MYCOBACTERIUM-AVIUM COMPLEX IN MACAQUES WITH AIDS IS ASSOCIATED WITH A SPECIFIC STRAIN OF SIMIAN IMMUNODEFICIENCY VIRUS AND PROLONGED SURVIVAL AFTER PRIMARY INFECTION

Mycobacterium avium complex (MAC) in simian immunodeficiency virus (SI V)-infected macaques is a frequent opportunistic infection that shares many features with the condition in human AIDS patients, A retrospect ive analysis of necropsies on 135 macaques with SIV-induced simian AID S that received neither antiretroviral nor antimicrobial therapy revea led that 17% (23/135) were infected with MAC, MAC developed in 31.3% ( 21/67) of the animals inoculated with uncloned SIVmac251 versus 1.9% ( 1/53) and 6.7% (1/15) of the animals inoculated with the molecular clo nes SIVmac239 and SIVmac239/316EM, respectively (P = .001). This is th e first example in which the risk of infection with a specific opportu nistic organism was affected by the infecting strain of immunodeficien cy virus, In addition, animals with MAC had a longer mean survival aft er primary infection and lower CD4 cell counts at death than animals t hat did not develop this opportunistic infection, The SIV-inoculated m acaque is a valuable model in which to study the pathogenesis of MAC i n the immunocompromised host.