China has double good news on the malaria front

Xinhua
Nobody was infected with malaria in China via mosquito bites in 2017 while researchers reported a draft genome sequence of a Chinese shrub producing a potent antimalarial compound.
Xinhua

Nobody was infected with malaria in China via mosquito bites in 2017, the National Health Commission said on Tuesday.

The country reported a total of 2,672 malaria cases in which patients were infected abroad, and three cases in which people were infected through blood transfusions, said Mao Qun’an, head of the disease control and prevention division of the commission.

Since 2010, the incidence of malaria has been reduced to less than one out of 10,000 in 95 percent of counties in China, according to Mao.

China used to have more than 24 million malaria cases annually in the early 1970s. It aims to eliminate all malaria cases by 2020, Mao said.

In another piece of good news, Chinese researchers reported Wednesday in the journal Molecular Plant a high-quality draft genome sequence of Artemisia annua, a Chinese shrub producing a potent antimalarial compound artemisinin and a way to extract more antimalarial medicine from the plant.

The findings can be used to metabolically engineer plant lines that produce higher levels of artemisinin as the low amount of artemisinin produced in the leaves of this sweet wormwood does not meet the global demand.

“Nearly half of the world’s population is at risk of malaria,” said senior study author Tang Kexuan with Shanghai Jiao Tong University.

“Our strategy for the large-scale production of artemisinin will meet the increasing demand for this medicinal compound and help to address this global health problem,” Tang said.

According to the World Health Organization, malaria affected about 216 million people in 91 countries in 2016 and caused an estimated 445,000 deaths worldwide that year alone.

The best available treatment for malaria is artemisinin-based combination therapy. In addition to its antimalarial activity, therapeutic effects of artemisinin have been reported for cancer, tuberculosis, and diabetes.

However, the supply of artemisinin is limited because this medicinal compound typically makes up only 0.1 percent to 1 percent of the dry weight of Artemisia annua leaves.

To fully harness this compound’s therapeutic potential, researchers have developed metabolic engineering strategies aimed at enhancing the expression of artemisinin biosynthetic pathway genes.

These efforts failed to generate Artemisia annua lines that produced high levels of artemisinin, though.

A major hurdle for metabolic engineering strategies has been the lack of reference genome sequences and limited information about the genes involved in regulating artemisinin biosynthesis.

Tang and his collaborators generated a high-quality draft assembly of the 1.74 gigabase Artemisia annua genome, which contains 63,226 protein-coding genes, one of the largest numbers among sequenced plant species. It took several years to complete the genome sequence due to its large size and high complexity.

The study added a wealth of information about Asteraceae, one of the largest families of plants consisting of more than 23,600 species of herbs, shrubs, and trees throughout the world, including many with considerable medicinal, ornamental, and economic importance.

Leveraging these findings, Tang and his team have sent artemisinin-rich seed samples to Madagascar for a field trial.

“We hope our research can enhance the global supply of artemisinin and lower the price from the plant source,” Tang said.

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