Simian immunodeficiency virus SIVmac chimeric virus whose env gene was derived from SIV-encephalitic brain is macrophage-tropic but not neurovirulent

We inoculated four rhesus macaques with molecularly cloned simian immunodeficiency virus SIVmac239/17E env, a chimeric virus whose env gene was derived from the brain of an SIV-encephalitic macaque. Blood and lymphoid tissues had high frequencies of infected cells. The virus was neuroinvasive, but productive virus replication did not occur in the brain, and animals did not develop encephalitis.