Identification and characterization of common B cell epitope in bovine leukemia virus via high-throughput peptide screening system in infected cattle

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.

A new genotype of bovine leukemia virus in South America identified by NGS-based whole genome sequencing and molecular evolutionary genetic analysis

“…Moreover, the two phosphorylation sites on Tax protein, and NES and NLS regions in Rex protein were also conserved well. Thus, the fact that limited sequence variations are compatible with the development of a vaccine [ 19 , 64 , 65 ].…”

“…gp51 is required for cell entry and the target of neutralizing antibodies [ 8 , 16 ]. The N-terminal half of BLV gp51 contains three conformational epitopes, F, G and H [ 17 ], and plays an important role in viral infectivity and syncytium formation [ 7 , 18 , 19 ], while the C-terminal half of BLV gp51 contains the linear epitopes A, B, D, and E [ 16 , 17 ]. Therefore, the gp51 region has been widely used for BLV genotyping studies and recent phylogenetic studies of this region from viral strains isolated worldwide demonstrate that BLV can be classified into at least eight genotypes [ 20 – 33 ].…”

Epidemiology and genetic diversity of bovine leukemia virus

“…1a ). The structural protein and enzyme coding genes, namely, gag , pro , pol , and env , have essential and indispensable roles in the viral lifecycle, viral infectivity, and the production of infectious virions [ 19 – 24 ]. The gag gene of BLV is translated as the precursor, Pr45 Gag, and processed to generate three mature proteins [ 19 , 23 ]: the matrix protein, p15, which binds viral genomic RNA and interacts with the lipid bilayer of the viral membrane [ 25 ]; the capsid protein, p24, which is the major target of the host immune response, with high antibody titers against this molecule found in the serum of infected animals [ 26 , 27 ]; and the nucleocapsid protein, p12, which binds to packaged genomic RNA [ 28 ] (Fig.…”

New evidence of bovine leukemia virus circulating in Myanmar cattle through epidemiological and molecular characterization

“…Similar to the other members of the Retroviridae family, the BLV env gene encodes the envelope glycoprotein precursor pr72env, which is important for viral infection and syncytium formation. BLV env gene also encodes a mature surface glycoprotein (gp51) and a transmembrane protein (gp30) [13][14][15]. The glycoprotein gp51 plays a crucial role in the viral life cycle and influences the capacity of BLV to enter cells and has been identified as a target of specific neutralizing antibodies [16][17][18].…”