Transcriptomic analysis reveals key pathways influenced by HIV-2 Vpx
Viral protein X (Vpx) is a unique accessory protein encoded by the genome of the Human immunodeficiency virus type 2 (HIV-2) and lineages of the simian immunodeficiency virus of sooty mangabeys. So far, counteracting the cellular restriction factor SAMHD1 and mediating efficient translocation of viral pre-integration complex have been recognized as key functions of Vpx, however, thorough exploration of its effects on the cellular transcriptome and cytokine milieu have not yet been explored.  In this study, we carried out transcriptomic analysis of THP-1 cells and determined differential gene expression induced by HIV-2 Vpx, additionally, we measured the effect of Vpx expression on secretion of key cytokines in the medium of transfected cells. Our findings revealed that wild-type HIV-2 Vpx can significantly alter the expression of genes coding for helicases, zinc finger proteins, chaperons, transcription factors and proteins involved in DNA methylation. Differentially altered genes were involved in negative regulation of viral process; type I interferon signaling pathway; DNA-templated transcription, elongation; positive regulation of interferon-beta production and negative regulation of innate immune response. Moreover, Vpx downregulated genes associated with negative regulation of TGF-ß1, resulting in stimulation of its production. Importantly, Vpx was also found to decrease the expression of HIV-2 Tat, possibly through downregulation of a crucial splicing factor required for maturation of Tat. Overall design: To explore the impact of HIV-2 Vpx on the cellular transcriptome and cytokine environment, we utilized a THP-1 monocyte cell line exposed to three distinct transfection conditions: with plasmids coding for wild type (1) and mutant (2) Vpx in conjugation with GFP, and one devoid of Vpx but still with GFP as mock control (3). We performed experiments in duplicates. We performed comparative gene expression profiling analysis using RNA-Seq data from the three distinct transfected cell variants, comprising a total of six samples.