Abstract
Background Toxoplasma gondii is an opportunistic protozoan closely associated with AIDS and vertical transmission. T. gondii actin depolymerizing factor (TgADF) plays an important role in actin cytoskeleton remodeling, and it is required to invade host cells. TgADF was a promising vaccine candidate. To observe the immunological changes and protective efficacy of recombinant TgADF protein (rTgADF) against T. gondii infection, we optimized the intranasal immunization dose of rTgADF and analyzed the survival rate and tachyzoite loads in mouse tissues after oral challenge with T. gondii tachyzoites.ResultsrTgADF was prepared, purified, and combined with mouse anti-His antibody and rabbit anti-T. gondii serum. After intranasal immunization with 10 μg, 20 μg, 30 μg, or 40 μg of rTgADF, the 30-μg group elicited high levels of secretory IgA (sIgA) in nasal, intestinal, and vesical washes, raised IgG titres in the sera, strong proliferation of splenocytes, and increased secretion of IL-2 and IFN-γ when compared with the control group. When the mice were orally challenged with T. gondii, an increase in the survival rate (36.36 %) and a decrease in the tachyzoite loads in the liver (67.77 %) and brain (51.01 %) were observed.ConclusionsOur findings demonstrate that intranasal immunization with rTgADF can simultaneously trigger mucosal and systemic immune responses and protect the mice against T. gondii infection.
Highlights
Toxoplasma gondii is an opportunistic protozoan closely associated with AIDS and vertical transmission
T. gondii actin depolymerizing factor (TgADF) was inserted into pET-30a(+) and verified using polymerase chain reaction (PCR), restriction endonuclease digestion, and sequencing
SDS-PAGE showed that the isolated protein was soluble and approximately 20 kDa, which is the molecular weight of the expressed recombinant TgADF protein (rTgADF) protein and a polyhistidine tag (Fig. 1b)
Summary
Toxoplasma gondii is an opportunistic protozoan closely associated with AIDS and vertical transmission. To observe the immunological changes and protective efficacy of recombinant TgADF protein (rTgADF) against T. gondii infection, we optimized the intranasal immunization dose of rTgADF and analyzed the survival rate and tachyzoite loads in mouse tissues after oral challenge with T. gondii tachyzoites. Toxoplasma gondii is an obligate intracellular protozoan that invades the nucleated cells of humans and many other mammals. The first commercial vaccine for toxoplasmosis was used to control abortion in sheep [6]. This vaccine from the live-attenuated S48 strain was not appropriate for humans because it could revert to the pathogenic strain [7]. Many studies focused on crude inactivated antigen vaccines, subunit
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