Gene Editing: How CRISPR Is Transforming the Fight Against Infectious Diseases

CRISPR allows scientists to edit DNA easily and with a high degree of precision. It’s like a pair of precision scissors, delicately snipping DNA fragments with astonishing accuracy.

CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats and uses bacterial genome to target and clip specific DNA sequences.

One of the most commonly used versions of CRISPR is the CRISPR-Cas9 system, with Cas9 being a virus-fighting bacterial enzyme, a vital part of the bacterial genome.

This gene-editing tool brings various benefits to the field of genetic research because:

• It allows for targeted modifications in DNA sequences, which means specific genes in the human genome can be edited or removed with unprecedented accuracy.
• It is highly efficient and cost-effective, making it accessible to a broader range of researchers.
• This technology has the potential to treat genetic diseases by correcting faulty genes and has intense potential to improve the fields of biotechnology, medicine, and disease prevention.

For their trailblazing work on the CRISPR-Cas9 system, scientists Jennifer Doudna and Emmanuelle Charpentier were awarded the Nobel Prize in Chemistry in 2020.

While this technology is rapidly being used in several applications, the field of gene editing is evolving fast. Recent advances include the discovery of CRISPR-Cas13 and fanzors. Fanzors are proteins found in eukaryotes (all organisms with a clearly defined nucleus in their cells) that also rewrite or edit parts of our genetic code.

While there are many ways gene editing can change the world, let’s look at five ways CRISPR is changing how we wage war against infectious disease.

Over 700,000 people, primarily children under five, die from vector-borne diseases each year, many of which are spread by mosquitoes.

The U.S. Centers for Disease Control and Prevention (US CDC) calls mosquitoes ‘the world’s deadliest animal‘ because mosquito-borne diseases like malaria, dengue, yellow fever, West Nile Virus, and Zika can be fatal without timely intervention.

Mosquitoes pose a severe threat to public health in several countries and are rapidly spreading to others. Due to global warming, disease-carrying mosquitoes are now found in previously non-endemic regions, like Northern Europe and the United States.

Making things worse, mosquitoes in several parts of the world are getting resistant to commonly used insecticides, making it harder to prevent the spread of disease.

CRISPR offers a promising solution.

Using CRISPR against malaria

There are a few ways in which CRISPR’s gene editing technology can help control the spread of mosquito-borne illnesses.

• Gene drives to alter female mosquitoes: Since female Anopheles mosquitoes are responsible for carrying and spreading malaria, a few of these mosquitoes are given CRISPR-edited genes. These genes get passed down to future generations of mosquitoes and genetically alter the females of the species. These females with altered genes develop a mix of male and female genitalia, rendering them unable to breed, which curbs the mosquito population in infested regions.
• Mosquito immunity versus malaria: Typically, mosquitoes are not infected by the malaria-causing parasite; they are merely carriers for the pathogen. However, researchers from the University of Irvine, California, used CRISPR to modify mosquito genes so that their immune systems created antibodies against the malaria parasite. The scientists used genes from mice to stimulate an immune response in mosquitoes, making it less likely for the insect to transmit the disease.

If these initiatives work well on a larger scale, CRISPR could be used to find solutions to West Nile Virus, Zika, Dengue, and other diseases spread by mosquitoes.

The Human Immunodeficiency Virus, or HIV, is a virus that attacks the immune system, making it harder for the body to fight off diseases. According to the World Health Organization (WHO), 39 million people were living with HIV by the end of 2022, including adults and children.

Most people living with HIV have an HIV-1 infection (HIV-2 is slow to develop and does not spread as fast). The HIV virus is spread by exchanging body fluids, mainly through unprotected sexual intercourse, sharing needles or syringes, and from an infected mother to her baby during childbirth or breastfeeding.

An HIV-1 infection is dangerous because the virus attacks the immune system, the human cells that defend against infection. It can be fatal without timely medical intervention and lifelong therapy.

Unfortunately, there is still no cure for HIV. One of the main reasons for this is the ability of the virus to mutate constantly, making it challenging to develop a single treatment that can target all strains. Also, some cells infected with HIV can become dormant, only to resurface years later. This is one of the reasons why HIV-infected individuals need treatment for life.

However, there is hope on the horizon with CRISPR.

Using CRISPR to treat HIV

Using CRISPR, scientists are editing out the HIV-infected immune cells in the body, including dormant ones. To achieve this, CRISPR is being used to cut fragments from the DNA of the HIV virus itself, rendering it unable to replicate and spread.

