About 2 million people suffer each year from a skin disease called leishmaniasis, caused by leishmaniasis. Humans have been fighting the parasite for centuries, and some cultures have adopted a primitive method of vaccination to prevent infection. This ancient treatment is known as leishmanization, in which a person is deliberately infected with a living parasite. This process can lead to a mild skin infection, which a person’s immune system hopes to overcome, ingesting lifelong immunity to parasites.
However, this traditional treatment is rarely used today, as patients often suffer from skin lesions that can last for months.
In a fascinating example of integrating ancient treatments with cutting-edge technology in the 21st century, a team of scientists genetically edited the leishman parasite to limit its infectious power. This allows the parasite to inject patients in the form of a vaccine, producing long-term immunity without causing disease.
“Such a live vaccine is the best vaccine, but it has the potential to cause serious illness in some people,” explained lead researcher Abhay Satoskar, a co-lead researcher on the new study from Ohio State University. “We refined this concept with modern technology, creating a parasite that does not cause clinical disease but induces immunity.”
Using CRISPR gene editing technology, the researchers removed two specific genes from the parasite to prevent it from producing a protein called centrin, which supports the physical structure of the parasite. When the parasite lacks centrin, it can still enter the host cell and replicate, but at a significantly slower rate, which means that infection does not cause disease.
“So we’re basically using the concept of leishmanization, and CRISPR technology has greatly improved the tolerance that allows us to do this,” Satoskar said. “The parasites can’t multiply, so they die. But they persist in the body for eight to nine months, which is enough to produce an accessive immunity. “
In their study, the researchers documented extensive development and animal testing of the new, forward-looking vaccine. The study showed that CRISPR-edited parasites do not cause disease in animal models of sand flies, which transmit parasites through bites, and mice do not. In addition, in most animal trials, including mice with compromised immune systems, mutant parasites effectively produced complete immunity.
“Multiple animal tests have also ensured that the genome does not return to normal,” Satoskar added. “And we found that if a sand fly bites at the vaccine site and brings a mutant parasite into the wild, the parasite cannot survive. So it’s safe for the environment. “
Researchers now hope to begin the first phase of human trials within the next two years. Satoskar also said the vaccine is likely to cost less than $5 a dose, providing hope that it will eventually be rolled out cheaply and easily in the worst-hit tropical countries.
The study was published in the journal Nature Communications.