Kasaija et al.
One-year follow-up evaluation of approved Subolesin anti-tick vaccine in Uganda Vaccine. 2024, 44:12656.
Doi: 10.1016/j.vaccine2024.126562
Ticks and tick-borne diseases affect cattle welfare and production. In Uganda, as a result, yearly losses are estimated to be more than US$ 1.1 billion.
A tick vaccine has been developed based on recombinant Rhipicephalus appendiculatus Subolesin (also known as 4D8 or akirin) as antigen adjuvanted by Montanide ISA V2 in a stable water in oil emulsion. Primary vaccination of cattle consisted of three doses applied on days 0, 30, and 181 (100 µg antigen each). A controlled field trial was carried out at different locations in Uganda, and infestation by various tick species and the prevalence of pathogens in cattle was evaluated.
Anti-Subolesin IgG titers were significantly higher in vaccinated cattle compared to controls, although titers decreased by day 180. Vaccinated cattle exhibited a significant reduction in tick infestation, as well as decreased fertility, fitness, and weight of ticks. Effectiveness varied by location and tick species. Surveillance over 367 days demonstrated a sustained reduction in tick manifestation compared to control cattle. The vaccination was found to be safe, with no adverse effects on organ function or overall cattle health. These results supported the vaccine’s registration and commercialization as a tool to reduce tick populations, mitigate risks associated with tick-borne diseases in humans and animals, and decrease reliance on chemical acaricides in Uganda.
Following vaccine approval, a one-year follow-up study was conducted. The Subolesin-specific IgG response persisted for at least seven months after the initial three immunizations, supporting the need for an annual booster dose to maintain protective antibody titers. Although not statistically significant, a trend toward a negative correlation was observed between Subolesin antibody titers and Crimean-Congo Hemorrhagic Fever-positive cattle.