Protection induced by virus-like particles containing <i>Toxoplasma gondii</i> microneme protein 8 against highly virulent RH strain of <i>Toxoplasma gondii</i> infection

<div><p><i>Toxoplasma gondii</i> (<i>T</i>. <i>gondii</i>) microneme protein 8 (MIC8) represents a novel, functional distinct invasion factor. In this study, we generated virus-like particles (VLPs) targeting <i>Toxoplasma gondii</i> MIC8 for the first time, and investigated the protection against highly virulent RH strain of <i>T</i>. <i>gondii</i> in a mouse model. We found that VLP vaccination induced <i>Toxoplasma gondii-</i>specific IgG and IgG1 antibody responses in the sera. Upon challenge infection with RH strain of <i>T</i>. <i>gondii</i> tachyzoites, vaccinated mice showed a significant increase of both IgG antibodies in sera and IgA antibodies in feces compared to those before challenge, and a rapid expansion of both germinal center B cell (B220⁺, GL7⁺) and T cell (CD4⁺, CD8⁺) populations. Importantly, intranasally immunized mice showed higher neutralizing antibodies and displayed no proinflammatory cytokine IFN-γ in the spleen. Mice were completely protected from a lethal challenge infection with the highly virulent <i>T</i>. <i>gondii</i> (RH) showing no body weight loss (100% survival). Our study shows the effective protection against <i>T</i>. <i>gondii</i> infection provided by VLPs containing microneme protein 8 of <i>T</i>. <i>gondii</i>, thus indicating a potential <i>T</i>. <i>gondii</i> vaccine candidate.</p>