We’ve got plenty of effective antibiotics – maybe even too many– to knock off bacteria we don’t like. But when it comes to viruses, it’s a different story, Stanford infectious-disease specialist Shirit Einav, MD, and postdoc Elena Bekerman, PhD, write in a recently published perspective piece in Science.
“Although hundreds of viruses are known to cause human disease, antiviral therapies are approved for fewer than 10,” the authors write, before going on:
[Antiviral drugs that interfere with crucial viral enzymes] have shown considerable success in the treatment of HIV and hepatitis C virus… infections. However, this approach does not scale easily and is limited particularly with respect to emerging viruses against which no vaccines or antiviral therapies are approved.
Which is too bad, because viruses can be nasty. Not to mention creepy: They’re master puppeteers when it comes to manipulating us into submission. They can’t even replicate on their own. The little body-snatchers need our own cells, which they break into, bamboozle, and bully into producing copies of themselves and then squirting them out so they can infect other cells and, with luck, other people.
A partial list of merging and re-emerging viruses for which there are no decent treatments includes dengue, estimated to infect 400 million people each year; SARS and MERS, responsible for outbreaks of severe acute respiratory syndromes; and Ebola, which, as everybody now knows, caused an ongoing epidemic in Africa.
Developing antiviral drugs is a huge challenge. It takes, on average, more than $2 billion and about a decade, plus or minus a couple of years, to develop a new drug targeting just one single type of virus, Bekerman and Einav write. To make things worse, these nano-villains evolve even faster than bacteria do.
Einav’s research has been taking a different tack. She’s working on drugs that, instead of gumming up this or that viral enzyme (at least until it mutates into a form the drug can’t gum up), interfere with the activity of components in our cells that the viruses absolutely depend on for their own survival and replication. There are already drugs, many of them already approved for far different indications such as cancer, that can do just that – without, however, disabling our own cells so much that the cure becomes worse than the disease.
Some of these drugs show efficacy against not just one but many different viral species, even ones representing entirely different viral types. Two approved cancer drugs that Einav is working with, erlotinib and sunitinib, have shown activity in a test tube against the viruses hepatitis C, dengue and Ebola.
These drugs’ doses can be fine-tuned to reduce toxicity to patients taking them for severe viral infections. And the length of the period over which they’re administered to fight a virus is much shorter than that for treating cancer. So, less a scorched-earth strategy than a braised-earth one, if you will.
Previously: Frenemies: Chronic cytomegalovirus infection boosts flu vaccination efficacy (IF you’re young), A conversation on West Nile virus and its recent California surge, Life-saving dollar-a-dose rotavirus vaccine attains clinical success in advanced India trial and Global community must do a better job of managing risk of Nipah virus, expert says
Photo by Julia Pichler