LAV/HTLV-III: fine-structure analysis, localization of structural proteins, and detection of envelope antigens by patient sera.

Abstract

LAV/HTLV-III was investigated by thinsection and immunoelectron microscopy. Formation of the virion takes place at the cell membrane. The inner components are assembled concomitant with budding, as is characteristic of type-C oncovirinae. Different from type-C viruses and typical for the subgroup of lentivirinae, these components in immature particles form an 18-nm broad, electron-dense spherical shell apposed to the viral membrane. After budding the structural components are rearranged (“maturation”). The electron-dense nucleoid formed is surrounded by a prismatic electron-opaque core shell 4–5 nm thick [1]. From immunocryoultramicrotomy, using monoclonal as well as monospecific antibodies, we concluded that the core shell is built up by p24. The inner leaflet of the envelope is covered by a 5–7-nm electron-dense layer with p18 antigenicity.