Table 1

Properties of W12 in long-term tissue culture

W12 passageHPV16 copy no.aPhysical state of HPV16 genomesbE7 protein levelcE2 expressiondTelomerase activitye% CFEf
100 cells500 cells
9100EpisomalLowPositivePositive9.3 ± 1.89.4 ± 0.5
1430Episomal & integratedIntermediateNegativePositive24.0 ± 1.021.2 ± 0.7
2410IntegratedHighNegativePositive38.7 ± 1.933.7 ± 0.8
3410IntegratedHighNegativePositive43.3 ± 1.935.7 ± 2.2
4410IntegratedHighNegativePositive56.0 ± 1.547.7 ± 0.6
5510IntegratedHighNegativePositive47.7 ± 5.840.1 ± 1.2
  • a Number of HPV16 genome copies per cell, as estimated by Southern blot using copy number reconstructions (10) . HPV, human papillomavirus.

  • b Episomal HPV16 genomes were present in both monomeric and multimeric forms. The emergent viral integration event had a type 1 pattern similar to that observed in SiHa (10 , 11) .

  • c Determined by Western blot (10) .

  • d Determined by reverse transcription-PCR for full-length HPV16 E2 mRNA (10) .

  • e Telomerase activity in protein extracts was determined by the telomeric repeat amplification protocol assay and was comparable at all passages analyzed (data not shown).

  • f Numbers represent the percentage of viable cells plated that gave rise to colonies 14 days after plating. CFE, colony-forming efficiency. Values shown are the mean % CFE ± se calculated for three independent platings.