Effects of pRmS-17-specific antibodies on reproductive performance and tissue integrity of Rhipicephalus microplus.

The cattle tick Rhipicephalus microplus is the most economically important ectoparasite worldwide, affecting animal health, welfare, and cattle production in tropical and subtropical regions. Anti-tick vaccines have emerged as a promising alternative to chemical acaricides for cattle tick control. To date, studies with a peptide derived from the RmS-17 antigen have demonstrated protective efficacy against R. microplus tick infestation in cattle and shown the ability to elicit a strong, specific humoral immune response. Based on these findings, the present study evaluated the direct effects of anti-pRmS-17 antibodies on reproductive performance and tissue integrity using in vitro assays. A total of 45 semi-engorged R. microplus females were divided into three experimental groups and artificially fed for 48 h with anti-pRmS-17 IgG, anti-Bm86 IgG, or control serum to assess reproductive parameters. Additionally, 15 semi-engorged ticks were similarly fed and divided into three groups for histological analysis. The results showed that ticks fed with antigen-specific IgG antibodies showed significant reductions in oviposition (55% in the anti-Bm86 group) and egg hatching (47% in the anti-pRmS-17 group) compared with control ticks (P < 0.05). The histological analysis revealed marked morphological alterations in the midgut of IgG-fed ticks, including loss of germinative cells and reduced formation of new digestive cells, suggesting a delay in digestive metabolism. In conclusion, these findings provide functional and histological evidence supporting the relevance of pRmS-17 as a promising antigen for anti-tick vaccine development and its potential inclusion in integrated tick management programs to reduce the impact of R. microplus on cattle production.