Sexual Dimorphism-Driven Differences Are Overcome in a Preclinical Vaccine Model Against Trypanosoma cruzi

Camila Bulfoni Balbi¹Maria Florencia Pacini¹Brenda Dinatale¹Cecilia Farre^1,2Paula Cacik³Estefanía Prochetto³Florencia Belén González¹Iván Marcipar³Gabriel Cabrera³Ana Rosa Pérez^1,2,4*

• ¹Instituto de Inmunología Clínica y Experimental de Rosario IDICER CONICET UNR, Rosario, Buenos Aires, Argentina
• ²Centro de INvestigación y Producción de Reactivos Biológicos (CIPREB), Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
• ³Laboratorio de Tecnología Inmunológica, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Buenos Aires, Argentina
• ⁴National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina

Currently, no vaccine is available to prevent Chagas disease. Experimental vaccines against Trypanosoma cruzi (Tc) have shown high protection, but their development for humans still requires further study. Additionally, the sexual dimorphism observed in Chagas disease, with greater resistance in females, highlights the need to include both sexes in vaccine research to avoid biases. To assess the impact of sex on a recombinant vaccine, we evaluated its immunogenicity and efficacy after oral infection in male and female BALB/c mice. Additionally, gonadectomized (Gx) and sham-operated (Ms) males were used to estimate testosterone's effect. Vaccine consisted of a recombinant fragment of Tc-derived Trans-sialidase (TS) formulated with a cyclic-di-adenylate known as c-di-AMP (A), administered intranasally in three doses, two weeks apart. Control groups received TS alone, A, or a vehicle.Immunogenicity results showed that sexual dimorphism persisted after TS+A vaccination, with females having higher TS-specific IgG2a, IgG1, IgA, IL-17, and IFN-γ levels, while males showed greater delayed-type hypersensitivity and increased TS-specific IFN-γ+ROR-γt+ T-cell proliferation. Gx-TS+A-vaccinated males showed enhanced TS-specific IgG but not IgA, with negative effects on T-cell proliferation and higher parasite loads.Notably, after oral challenge with Tc, both sexes vaccinated with TS+A controlled parasitemia, reduced tissue parasite load, improved clinical outcomes, and attenuated myocarditis. In males, the vaccine also prevented the parasite-induced increase in splenic MDSCs and preserved CD4+FoxP3+ regulatory T-cells. Overall, TS+A nasal vaccination enhanced protection in both sexes, overcoming sexual dimorphism, highlighting its potential for human vaccine development.