2nd National Conference Human Retroviruses and Related Infections Washington, DC - January 29 - February 2, 1995

Natl Conf Hum Retrovir Relat Infect 1995 Jan 29-Feb 2;2: (abstract no. 27)

Chowers M, Spina C, Richman D, Guatelli J
University of California, San Diego and the San Diego Department of Veterans Affairs Medical Center, 9500 Gilman Dr., La Jolla, CA 92093-0679

Previous studies using T cell lines have shown a positive impact of the nef gene on the infectivity of HIV-1 virions and consequently a positive impact on viral growth rate. However, gene expression from established proviral DNA appears uneffected by Nef, suggesting that Nef influences early events in viral replication that precede the establishment of viral DNA. To confirm this hypothesis, the relative accumulation of viral DNA following a single cycle of viral replication using wild-type and nef-negative HIV-1 was compared; cells infected with nef-negative virus accumulated less viral DNA. To determine more specifically the effect of Nef, the following parameters of wild-type and nef-negative viruses were compared. The endogenous reverse transcriptase activities of wild-type and nef-negative virions were equal. Wild-type and nef-negative viruses entered cells equally as assessed using a cell-associated p24 assay. Wild-type and nef-negative viruses bound to cells equally as assessed using flow cytometry. The finding of equal binding and entry suggested that the effect of Nef on infectivity was independent of Env/CD4 interactions. The hypothesis that CD4 downregulation by Nef is unrelated to the more rapid growth of wild-type virus was supported by growth curve studies using cells that express a truncated CD4 molecule lacking the cytoplasmic domain. These results suggest that the attenuation in vitro of nef-negative HIV-1 is due to post-entry events that lead to the establishment of the provirus and is unrelated to CD4 downregulation.

Keywords: Antigens, CD4, Cell Line, DNA, Viral, Genes, env, Genes, nef, HIV-1, In Vitro, Proviruses, RNA-Directed DNA Polymerase, T-Lymphocytes, Virion, genetics, immunology, virology

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1995-01-29
27

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