New gene-deletion strain offers promising vaccine breakthrough for African swine fever

Researchers have developed an attenuated African swine fever virus lacking 24 genes, showing full protection in pigs and potentially revolutionising vaccine strategies against this deadly livestock disease.

Researchers have reported a new attenuated African swine fever virus strain, ASFV-Δ24, that removed 24 genes across three separate genomic regions, including complete deletion of the MGF100 and MGF300 families. In pigs, the mutant caused no typical clinical disease and delivered full protection against a homologous challenge, according to the study.

The findings matter because African swine fever remains one of the most difficult livestock diseases to vaccinate against. Reviews in PubMed and Nature have noted that inactivated and subunit approaches have repeatedly fallen short, leaving live attenuated vaccines as the most credible route, albeit one complicated by safety concerns, residual virulence and the risk of reversion.

In the new work, ASFV-Δ24 replicated more slowly in cell culture, showed weaker adsorption and internalisation, and produced far more abnormal viral particles under electron microscopy. In pigs, all vaccinated animals survived the challenge, while unvaccinated controls developed fever and died within days. The vaccinated group also mounted a strong antibody response and showed much lower viral loads and tissue damage.

The result adds weight to the gene-deletion strategy that has already produced experimental candidates in Vietnam, the United States and elsewhere, while also offering a useful tool for studying how multigene families shape ASFV pathogenicity.

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