3 ms·

Given the observation "something medically bad is happening to kids", how to scientists get to the conclusion, "this is caused by virus xyz"? I'm really curiou

Given the observation "something medically bad is happening to kids", how to scientists get to the conclusion, "this is caused by virus xyz"? I'm really curious what the roadmap for the research looks like. Because it seems to me that the potential search space -- all the things that could potentially cause problems -- is mind-bogglingly huge. And any given victim of the illness is likely to have some quirks - history of exposure to various stuff, family history of different diseases, an odd bacterium or two in the gut, etc. How does it all get sorted out?

Fomite 13y ago
You look into things known to cause symptoms like these - enteroviruses in this case - and test for known versions in the patients. You send samples to labs to look for new, unknown viruses. You take pretty exhaustive biological and social histories from the patients, and look for commonalities - shared exposures, other underlying conditions, etc.
- CWuestefeld 13y ago
  I've got a handle on all that stuff with looking for commonality. But how does one look for new, unknown viruses? I don't think you can just grow them in petri dishes like bacteria.
  - bertil 13y ago
    Viruses don't exist out of the blue: they often use common and well-known envelope to carry genetic information. These are easy to isolate: that's the reason why they are classified and described as entemo-viruses, retro-viruses, etc. That's also why it took a while to find HIV. The Wikepedia you link you probably want to look at is: http://en.wikipedia.org/wiki/Polymerase_chain_reaction http://en.wikipedia.org/wiki/Polymerase_chain_reaction (Source: MD girlfriend).
    - twic 13y ago
      The advent of PCR and complete sequences of large numbers of viral genomes makes this sort of analysis fairly easy, although far from foolproof, these days. Before the era of molecular biology, isolating the agents of disease was considerably more painstaking. There's an outline of the isolation of the polio virus here: http://www.virology.ws/2008/12/19/100th-anniversary-of-the-isolation-of-poliovirus/ http://www.virology.ws/2008/12/19/100th-anniversary-of-the-i... But even once that was done, all scientists had was a procedure to make a test-tube full of liquid which would give you polio. They could reasonably surmise it was a virus (and they were lucky it wasn't a prion!), but beyond that, they knew nothing: not the nature of the virus, not how to culture it, not how to fight it. Gleaning that knowledge meant putting their lab coats back on and going back to the bench for a few more decades.
  - twic 13y ago
    It's not like you can just grow most bacteria on petri dishes, either. They often have extremely specific requirements to be cultured, and there are plenty that nobody has managed to culture. See: http://schaechter.asmblog.org/schaechter/2010/07/the-uncultured-bacteria.html http://schaechter.asmblog.org/schaechter/2010/07/the-uncultu...

Fomite 13y ago

You look into things known to cause symptoms like these - enteroviruses in this case - and test for known versions in the patients. You send samples to labs to look for new, unknown viruses. You take pretty exhaustive biological and social histories from the patients, and look for commonalities - shared exposures, other underlying conditions, etc.

CWuestefeld 13y ago
I've got a handle on all that stuff with looking for commonality. But how does one look for new, unknown viruses? I don't think you can just grow them in petri dishes like bacteria.
- bertil 13y ago
  Viruses don't exist out of the blue: they often use common and well-known envelope to carry genetic information. These are easy to isolate: that's the reason why they are classified and described as entemo-viruses, retro-viruses, etc. That's also why it took a while to find HIV. The Wikepedia you link you probably want to look at is: http://en.wikipedia.org/wiki/Polymerase_chain_reaction http://en.wikipedia.org/wiki/Polymerase_chain_reaction (Source: MD girlfriend).
  - twic 13y ago
    The advent of PCR and complete sequences of large numbers of viral genomes makes this sort of analysis fairly easy, although far from foolproof, these days. Before the era of molecular biology, isolating the agents of disease was considerably more painstaking. There's an outline of the isolation of the polio virus here: http://www.virology.ws/2008/12/19/100th-anniversary-of-the-isolation-of-poliovirus/ http://www.virology.ws/2008/12/19/100th-anniversary-of-the-i... But even once that was done, all scientists had was a procedure to make a test-tube full of liquid which would give you polio. They could reasonably surmise it was a virus (and they were lucky it wasn't a prion!), but beyond that, they knew nothing: not the nature of the virus, not how to culture it, not how to fight it. Gleaning that knowledge meant putting their lab coats back on and going back to the bench for a few more decades.
- twic 13y ago
  It's not like you can just grow most bacteria on petri dishes, either. They often have extremely specific requirements to be cultured, and there are plenty that nobody has managed to culture. See: http://schaechter.asmblog.org/schaechter/2010/07/the-uncultured-bacteria.html http://schaechter.asmblog.org/schaechter/2010/07/the-uncultu...