Multiple effects of mutations in human immunodeficiency virus type 1 integrase on viral replication.
The integration of a DNA copy of the human immunodeficiency virus type 1 (HIV-1) genome into a chromosome of an infected cell is a pivotal step in virus replication. Integration requires the activity of the virus-encoded integrase, which enters the cell as a component of the virion. Results of numerous mutagenesis studies have identified amino acid residues and protein domains of HIV-1 integrase critical for in vitro activity, but only a few of these mutants have been studied for their effects on HIV replication. We have introduced site-directed changes into an infectious DNA clone of HIV-1 and show that integrase mutations can affect virus replication at a variety of steps. We identified mutations that altered virion morphology, levels of particle-associated integrase and reverse transcriptase, and viral DNA synthesis. One replication-defective mutant virus which had normal morphology and protein composition displayed increased levels of circular viral DNA following infection of a T-cell line. This virus also had a significant titer in a CD4-positive indicator cell assay, which requires the viral Tat protein. Although unintegrated viral DNA can serve as a template for Tat expression in infected indicator cells, this level of expression is insufficient to support a spreading viral infection in CD4-positive lymphocytes.
Engelman
A
A
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.
Englund
G
G
Orenstein
J M
JM
Martin
M A
MA
Craigie
R
R
D001483:Base Sequence; D003001:Cloning, Molecular; D004254:DNA Nucleotidyltransferases / Q000235:genetics* / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D004279:DNA, Viral / Q000096:biosynthesis / Q000235:genetics; D003673:Defective Viruses / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D015870:Gene Expression; D015751:Genes, pol; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D019426:Integrases; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017354:Point Mutation; D012194:RNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D016662:Virus Integration / Q000187:drug effects / Q000502:physiology; D014779:Virus Replication / Q000235:genetics* / Q000502:physiology
D017931:DNA Primers; D004279:DNA, Viral; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase