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. 2021 Feb 21;13(2):335. doi: 10.3390/v13020335

Figure 1.

Figure 1

Schematic overview of human immunodeficiency virus (HIV)/ simian immunodeficiency virus (SIV) life cycle and measurable viral parameters. Viral particles enter target cells, followed by reverse transcription, integration, transcription, splicing, translation, and virion packaging. The unspliced viral RNAs are transcribed from the integrated provirus. The transported single 5′ capped genomic viral RNAs (~9 Kb) are assembled to the nascent virions. Two or three guanosines 5′ full-length viral RNAs directly translate viral proteins (gag and pol). Rev-dependent export of incompletely spliced RNAs (~4 Kb) to cytoplasm contributes to env, vif, vpr, and vpu expression, whereas rev-independent multiply spliced species (~2 Kb) constitutively express accessory and regulatory proteins (tat, rev, and nef). Cell-associated viral RNA transcripts and viral DNA can be directly measured [18,19,20].