Visualisation of phenotypically mixed HIV-1 and HTLV-1 virus particles by electron microscopy

Virions produced after HIV-1 infection of HTLV-I transformed cells have an expanded tropism that has been attributed to the presence of HTLV-I glycopr oteins in the envelope, This report now directly identifies these phenotypi cally mixed virions by immunogold labelling electron microscopy. Furthermor e we estimate there are 2% of these in cell-free supernatant, which represe nts up to 1 x 10(7) particles/ml from an in vitro infection, HTLV-1 envelop e labelling was localised to a single region, suggesting a defined event in packaging of foreign envelope proteins into HIV-1 virus particles. Copyrig ht (C) 2000 National Science Council, ROC and S. Karger AG, Basel.