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Scientists plan to infect mosquitoes with bacteria to stop Zika, Dengue viruses


ZIKA• Biotech firm seeks approval to market product as pesticide to prevent spread of diseases
• Warmer temperatures quickens spread of cholera as risk identified in procedure for ‘three-parent babies’

The United States (U.S.) could soon become the first country to approve the commercial use of a common bacterium to fight the spread of mosquitoes that can transmit viruses such as Zika, dengue and Chikungunya.

According to a report published in Nature, the U.S. Environmental Protection Agency (EPA) is reviewing an application from the biotechnology start-up MosquitoMate to use the bacterium Wolbachia pipientis as a tool against the Asian tiger mosquito (Aedes albopictus). The company plans to market Wolbachia as a pesticide — one that kills only mosquitoes, and leaves other insects untouched. The EPA’s decision on the matter will come after a public-comment period that ends on May 31.

MosquitoMate’s strategy involves rearing mosquitoes infected with a particular strain of Wolbachia and releasing the males into the environment. When these male mosquitoes mate with wild females who do not carry the same strain of Wolbachia, the resulting fertilized eggs don’t hatch, because the paternal chromosomes do not form properly. As infected male mosquitoes continue to be released to breed with wild partners, the pest population dwindles.

Meanwhile, scientists have also found that warmer temperatures hastens the spread of Vibrio cholera (the causative organism of cholera), which infects roughly four million people annually, worldwide, causing severe diarrheal disease, and killing an estimated 140,000 people.

A team of investigators from the University of California, Santa Cruz, United States, provides new insights into how different temperatures in the bacterium’s environment control expression of genes required for life at those temperatures.

The research was published ahead of print May 20, 2016 in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

In the study, the investigators investigators found that expression of a major regulator of virulence is notably reduced at low temperature. That means that expression of virulence factors is curtailed at low temperatures, which makes sense since they are only needed during infection of a human host — which happens at body temperature.

Also, a new study has sounded a cautionary note for a controversial procedure used in creating “three-parent babies.”

That procedure replaces defective mitochondria, the energy-generating organelles in cells, with healthy ones. But even a tiny amount of defective mitochondria may replicate and take over the cell, researchers report online May 19 in the journal Cell Stem Cell.

Stem cell biologist Dieter Egli of the New York Stem Cell Foundation and colleagues say exactly which mitochondria can stage a comeback and when is unpredictable.

Mitochondrial replacement therapy is designed to prevent women from passing diseased mitochondria to their children. Mutations in the Deoxy Nucleic Acid (DNA)/genetic material of mitochondria can impair energy generation, starving some organs, such as the brain and muscles.

Scientists designed a work-around in which they could transfer an egg cell nucleus from a would-be mother carrying a mitochondrial disease into the shell of a donor egg containing healthy mitochondria.

Fertilization by sperm would create a three-parent baby who gets most of his or her DNA from the mother and father but gets mitochondrial DNA from a donor woman.

Researchers have always known that the therapy could fail if too many of the unhealthy mitochondria were transferred along with the mother’s nucleus.

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