BY138 Essential skills for Bioscientists | Curb Disease Transmission

Different insect spread diseases that can be targeted by GM

Genetic modifications of insects is a technique that involves altering genes of insects to introduce certain characteristics .Insects have been known to transmit different diseases over the years. Some of the notable diseases that are transmitted or spread by insects include malaria, Zika virus, dengue fever and chikungunya virus. Majority of this diseases are spread through the bite of the female Aedes Aegyptus mosquito since they can be found in blood after infection. Other diseases caused by insects include tick borne encephalitis which is caused by ticks of the lxodes ricinus species.

Where the disease occur and how the insects spread them

The Zika virus is one of the new diseases that is sweeping across Brazil. This disease is spread by the female Aedes aegypti mosquito. This breed of mosquitoes usually lay their eggs near pools of water, animal dishes and flower pots and they transmit the disease from one person to another through bites. The Zika virus is usually found in blood one week after infection and this is the reason why it is possible to be transmitted through the bite of a female Aedes Aegyptus mosquito. Chikungunya is another disease that occur mainly in Africa and Asia though there have been reported cases in America from 2000.Just like the Zika virus, this disease is spread by bites from two species of mosquitoes which include the Aedes albopictus and the Aedes aegypti. However, it is only the female mosquito of either of the species that spread the virus. Dengue fever is a condition or disease that is caused by the dengue virus and it occurs in over 110 countries (Adelman, Pledger, & Myles, 2017, p.440). This virus is also spread from one person to another through the bite of different types of mosquitoes though the principle is the female Aedes aegypti. Malaria on the other hand is a disease that is found in tropical and sub-tropical regions. It is spread from one person to another through the bite of the female anopheles mosquito.

How GM technique compares to other options

There have been different options explored in the treatment of this conditions or diseases that are spread from one person to another through bites from insects. The different techniques include vaccination, sanitation and use of pesticides. When compared to use of pesticides, genetically modification of mosquitoes is an environmental friendly option (Yakob & Walker, 2016,p e148). Pesticides have been known to be toxic to both human beings and animals in case there is contact.GM is also an effective method when compared to other physical methods such as use of mosquito nets. This is because the mosquito nets only shields access of the mosquito to the human beings but it does not eliminate the dangerous species as GM does. The GM insects have some short comings when compared to other methods of preventing diseases (Adelman & Tu, 2016, p.220). This is a very expensive technique and wastes a lot of time. There also increased concerns that GM can lead to mutation and form stronger insects that could pose a new threat of the diseases. Majority of the governments have ruled pesticides as being safe and therefore there would be no need of taking risks with genetically modified insects which could undergo subsequent mutation and transmit other diseases.

What GM involves and what techniques are available

Genetic modification is simply the alteration of genes in the living organisms to come up with certain desired characteristics. There are different techniques currently available for genetic modification. Living organisms usually contain a barrier that protects introduction of new DNA from opposite species (Araújo, Carvalho, Ioshino, Costa-da-Silva, & Capurro, 2015, p.580). However, during genetic modification, the engineers or the scientists find a way of bridging this barrier to force the DNA of another species into another the organism that want to be altered. This can be done either by using bacteria or viruses to infect the insect of desire (Carvalho, Costa-da-Silva, Lees, & Capurro, 2014, p.s176). Another technique is where the DNA is coated with small tiny metals pellets and using a special gun to fire them into cells. The other technique involves injection of the new DNA into the fertilized eggs by using a very fine needle.

There are other GM technologies that are utilized in creating genetically modified insects to reduce spread of diseases. Gene drive is an example of the technique where modified genes are introduced into the insect with DNA so that they are inherited by subsequent generations (Gabrieli, Smidler, & Catteruccia, 2014, p.11). Gene drive also involve CRISPR which is a gene editing technique that allows scientists to make necessary changes to DNA.

Homing Endonuclease Genes, sterile Insect technique and the release of insects carrying a dominant lethal (RIDL) are other techniques that are currently available. RIDL was introduced by British biotech company Oxitec and it involves inserting a lethal gene into an insect using transgenic technology (Dantas-Torres & Otranto, 2016, p.52). The sterile technique on the other hand involves the use of radiation sterilized male insects to mate with the female and this eventually reduce reproduction of the target population thus reducing their population.

Examples of past successful trials and potential future scopes

There are different trials in which GM technique has been successful. One of the cases is the control of the Aedes aegypti mosquitoes in Cayman Islands. In this exercise, the Release of insects carrying a dominant lethal (RIDL) using male Aedes aegypti was conducted with the objective of preventing dengue fever in the region. The results were quite impressive since there was 80% suppression of the mosquitoes. The same technique was also used in Brazil and the population of Aedes aegypti reduced by between 81% and 91% (Taracena et al., 2015, p.3). The future scope of GM insects looks a bit dim. This is because the European Nation perceives this to be an expensive, slow and also deters innovation as well as technology transfer. Further research ought to be carried out in future to make it a better option

References

Adelman, Z. N., Pledger, D., & Myles, K. M. (2017). Developing standard operating procedures for gene drive research in disease vector mosquitoes. Pathogens and Global Health, 111(8), 436-447. doi:10.1080/20477724.2018.1424514

Adelman, Z. N., & Tu, Z. (2016). Control of Mosquito-Borne Infectious Diseases: Sex and Gene Drive. Trends in Parasitology, 32(3), 219-229. doi:10.1016/j.pt.2015.12.003

Araújo, H., Carvalho, D., Ioshino, R., Costa-da-Silva, A., & Capurro, M. (2015). Aedes aegypti Control Strategies in Brazil: Incorporation of New Technologies to Overcome the Persistence of Dengue Epidemics. Insects, 6(2), 576-594. doi:10.3390/insects6020576

Carvalho, D. O., Costa-da-Silva, A. L., Lees, R. S., & Capurro, M. L. (2014). Two step male release strategy using transgenic mosquito lines to control transmission of vector-borne diseases. Acta Tropica, 132, S170-S177. doi:10.1016/j.actatropica.2013.09.023

Dantas-Torres, F., & Otranto, D. (2016). Best Practices for Preventing Vector-Borne Diseases in Dogs and Humans. Trends in Parasitology, 32(1), 43-55. doi:10.1016/j.pt.2015.09.004

Gabrieli, P., Smidler, A., & Catteruccia, F. (2014). Engineering the control of mosquito-borne infectious diseases. Genome Biology, 15(11). doi:10.1186/s13059-014-0535-7

Taracena, M. L., Oliveira, P. L., Almendares, O., Umaña, C., Lowenberger, C., Dotson, E. M., … Pennington, P. M. (2015). Genetically Modifying the Insect Gut Microbiota to Control Chagas Disease Vectors through Systemic RNAi. PLOS Neglected Tropical Diseases, 9(2), e0003358. doi:10.1371/journal.pntd.0003358

Yakob, L., & Walker, T. (2016). Zika virus outbreak in the Americas: the need for novel mosquito control methods. The Lancet Global Health, 4(3), e148-e149. doi:10.1016/s2214-109x(16)00048-6