Fig. 2.

HIV-1 life cycle presents probable CRISPR-Cas9 targets. Five steps make up the life cycle of HIV-1 as follows: (a) Attachment and introduction: The penetration of HIV-1 into host cell occurs following the attachment of its gp120 to the surface receptor CD4 and subsequently to CXCR4 or CCR5 co-receptor, thereby leading to the fusion of cell membrane and HIV-1 and then the introduction of HIV-1 into host cells and the liberation of viral RNA. (b) Reverse transcription process: the viral RNA reverse transcription occurs in the host double-stranded DNA utilizing the reverse transcriptase. (c) Integration: After nuclear introduction of viral DNA, it is integrated into the genomic DNA of host cell exploiting the enzyme integrase. (d) Replication and assembly: After generation of viral RNA via the pro-viral DNA, the novel genomic RNA takes part for the synthesis of viral proteins that embrace the viral RNA to produce immature viral particles near the cell surface. (e) Budding: The novel particles are liberated outside to form viral protease capable of cleaving long protein chain leading to form viral maturation. Engineering processes convert the Cas9 to inactive Cas9 (dCas9) by inducing mutations in the two RuvC and HNH domains of nuclease. The subsequent dCas9 fusion using different agents into the DNA-binding domain specific to site can trigger latent virus through sgRNAs that target the LTR region of HIV-1.