Calculating copy number from Ct values/ DNA concentration

The genome copy number equivalent to the amount of template in a qPCR reaction was calculated using the formula: copy number = 50 x (amount of template in ng * 6.022x10²³) / (length of genome in bp x 1x10⁹ * 650). The 50x accounts for the 200 μl volume of extracted gDNA divided by 4 μl of gDNA used in the qPCR reaction. 650 Daltons denotes the average mass of a base pair (bp) and the number of molecules of the template/ gram can be calculated using Avogadro’s number, 6.022x10²³ molecules/mole. The genome of B1917 is 4,102,186 bp [28]. The genome of BP536, UK48, and the mean of all classical B. pertussis closed genomes available on RefSeq as of March 2019 was 4.1 mb [22,29,31].