Functional and structural defects in HIV type 1 nef genes derived from pediatric long-term survivors

Area of Science:

• Virology
• Immunology
• Genetics

Background:

• The human immunodeficiency virus (HIV) Nef protein plays a crucial role in viral pathogenesis.
• Understanding variations in Nef function is key to explaining differential disease progression in HIV-infected individuals.

Purpose of the Study:

• To investigate the DNA sequences and in vitro functions of the HIV Nef protein in perinatally infected children with varying disease progression rates.
• To correlate specific Nef gene mutations and functional defects with viral replication and infectivity in T cells.

Main Methods:

• Analysis of nef gene sequences from HIV-infected children, including those with non-/slow progression.
• In vitro functional assays of Nef proteins, including p62 binding, viral replication enhancement, and infectivity in T cell lines and peripheral blood mononuclear cells.
• Assessment of the impact of specific Nef mutations on viral replication upon reversion.

Main Results:

• One of five non-/slow progressors had a virus with large nef gene deletions; others had full-length nef genes with more discrete changes.
• Most Nef proteins (40/44) retained the ability to bind the cellular serine kinase p62, indicating conserved function.
• Nef proteins from long-term non-/slow progressors often showed defective enhancement of viral replication and/or infectivity in T cells.
• Restoring prevalent point mutations in defective Nef proteins restored viral replication to wild-type levels.

Conclusions:

• Pediatric long-term non-progressors can harbor HIV with nef genes exhibiting gross deletions or a higher frequency of discrete changes.
• These discrete changes may impair specific Nef functions, particularly those related to viral replication and infectivity in primary T cell assays.
• Not all reported Nef functions are affected, suggesting a nuanced impact on viral pathogenesis.