Reporter Journal / Chris Davis

Science making gains against Zika virus on multiple fronts

By Chris Davis (China Daily USA) Updated: 2017-08-02 10:31

The dreaded Zika virus made news again, but this time in a way that gives hope.

The World Health Organization (WHO) says that the virus continues to spread geographically to areas where the vectors or carriers - female Aedes aegypti mosquitoes and infected humans - are present. They number 84 countries and territories as of March.

"Although a decline in cases of Zika virus infection has been reported in some countries," WHO says in its latest situation report, "vigilance needs to remain high."

In normal people, the virus causes mild flulike symptoms, rash and fever that go away in four days to a week. But in pregnant women, the virus has been linked to birth defects including Guillain-Barre syndrome and microcephely - abnormally small head size and brain damage.

So it comes as great news that medical researchers in China have developed an antiviral peptide called Z2 that has killed the Zika virus in lab mice and pregnant lab mice without affecting their fetuses.

The development of peptide drugs, study authors Lu Lu and Jiang Shibo write in Nature Communications, "has attracted growing attention because of their better safety and lower development cost".

It's been a team effort between the School of Basic Medical Sciences at Fudan University, the Shanghai Public Health Clinical Center and the Institute of Microbiology and Epidemiology at the Academy of Military Medical Sciences.

The agent works by attaching itself to the surface of the virus rendering it incapable of interacting with the body's cells. Z2 can also penetrate the placenta preventing vertical transmission to the unborn.

There have also been developments on the vaccine front. In an article published in the journal Cell two weeks ago, researchers at Washington University School of Medicine in St Louis announced two vaccines that "provided substantial protection" from Zika infection in female mice after they became pregnant, according to Michael S. Diamond, MD PhD, of Washington University.

One is genetically engineered off a "blueprint" of the virus' shell; the other is a live but weakened form of the virus itself, both intended to teach the immune system to attack Zika.

Groups of female mice were given one of the two vaccines or a placebo and some received a second dose a month later. Three weeks later researchers found high levels of neutralizing antibodies against Zika, but not in the placebo mice.

The mice were then impregnated and on their sixth day infected with the Zika virus and checked a week later. For the first vaccine, more than half the placentas and fetuses had no detectable Zika material at all. The live virus vaccine did even better - 78 percent of the placentas and 83 percent of the fetuses had no trace of Zika.

Diamond, who co-wrote the study with Pei-Yong Shi of the University of Texas Medical Branch, said that the amount of Zika material they found in the vaccinated females "was just above the limit of detection", and it wasn't clear whether it was infectious virus or scraps of virus that had been killed.

"There are several vaccines in human trials right now," Diamond said, "but to date, none of them has been shown to protect during pregnancy".

Scientists are attacking Zika on yet another front and leave it to Silicon Valley to come up with an approach that thinks outside the box - literally.

Aedes aegypti mosquitoes, which also spread dengue fever and chikungunya, are an invasive species that only arrived in California's Central Valley in 2013, and by all accounts they love it there. They're flourishing and driving people crazy.

"It's a terrible nuisance, a terrible biting nuisance," Steve Mulligan, district manager of the Consolidated Mosquito Abatement District, told the Daily Herald. "It's changed the way people can enjoy their backyard and it's a threat for disease transmission. So we're looking for new ways to eliminate it."

As part of the "Debug Fresno" project, millions of Aedes aegypti mosquitoes will be infected with Wolbachia bacteria, which change the reproductive ability of the males. The males will then be separated from the females and released into the wild to mate with females and make eggs that will never hatch.

Separating millions of male mosquitoes from females? Enter Verily, a subsidiary of Alphabet, formerly Google Life Sciences. Their automated sex-sorting uses computer vision algorithms to identify the sex of a mosquito and only let the males through.

White vans with the "Debug Fresno" logo will soon be driving around releasing 20 million sterile male mosquitoes into the wilds of selected neighborhoods.

The approach mimics what Chinese scientists did last summer on Shazai Island, releasing millions of Wolbachia-infected male Aedes aegypti mosquitoes producing stunning results - now a year later, 99 percent of the population has been suppressed.

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