• Vaccine Name: V-LSN
• Target Pathogen: Lassa Fever Virus
• Target Disease: Lassa fever
• Vaccine Ontology ID: VO_0004079
• Type: Vaccina virus
• Preparation: The sequence is derived from the Josiah strain of Lassa virus, isolated from a patient in Sierra Leone (Fisher-Hoch et al., 2000).
• Virulence:
• Description: V-LSN is a vaccinia viruses expressing the S-segment Lassa nucleoprotein (Fisher-Hoch et al., 2000).

Monkey Response

• Host Strain: Rhesus and Cynomolgus
• Vaccination Protocol: All animals received a single vaccination consisting of 0.2 ml of vaccine given intradermally and simultaneously at four separate sites (each forearm and the lateral aspect of each thigh) at a dilution which delivered to each animal a total dose of 10^9 PFU. All animals were challenged subcutaneously with 10^3 to 10^4 PFU of the Josiah strain of Lassa virus in 0.5 ml of phosphate-buffered saline within 36 to 700 days (Fisher-Hoch et al., 2000).
• Persistence: The latest day on which virus could be recovered from serum was day 14, and that from tissues was day 21. Evidence for persistence elsewhere in tissues or fluids in survivors could not be found by cocultivation of tissues taken up to 112 days following challenge. However, autopsy and biopsy material examined by RT-PCR revealed that viral RNA could be detected at least 112 days after challenge (Fisher-Hoch et al., 2000).
• Side Effects: Monkeys had marked lymphopenia and higher mean aspartate aminotransferase values than unvaccinated animals. The V-LSN-vaccinated animals were observed to be sicker and died earlier than unvaccinated animals (Fisher-Hoch et al., 2000).
• Efficacy: Vaccination using the nucleoprotein may protect primates against a lower challenge dose of Lassa virus, however, the V-LSN vaccine was not significantly protective (Fisher-Hoch et al., 2000).
• Description: 8 of the 11 vaccinated animals died, which shows that this vaccine was not significantly protective. The V-LSN animals appeared to have a shorter and more acute process than unprotected animals. The median day of death for V-LSN animals was day 11.5, compared with day 13 for the control animals. This phenomenon was related to the challenge dose. Back titration of the challenge inoculum used in the final experiment showed that the titer had dropped from 10^4 to 10^3 PFU/ml. The three V-LSN-vaccinated animals in that experiment that received the lower challenge titer survived. These three animals were rhesus monkeys (Fisher-Hoch et al., 2000).