Anti-Env antibody titer in asymptomatic HTLV-I-infected carriers correlates with the proviral load. Asymptomatic HTLV-I-infected patients and HAM/TSP patients were evaluated for proviral load as described in the material and methods. (A.) Linear regression analysis showed that the anti-Env antibody titer determined by LIPS did not correlate in HAM/TSP patients. (B.) In contrast, proviral load significantly correlated (Pearson correlation R = 0.76) with anti-ENV antibody titers in asymptomatic HTLV-I carriers.