Genetically Modified Mosquitoes | HHMI BioInteractive Video

Summary

In late 2014, an alarming increase in microcephaly cases in Brazil was linked to the Zika virus, spread by Aedes aegypti mosquitoes. To combat mosquito-borne diseases, scientists at Oxitec developed genetically modified mosquitoes (OX513A) designed to reduce wild populations. These modified mosquitoes carry a lethality gene, which causes their offspring to die before maturing unless exposed to tetracycline, unavailable in the wild. The technique has proven successful in reducing mosquito populations by up to 95%, and could be expanded to fight other diseases like dengue and chikungunya.

Takeaways

• 😀 An alarming rise in microcephaly cases in Brazil was linked to the Zika virus, which is transmitted by mosquitoes.
• 😀 Microcephaly, a condition where babies are born with abnormally small heads, became a major concern in 2014.
• 😀 The Zika virus spread rapidly across the Americas, following outbreaks of other mosquito-borne diseases like chikungunya and West Nile virus.
• 😀 Health officials have long fought against diseases spread by mosquitoes like Zika, dengue, and yellow fever, using sprays and screens.
• 😀 A biotech company called Oxitec has developed a genetically modified mosquito, OX513A, to reduce the population of Aedes aegypti mosquitoes.
• 😀 The OX513A mosquitoes are genetically modified with two genes: one that causes lethality in offspring and another that glows under specific light to track them.
• 😀 The modified mosquitoes are designed to mate with wild mosquitoes, passing on a lethality gene that ensures their offspring die before reaching maturity.
• 😀 Scientists breed these genetically modified mosquitoes in large colonies, feeding them tetracycline in the lab to keep them alive until they are released into the wild.
• 😀 Only male mosquitoes, which do not bite humans, are released into the wild, where they mate with females and spread the lethal gene.
• 😀 Studies show that with repeated releases, the genetically modified mosquitoes can reduce the wild mosquito population by up to 95%, potentially helping control the spread of diseases like Zika.
• 😀 If proven safe and effective, this genetic modification technique could be applied to other species of mosquitoes, offering a new tool in the fight against vector-borne diseases.

Q & A

What condition was observed in a growing number of babies in Brazil in late 2014?

In late 2014, doctors noticed an increasing number of babies born with microcephaly, a condition where babies have abnormally small heads.

What virus was linked to the increase in microcephaly cases in Brazil?

The increase in microcephaly cases was linked to the Zika virus, which is spread by mosquitoes.

What other mosquito-borne viruses were spreading in the Americas before the Zika outbreak?

Before the Zika outbreak, viruses like chikungunya, which causes joint pain, and West Nile virus, which can cause symptoms ranging from fever to paralysis, were also spreading in the Americas.

What mosquito species is responsible for spreading Zika and other viral diseases like dengue and yellow fever in South America?

The Aedes aegypti mosquito is responsible for spreading Zika, dengue, chikungunya, and yellow fever in South America.

What are some of the challenges in controlling Aedes aegypti mosquitoes?

Aedes aegypti mosquitoes are difficult to control because they live both indoors and outdoors, bite at any time of day or night, develop resistance to insecticides easily, and their eggs can survive for a year.

How does the genetic engineering approach aim to control Aedes aegypti populations?

The genetic engineering approach involves creating genetically modified mosquitoes (OX513A) that, when released into the wild, mate with wild mosquitoes and cause their offspring to die before reaching maturity.

What two genes were inserted into the genetically modified Aedes aegypti mosquitoes?

The genetically modified mosquitoes were engineered with a lethality gene and a fluorescent marker gene.

How does the lethality gene work in the genetically modified mosquitoes?

The lethality gene makes the developing mosquitoes dependent on the antibiotic tetracycline, which is supplied in the lab but is not available in the wild. Without tetracycline, the mosquitoes die before reaching adulthood.

What role does the fluorescent marker gene play in the genetic modification of mosquitoes?

The fluorescent marker gene produces a red glow when exposed to a certain wavelength of light, helping scientists identify which mosquitoes carry the lethality gene.

How are male genetically modified mosquitoes used in the field, and why are they chosen for release?

Male genetically modified mosquitoes are released into the wild because they do not bite humans but can still mate with wild female mosquitoes. When they mate, they pass on the lethality gene to the offspring, which ultimately leads to the death of those mosquitoes before they reach maturity.

What is the result of repeated releases of genetically modified mosquitoes in a targeted area?

Repeated releases of genetically modified mosquitoes can reduce the wild mosquito population by up to 95%, as the offspring of the modified mosquitoes die due to the lethality gene.

How can this genetic engineering technology potentially be used beyond controlling Zika?

If proven effective and safe, this genetic engineering technique could be applied to other species of mosquitoes, potentially helping to control the spread of various mosquito-borne diseases such as dengue, chikungunya, and yellow fever.