Immune Response of BALB/c Mice toward Putative Calcium Transporter Recombinant Protein of Trichomonas vaginalis

Abstract

Trichomoniasis is a common sexually transmitted infection caused by Trichomonas vaginalis, which actually does not exist a vaccine for control or prevention. Thus, the identification of new and potent immunogens in T. vaginalis, which can contribute to the development of a vaccine against this parasite, is necessary. Therefore, the aim of this work was to evaluate the potential of a recombinant Transient Receptor Potential-like channel of T. vaginalis (TvTRPV), as a promising immunogen in BALB/c mice. First, TvTRPV was cloned and expressed as a recombinant protein in Escherichia coli BL21 cells and purified by nickel affinity. Next, BALB/c mice were immunized and the antibody levels in mice serum and cytokines from the supernatant of macrophages and from co-culture systems were evaluated. Recombinant TvTRPV triggered high levels of specific total IgG in sera from the immunized mice. Also, a statistically significant increase of cytokines: IL-1β, IL-6, and TNF-α after stimulation with the corresponding antigens in vitro, was identified. Moreover, co-cultures using CD4+ T cells from immunized mice were able to identify higher levels of IL-10 and IFN-γ. These results were useful to validate the immunogenicity of TvTRPV in BALB/c mice, where IL-10-IFN-γ-secreting cells could play a role in infection control, supporting the potential of TvTRPV as a promising target for vaccine against T. vaginalis.

Keywords: BALB/c mouse; TRPV channel; Trichomonas vaginalis; immune response; recombinant protein.

Fig. 1

Prokaryotic expression and purification of recombinant TvTRPV. 0 hr, E. coli BL21 not induced; 24 hr, induction time after adding 1 mM IPTG; IF, insoluble fraction of induced cells; SF, soluble fraction of induced cells; W1 and W2, washings E1 and E2, TvTRTPV protein obtained by elution; MW, molecular weight marker.

Fig. 2

Effect of recombinant TvTRPV on the macrophages 1L-1β, IL-6 and TNF-α production. Each bar represents the mean value±standard deviation (SD). Significance was accepted by comparison with the unimmunized control: (C-), (Dunnett, *P <0.05). Macrophages stimulated with LPS (1 μg/ml) were used as positive controls for cytokine production.

Fig. 3

IFN-γ and IL-10 levels detected in co-culture system. Purified CD4⁺ T cells from immunized mice with different doses of recombinant TvTRPV (TvTRPV50, TvTRPV100, and TvTRPV200) stimulated with macrophages treated with different doses of recombinant TvTRPV (1, 10, and 100 μg). Co-culture systems were set up with 1:2 CD4⁺ T-cell:MØ. Each bar represents the mean value±standard deviation (SD). Significance was accepted by comparison with CD4⁺ T cells stimulated with macrophages without treatment: C (-), (Dunnett, *P<0.05).