CRISPR-based strategies in infectious disease diagnosis and therapy

Abstract

Purpose: CRISPR gene-editing technology has the potential to transform the diagnosis and treatment of infectious diseases, but most clinicians are unaware of its broad applicability. Derived from an ancient microbial defence system, these so-called "molecular scissors" enable precise gene editing with a low error rate. However, CRISPR systems can also be targeted against pathogenic DNA or RNA sequences. This potential is being combined with innovative delivery systems to develop new therapeutic approaches to infectious diseases.

Methods: We searched Pubmed and Google Scholar for CRISPR-based strategies in the diagnosis and treatment of infectious diseases. Reference lists were reviewed and synthesized for narrative review.

Results: CRISPR-based strategies represent a novel approach to many challenging infectious diseases. CRISPR technologies can be harnessed to create rapid, low-cost diagnostic systems, as well as to identify drug-resistance genes. Therapeutic strategies, such as CRISPR systems that cleave integrated viral genomes or that target resistant bacteria, are in development. CRISPR-based therapies for emerging viruses, such as SARS-CoV-2, have also been proposed. Finally, CRISPR systems can be used to reprogram human B cells to produce neutralizing antibodies. The risks of CRISPR-based therapies include off-target and on-target modifications. Strategies to control these risks are being developed and a phase 1 clinical trials of CRISPR-based therapies for cancer and monogenic diseases are already underway.

Conclusions: CRISPR systems have broad applicability in the field of infectious diseases and may offer solutions to many of the most challenging human infections.

Keywords: CRISPR gene editing; Infectious diseases; Pandemic viruses; Resistant bacteria; Viral infections.

Fig. 1

CRISPR/Cas9 function in bacteria. a Genetic material from a virus, phage, or plasmid enters the bacterium. b Short segments of genetic information from the invading agent are inserted into the CRISPR region interleaved with spacer segments. c crRNA segments consisting of CRISPR repeats and spacers are constitutively expressed in the bacterium. d Invading nucleic acid segments are recognized by crRNAs, leading to assembly of a cleavage complex containing the foreign DNA, crRNA, and Cas9 protein and resulting in cleavage of the invading DNA

Fig. 2

Mechanisms of CRISPR/Cas9 gene editing. a A construct that expresses a crRNA segment and the Cas9 protein is introduced into the target cell. b The target DNA is bound by the crRNA and Cas9 complex. c A double-strand break is introduced at the target site by the Cas9 nuclease. d The free ends of the DNA are subsequently repaired by the cell’s DNA repair mechanisms, either through error-prone non-homologous end joining (NHEJ) or, with the addition of a homology template, through homology-directed repair (HDR)