Single-dose VSV-based vaccine protects against Kyasanur Forest disease in nonhuman primates

Kyasanur Forest disease virus (KFDV) is an endemic arbovirus in western India mainly transmitted by hard ticks of the genus Haemaphysalis. KFDV causes Kyasanur Forest disease (KFD), a syndrome including fever, gastrointestinal symptoms, and hemorrhages. There are no approved treatments, and the efficacy of the only vaccine licensed in India has recently been questioned. Here, we studied the protective efficacy of a vesicular stomatitis virus (VSV)–based vaccine expressing the KFDV precursor membrane and envelope proteins (VSV-KFDV) in pigtailed macaques. VSV-KFDV vaccination was found to be safe and elicited strong humoral and cellular immune responses. A single-dose vaccination reduced KFDV loads and pathology and protected macaques from KFD-like disease. Furthermore, VSV-KFDV elicited cross-reactive neutralizing immune responses to Alkhurma hemorrhagic fever virus, a KFDV variant found in Saudi Arabia.