PATZ1 is required for efficient HIV-1 infection.

Successful HIV-1 infection and subsequent replication deeply depend on how the virus usurps the host cell machinery. Identification and functional characterization of these host factors may represent a critical strategy for developing novel anti-HIV-1 therapy. Here, expression cloning with a cDNA expression library identified as an inhibitor of HIV-1 infection, a carboxy-terminally truncated form of human POZ/BTB and AT-hook- containing Zinc finger protein 1 (PATZ1), a transcriptional regulatory factor implicated in development and cancer. Knockdown or knockout of endogenous PATZ1 revealed a supportive role of PATZ1 in HIV-1 infection, but not in transduction with murine leukemia virus-based retroviral vector. More specifically, knockdown or knockout of PATZ1 impaired the viral cDNA synthesis but not the entry process and expression of two PATZ1 isoforms in PATZ1-KO cells restored susceptibility to HIV-1 infection. These results indicate that PATZ1 plays an important role in HIV-1 infection.

Discovery of 4-oxoquinolines, a new chemical class of anti-HIV-1 compounds.

Antiretroviral therapy (ART) against HIV-1 infection offers the promise of controlling disease progression and prolonging the survival of HIV-1-infected patients. However, even the most potent ART regimens available today cannot cure HIV-1. Because patients will be exposed to ART for many years, physicians and researchers must anticipate the emergence of drug-resistant HIV-1, potential adverse effects of the current drugs, and need for future drug development. In this study, we screened a small-molecule compound library using cell-based anti-HIV-1 assays and discovered a series of novel anti-HIV-1 compounds, 4-oxoquinolines. These compounds exhibited potent anti-HIV-1 activity (EC50 < 0.1 µM) with high selectivity indexes (CC50/EC50 > 2500) and favorable pharmacokinetic profiles in mice. Surprisingly, our novel compounds have a chemical backbone similar to the clinically used integrase (IN) strand transfer inhibitor (INSTI) elvitegravir, although they lack the crucial 3-carboxylate moiety needed for the common INSTI diketo motif. Indeed, the new 4-oxoquinoline derivatives have no detectable INSTI activity. In addition, various drug-resistant HIV-1 strains did not display cross resistance to these compounds. Interestingly, time-of-addition experiments indicated that the 4-oxoquinoline derivative remains its anti-HIV-1 activity even after the viral integration stage. Furthermore, the compounds significantly suppressed p24 antigen production in HIV-1 latently infected cells exposed with tumor necrosis factor alpha. These findings suggest that our 4-oxoquinoline derivatives with no 3-carboxylate moiety may become novel lead compounds in the development of anti-HIV-1 drugs.

Human SMOOTHENED inhibits human immunodeficiency virus type 1 infection.

Human SMOOTHENED (SMO) was identified by expression cloning as a new host factor that inhibits HIV-1 infection. Forced expression of SMO inhibited HIV-1 replication and infection with a single-round lentiviral vector, but not infection with a murine leukemia virus-based retroviral vector in human MT-4 T cells. Quantitative PCR analyses revealed that stable expression of SMO impaired formation of the integrated form of lentiviral DNA, but did not interrupt reverse transcription. This inhibition was evident in MT-4 and HUT102 human T cell lines expressing low levels of SMO mRNA, but not in SupT1 or Jurkat T cell lines expressing higher levels of SMO mRNA. Depletion of SMO mRNA in Jurkat cells facilitated HIV-1 vector infection, suggesting that endogenous SMO plays a role in limiting lentiviral infection. These results suggest that SMO inhibits HIV-1 replication after completion of reverse transcription but before integration.

5' long terminal repeat (LTR)-selective methylation of latently infected HIV-1 provirus that is demethylated by reactivation signals.

We previously described selective hypermethylation of the 5'-long terminal repeat (LTR) of HTLV-1 provirus in vivo and in vitro. This prompted us to analyze CpG methylation of the two LTRs of the HIV provirus in chronically infected cell lines. The results demonstrate selective hypermethylation of the 5' LTR of the HIV provirus in ACH-2 cells. Moreover, induction of viral gene expression by TNF-alpha resulted in demethylation of the 5'-LTR. These results suggest that selective epigenetic modification of the 5'LTR of the HIV-1 provirus may be an important mechanism by which proviral activity is suppressed.