Molecular Characterization and Immunogenicity Analysis of 4D8 Protective Antigen of Hyalomma anatolicum Ticks Collected from Western India

Vector-borne diseases, mainly transmitted by ticks, have a significant impact on the productivity and health of the animals in the developing countries. The quest for vaccine candidates to control these arthropod vectors remains pivotal and only rationale approach in controlling these diseases. Several candidate antigens have been screened over the years of which 4D8 tick protective antigen have shown promising results in controlling ixodid tick infestations. The 4D8 tick protective antigen is a structural and functional ortholog of insect subolesin/akirin and an evolutionary conserved protein, associated with multiple essential cellular processes in tick biology. Variable efficacy of recombinant subolesin/4D8 vaccine in field trials propels the approach towards synthetic peptide vaccine through reverse vaccinology. Advancement in reverse vaccinology has opened a new paradigm in the search of a perfect candidate antigen. The present study focused on full length amplification, cloning and sequencing of the 4D8 gene from Hyalomma antolicum. Combination of bioinformatics analysis and computational modeling tools identified linear as well as conformational B-cell and MHC class II epitopes conserved in many ixodid ticks which may be useful to design an universal synthetic peptide vaccine against multiple tick species. Western blot analysis using rabbit antisera against recombinant 4D8 protein has also confirmed the immunogenic potential of the candidate.