An attenuated Lassa vaccine in SIV-infected rhesus macaques does not persist or cause renavirus disease but does elicit protective immunity

Lassa fever (LF) is a rodent-borne viral disease that can be fatal for human beings. In this study, an attenuated Lassa vaccine candidate, ML29, was tested in SIV-infected rhesus macaques for its ability to elicit immune responses without instigating signs of virulent disease. ML29 is a reassortant between Lassa and Mopeia viruses that causes a transient infection in non-human primates and confers sterilizing protection from lethal Lassa viral challenge. However, since the LF endemic area of West Africa also has high HIV seroprevalence, it is important to determine whether vaccination could be safe in the context of AIDS. SIV-infected and uninfected rhesus macaques were vaccinated with the ML29 virus and monitored for classical and non-classical signs of arenavirus disease. Classical disease signs included viremia, rash, weight loss, high liver enzyme levels, and virus invasion of the central nervous system. Non-classical signs derived from profiling the blood transcriptome of virulent and non-virulent arenavirus infections included increased expression of interferon response genes and decreased expression of COX2, IL-1?, coagulation intermediates and nuclear receptors needed for stress signaling. Here it is demonstrated that SIV-infected and uninfected rhesus macaques responded similarly to ML29 vaccination, and that none developed signs of arenavirus disease or persistence. Furthermore, 5 of 5 animals given a heterologous challenge with a lethal dose of LCMV-WE survived without developing disease signs.

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Zapata JC, Poonia B, Bryant J, Davis H, Ateh E, George L, Crasta O, Zhang Y, Slezak T, Jaing C, Pauza CD, Goicochea M, Moshkoff D, Lukashevich IS, Salvato MS