A vaccine candidate for Lassa virus (LASV) is to be shortly trialled in humans following positive pre-clinical animal model tests, according to study findings published in the journal Science Translational Medicine.
Researchers used two vaccine platforms based on live attenuated viruses modified to express LASV antigens: a recombinant measles vaccine strain, which had already produced very positive results in clinical trials for chikungunya; and a recombinant Mopeia virus, closely related to the Lassa virus but not pathogenic for humans, that was genetically hyperattenuated by the study team.
In cynomolgus monkey subjects the vaccines were well tolerated and protected from LASV infection and disease after a single immunisation but with varying efficacy.
Analysis of the immune responses showed that complete protection was associated with robust secondary T cell and antibody responses against LASV. Transcriptomic and proteomic analyses showed an early activation of innate immunity and T cell priming after immunisation with the most effective vaccines, with changes detectable as early as two days post-immunisation.
“The most effective vaccine, the one based on the measles vaccine platform expressing LASV antigens, was recently selected by the CEPI (Coalition for Epidemic Preparedness Innovations) to enter clinical trials in humans by the end of the year,” said study author Sylvain Baize.