Immunocytochemical evidence of the presence of CD4-Nef complexes on human T-cell surface enhancing CD4 down-regulation / 中华传染病杂志

ABSTRACT

Objective This study aims to investigate the role of Nef or Vpu of HIV 1 in the process of CD4 down regulation. Methods After transfection/infection, the cells that constitutively express Nef or Vpu were then properly prepared for indirect pre or post embedding immunocytochemistry and for further semiquantitative analyses. Results The number of CD4 molecules on the cell surface and in the cytoplasm of Vpu + cells was less than those in Vpu - cells. The number of CD4 molecules on the cell surface of Nef + Jurkat and HPBALL cells was less than that on the Nef - cell membranes. While CD4 molecules in the cytoplasm of Nef - Jurkat and HPBALL cells were less than those in the cytoplasm of Nef + cells. That Vpu partially co localized with Gag was analyzed by confocal microscopy; however, no CD4 Vpu complex was found in the cytoplasm. Furthermore, neither Nef nor Vpu shows effect on the incorporation of Gag into viral particles. Conclusions The results showed that CD4 Nef complexes formed at the coated pits of cell surfaces, with or without expressing Vpu. Formation of CD4 Nef complexes could be important for the enhancement of CD4 down regulation.