Study of the Week: Scientists Develop Tick Gene Editing Approach, Facilitating Disease Prevention Research

Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.

If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.

 

This week’s study is…

Cas9-mediated gene editing in the black-legged tick, Ixodes scapularis, by embryo injection and ReMOT Control

We previously published about this research in a story titled “Gene Editing in Ticks May Help Prevent Tick-Borne Diseases” which can be found here. The study was originally published in the journal iScience. You can view the full text of the study here.

This research team was affiliated with the University of Nevada, Reno.

What Happened?

Ticks serve as important vectors of several uncommon but potentially deadly infectious diseases. The most well known of these is Lyme disease, but there are several others as well, such as babesiosis, Rocky mountain spotted fever, and alpha-gal syndrome. For many of these diseases, outcomes can vary greatly and can sometimes results in lifelong chronic symptoms and debilitation.

More information is needed in order to reduce the impacts of these diseases on humans. With this goal in mind, the research team sought to develop an approach to gene editing in ticks. Unlike mosquitos, another arthropod that is a major vector for disease, very little research has been conducted in the genetic makeup of ticks. The scientists utilized CRISPR-Cas9 technology in this study to develop an approach for gene editing in these animals. The tick species used in the study was Ixodes scapularis, commonly known as the black-legged tick or the deer tick. This species is known for spreading Lyme disease in the US as well as other infections.

Part of the reason an approach hasn’t been developed is due to the limited knowledge of tick embryo development. The scientists decided to work with tick embryos, and in order to do this they had to introduce CRISPR to tick eggs. Tick eggs are under high internal pressure and have a hardened outer layer. This layer is further surrounded by a waxy coating. The team found that this coating had to be removed before injection. 

In order to do this, the team had to carefully dissect a female tick that was full of developing eggs and remove the organ that produces the waxy egg coating. The unwaxed eggs were still viable for use in research and allowed for the injection of CRISPR. This was a new approach that hadn’t been used successfully before.

About Lyme Disease

Lyme disease is an infectious disease caused by bacteria of the genus Borrelia. This bacteria is commonly spread to humans through the bite of a tick. In the US, the species of tick associated with Lyme disease is called the deer tick or the black legged tick (Ixodes scapularis). A tick must be attached to a person for at least 36 hours to transmit the bacteria. Symptoms of this disease include a distinctive bullseye rash surrounding the bite, fatigue, malaise, headache, and fever. Delays in treatment can lead to more serious symptoms, such as facial paralysis, mood changes, memory loss, sleeping difficulties, meningitis, arthritis, and others. In most cases, prompt treatment can effectively cure the infection. Delayed treatment increases the chance of serious complications and long term, lingering symptoms. The number of cases of the disease appears to be growing annually. To learn more about Lyme disease, click here.

Why Does it Matter?

While tick-borne infectious diseases haven’t caused the level of mass death and devastation as those passed along by mosquitos, the harsh reality is that thousands of people still get infected with disease by tick bites every year. While treatment can be successful if the disease is detected early, not all patients get diagnosed when they should, and testing, particularly for Lyme disease, isn’t that reliable.

Furthermore, the risk of infection with Lyme disease and other tick-borne illnesses is increasing. This is a result of climate change, as the warmer temperatures allow ticks to remain active for more days during the year. This allows them more opportunities to increase their population.

There’s a lot that we still don’t understand about these diseases and understanding the genetic characteristics of tick species that pass along these illnesses could go a long way in helping the scientific community learn more.

“Having genome-editing tools available will allow us to unlock some of the secrets of the tick genome and allow us to determine how these unique animals survive in the environment, how they interact with pathogens, and how we might prevent ticks from spreading diseases to humans and livestock.” – Monika Gulia-Nuss, study co-author and molecular biologist, University of Nevada, Reno

Hopefully, future research will be able to use the approach developed in this study to investigate the genetic characteristics of ticks and develop a blueprint for preventing infectious disease.

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