title: Effects of vpu start-codon mutations on human immunodeficiency virus type 1 replication in macrophages.
abstract: The human immunodeficiency virus type 1 (HIV-1) vpu protein increases the release of virus particles from infected cells. Mutations that abrogate vpu function have a profound effect on HIV-1 replication in primary macrophage cultures. About 1.24 % of primary isolates in the HIV databases have vpu start-codon mutations. In addition, the envelope of the AD8 isolate was reported to compensate for the lack of vpu, whilst the YU-2 virus (cloned directly from the brain tissue of an infected individual) is macrophage-tropic, despite having a vpu start-codon mutation. These observations raise the possibility that envelopes evolve to compensate for the loss of vpu function in vivo. Chimeric vpu+ and vpu- replication-competent clones were constructed that contained the envelopes of SF162, AD8 or YU-2. Macrophages were infected with these chimeras and virus release was measured over time by a reverse transcriptase ELISA. It was found that vpu-deficient chimeras carrying AD8 and YU-2 envelopes were consistently released at lower levels than their wild-type (wt) vpu counterparts, indicating that these envelopes did not compensate for the lack of vpu. Non-chimeric vpu+ and vpu- AD8 and YU-2 followed similar patterns, although replication by vpu-deficient AD8 was variable, with virion release reaching 60 % of that recorded for AD8 with a wt vpu. In summary, no evidence was found that the AD8 or YU-2 envelopes can compensate for the lack of vpu for replication in macrophages.
authors.affiliation: Suite 315, Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
authors.forename: Kathryn H
authors.initials: KH
authors.lastname: Richards
authors.affiliation: Suite 315, Biotech 2, Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clapham
mesh_terms: D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics*; D016679:Genome, Viral; D016655:HIV Core Protein p24 / Q000235:genetics; D015497:HIV-1 / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D054298:Human Immunodeficiency Virus Proteins; D006801:Humans; D007668:Kidney; D008264:Macrophages / Q000821:virology*; D020641:Polymorphism, Single Nucleotide; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D015183:Restriction Mapping; D014759:Viral Envelope Proteins / Q000235:genetics; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*; D000086082:Viroporin Proteins
chemical_list: D003062:Codon; D016655:HIV Core Protein p24; D054298:Human Immunodeficiency Virus Proteins; D012194:RNA-Directed DNA Polymerase; D014759:Viral Envelope Proteins; D054334:Viral Regulatory and Accessory Proteins; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins