title: HIV-1 Gag processing intermediates trans-dominantly interfere with HIV-1 infectivity.
abstract: Protease inhibitors (PI) act by blocking human immunodeficiency virus (HIV) polyprotein processing, but there is no direct quantitative correlation between the degree of impairment of Gag processing and virion infectivity at low PI concentrations. To analyze the consequences of partial processing, virus particles were produced in the presence of limiting PI concentrations or by co-transfection of wild-type proviral plasmids with constructs carrying mutations in one or more cleavage sites. Low PI concentrations caused subtle changes in polyprotein processing associated with a pronounced reduction of particle infectivity. Dissection of individual stages of viral entry indicated a block in accumulation of reverse transcriptase products, whereas virus entry, enzymatic reverse transcriptase activity, and replication steps following reverse transcription were not affected. Co-expression of low amounts of partially processed forms of Gag together with wild-type HIV generally exerted a trans-dominant effect, which was most prominent for a construct carrying mutations at both cleavage sites flanking the CA domain. Interestingly, co-expression of low amounts of Gag mutated at the CA-SP1 cleavage site also affected processing activity at this site in the wild-type virus. The results indicate that low amounts (<5%) of Gag processing intermediates can display a trans-dominant effect on HIV particle maturation, with the maturation cleavage between CA and SP1 being of particular importance. These effects are likely to be important for the strong activity of PI at concentrations achieved in vivo and also bear relevance for the mechanism of action of the antiviral drug bevirimat.
authors: Department of Virology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany. barbara_mueller@med.uni-heidelberg.de
authors: Barbara
authors: B
authors: Müller
authors: Maria
authors: M
authors: Anders
authors: Hisashi
authors: H
authors: Akiyama
authors: Sonja
authors: S
authors: Welsch
authors: Bärbel
authors: B
authors: Glass
authors: Krisztina
authors: K
authors: Nikovics
authors: Francois
authors: F
authors: Clavel
authors: Hanna-Mari
authors: HM
authors: Tervo
authors: Oliver T
authors: OT
authors: Keppler
authors: Hans-Georg
authors: HG
authors: Kräusslich
mesh_terms: D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D054303:HIV Reverse Transcriptase / Q000235:genetics / Q000378:metabolism; D015497:HIV-1 / Q000472:pathogenicity* / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D017434:Protein Structure, Tertiary / Q000235:genetics; D013386:Succinates / Q000494:pharmacology*; D014315:Triterpenes / Q000494:pharmacology*; D053586:Virus Internalization / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects / Q000502:physiology; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*; D053978:Pentacyclic Triterpenes
chemical_list: D017320:HIV Protease Inhibitors; D054303:HIV Reverse Transcriptase; D013386:Succinates; D014315:Triterpenes; D054301:gag Gene Products, Human Immunodeficiency Virus; C514824:reverse transcriptase, Human immunodeficiency virus 1; C479935:bevirimat; D053978:Pentacyclic Triterpenes