03.01.2013 – GOLLYGEE!

Oseltamivir, also known as Tamiflu, inhibits the enzyme neuraminidase in influenza virus. The lab of Stephen Winters has developed new neuraminidase inhibitors that bind the enzyme covalently, and may have potential as new antiviral drugs.

Each year untold numbers of people come down with the flu during flu season. There are several antiviral medications that can be used to treat the flu and get rid of the infection. The most popular of these is Tamiflu, which works by inhibiting an enzyme called neuraminidase present in the influenza virus. Neuraminidase is the “N” in the strain names (i.e. H1N1, H3N2, etc.). With prolonged exposure, flu strains can become resistant to antiviral medications like Tamiflu. So there is a need for new drugs to be developed. Chemical and Engineering News covers a recent Science paper from the lab of Stephen G. Winters that investigates new neuraminidase inhibitors:

Four neuraminidase inhibitors are approved or in development for postinfection treatment. Tamiflu is the most popular, but flu can evolve into strains insensitive to it. Relenza is administered by oral inhalation, which has limited its use. Peramivir was withdrawn from a Phase III trial last year, and laninamivir is scheduled to enter Phase II, although both are approved in Asia.

The new compounds emerged from efforts by Stephen G. Withers and coworkers to determine how neuraminidase works molecularly (Science,DOI: 10.1126/science.1232552). Their study shows that neuraminidase catalyzes sialic acid cleavage by a mechanism involving a covalent intermediate. They determined the structure of the intermediate and designed sialic acid analogs that bond covalently to the viral neuraminidase active site but release very slowly, thus disabling it, and do not inhibit human neuraminidase. The compounds may evade viral resistance more effectively than Tamiflu because their structures more closely resemble that of sialic acid. Also, covalent bonding permanently inactivates the neuraminidase active site; Tamiflu and the three other inhibitors bind noncovalently.

The Centre for Drug Research & Development, in Vancouver, is seeking private-sector partners and investors to help develop the new inhibitors commercially.

NPR helps us continue our bee coverage. Today they summarize these two studies on wild bees and pollination. The first study examines the importance of wild bees in pollinating crops. Wild bees are thought to be better pollinators than honey bees and to help boost crop harvests:

Farmers who grow these crops often rely on honeybees to do the job. But scientists are now reporting that honeybees, while convenient, are not necessarily the best pollinators.

A huge collaboration of bee researchers, from more than a dozen countries, looked at how pollination happens in dozens of different crops, including strawberries, coffee, buckwheat, cherries and watermelons. As they report in the journal Science, even when beekeepers installed plenty of hives in a field, yields usually got a boost when wild, native insects, such as bumblebees or carpenter bees, also showed up.

“The surprising message in all of this is that honeybees cannot carry the load. Honeybees need help from their cousins and relatives, the other wild bees,” says Marla Spivak, a professor of entomology at the University of Minnesota. “So let’s do something to promote it, so that we can keep honeybees healthy and our wild bee populations healthy.”

The second study brings the not so good news that wild bee species might be in decline. From NPR again:

Robertson taught biology and Greek at Blackburn College in Carlinville, Ill., and he was fascinated by the close connection between insects and flowers. He spent years in the forests around Carlinville, carefully noting which insects visited which wild flowers at what time of year.

Burkle and Tiffany Knight, a colleague at Washington University in St. Louis, went back to Carlinville to see how much of the ecosystem that Robertson observed still exists today.

Much of the forested area around the town has been converted into fields of corn and soybeans — or suburbs. In the fragments of forest that remain, Burkle and Knight found all of the flowering plants that Robertson recorded in his notes a century ago. Of the 109 species of bees that Robertson saw, though, just over half seemed to have disappeared from that area.

If you have time you can listen to the NPR story here. Or check out the research papers here and here.

GOLLYGEE!

Date: 03.01.2013

fighting the flu

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