Calculate TCID50/mL
 
 

TCID50/mL (Tissue Culture Infectious Dose 50%/mL) is the concentration of infectious organisms in the inoculum determined from the dilution at which the inoculum infects 50% of the target cultures (i.e., when the starting sample is diluted by an amount equal to the TCID50/mL, 1mL aliquots added to multiple target cultures will infect, on average, 50% of the cultures).

 

The calculation [Reed, LJ, H Muench. 1938. A simple method of estimating fifty percent endpoints. Am. J. Hygiene 27: 493–497.] assumes a typical assay set up of 5 replicates at each concentration of the infectious agent and the inoculum added to each row of replicates is 10-fold more dilute than that used in the preceding row. The inoculum used in the first row is 1/10 the concentration of the stock to which the TCID50/mL calculation applies. Other configurations are used, and I may eventually program that flexibilty into the program. For now, we have 5 replicates, with 10-fold dilutions between rows.

 

The calculation requires checking only 1 or 2 boxes:

---(1) Check the box corresponding to the number of infected cultures (3 to 5) in the last row from the top with 3 or more (50% or more) infected cultures.

---(2) Check the number of infected cultures (none, 1, or 2) in the row at the next dilution (should be <50% or it would be the row selected in (1)).

 
|----Replicates----|
 
    Dilution
1
2
3
4

5

Clear
 
Inoculum volume= uL
1e-1
    1e-2  
    1e-3  
    1e-4  
    1e-5  
    1e-6  
    1e-7  
    1e-8  
                submitButton