Neutralization of RRV-SEAP by sera from Mm 26-95 and rhesus monkeys experimentally infected with RRV26-95. (A) Neutralization of RRV-SEAP by Mm 26-95 sera. RRV-SEAP (MOI of 0.006 PFU/cell) was incubated with either DH20 medium (No Antibody) or various dilutions of serum from Mm 26-95 isolated at different dates. After a 3-h incubation at 37°C, rhesus fibroblasts were inoculated with either DH20 medium (dotted line) or the virus-sera mixture. At 24 h p.i., cultures were rinsed five times with HBSS and refed with DH20. At day 4 p.i., an aliquot of medium was removed to determine the level of SEAP expression. The results show the percent infectivity for each serum dilution at the serum isolation dates indicated. (B) Neutralization of RRV-SEAP by sera from rhesus monkeys experimentally infected with RRV26-95. At 8, 24, 36, and 48 weeks after inoculation of RRV-naïve rhesus monkeys with RRV26-95, sera was collected and used to determine its efficacy in neutralizing RRV-SEAP as previously described. The results show the percent infectivity for each serum dilution at the indicated week postinoculation.