Human immunodeficiency virus type 1 Vpu modifies viral cytopathic effect through augmented virus release

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Human immunodeficiency virus type 1 (HIV-1) infection leads to varying degrees of cellular damage (cytopathicity).
• The mechanisms underlying differential cytopathicity among HIV-1 strains are not fully understood.

Purpose of the Study:

• To investigate the molecular basis for differing cytopathic effects between two HIV-1 strains, HIVMCK (non-cytopathic) and HIV213 (highly cytopathic).
• To identify the viral component responsible for modulating cytopathicity.

Main Methods:

• Characterization of HIV-1 strains HIVMCK and HIV213.
• Construction and analysis of chimeric viruses using cloned infectious DNAs.
• Biological assays to assess cytopathic effects.
• Analysis of viral protein expression and cell surface associated viral components.

Main Results:

• HIV213 exhibited significantly higher cytopathicity than HIVMCK.
• The Vpu protein region was identified as the determinant of differential cytopathicity.
• HIV213 was Vpu-deficient due to a start codon mutation, while HIVMCK expressed Vpu.
• Vpu-deficient viruses showed increased accumulation of envelope glycoprotein and virions on the cell surface compared to Vpu-positive viruses.

Conclusions:

• The Vpu protein plays a critical role in regulating HIV-1 cytopathicity.
• Vpu deficiency leads to the accumulation of viral envelope glycoproteins and virions at the cell surface, likely by impairing virion release.
• This accumulation of cell-surface viral components in Vpu-deficient strains contributes to their heightened cytopathic effects.