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TCID50 calculation

Ian A. York iayork at panix.com
Tue Jan 7 03:49:33 EST 1997

I'm embarassed to have to ask this question.  Fortunately, I'm used to
making a fool of myself.

I want to calculate a TCID50.  I've done serial ten-fold dilutions of
my virus, five wells per dilution.  At 10e-8 all five wells show CPE;
at 10e-9, two of five wells show CPE; none of the wells at 10e-10 show
CPE. I know that you can calculate TCID50 from this according to the
method of Karber, and in fact I have a paper which spells out the
formula.  Problem is that the paper is so poorly written at this part
that the formula doesn't make sense to me.  (The real problem is that
the bozo who wrote the paper was me.  At the time I had the formula
sitting beside me, used it every day, and took it for granted that I
would never forget it.  Let that be a lesson to me.)  (The rest of the
paper isn't as bad, I'll say in my own defense.) (It was my first,

So.  Anyone feel like spelling it out to me?  Thanks.

Ian "bozo" York
      Ian York   (iayork at panix.com)  <http://www.panix.com/~iayork/>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England

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