Oh, the things researchers get people to do in the name of Science…
When most microbiologists talk about poop, they are talking about bacteria. Salmonella, E. coli, Cholera– they have all evolved different, wonderfully complex ways of making people poopy.
But if you really want to make a lot of people poop, and fast, you need a virus!
While we get a pathogenic Salmonella outbreak every now and then, GoogleNews ‘norovirus’ real quick. You can find tons of current articles on outbreaks on cruises, parties, schools, weddings– This bastard is everywhere, all the time, ruining peoples good times. Like other non-enveloped viruses (ie polio), noroviruses are tough bastards that require special cleaning/cooking protocols to ensure the buggars are dead. So when those protocols arent followed, noroviruses spread like wildfire.
But despite all the diarrheal damage noroviruses cause, we didnt even know they existed until very recently. We thought enteric diseases were caused by bacteria… but then in the 1940s, scientists filtered poop from infected individuals (cell free=no bacteria) and got volunteers to swallow it. I shit you not. These volunteers subsequently got sick too.
So, something smaller than a bacteria, ie, a virus, was causing the illness.
But the actual virus wasnt identified until 1972, when scientists got volunteers to swallow cell-free poop once again after an outbreak in a Norwalk, Ohio elementary school. Scientists used the volunteers antibodies to get the virus to clump together to get chunks they could visualize with electron microscopy. Importantly, the clumps didnt form with pre-infection sera, thus, the apparent virus that these antibodies were sticking to was the etiologic agent behind non-bacterial enteric disease. So thats how noroviruses got the nickname ‘Norwalk virus’.
But even now that the scientists knew what they were dealing with, they couldnt get the virus to grow in tissue culture. Like, with HIV-1, I can get a ton of virus in 48 hours with an infectious molecular clone. Or you can just throw virus on white blood cells from volunteers, and in a week, youve got a ton of HIV-1 in your flask. No big whoop.
These tricks dont work with noroviruses.
So, to get enough virus to characterize its genome, scientists fed volunteers yet more poop, collected their poop, and purified the viral RNA. By 1990, we had the Norwalk virus sequence!
Now, this is a lighthearted post, but many people (especially children/elderly) die from bacterial/viral enteric diseases. Sure, poopy is funny. Dead, dehydrated babies, not so much. So obviously we are trying to make a vaccine.
Unfortunately, it appears that none of us have long-term immunity to noroviruses. After feeding volunteers filtered poop, scientists discovered that after an infection, you are protected from another infection for a couple of weeks. But then youre right back to being just as susceptible as you were in the first place.
Some volunteers drank the filtered poop and didnt get sick… but scientists cant figure out why. Seems it has nothing to do with the concentration of norovirus-specific antibodies in your system, because some of the people who didnt get sick didnt have any norovirus antibodies… an unfortunate, unexpected stumbling block for vaccine developers.
To make matters worse, we cant even get an animal model going. Scientists have fed poop to mice, guinea pigs, rabbits, cats, cows, baboons, rhesus macaques, marmosets, owl monkeys, patas monkeys, cebus monkeys, chimpanzees, mangabeys, and pig-tailed macaques… they dont get poopy. Only humans get poopy.
There is some hope in the recent discovery of a murine norovirus, but for the time being, it seems we still need to rely on the generosity of volunteers who dont mind pooping a couple days for The Greater Good.