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Table 1 An example of the calculation used to estimate the proportion of cells that contained the provirus.

From: A method to estimate the efficiency of gene expression from an integrated retroviral vector

Dilution

(1)

(2)

(3)

(4)

(5)

(6)

(7)

Dilution from (1) (d)

 

2

10

20

100

200

1000

Number of wells in which cell growth occurred

30

30

18

18

19

13

3

Number of wells in which cell growth did not occur

0

0

0

0

5

17

27

Proportion of wells that did not result in cell growth (f(x))

0/30

0/30

0/18

0/18

5/24 = 0.208

17/30 = 0.566

27/30 = 0.9

Mean number of cells (m = -ln f(x))

    

1.568

0.567

0.105

Estimated average number of cells per well in dilution (1) (m × d)

    

156.8

113.4

105

  1. Cells from dilution (1) were amplified into 10 ml cultures and DNA was extracted for PCR detection of provirus, and the results are shown in figure 2. At higher dilutions (dilutions 5, 6 and 7), a proportion of wells showed no cell growth, allowing the average number of cells seeded in each well to be determined by the Poisson formula. This was used to estimate the average number of cells represented by each sample in dilution (1). In this case, the average number of cells represented is 125 (the average of 156.8, 113.4 and 105).