Safety and immunogenicity of an adjuvanted human onchocerciasis vaccine candidate, Ov MANE1 : preclinical evaluation in a mice model

Abstract

Abstract Objectives Onchocerciasis, caused by the filarial worm Onchocerca volvulus , remains a major public health challenge because of the limitations of ivermectin‐based control strategies, thereby highlighting the need for more innovative tools such as vaccines. Methods This study investigated the safety and immunogenicity of a novel multi‐epitope chimeric antigen, Ov MANE1 formulated with Freund's adjuvant, in BALB/c mice. Mice were immunised at three time points of 2‐week intervals, with blood collected at each point to measure antibody levels and immune cells. Results Adjuvanted‐ Ov MANE1 exhibited a promising safety profile, revealing neither any physical signs of toxicity nor behavioural abnormalities. Immunological assays showed significant increases in total IgG absorbance (OD 450 nm) after the first ( P = 0.0260) and final booster doses ( P = 0.026). Total IgG ( P = 0.0086) and IgG1 ( P = 0.0465) absorbances also increased significantly over the study period, suggesting sustained humoral immunity. Moreover, cellular responses were significantly enhanced, with elevated leucocyte count ( P = 0.0190) and increased lymphocyte activity ( P = 0.0397) observed in the adjuvanted‐ Ov MANE1 group compared to the control. Indeed, total leucocytes increased progressively from Day 0 to Day 39, with significant differences recorded in the test group between doses: Days 0–14 ( P = 0.0043) and Days 14–28 ( P = 0.0079). The pronounced production of relevant antibodies and induction of cellular immunity is indicative of a mixed Th1/Th2 response and antibody‐dependent cellular cytotoxicity (ADCC) targeting O. volvulus L3 and/or other larval stages of the parasite. Conclusion These results position Ov MANE1 as a promising vaccine candidate against human onchocerciasis. However, further in vivo studies are needed to confirm and expand these findings.