Comparative pathogenesis of epidemic and enzootic Chikungunya viruses in a pregnant Rhesus macaque model.

Since 2004, an East African genotype of Chikungunya virus (CHIKV) has emerged, causing significant epidemics of an arthralgic syndrome. In addition, this virus has been associated for the first time with neonatal transmission and neurological complications. In the current study, pregnant Rhesus macaques were inoculated with an enzootic or epidemic strain of CHIKV to compare pathogenesis and transplacental transmission potential. Viremias were similar for both strains and peaked at 2-3 days post-inoculation (dpi). Viral RNA was detected at necropsy at 21 dpi in maternal lymphoid, joint-associated, and spinal cord tissues. The absence of detectable viral RNA and the lack of germinal center development in fetuses indicated that transplacental transmission did not occur. Neutralizing antibodies were detected in all dams and fetuses. Our study establishes a non-human primate model for evaluating vaccines and antiviral therapies and indicates that Rhesus macaques could serve as a competent enzootic reservoir.