Abstract
BackgroundToxoplasmosis is an important zoonosis, being a cause of congenital disease and abortion in animals and humans. DNA vaccination as a promising vaccine remains a challenge for an improved delivery system.MethodsIn this study, attenuated Salmonella typhimurium BRD509 was used to deliver a DNA vaccine encoding several epitopes, derived from the tachyzoite proteins SAG1, GRA1, ROP2, GRA4 and bradyzoite proteins SAG2C, SAG2X of Toxoplasma gondii and A2/B subunit of cholera toxin. The recombinant plasmids were electroporated into attenuated Salmonella typhimurium. Humoral and cellular immune responses were evaluated for BALB/c mice administered with this attenuated recombinant Salmonella vaccine via the oral and nasal route or by intramuscular injection with DNA plasmid directly.ResultsHigh IgG levels were present in the mice immunized intramuscularly, while IgA levels were higher in the oral and nasal immunization groups. Furthermore, cellular immunity was activated in oral immunization groups with 60% survival rate following challenge with high virulent RH strain.ConclusionsThe results from this study indicate that a DNA vaccine encoding multi-epitopes of T. gondii delivered by attenuated Salmonella is promising.
Highlights
Toxoplasmosis is an important zoonosis, being a cause of congenital disease and abortion in animals and humans
Despite many efforts and significant advances in the understanding of the immune responses that occur after infection by T. gondii, animal experiments have shown that the effect of monovalent antigen vaccine is not ideal [5,6,7]
Recombinant Salmonella carrying pVAX1-multi-epitope genes (MEG)-CTXA2/B plasmid were identified by enzyme digestion, by PCR (Figure 1B) and further confirmed by sequencing
Summary
Toxoplasmosis is an important zoonosis, being a cause of congenital disease and abortion in animals and humans. Toxoplasma gondii is a single-cell obligate intracellular protozoan, which is widely prevalent in humans and animals [1,2]. This parasite is of major medical and veterinary importance, being a cause of congenital disease and abortion [3,4]. Recombinant Salmonella have been used as vaccine vectors to deliver both DNA and protein vaccines from a wide variety of bacterial, viral and parasitic sources [16,17]. Attenuation virulence bacteria, which can penetrate host cells delivering vaccine antigen to APCs, can be used effectively to transport immunogens [18,19]
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