Analysis of Genetic Diversity in Indian Isolates of Based on Gene Sequence.

The control of cattle tick, is focused on repeated use of acaricides. However, due to growing acaricide resistance and residues problem, immunization of animals along with limited use of effective acaricides is considered a suitable option for the control of tick infestations. To date, more than fifty vaccine candidates have been identified and tested worldwide, but two vaccines were developed using the extensively studied candidate, . The main reason for limited vaccine commercialization in other countries is genetic diversity in the gene leading to considerable variation in vaccine efficacy. India, with 193.46 million cattle population distributed in 28 states and 9 union territories, is suffering from multiple tick infestation dominated by . As has developed multi-acaricide resistance, an efficacious vaccine may provide a sustainable intervention for tick control. Preliminary experiments revealed that the presently available commercial vaccine based on the gene is not efficacious against Indian strain. In concert with the principle of reverse vaccinology, genetic polymorphism of the gene within Indian isolates of was studied. A 578 bp conserved nucleotide sequences of from 65 isolates collected from 9 Indian states was sequenced and revealed 95.6-99.8% and 93.2-99.5% identity in nucleotides and amino acids sequences, respectively. The identities of nucleotides and deduced amino acids were 94.7-99.8% and 91.8-99.5%, respectively, between full-length sequence (orf) of the gene of IVRI-I strain and published sequences of vaccine strains. Six nucleotides deletion were observed in Indian sequences. Four B-cell epitopes (D519-K554, H563-Q587, C598-T606, T609-K623), which are present in the conserved region of the IVRI-I sequence, were selected. The results confirm that the use of available commercial vaccines is not a suitable option against Indian isolates of . A country-specific multi-epitope vaccine consisting of four specific B-cell epitopes along with candidate molecules, subolesin and tropomyosin in chimeric/co-immunization format may provide a sustainable option for implementation in an integrated tick management system.