Tuesday, April 26, 2016

Zika research: Science in a hurry

Recently headlines have declared that Zika has been confirmed to cause microcephaly.  If you haven't been following, Zika is a viral infection similar to Yellow Fever or Denguy Fever that has broken out in Brazil over the last year.  At the same time, Brazil has witnessed an epidemic of a severe birth defect called microcephaly.  It's alarming both for it's consequence and it's mystery.  Microcephaly is a terrible birth defect in which babies are born with small, malformed brains.  But although it seems likely that the microcephaly epidemic is the result of an outbreak of another virus occurring at the same time, we don't actually know how Zika causes microcephaly or how often microcephaly occurs in women with Zika.  This is a huge question.

In order to firmly establish that Zika is actually CAUSING birth defects that are occurring, researchers in Brazil grew neruons in a dish and then infected them with Zika.  When they did, the neurons died.

What's funny about this news story was the reaction it elicited at my workplace.  My lab is actually in the process of getting certified to do a very similar experiment to the one which supposedly confirmed that ZIKA CAUSES MICROCEPHALY.  In the process of preparing I presented a paper two weeks ago at lab meeting.  The paper was not yet formally published, but I found it on a preprint server.  This is part of a growing trend in which researchers will post a copy of their work online for anyone to read while they're still in the process of getting a publisher to publish it.  When I presented the paper my lab mates and boss declared it to be rubbish.  You see, the researchers had introduced Zika to neurons and then declared that over 99% of the neurons had died.  The problem is that this is sloppy in several ways.  For one, it's far too convenient.  Zika does not cause all neurons to die.  Microcephaly is the result of reduced brain mass, but if all neurons died the infants wouldn't be born alive at all.  And what about adults?  Zika doesn't cause neurons to die in adults.

The results sound like a movie.  The scientist takes a slide with blood on it and drops one drop of THE CHEMICAL onto the slide.  Then the blood cells all turn green.  In real life, biology doesn't usually manifest obvious visible changes.  Normally we measure the strength of an effect or demonstrate a mechanism of action.

For what it's work, I still think Zika causes microcephaly.  But I look forward to seeing new results with more reliable information.

No comments:

Post a Comment