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Analysis of long-term viral expression in CEM cells persistently infected with non syncytium-inducing HIV-1 strains
J Yelle1, R Morisset, L Thibodeau
1Centre de recherche en virologie, Institut Armand-Frappier, Laval, Québec, Canada.
Abstract:
CEM cells were infected with three HIV-1 non syncytium-inducing (NSI) strains obtained from AIDS patients or seropositive individuals. The surviving cells were followed for several months in the persistently infected cultures designated 65870/CEM, 65871/CEM and 3929/CEM, and analyzed for virus expression using light and electron microscopy, immunofluorescence, reverse transcriptase assay, polymerase chain reaction amplification (PCR), nucleic acid hybridization and flow cytometry. The virus isolates induced relatively few syncytia and other cytopathic effects in the corresponding cell lines and the number of cells positive for virus expression never rose above 44%. Distinct peaks of antigen-positive cells were obtained, coincident with high levels of reverse transcriptase activity. The cultures were strongly resistant to superinfection by laboratory strain Lai, with the exception of 65870/CEM which expressed HIV antigens in up to 15% of the cells for a few days. However, cell lysis was minimal in all cases. After long-term cultivation of the three cultures, no antigen-positive cells were detected and no trace of virus expression could be observed. The remaining cells consisted entirely of CD4-negative cells. PCR analyses indicated that cells harboring a provirus were progressively eliminated from the cultures, leaving only virus-free cells. In this system, cells carrying a latent provirus survive for a limited period of time before virus activation induces cell lysis. These results suggest that at least three types of cells exist in the CEM cell line: CD4-positive cells which are rapidly killed by the virus, a second type harboring a latent viral genome after the infection and which grow normally until activation of the resident genome by external or internal signal(s), and a third type which represents rare CD4-negative cells present in the initial CEM population and which are selected for by the NSI isolates. This is the first study documenting specific interactions between NSI strains of HIV-1 and distinct subpopulations of CEM cells grown as a single cell culture.
Insights
This study reveals that human immunodeficiency virus type 1 (HIV-1) non-syncytium-inducing strains interact uniquely with CEM cell subpopulations. Long-term cultures show elimination of provirus-carrying cells, leaving only CD4-negative cells.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Human immunodeficiency virus type 1 (HIV-1) infection establishes persistent reservoirs within host cells.
- Understanding the interaction between HIV-1 strains and host cell subpopulations is crucial for developing effective therapeutic strategies.
- CEM cells are a commonly used T-lymphoblastoid cell line for HIV-1 research.
Purpose of the Study:
- To investigate the long-term effects of non-syncytium-inducing (NSI) HIV-1 strains on CEM cell subpopulations.
- To characterize the cellular responses and viral dynamics in persistently infected CEM cultures.
- To identify distinct cell types within the CEM line based on their interaction with NSI HIV-1.
Main Methods:
- CEM cells were infected with three NSI HIV-1 strains.
- Persistent cultures were maintained for several months.
- Virus expression was analyzed using microscopy, immunofluorescence, reverse transcriptase assays, PCR, nucleic acid hybridization, and flow cytometry.
- Superinfection resistance was assessed using the laboratory strain Lai.
Main Results:
- NSI HIV-1 isolates induced minimal cytopathic effects and low percentages of virus-expressing cells (≤44%).
- Persistent cultures showed resistance to superinfection, with transient antigen expression in one culture.
- Long-term cultivation resulted in the elimination of antigen-positive and provirus-carrying cells, leaving only CD4-negative cells.
- PCR analysis confirmed the progressive elimination of provirus-harboring cells.
Conclusions:
- CEM cell populations contain distinct subpopulations with differential susceptibility to NSI HIV-1 infection.
- CD4-positive cells are susceptible to rapid lysis, while others harbor latent provirus before potential activation and lysis.
- Rare CD4-negative cells are selected for and survive NSI HIV-1 infection.
- This study highlights the complex interplay between NSI HIV-1 and distinct CEM cell types, leading to eventual viral clearance from surviving cells.