MOLECULAR-DETECTION AND ISOLATION OF HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-I (HTLV-I) FROM PATIENTS WITH HAM TSP IN SAO-PAULO, BRAZIL/

Background: Infection with HTLV-I is etiologically linked with HTLV-I- associated myelopathy/tropical spastic paraparesis (HAM/TSP). However some patients with chronic progressive paraparesis resembling HAM/TSP have been shown to be infected with HTLV-II. Objective: To clarify the role of each of these human retroviruses in the etiology of HAM/TSP i n Sao Paulo, Brazil. Study design: A detailed serological and molecula r analysis of HTLV-I/II infection was performed in a cohort of 19 pati ents with HAM/TSP attending a neurological clinic. Results: Plasma sam ples analyzed for anti-HTLV-I/II antibodies using a Western blot assay , comprising HTLV-I (rgp46(I))-and HTLV-II (rgp46(II))-specific recomb inant env epitopes, demonstrated reactivity to rgp46(I) and hence were typed as seropositive for HTLV-I. Presence of HTLV genomic sequences in peripheral blood mononuclear cells (PBMC) was sought after by PCR u sing consensus primers SK 110 and SK 111 for the pol region of HTLV pr oviral DNA followed by hybridization with type-specific probes-SK 112 (HTLV-I) and SK 188 (HTLV-II). Southern blots from all individuals hyb ridized with SK 112 but not with SK 188, further confirming HTLV-I inf ection. Cocultivation of PBMC from eight of these patients with activa ted lymphocytes from normal individuals resulted in active viral produ ction, detected as presence of soluble p24(gag) antigen in culture sup ernatants. Investigation of risk factors for HTLV-I infection in these individuals revealed that five out of 19 patients studied (26.3%) had received blood transfusions previous to disease onset. Conclusions: W e demonstrate HTLV-I as the only viral type involved in the etiology o f HAM/TSP in a cohort from Sao Paulo, Brazil, and emphasize that preve ntion measures, including widespread routine screening of blood donati ons for HTLV should be conducted in Brazil. (C) 1998 Elsevier Science B.V. All rights reserved.