Attenuation of human immunodeficiency virus type 1 cytopathic effect by a mutation affecting the transmembrane...

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Human immunodeficiency virus type 1 (HIV-1) infection causes cytopathic effects, specifically syncytium formation and single-cell lysis, in CD4 receptor-expressing cells.
• The mechanisms driving HIV-1 cytopathicity are not fully understood, particularly the role of specific viral components beyond viral load.

Purpose of the Study:

• To investigate the role of the amino terminus of the HIV-1 gp41 transmembrane envelope glycoprotein in mediating viral cytopathic effects.
• To determine if mutations in gp41 affect viral replication, protein expression, or virion production while altering cytopathicity.

Main Methods:

• Introduction of a specific mutation (517A) into the amino terminus of the HIV-1 gp41 gene.
• Comparative analysis of the replication ability, viral protein expression, virion production, and CD4 interaction of the mutant virus versus wild-type HIV-1.
• Assessment of syncytium formation and single-cell lysis as measures of cytopathic effect in infected cell systems.

Main Results:

• The 517A mutant HIV-1 exhibited markedly reduced cytopathic effects compared to wild-type HIV-1.
• Viral replication ability, protein expression, virion production, and CD4 interaction remained comparable between the 517A mutant and wild-type viruses.
• Syncytium formation and single-cell lysis were significantly attenuated in cells infected with the 517A mutant virus.

Conclusions:

• A specific region within the HIV-1 gp41 envelope glycoprotein, crucial for post-receptor binding events in cell membrane fusion, is essential for inducing HIV-1 cytopathic effects.
• The mere presence of HIV-1 viral proteins or particles is insufficient to cause cytopathic effects; specific functional interactions mediated by viral components are required.