Current research for a vaccine against Lassa hemorrhagic fever virus

Warner, Bryce M; Safronetz, David; Stein, Derek R

Another recombinant vaccine developed by the same research group 53 makes use of the yellow fever 17D (YF17D) vaccine, which is one of the safest and most effective vaccines ever developed. The YF17D vaccine is highly immunogenic, induces strong cell-mediated immunity, and tolerates recombinant addition of transgenes into its genome. An initial vaccine developed to express the LASV GPC was able to protect 80% of strain 13 guinea pigs from lethal LASV challenge. However, the genetic stability of the virus was less than ideal and GPC expression waned over 5 passages. 53 In an attempt to remedy the genetic instability, separate recombinant viruses were generated expressing GP1 or GP2, as well as attempts to shorten the transgene. 54 A mixture of the two recombinant viruses protected strain 13 guinea pigs from fatal LASV challenge; however, sterilizing immunity was not achieved. Unfortunately, further testing of the YF17D-GPC LASV vaccine in marmosets resulted in poor immunogenicity and no protection from lethal LASV challenge. 55 While YF17D is a safe vaccine, more development is currently needed to achieve an efficacious vaccine for both yellow fever and LASV.