According to a recent article from MedicineNet, scientists are editing the genomes of ticks to help prevent tick-borne diseases such as Lyme disease.
Lyme Disease
Lyme disease is a vector-borne disease that is typically caused by the bacteria Borrelia burgdorferi and spread by ticks. About 30,000 cases of Lyme disease are reported to the CDC annually, but not all cases are reported. The actual number of cases is most likely higher.
Symptoms:
Symptoms come in stages, so they differ depending on how long one has had the disease. Early symptoms include fever, chills, headaches, fatigue, aches in the muscles and joints, swollen lymph nodes, and erythema migrans rash. This rash forms at the site of the tick bite. These symptoms will occur three to 30 days after infection.
Later effects begin to appear days or months after the bite. They include severe headaches, neck stiffness, additional rashes, facial palsy, arthritis, severe joint pain and swelling, intermittent pain in the tendons, muscles, joints, and bones, an irregular heart beat, dizziness, shortness of breath, inflammation in the brain and spinal cord, nerve pain, and shooting pains, numbness, and tingling.
Causes:
A bacteria is responsible for Lyme disease, and it is called Borrelia burgdorferi. Infected deer ticks transmit the disease throughout the northeastern, mid-Atlantic, and north-central portions of the United States, while the western blacklegged tick spreads the disease on the Pacific coast.
Looking at the Genetics of Ticks
Ticks are transmitters of a number of different diseases to humans, including Lyme disease, anaplasmosis, Rocky Mountain spotted fever, and tularemia. Despite all of this, the genetics of ticks are still widely unknown to scientists. This is mainly due to issues in applying genetic and molecular tools.
Therefore, researchers decided to try gene editing in ticks to decrease tick-borne diseases in humans. If genome-editing tools are available to look at tick genomes, researchers will then be able to understand how they survive, interact with various pathogens, and figure out the ways ticks transmit their diseases to humans and animals.
Overcoming the Obstacles
Scientists started by attempting to conduct gene editing in tick embryos. This came with a number of issues since the eggs of ticks have a higher interior pressure, a hard outer shell, and a wax layer outside, all of which has to be removed in order to access the embryo for injection. To negate this issue, scientists removed the organ that produces the wax layer in pregnant female ticks while still allowing the pregnant tick to produce viable eggs. Without the layer of wax, scientists were able to inject the embryos with the materials needed for genome modification.
The other issue that researchers faced was understanding the timeline of tick embryo development. They needed to know the exact timing of their development to know when CRISPR-Cas9 should be introduced to allow for the best chance of creating genetic changes. However, this information was not previously known about tick embryology.
Despite all of their challenges, researchers were able to use a technique known as CRISPR-Cas9 to specifically edit the genomes of black-legged ticks, which are known to spread Lyme disease. The tools they are creating provide hope for understanding ticks and how the transmission of diseases from tick to humans can be prevented.
