SAFETY AND IMMUNOGENICITY OF A LIVE-ATTENUATED JUNIN (ARGENTINE HEMORRHAGIC-FEVER) VACCINE IN RHESUS MACAQUES

The safety and immunogenicity of Candid #1, a live-attenuated Junin vi rus vaccine, were evaluated in rhesus macaques. Candid #1 was inoculat ed subcutaneously in graded doses ranging from 16 to 127,200 plaque-fo rming units (PFU) into four groups of five animals each; four controls received saline. There was no significant effect of the immunization on any physical, hematologic, or biochemical parameter measured. Junin virus was recovered by cocultivation from peripheral blood mononuclea r cells (PBMC) of 14 (70%) of 20 animals from 1 to 21 days after immun ization; 27 (12%) of 223 PBMC samples that represented animals in all four dose groups were positive. In contrast, virus was recovered from the plasma of only two of 20 macaques (two of 225 samples [0.9%]), and only once (by amplification) from throat swabs. No evidence of revers ion was detected in any blood isolate. All animals developed a detecta ble neutralizing antibody response following vaccination. These result s indicate that Candid #1 is safe and immunogenic in nonhuman primates .