequences at 17 amino acid positions within gp51p16-C revealed that R7, R9, F10, V16, and Y18 were the common binding sites to BLV antibodies, and two of these sites were found to be highly conserved. Transient expression in the cells of five infectious molecular clones of BLV with a single alanine mutation at five common antibody binding sites had no effect syncytia formation of the gp51 protein. In addition, the mutant proteins, R7A and R9A had no effect on the expression of gp51 protein; the gp51 protein expressions of F10A, V16A and Y18A were lower than that of the wild type protein.ConclusionsThis is the first report to identify a common B cell epitope in BLV by comprehensive screening of BLV-infected cattle with varied genetic backgrounds in BoLA-DRB3. Our results have important implications for disease control and diagnosis.
Highlights
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, the most common neo‐ plastic disease of cattle
Identification of a common B cell epitope via a high‐throughput peptide enzyme-linked immunosorbent assay (ELISA) system To identify a B cell epitope in BLV, 156 synthetic peptides of 15 amino acids in length that were derived from the whole BLV Gag proteins, p12, p24, and p15, and the Env gp51 protein, were prepared, followed by peptide microarray [39]
The responses between the negative and positive serum samples obtained before and after experimental infection of four cattle, JBS4, JBS6, JBN1, and JBN2, that carried the bovine leukocyte antigen (BoLA)-DRB3*1601, *1501, *2703, or *0503 alleles (Table 1), resulted in the detection of B cell epitopes that responded with the positive serum from each cattle (Table 3)
Summary
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, the most common neo‐ plastic disease of cattle. BLV is closely related to human T cell leukemia virus. A common B cell epitope for BLV has not yet been found due to individual differences in disease susceptibility. Bovine leukemia virus (BLV) is the etiologic agent of enzootic bovine leukosis (EBL), the most common neoplastic disease of cattle, and is closely related to human T cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2). BLV is highly prevalent in several regions of the world and induces major economic losses in cattle production and export [4]. In 1995, losses in the dairy industry due to BLV from USA were estimated to be $US 525 million annually [4]. Study had been reported the economic losse per case of lymphosarcoma was estimated to be $412 [7].
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