# Exploring the Combined Effect of Bm86 and Subolesin Polypeptide Vaccines in Cattle Naturally Infested with Rhipicephalus microplus

## TL;DR

A new vaccine combining two tick antigens significantly reduced tick infestations and reproduction in cattle, offering a sustainable alternative to chemical treatments.

## Contribution

The study demonstrates that a cocktail vaccine formulation of pBm86 and pSubolesin is more effective than co-immunization in controlling cattle ticks.

## Key findings

- The cocktail vaccine reduced adult female tick numbers, oviposition, and larvae hatching by 75% efficacy.
- Vaccinated cattle showed increased IgG levels specifically against Subolesin antigen.
- The cocktail formulation outperformed co-immunization in affecting tick biology and reproduction.

## Abstract

Cattle tick (Rhipicephalus microplus) is a major problem for cattle production in tropical and subtropical regions, where control often relies on chemical treatments that can be costly and may lose effectiveness over time due to the development of resistant tick populations. Vaccination is considered a sustainable alternative to chemical acaricides; however, improving vaccine efficacy remains a challenge. In this study, we evaluated a vaccine formulation combining two tick antigens, pBm86 and pSubolesin, in naturally infested cattle. The combined formulation reduced tick numbers and negatively affected tick reproduction, showing improved performance compared with the co-immunization group within this study. Vaccinated cattle developed significantly increased antigen-specific IgG levels, particularly against Subolesin. These results advance the development of cocktail vaccines to control R. microplus ticks and support further evaluation of multi-antigen vaccines as part of integrated tick management strategies to improve tick control and promote sustainable cattle production.

Rhipicephalus microplus infestations are a major concern for cattle production in neotropical regions. Anti-tick vaccines represent a sustainable alternative to chemical acaricides; however, improving vaccine efficacy remains challenging. This study evaluated the protective efficacy of polypeptide-based formulations of pBm86 and pSubolesin administered as co-immunization or as a cocktail in naturally infested cattle. Twelve calves were assigned to three groups: G1: 100 μg pBm86 + 50 μg pSubolesin co-immunized; G2: same formulation in cocktail; and G3: control. The cocktail significantly reduced adult female tick numbers, oviposition, and larvae hatching (p < 0.05), achieving a vaccine efficacy of 75%. In contrast, co-immunization achieved 50% efficacy. Vaccinated cattle developed significantly increased antigen-specific IgG levels against Subolesin than Bm86. IgG antibodies recognized native tick proteins by Western blot, and their efficacy was confirmed in vitro using blood-feeding assays. These results indicate that the cocktail formulation showed improved efficacy compared with co-immunization in this study, possibly by affecting complementary biological processes in ticks. Finally, this study supports the development of multi-antigen, polypeptide-based vaccines as a promising and sustainable approach for the control of R. microplus under natural field conditions.