Early progress in this field has shown promising results, with researchers successfully using the CRISPR-Cas system to remove HIV from infected cells in laboratory experiments. However, it is still being studied in clinical trials to understand its effects on HIV-1 infections in humans.

With continued advancements, there is hope that CRISPR technology will lead to a future where HIV can be effectively treated or even cured.

Creating more accurate and sensitive at-home tests or point-of-care tests for viral infections like COVID-19, Ebola, and Zika is crucial for early detection and containment of these diseases.

Using CRISPR to develop more sensitive diagnostic tests

Scientists can use genome editing technology like CRISPR to identify and target specific RNA sequences in a disease-causing virus, like the COVID-19 virus.

CRISPR’s Cas enzymes can tag RNA in the viral cells without altering them, which makes CRISPR-based tests incredibly sensitive and accurate compared to today’s at-home test kits.

These tests promise to be more accurate and a low-cost option for at-home COVID-19 testing and other virus-related infections.

Bird flu, or avian flu, is a highly contagious viral infection that primarily affects birds and, rarely, humans. However, in July 2023, WHO warned about avian influenza outbreaks in humans that threaten human lives.

Due to changes in the ecology and epidemiology of avian flu, the disease is spreading to new regions, and there is a rise in cases affecting mammals, including humans. Although rare, human bird flu cases are often severe and have a high mortality rate.

Caused by the influenza type A virus (H5N1), highly pathogenic bird flu is a significant problem that can lead to massive losses in the poultry industry, as infected birds have to be culled to prevent spread. This can lead to billions of dollars in economic losses.

The virus can lead to massive losses in the poultry industry, as infected birds must be culled to prevent further spread. Additionally, outbreaks lead to trade restrictions on poultry products, resulting in billions of dollars in economic losses.

Using CRISPR to create chickens resistant to bird flu (partially)

Scientists from the University of Edinburgh used CRISPR to create bird flu-resistant chickens; well, almost.

The researchers targeted ANP32, a specific gene in the chickens’ DNA that makes them susceptible to bird flu. Using CRISPR, they modified this gene, making the chickens more resistant to the virus.

More research is needed to ensure the chickens are resistant to more potent strains of the avian flu virus, but this is a promising step.

Antibiotic resistance is a menace to society and a pressing issue today because it poses a significant threat to human health. It occurs when bacteria and other pathogens develop the ability to survive and grow in the presence of antibiotic drug therapy, rendering these medications ineffective in treating infections.

Antimicrobial resistance (AMR) plays a role in almost 5 million deaths, and in 2019 alone, it killed 1.2 million people worldwide. It can lead to more prolonged and severe illnesses, increased mortality rates, and higher healthcare costs.

Antibiotic resistance places a considerable burden on healthcare systems, with the costs associated with treating resistant infections estimated to be $55 billion in the United States alone, according to the US CDC.

Common antibiotic-resistant pathogens include methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, escherichia coli (E.coli), and carbapenem-resistant Enterobacteriaceae (CRE).

Using CRISPR to tackle antimicrobial resistance or AMR

Scientists are using CRISPR to fight antibiotic-resistant microbes in two ways:

• Slow down or stop AMR development, and
• Resensitize resistant bacteria to the effects of common antibiotics.

Antimicrobial resistance occurs when bacteria and other pathogens evolve to protect themselves from antibiotics and other targeted drugs. Usually, these resistant genes are shared between bacteria through plasmids, circular DNA strands that replicate quickly.

Using the CRISPR-Cas system, scientists re-engineered plasmids to target AMR genes. This process prevented AMR plasmid uptake into new bacterial cells and removed resistant plasmids from a population of E. coli (in lab studies).

These researchers also developed a resistance gene for gentamicin, a commonly used antibiotic. This way, they protected the host cells from developing resistance, so they were still sensitive to the effects of the drug.

Now, the scientists have to prove that their methods work in real-life breeding grounds for resistant pathogens and demonstrate effectiveness in protecting human cells.

In conclusion, CRISPR is an incredible breakthrough in the battle against infectious diseases. Its gene-editing ability can potentially eradicate mosquito-borne human diseases, combat antimicrobial resistance, and even help us find a cure for HIV-1 infections.

The best part is that the CRISPR-Cas system is highly efficient and cost-effective, making it accessible to more researchers worldwide. This technology can foster greater collaboration among the scientific community and help us achieve extraordinary advancements in the fight against infectious diseases to improve global health.

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