Coinfection of macaques with simian immunodeficiency virus and simian T cell leukemia virus type I: Effects on virus burdens and disease progression

To test the hypothesis that coinfection with human immunodeficiency virus ( HIV) and human T cell leukemia/lymphoma virus types I or II (HTLV-I or -II) accelerates progression to AIDS, pig-tailed macaques were inoculated with the simian counterparts, SIV and STLV-I. During 2 years of follow-up of sin gly and dually infected macaques, no differences in SN burdens, onset of di sease, or survival were detected. However, in the first coinfected macaque that died of AIDS (1 year after infection), >50% of CD4(+) and CD8(+) lymph ocytes expressed CD25. On the basis of the low incidence of HTLV-I- and STL V-I-associated disease during natural infections, this early evidence of ne oplastic disease was unexpected. While these results demonstrate that coinf ection with SIV and STLV-I has no influence on the development of immunodef iciency disease, they do establish a reliable macaque model of persistent S TLV-I infection.