Analysis of non-infectious HIV particles produced in presence of HIV proteinase inhibitor

Abstract

Newly developed substrate analogue peptidomimetics are able to inhibit the human immunodeficiency virus, HIV-1 proteinase at nanomolar concentration. In HIV infected cell culture they exhibit antiviral activity. We have analyzed the non-infectious HIV particles produced in chronically HIV infected cell culture in presence of one of these inhibitors. The total production of virus particles was not substantially reduced in drug treated cultures, compared to non-inhibited control cultures, but the infectivity of these virus particles was reduced about 100 fold. The processing of gag and gag-pol protein precursor was inhibited; only borderline activity of reverse transcriptase (RT) could be detected in these particles and they contained nonprocessed gag precursor protein. Thin section electron microscopy of inhibitor-treated, HIV-infected cells revealed reduced viral cytopathogenicity and both inhibition of particle assembly and incomplete maturation of the particles formed. The HIV particles produced in the presence of the proteinase inhibitor were studded with envelope glycoprotein knobs and often comprised multiple budding regions, but were morphologically immature.

Multi-step inhibition explains HIV-1 protease inhibitor pharmacodynamics and resistance

“…The virions budding from PI-treated cells are morphologically aberrant and show reduced infectivity (50,51,(53)(54)(55). This can be partially explained by lack of processing of Pr160 Gag-Pol .…”

Human immunodeficiency virus type 1 (HIV-1) protease inhibitors block cell-to-cell HIV-1 endocytosis in dendritic cells

“…Conversely, the extent to which the cell-to-cell HIV-1 endocytosis in DCs contributes to trans-infection has not yet been established. PI treatment of HIV-infected cells is the release of immature virions that, although still able to enter target cells, then abort their life cycle at a post-entry step (Kaplan et al, 1993;Schatzl et al, 1991). PIs are now part of highly active antiretroviral therapy, which allows millions of infected people to co-exist with the virus and experience a good quality of life.…”

The gag proteins of human immunodeficiency virus type 1: mechanisms of virus assembly and possibilities for interference

“…Recently, peptide-transporter complexes also have been found in the membranes of rabbit small intestine and various other cells [67]. It may be assumed that similar proteins, which actively transport organic compounds, are involved in the The particulate structures released from peptide-treated cells were similar to immature particles produced in HIV-infected cell cultures treated with inhibitors specific for the HIV protease [58], or when the sequences encoding the protease were mutated [68]. This morphological similarity implied that the active peptides could represent unnatural substrates exerting their inhibitory activity in a competitive way to the cleavage sites in the Pr55gag-and Prl60gag-pol-precursor proteins.…”

“…The elucidation of the molecular structure of the HIV protease by X-ray crystallography [32] and molecular dynamic simulation [57] facilitated the development of improved compounds able to inhibit its proteolytic activity and, therefore, the succeeding maturation events. HIV-infected cells treated with inhibitors of the viral protease do not lead to the production of infectious viral particles [58,59]. The particulate structures still budding from the cell surface represent immature, spherical HIV particles lacking the ability to form the conical capsid-core structure characteristic for infectious virions.…”