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Dead-box RNA Helicases / Chronic Disease / Infectious Disease Transmission, Vertical · Journal article
Virulence · August 7, 2026
Encouraging direction, but not yet definitive.
A live-attenuated Toxoplasma gondii RHΔddx6 vaccine candidate induced Th1-biased immunity and demonstrated complete or near-complete protection in mice against acute, chronic, and congenital infection. This preclinical study suggests the candidate warrants further development, but human safety and efficacy remain unknown.
Preclinical controlled animal experiments in mice. Female mice (strain not specified); includes pregnant mice for congenital transmission model. Virulence phenotype characterized in unvaccinated mice challenged with high inoculums (10^6 tachyzoites).. Intervention: Single immunization with live-attenuated T. gondii RHΔddx6 mutant at dose 1 × 10^6 tachyzoites. Compared with: Unvaccinated control mice challenged with wild-type RH or PRU strains. Xinxiang, China (affiliation of principal laboratories: Henan Medical University, Henan Institute of Science and Technology)..
Single immunization with 1 × 10^6 Δddx6 tachyzoites induced high T. gondii-specific IgG titers, CD4+/CD8+ T-cell activation, and IFN-γ production Vaccinated mice achieved 100% survival against lethal RH challenge 99.5% reduction in brain cyst burden following PRU strain infection (chronic model)
Safety was not reported in the material analysed. Check the source before drawing any conclusion about harm.
This vaccine candidate addresses an unmet need (no licensed human T. gondii vaccine exists) and demonstrates cross-stage protection. However, preclinical mouse models do not guarantee human safety or efficacy; additional development, including toxicology studies and potential Phase 1 trials in humans, would be necessary before clinical use.
A single-center preclinical study in mice showing robust immunogenicity and protection against multiple T. gondii challenge forms, but lacking human data and requiring further development before clinical translation.
As stated by the source record.
Quoted from the source exactly as published.
This vaccine candidate addresses an unmet need (no licensed human T. gondii vaccine exists) and demonstrates cross-stage protection. However, preclinical mouse models do not guarantee human safety or efficacy; additional development, including toxicology studies and potential Phase 1 trials in humans, would be necessary before clinical use.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
Toxoplasma gondii is an obligate intracellular parasite causing severe disease in immunocompromised individuals and congenitally infected infants. Despite decades of research, no licensed human vaccine exists. This study evaluates a novel live-attenuated vaccine candidate based on depletion of DDX6, a conserved DEAD-box RNA helicase involved in post-transcriptional gene regulation. A Δddx6 strain was generated in the type I virulent RH strain using CRISPR/Cas9, and its phenotype was comprehensively assessed. Although the mutant displayed only subtle defects in certain in vitro assays, it exhibited almost complete avirulence in mice even at high inoculums (106 tachyzoites), representing a dramatic attenuation phenotype not fully predicted by in vitro analyses. A single immunization with 1 × 106 Δddx6 tachyzoites induced robust Th1-biased immunity characterized by high T. gondii-specific IgG titers, CD4+/CD8+ T-cell activation, and IFN-γ production. Vaccinated mice achieved 100% survival against lethal RH challenge and showed a 99.5% reduction in brain cyst burden following PRU strain infection. Furthermore, the vaccine completely prevented vertical transmission in a pregnancy model. Transcriptomic analysis revealed widespread dysregulation in the Δddx6 strain, particularly downregulation of key virulence factors (ROPs, SAGs) and genes involved in intracellular transport. These findings demonstrate that targeting DDX6 generates a highly attenuated yet strongly immunogenic strain with exceptional cross-stage protective efficacy against acute, chronic, and congenital toxoplasmosis, representing a promising vaccine candidate worthy of further development.
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