By: Jeongmin Lee
Over this past summer, the Zika virus infected not only unborn children but also the news, directing the public’s attention towards the medical community. Health segments were filled with descriptions of the Zika virus, research updates, and the quickly rising number of cases. In a consultation of the World Hunger Organization, one of the most popular methods discussed to defeat the Zika virus employed a “live, attenuated target organism” (1). In other words, many wished to use weakened viruses as vaccines. This common practice, used in vaccines ranging from the very first vaccine created by Edward Jenner to combat smallpox to today’s chicken pox vaccine, uses less dangerous forms of the target viruses and allows the body’s immune system to digest the weak viruses (2). The immune system remembers specific tags from the virus, so once the same virus (or even a more potent form) enters the body again, the immune system is prepared to quickly track down and eliminate the disease before it can spread. Many researchers want to combat Zika with this proven method, but some want to think “outside of the pox.”
The Zika virus comes mainly from one non-human vector: mosquitoes. Eradicating all mosquitoes would theoretically leave the disease to be only transmittable between humans. Using genetics, researchers can engineer ways to reduce the number of mosquitoes. For example, mosquitoes can be given a template of genes that can repress the growth of a mosquito embryo. These altered genes only affect fertilized eggs that contain two copies, while a mosquito that inherits only one copy of the gene can serve as a carrier. Through the mechanics of normal genetics, carriers would not propagate the gene effectively. So, researchers have found a way to make the engineered gene replicate itself when the carrier is about to reproduce. While the carrier might never be affected by the gene, mating with another carrier would always yield offspring with both copies of the gene that die immediately. A company called Oxitec tries to reduce the number of mosquitoes with yet another strategy (3). They breed male mosquitos (which do not bite like females) with a “self-limiting gene” that is inactivated until the mosquitos pass it down to their offspring. The offspring would not be able to create essential proteins during development and would die.
This revolutionary idea is met with criticism. Genetically modified organisms are controversial because the effects of introducing an artificial element into the natural world are often underestimated. For example, see the infamous dichloro-diphenyl-trichloroethane (most commonly known as DDT), a pesticide that was first widely used in the 1940s (4). The deleterious effects did not appear until decades later, when people found out that birds who ate the dead insects killed by the pesticide had birth defects. Humans who ate livestock or drank water containing DDT suffered birth defects as well. Could the reduction of mosquitos cause an imbalance in the ecosystem? The effects of Oxitec’s technology were only tested on a small scale in respect to both time and space, but controlling populations of species is nothing new for humans — consider open hunting season. In fact, the US Food & Drug Administration (FDA) recently approved the drug’s usage on the grounds that the change would not bring too heavy an imbalance to the ecosystem (5). The decision was made this past August, and we have yet to see if there are any downsides. So far, it appears that this new method of targeting disease vectors to prevent humans from contracting the disease may be a new page being written down in medical history.
Jeongmin Lee ‘19 is a Sophomore in Lowell house.
WORKS CITED
[1] “Zika Virus Vaccine Product Development.” World Health Organization. World Health Organization, n.d. Web. 11 Sept. 2016.
[2] Riedel, Stefan. “Edward Jenner and the History of Smallpox and Vaccination.” Proceedings (Baylor University. Medical Center) 18.1 (2005): 21–25. Print.
[3] “Our Solution | Oxitec.” Oxitec. N.p., n.d. Web. 30 Sept. 2016.
[4] “DDT – A Brief History and Status.” EPA. Environmental Protection Agency, n.d. Web. 01 Oct. 2016.
[5] Brown, By Kristen V. “The FDA Just Greenlit Releasing Mutant Zika-killing Mosquitoes in Florida.” Fusion. N.p., n.d. Web. 30 Sept. 2016.
[6] “Zika Virus | NIH: National Institute of Allergy and Infectious Diseases.” U.S National Library of Medicine. U.S. National Library of Medicine, n.d. Web. Sept.-Oct. 2016.
[7] Lipsitch, Marc, and Benjamin J. Cowling. “Zika Vaccine Trials.” Science. N.p., 09 Sept. 2016. Web. 12 Sept. 2016.
Harvard Science Review 