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In a major advancement in the fight against Lassa fever, researchers from Texas Biomedical Research Institute (Texas Biomed), The Scripps Research Institute, and the National Institute of Allergy and Infectious Diseases (NIAID) have developed a promising new vaccine candidate that successfully protected guinea pigs from a lethal dose of the Lassa virus. This groundbreaking research, recently published in npj Vaccines, marks a significant milestone in the quest to combat this deadly disease.
Lassa fever, caused by the Lassa virus, is a major health concern in West Africa, with fatality rates estimated between 15% and 20%. Despite its impact, there are currently no approved vaccines or cures. The virus spreads through contact with food or surfaces contaminated by infected rodents, and while many people remain asymptomatic, others can experience severe symptoms including high fever, bleeding, and organ failure.
Given its potential to cause public health emergencies, the World Health Organization has classified Lassa fever as a priority for vaccine research and development.
A Decade of Groundbreaking Research
For the past decade, Dr. Luis Martínez-Sobrido of Texas Biomed and Dr. Juan Carlos de la Torre of Scripps Research have been working on a live-attenuated vaccine for Lassa virus. Live-attenuated vaccines use weakened versions of the virus to stimulate the immune system, providing long-lasting and broad protection. This approach has proven successful for other viruses, including measles and smallpox.
To ensure safety, the researchers developed a modified Lassa virus that cannot revert to its original form or recombine with other virus strains to cause disease. Their innovative method involved editing two sections of the virus’s genome—one by codon deoptimization to reduce the production of a key viral protein, and the other by replacing a segment of the virus’s RNA. This double attenuation strategy resulted in a vaccine candidate that, according to the researchers, is “unbreakable” and highly unlikely to regain virulence.
Promising Results in Animal Trials
In preclinical studies, the vaccine demonstrated exceptional safety and efficacy. The researchers tested it on 50 guinea pigs, half of which received the vaccine and half remained unvaccinated. After exposure to a normally lethal dose of the virus, all vaccinated guinea pigs remained healthy, with no adverse effects. The vaccine proved to be 100% protective—an outstanding result that researchers are eager to build upon.
Dr. Martínez-Sobrido called the findings “exactly what you want” in a vaccine, emphasizing that the results were a clear indication of its potential.
Next steps include testing the vaccine on nonhuman primates, which is the gold standard for evaluating vaccine safety and efficacy before human clinical trials. If successful, this vaccine could become a critical tool in the fight against Lassa fever.
This breakthrough brings hope to the millions at risk of the disease, marking a promising step toward a future where Lassa fever may no longer be a public health threat.
Reference: “A Lassa virus live attenuated vaccine candidate that is safe and efficacious in guinea pigs” by Brian D. Carey, Shuiqing Yu, Jillian Geiger, Chengjin Ye, Louis M. Huzella, Rebecca J. Reeder, Monika Mehta, Shawn Hirsch, Rebecca Bernbaum, Beatrice Cubitt, Bapi Pahar, Scott M. Anthony, Anthony Marketon, John G. Bernbaum, Julie P. Tran, Ian Crozier, Luis Martínez-Sobrido, Gabriella Worwa, Juan Carlos de la Torre and Jens H. Kuhn, npj Vaccines, November 17, 2024. DOI: 10.1038/s41541-024-01012-w.
