Cocktail vaccine for the management of Hyalomma anatolicum and Rhipicephalus microplus

Dual gene silencing of FER2 and TPM genes in <i>Hyalomma anatolicum</i> resulted in a 75.3% reduction in infested ticks, a 95.4% decrease in egg masses, and a complete loss of egg hatching when compared to control ticks. Microscopically, an altered ovarian cellular architecture, marked by vacuolation and reduced nucleus-to-cytoplasmic ratio were noted in the gene knocked down ticks. An immunization with cocktails of 300 µg dose of each protein, rHaFER2 and rHaTPM was standardized in a rat model and was used to immunize cross-bred (<i>Bos indicus</i> x <i>B. taurus</i>) male cattle with Montanide ISA 50V2 adjuvant on days 0, 28, and 49. A significant (<i>p</i> < 0.001) IgG and IgG2 antibody response was observed in the immunized animals with high IgG levels sustained until day 119 post-primary immunization, showing a 4.1-fold increase over the pre-immunization period. The animals were challenged with larvae and adults of <i>H. anatolicum</i> and larvae of <i>Rhipicephalus microplus</i>. Immunization with the cocktail antigen resulted an efficacy of 70% and 76% against <i>H. anatolicum</i> larvae and adults, respectively, and 54% against <i>R. microplus</i> infestations. Compared to single-antigen immunization, the immunization with cocktail antigens demonstrated higher protection against <i>R. microplus</i> and <i>H. anatolicum</i> ticks. The results advance the development of cocktail vaccines to control multiple tick species.