Question

The Term "Titer" in Medicine refers to the Concentration of Antibody Molecules or Virus Particles as determined by a Dilution Series. The Titer of our fX174 Bacteriophage is usually ~ 1.0 times 10^10 Plaque Forming Units per Milliliter (pfu/ml), indicating that there are at least 1.0 times 10^10 Bacteriophage per Milliliter. Assuming that our fX174 Bacteriophage Titer actually is 1.0 times 10^10 Pfu/ml, and assuming that each Bacteriophage actually produces a Plaque, approximately how many Plaques should you expect to see on your 10^-7 ("17"), 10^-8 ("8") and 10^-9 ("9") Phage Plates next Week?

Answer 1

Use the following formula to determine the titre of your viral stock:

Titer(pfu/ml)= No. of plaques/d*v

Where,

d= dilution

v= volume of diluted virus added to the plate

Here, in the question, we have to calculate no. of plaques.

Given,

Titer= 1.0 X 10¹⁰ PFU/ml

d=10^-7

(i) For (10^-7) =

1*10¹⁰pfu/ml= No. of plaques/10^-7*1

=1*10¹⁰ *10^-7= 10³=1000 plaques

(ii) For 10^-8

=1* 10¹⁰*10^-8=10²

=100 plaques

(iii) For 10^-9

1*10¹⁰*10^-9=10¹

=10 plaques