West Nile Virus, Malaria, Dengue Fever; some of the potentially fatal illnesses humans can receive from
mosquitos. For years, efforts to combat the spread of these diseases have been focused on secondary
and tertiary disease prevention, which focus on early detection and proper response to progressed
infection, respectively. Primary prevention strategies, which offer the best patient outcomes, focus on
preventing a disease from ever being contracted. We recognize bug sprays, citronella plants, and
staying inside as some of the most effective, if not most universally effective, strategies for primary
prevention of mosquito-borne illnesses, but these are simply strategies to protect ourselves from a
threat; scientists have now begun laying the foundation for removing the threat instead of trying to
protect against it.
A study was published in mid-July 2020 which illuminates a way to potentially suppress the mosquito
population, specifically Aedes aegypti. A gene called Nix has been associated with the determination of
sex phenotype, where removal in males leads to development of feminine characteristics, and the
addition of which in females leads to development of masculine characteristics; however, the full
conversion from a genotypic sex to the opposite phenotypic sex has heretofore not been accomplished.
The researchers in this study created a modified Nix gene, referred to as the Nix transgene, which forces
the full phenotypic conversion from female to male in offspring as demonstrated in 28 consecutive
generations of the mosquitos. It was determined that the mating of the transgenic males with wild-type
females also consistently led to male-only offspring.
One hurdle of the study was that the genetic females which were converted to males were flightless,
rendering them incapable of mating. If a male possesses a mutated myosin heavy-chain gene called
myo-sex, it will be incapable of flight; however, if the Nix transgene (present on the same M-locus as
myo-sex), is substituted while attached to the unmutated myo-sex gene, flight-capable males will mate
with females to produce male-only offspring. This method of population suppression would be more
attainable and sustainable than previous methods of population control, such as selective sterilization or
female killing.
The implications of this study raise an ethical question: given the power to force extinction upon an
entire species, regardless of how inconvenienced we are by their presence, should we act upon that
power? How would this action affect other species in the food chain, in the environment, or even the
nutrition of the soil? If we attempt the partial suppression of the species, are we prepared to face the
potential accidental extinction of the species?

 

By Jordan Lyons, PharmD Candidate 2021
Read full article at https://www.pnas.org/content/pnas/early/2020/07/10/2001132117.full.pdf

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