Abstract
BackgroundToxoplasmosis, caused by an obligate intracellular protozoan parasite Toxoplasma gondii, has been a serious clinical and veterinary problem. Effective DNA vaccines against T. gondii can prevent and control the spread of toxoplasmosis, which is important for both human health and the farming industry. The T. gondii 14-3-3 protein has been proved to be antigenic and immunogenic and was a potential vaccine candidate against toxoplasmosis. In this study, we evaluated the immune responses induced by recombinant plasmids encoding T. gondii surface antigen 1 (SAG1) and 14-3-3 protein by immunizing BALB/c mice intramuscularly.MethodsIn the present study, BALB/c mice were randomly divided into five groups, including three experimental groups (pSAG1, p14-3-3 and pSAG1/14-3-3) and two control groups (PBS and pBudCE4.1), and were immunized intramuscularly three times. The levels of IgG antibodies and cytokine production in mouse sera were determined by enzyme-linked immunosorbent assays (ELISA). Two weeks after the last immunization, all mice were challenged intraperitoneally (i.p.) with 1×104 tachyzoites of T. gondii and the survival time of mice was observed and recorded every day.ResultsMice vaccinated with pSAG1, p14-3-3 or pSAG1/14-3-3 developed high levels of IgG2a and gamma interferon (IFN-γ) and low levels of interleukin-4 (IL-4) and interleukin-10 (IL-10) compared to control groups (PBS or pBudCE4.1), which suggested a modulated Th1 type immune response (P<0.05). After intraperitoneal challenge with 1×104 tachyzoites of T. gondii (RH strain), the survival time of mice in experimental groups was longer than control groups (P<0.05). Mouse immunized with pSAG1/14-3-3 induced a higher level of IgG antibody response and significantly prolonged the survival time when compared with pSAG1 or p14-3-3 (P<0.05).ConclusionsThe study suggested that T. gondii 14-3-3 protein can induce effective immune responses in BALB/c mice and was a novel DNA vaccine candidate against toxoplasmosis, and the immune protective efficacy elicited by SAG1 gene was also demonstrated. Our results also showed multi-gene vaccine significantly enhanced immune responses and protective efficacy and was superior to the single-gene vaccine.
Highlights
Toxoplasmosis, caused by an obligate intracellular protozoan parasite Toxoplasma gondii, has been a serious clinical and veterinary problem
Gene expression in Hela cells Hela cells were transfected with pSAG1, p14-3-3 or pSAG1/14-3-3 for 48h, the level of mRNA and gene expression was evaluated by RT-PCR and Western blotting, respectively
In the Western blotting analysis (Figure 2C), the expression of surface antigen 1 (SAG1) gene and 14-3-3 protein was respectively detected in Hela cells transfected with pSAG1 or p14-3-3; These two kinds of protein were both detected in cells transfected with pSAG1/14-3-3, whereas the empty vector transfected cells did not show any band
Summary
Toxoplasmosis, caused by an obligate intracellular protozoan parasite Toxoplasma gondii, has been a serious clinical and veterinary problem. Effective DNA vaccines against T. gondii can prevent and control the spread of toxoplasmosis, which is important for both human health and the farming industry. The T. gondii 14-3-3 protein has been proved to be antigenic and immunogenic and was a potential vaccine candidate against toxoplasmosis. Toxoplasma gondii is a crescent shaped intracellular protozoan parasite that lives in various tissues of humans and other warm-blooded animals, causing toxoplasmosis [1]. There are three different infectious stages in the life cycle of T. gondii, i.e. tachyzoites, bradyzoites contained in tissue cysts and sporozoites inside sporulated oocysts, which are infectious for both intermediate and definitive hosts [4]. Toxoplasmosis has been an important public health concern in some countries, especially in tropical countries, which leads to significant economic loss in human health and the farming industry [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
