Intrapatient variability of the human immunodeficiency virus type 2 envelope V3 loop

Area of Science:

• Virology
• Immunology
• Genetics

Background:

• Human Immunodeficiency Virus type 2 (HIV-2) exhibits distinct epidemiological and clinical characteristics compared to Human Immunodeficiency Virus type 1 (HIV-1), including reduced transmission rates and slower disease progression.
• Genetic variability within viral genomes is a key factor influencing viral pathogenesis and disease outcomes.

Purpose of the Study:

• To investigate the intrapatient genetic variability of the HIV-2 envelope V3 loop over time.
• To compare the genetic heterogeneity of HIV-2 with that of HIV-1.
• To explore the relationship between HIV-2 genetic variability and disease progression.

Main Methods:

• Sequencing of the V3 loop region of the HIV-2 envelope gene from peripheral blood mononuclear cell (PBMC) DNA of five HIV-2-seropositive individuals.
• Analysis of proviral sequences (n=102) to determine intrapatient sequence heterogeneity.
• Comparison of HIV-2 V3 loop variability with previously reported data for HIV-1.

Main Results:

• HIV-2 demonstrated significantly lower average intrapatient sequence heterogeneity (1.4%) in the V3 loop compared to HIV-1 (up to 6.1%).
• A lower nucleotide variability rate (0.6%) was observed in healthy HIV-2-seropositive patients compared to those with clinical AIDS (2.0%).

Conclusions:

• The reduced genetic variability of HIV-2, particularly in the V3 loop, is consistent with its observed lower rates of sexual and perinatal transmission and slower progression to AIDS compared to HIV-1.
• Intrapatient genetic variability of HIV-2 may play a role in its distinct pathogenesis and clinical course.