Quantitative proviral DNA and antibody levels in the natural history of HTLV-I infection

The pathogenesis of human T-cell lymphotropic virus type I (HTLV-I) in adult T-cell leukemia/lymphoma (ATL) and HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) is poorly understood. We prospectively followed up and evaluated the virologic correlates of infection in transfusion recipients after seroconversion, in asymptomatic carriers, and in ATL and HAM/TSP patients. Proviral DNA levels (copies/10(5) lymphocytes) were determined by real-time automated polymerase chain reaction and antibody titers by endpoint dilution by use of an HTLV-I enzyme-linked immunoassay, In early infection, proviral load was initially elevated (median, 212 copies/10(5) lymphocytes at time 1) and later decreased (median, 99 copies at time 2, and 27 copies at time 3), Corresponding antibody titers were low at time 1 (1 :2154), had significantly increased by time 2 (1 : 12312), and were stable by time 3 (1 :4694), These viral markers were significantly lower in asymptomatic carriers than in HAM/TSP or ATL patients. Therefore, proviral load and antibody titers may be useful as predictive markers of disease among carriers.