Immunoproteomic Identification and Vaccine Assessment of Trypanosoma vivax Invariant Surface Glycoprotein

African animal trypanosomosis, caused by Trypanosoma vivax, remains a significant challenge to cattle health and productivity in regions where it is endemic. The development of vaccines against this parasite is particularly challenging due to its highly effective immune evasion mechanisms.

An immunoproteomic approach was employed to identify T. vivax antigens through the immunocapture of parasite proteins using purified IgG from naturally infected sera. The objective of this strategy was to identify novel vaccine candidates, evaluated in a BALB/c murine model, aimed at promoting the induction of trypanotolerance.

An invariant surface glycoprotein (Uniprot code: F9WVM3, Tritryps code: TvY486_0045500), here designated TvISGAf, was selected based on its reported diagnostic relevance and its classification within the vivaxin antigen family. The protective potential of TvISGAf was evaluated in a murine model of T. vivax infection. Immunization with TvISGAf induced a robust antigen-specific humoral response, accompanied by a substantial cellular immune response. Following challenge, mice immunized with TvISGAf formulated with the ISPA adjuvant demonstrated enhanced control of body weight and hematocrit, and improved survival during the acute phase of infection in comparison to control group. Cytokine profiling revealed elevated levels of IFN-γ and TNF-α, accompanied by increased IL-10 production.

Collectively, these findings demonstrate that TvISGAf formulated with ISPA confers partial protection during acute phase of infection, consistent with the induction of trypanotolerance. These results support its potential as a promising component of a multivalent vaccine strategy against T. vivax, and highlight the need for further evaluation prior to assessment in the bovine host.