HIV-1 envelope subregion length variation during disease progression

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• The V1V2 loop of HIV-1 Env glycoprotein gp120 influences coreceptor usage and shields sensitive regions from antibodies.
• Polymorphisms in V1V2, including length and glycosylation, affect function and antigenicity but their link to HIV pathogenesis is unclear.

Purpose of the Study:

• To investigate the relationship between HIV-1 gp120 V1V2 loop length, N-linked glycosylation, and HIV pathogenesis.
• To understand how HIV-1 adapts to host immune responses over the course of infection.

Main Methods:

• Analysis of 5185 HIV-1 gp120 nucleotide sequences and clinical data from 154 individuals.
• Sequences were analyzed for V1V2 loop length and potential N-linked glycosylation sites (PNLGS).
• Cross-sectional and longitudinal analyses examined these factors in relation to time since infection, CD4 count, viral load, and calendar year.

Main Results:

• V1V2 loop length and PNLGS significantly increased during chronic HIV-1 infection, declining in late-stage disease.
• V1V2 length also showed an increasing trend over calendar years (1984-2004) in early/mid-stage infections.
• Little selection for loop length was observed at transmission, suggesting adaptation post-infection.

Conclusions:

• HIV-1 appears to adapt to host immunity by increasing V1V2 loop length and glycosylation during chronic infection.
• V1V2 shortening in early and late stages might reflect immune evasion or compromised host immunity.
• The pandemic increase in V1V2 length may be linked to transmission from chronically infected individuals.