Electron microscopic observation of a Brazilian HTLV-I isolated.

Several studies carried out in Brazil have shown a high incidence of HTLV-I infection among the general population and in different groups, such as blood donors, hemophiliacs, hematological and neurological patients. Cases of adult T-cell leukemia/lymphoma as well as tropical spastic paraparesis/HTLV-I associated myelopathy have already been described. Therefore, it is important to characterize Brazilian HTLV strains using different technical approaches. The purpose of this paper is to characterize and recognize HTLV particles employing routine and immunoelectron microscopy in lymphocyte cocultures. Ultrastructural analysis showed typical large and small virus particles in close relation with the lymphocyte membrane. Immunoelectron microscopy, carried out with HTLV positive sera, allowed the identification of the virus as a type C oncovirus, group HTLV-BLV. The first interaction events between virus and lymphocyte membrane have also been analysed and structures related to the endocytic route for HTLV entrance were pointed out.