A screening for DNA damage response molecules that affect HIV-1 infection

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Host DNA damage response (DDR) pathways are crucial for maintaining genomic integrity.
• Retroviral life cycles, including Human Immunodeficiency Virus type 1 (HIV-1), involve viral DNA intermediates that interact with host cellular machinery.
• The precise interplay between HIV-1 and host DDR molecules remains incompletely understood.

Purpose of the Study:

• To identify host DNA damage response molecules that modulate HIV-1 infection.
• To elucidate the mechanisms by which specific DDR proteins affect viral replication stages.

Main Methods:

• Screening of 32 DNA-repair-deficient DT40 isogenic mutant cell lines for HIV-1 infectivity.
• Quantitative PCR analysis to assess viral DNA forms (e.g., 2-LTR circles, integrated proviral DNA).
• Over-expression and knockdown experiments in human cells to validate findings for RAD18.

Main Results:

• Seven mutant cell lines exhibited significantly reduced HIV-1 infectivity, suggesting a supportive role for the deficient DDR molecules in infection.
• Mutations in EXO1, TP53BP1, and WRN led to increased viral 2-LTR circles and impaired proviral DNA integration.
• RAD18-deficient cells showed enhanced HIV-1 infectivity and reverse transcription, indicating a suppressive role for RAD18.
• A DNA-binding deficient mutant of RAD18 (L274P) demonstrated impaired viral suppression, highlighting the importance of DNA binding.

Conclusions:

• Host DNA repair proteins, including EXO1, TP53BP1, and WRN, are important for efficient HIV-1 integration.
• RAD18 acts as a host antiviral factor, suppressing HIV-1 reverse transcription through direct binding to viral DNA intermediates.
• Understanding these host-virus interactions can reveal novel therapeutic targets for HIV-1 infection.