Human immunodeficiency virus infection is a chronic disease that affects upwards of 35 million people around the world. Antiretroviral therapy controls infection, but there isn’t a complete cure. Radicating cells which are latently infected with HIV-1 is difficult as when the virus proliferates the viral gene is inserted into chromosomes in infected cells.
Genome editing methods cut specific parts of genes allowing sections of DNA sequences to be added or removed. Great promise is being shown by CRISPR/Cas9 systems as a tool for deactivating HIV-1 genes which have been incorporated into chromosomes of infected patients.
Rev and Tat genes were targeted which regulate proliferation of HIV-1. Using genetic information from 6 major HIV-1 subtypes, 6 types of guides of RNA were designed that enable specific genome editing using CRISPR/Cas9 systems. Lentiviral vectors created that express Cas9 and gRNA introduced to cultured cells expressing regulatory gene products Rev and Tat displayed decreased expression and functions of Rev and Tat. Expression of gRNA and Cas9 did not affect survival rate of the cultured cells, and no off target mutations were found.
Suppressed cytokine dependent HIV-1 reactivation in latently infected cells and HIV-1 replication from persistently infected cells was displayed in cultured cells with latent or persistent HIV-1 infection introduced to Cas9 and gRNA. Introducing all 6 types of gRNA together almost completely blocked virus production from infected cells.
It was noted that further investigation is required of how to introduce these systems that target HIV-1 genes into infected cells of patients, and that vectors must be improved in order to introduce CRISPR/Cas9 systems safely and effectively.
