Exploiting HIV-1 tropism to target CD4+ T cells for CRISPR

Employing CRISPR-Cas9 to Enhance T Cell Effector Function

As part of the adaptive immune system, T cells are critical to maintain immune homeostasis. T cells provide protective immunity by killing infected cells and combatting cancerous cells. To do so, T cells produce and secrete effector molecules, such as granzymes, perforin, and cytokines such as tumor necrosis factor α and interferon γ. However, in immune suppressive environments, such as tumors, T cells gradually lose the capacity to perform their effector function. One way T cell effector function can be enhanced is through genetic engineering with tools such as clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9). This protocol explains in a step-by-step fashion how to perform a controlled electroporation-based CRISPR experiment to enhance human T cell effector function. Of note, these steps are suitable for CRISPR-mediated genome editing in T cells in general and can thus also be used to study proteins of interest that do not influence T cell effector function.

Closing the Door with CRISPR: Genome Editing of CCR5 and CXCR4 as a Potential Curative Solution for HIV

Human immunodeficiency virus (HIV) infection can be controlled by anti-retroviral therapy. Suppressing viral replication relies on life-long medication, but anti-retroviral therapy is not without risks to the patient. Therefore, it is important that permanent cures for HIV infection are developed. Three patients have been described to be completely cured from HIV infection in recent years. In all cases, patients received a hematopoietic stem cell (HSC) transplantation due to a hematological malignancy. The HSCs were sourced from autologous donors that expressed a homozygous mutation in the CCR5 gene. This mutation results in a non-functional receptor, and confers resistance to CCR5-tropic HIV strains that rely on CCR5 to enter host cells. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) system is one of the methods of choice for gene editing, and the CRISPR/Cas system has been employed to target loci of interest in the context of HIV. Here, the current literature regarding CRISPR-mediated genome editing to render cells resistant to HIV (re)-infection by knocking out the co-receptors CCR5 and CXCR4 is summarized, and an outlook is provided regarding future (research) directions.