Evaluation of Protective Immune Responses Induced by Recombinant TrxLp and ENO2 Proteins againstToxoplasma gondiiInfection in BALB/c Mice

Abstract

Toxoplasma gondii is an obligate intracellular parasitic protozoan that can infect almost all species of warm-blooded animals. As any chemical-based drugs could not act against the tissue cyst stage of T. gondii, vaccination may be one of the ideal control strategies. In the present study, two new vaccine candidates, named TgENO2 and TgTrxLp, were purified from Escherichia coli with pET-30a(+) expression system and then were injected into BALB/c mice to evaluate the protective efficacy against acute and chronic toxoplasmosis. The results showed that both the recombinant proteins, either alone or in combination, could elicit strong humoral and cellular immune responses with a higher level of IgG antibodies, IFN-γ, IL-2, CD4+, and CD8+ T cells as compared to those in mice from control groups. After acute challenge with tachyzoites of the GJS strain, mice immunized with rTgTrxLp (8 ± 2.77 d), rTgENO2 (7.4 ± 1.81 d), and rTgTrxLp + rTgENO2 (8.38 ± 4.57 d) proteins showed significantly longer survival time than those that received Freund's adjuvant (6.78 ± 2.08 d) and PBS (6.38 ± 4.65 d) (χ 2 = 9.687, df = 4, P = 0.046). The protective immunity of rTgTrxLp, rTgENO2, and rTgTrxLp + rTgENO2 proteins against chronic T. gondii infection showed 69.77%, 58.14%, and 20.93% brain cyst reduction as compared to mice that received PBS. The present study suggested that both TgENO2 and TgTrxLp were potential candidates for the development of multicomponent vaccines against toxoplasmosis.

Evaluation of protective immunity induced by recombinant calcium-dependent protein kinase 1 (TgCDPK1) protein against acute toxoplasmosis in mice

“…The percentages of both CD3 + CD4 + CD8 − and CD3 + CD8 + CD4 − cells increased, which were synergistic to cytotoxic activity against Toxoplasma infection and also responsible for the secretion of the increased levels of IFN-γ. These findings were similar to the previous results reported by other researchers [36,43,44].…”

“…Therefore, the IgG isotype was detected by ELISA assay to determine the T-helper response in immunized mice. As result, high level of IgG1 and IgG2a were induced by rTgCDPK1 protein in the experimental group in contrast to the control group, which is consistent to previous findings [17,[35][36][37][38]. The result indicated both the two humoral response were occurred simultaneously.…”

Resistance to ChronicToxoplasma gondiiInfection Induced by a DNA Vaccine Expressing GRA16

“…It is thus particularly urgent to develop effective vaccines. In recent years, numerous studies have evaluated the protective efficacy of different antigens, such as MIC6 [ 27 ], ROP18 [ 28 ], NTPase II [ 29 ], TrxLp, and ENO2 [ 30 ]. Most of them showed partial protection against toxoplasmosis.…”

Evaluation of Protective Immune Response Induced by a DNA Vaccine Encoding GRA8 against Acute Toxoplasmosis in a Murine Model

“…In recent years, owing to the easy production and low cost of DNA vaccines and the fact that DNA vaccines can elicit long-lasting humoral and cellular immune responses, the development of effective DNA vaccines has emerged as an active research field in the fight against toxoplasmosis [ 22 , 30 , 31 ]. Numerous studies have evaluated the protective efficacy of different antigens, such as SAG4, GRA15, MIC13, ROP18, NTPase II, TrxLp, and ENO2 [ 18 , 24 , 32 – 35 ]. Most of them showed partial protection against toxoplasmosis.…”