Homologous superinfection of both producer and nonproducer HIV-infected cells is blocked at a late retrotranscription step.
An HUT-78 cell clone (F12) chronically infected by a nonproducer HIV-1 variant (Federico et al., (1989) AIDS Res. Hum. Retroviruses 5, 385-396) is fully resistant to superinfection with HIV-1 or HIV-2. We demonstrate that, in spite of the down-regulation of CD4 receptors, superinfecting-HIV-1 and -HIV-2 cross the F12 plasma membrane (even in the presence of OKT4A monoclonal antibodies) but fail to complete retrotranscription. We utilized a series of polymerase chain reaction primers designed to detect certain steps in the reverse transcription process. Superinfecting-HIV-1 (an African strain) and -HIV-2 are detectable using primers specific for env (for HIV-1), 5' LTR (the R and U5 regions), and vpx (for HIV-2). No amplification is visible when primers amplifying either HIV-2 gag or the "primer binding site" region of 5' LTR of HIV-2 are used. DNA-PCR performed on DNAse-pretreated HIV-1 and HIV-2 stocks failed to show any amplification. This rules out that any extra- or intravirion viral DNA contamination may have interfered with our results. In addition, no DNA amplification was observed in F12 and HUT-78 cells exposed to heat-inactivated HIV-2. Finally, when the nonproducer F12 cells as well as control CEMss cells are transfected with the HIV-1 infectious molecular clone pNL4-3, progeny infectious virus is obtained. These findings indicate that reverse transcription of HIVs superinfecting F12 cells is prevented from completing viral DNA synthesis. A similar block occurs in HIV-1-infected producer cells. When integration of the HIV genome into the F12 genome is achieved via transfection of a molecular clone, the virus life cycle can proceed as in control CEMss cells.
Laboratory of Virology, Istituto Superiore di Sanitá, Rome, Italy.
B
B
Taddeo
M
M
Federico
F
F
Titti
G B
GB
Rossi
P
P
Verani
D001483:Base Sequence; D015704:CD4 Antigens / Q000032:analysis; D002999:Clone Cells / Q000382:microbiology; D004279:DNA, Viral / Q000032:analysis; D015536:Down-Regulation; D015752:Genes, env; D015750:Genes, gag; D015497:HIV-1 / Q000502:physiology*; D015498:HIV-2 / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D013045:Species Specificity; D015163:Superinfection / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection; D014762:Viral Interference / Q000235:genetics*; D014779:Virus Replication
D015704:CD4 Antigens; D004279:DNA, Viral