Table 4.

Comparison of HPV16 viral load and physical state determined by Southern hybridisation with NA6 qPCR analysis of HPV16 E2 and E6 copy numbers in cervical keratinocyte cell lines.

Cell line	Ploidy	Southern analysis Copy numbers per cell	NA6 qPCR analysis
			E2 copies per diploid genome	E6 copies per diploid genome	Viral load per cell	Ratio of E2/E6 (range)
C33A	Near triploid	HPV16 negative	0	0	0	0.00
W12.Ser1p16	Diploid	Episomal (approx 100 copies)	148	143	143	1.04 (0.76–1.32)
W12.Ser1p57	Tetraploid	Integrated (approx 1 copy)	0.2	0.3	1	0.72 (0.57–3.82)
SiHa	Triploid	Integrated (2–3 copies)	0.7	3.4	5	0.20 (0.11–0.24)
CaSki	Tetraploid	Integrated (>1000 copies)	2,272	869	1,738	2.61 (1.37–3.46)

Values less than 1 were rounded to the nearest whole number when calculating viral load per cell. E2/E6 ratio values were calculated from the qPCR readings for E2 and E6 and rounded to the nearest two decimal places.