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Updated: Aug 8, 2026
In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function
Published on: October 16, 2013
Quantification of HIV-specific CD8 T cells by in vitro stimulation with inactivated viral particles
Jianqing Xu1, Lucia Whitman, Franco Lori
1Research Institute for Genetic and Human Therapy (RIGHT), Washington, DC 20007, USA.
Insights
A new assay, CD8VIR, accurately quantifies HIV-specific CD8 T cells, crucial for immune control. This method aids in predicting viral load rebound in HIV-infected individuals.
Area of Science:
- Immunology
- Virology
- Diagnostic Assay Development
Background:
- CD8 T cells are vital for controlling HIV replication.
- Accurate quantification of HIV-specific CD8 T cells is needed for clinical management.
- Understanding CD8 T cell responses is key to managing HIV-infected individuals.
Purpose of the Study:
- To develop and validate the CD8 T cell-mediated virus-specific immune response (CD8VIR) assay.
- To quantify HIV-specific CD8 T cells in HIV-infected individuals.
- To assess the assay's utility in predicting viral load rebound.
Main Methods:
- The CD8VIR assay uses replication-defective HIV particles to stimulate peripheral blood mononuclear cells.
- Antigen-presenting cells process HIV, presenting viral epitopes to T cells.
- Activated HIV-specific CD8 T cells are quantified using flow cytometry (CD3CD8 IFNγ+ T cells).
Main Results:
- The CD8VIR assay reliably detects functional HIV-specific CD8 T cells during viral load rebound.
- Whole HIV particle stimulation in CD8VIR mirrors combined Gag, Pol, Env, and Nef stimulation.
- HIV-specific CD8 T cell percentages correlate with Gag-specific cytotoxicity and immune control in patients.
Conclusions:
- The CD8VIR assay quantifies HIV-specific CD8 T cells that kill infected cells during viral load rebound.
- This versatile and reproducible assay can be performed on specimens used for CD4 analysis.
- Clinical validation of CD8VIR could establish it as a diagnostic tool for predicting viral load rebound post-treatment interruption.
Objectives:
HIV-specific CD8 T cells play a central role in the immune control of virus replication. To further understand the role of CD8 T cells in clinical settings, there is a need for a diagnostic assay that quantifies HIV-specific CD8 T cells in all HIV-infected individuals.
Design:
and methods: The CD8VIR (CD8 T cell-mediated virus-specific immune response) assay was designed to mimic viral load rebound by adding replication defective HIV particles to peripheral blood mononuclear cells. Antigen presenting cells processed the virus and presented most of the viral epitopes to T cells. Activated HIV-specific CD8 T cells were quantified by flow cytometry analysis as CD3CD8 IFNgamma producing T cells.
Results:
The CD8VIR assay reproducibly detected a large proportion of functional HIV-specific CD8 T cells responding to viral load rebound. The whole HIV particle stimulation used in the CD8VIR assay was comparable to the sum of Gag, Pol, Env and Nef stimulations. The percentage of HIV-specific CD8 T cells also significantly correlated with the percentage of Gag-specific cytotoxicity measured by the traditional Cr release assay. HIV-specific CD8 T cells correlated with immune control of HIV in chronically infected patients.
Conclusions:
The CD8VIR assay quantifies the majority of HIV-specific CD8 T cells capable of killing HIV-infected cells during viral load rebound. This simple, versatile and reproducible assay can be performed from the specimen submitted for CD4 analysis. Upon clinical validation, the CD8VIR assay can be a new diagnostic tool to predict the control of viral load rebound after treatment interruption.
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