A comparison between real-time polymerase chain reaction and hybrid capture 2 for human papillomavirus DNA quantitation.
Studies investigating human papillomavirus (HPV) viral load as a risk factor in the development of squamous intraepithelial lesions (SILs) and cancer have often yielded conflicting results. These studies used a variety of HPV viral quantitation assays [including the commercially available hybrid capture 2 (HC 2) assay], which differ in their ability to account for differences in cervical cell collection, linear dynamic range of viral load quantitation, and determination of type-specific versus cumulative viral load measures. HPV-16 and HPV-18 viral quantitation using real-time PCR assays were performed to determine whether type-specific viral load measurements that adjust for specimen cellularity result in a different association between viral load and prevalent SIL and cancer, compared with HC 2 quantitation (which does not adjust for cellularity or multiple infections). In general, HPV-16 viral load as measured by real-time PCR increased linearly with increasing grade of SIL while HPV-18 measured using similar techniques increased through low-grade SIL (LSIL), with HPV-18 viral load among high-grade SIL and cancers near the level of cytologically normal women. HC 2 viral load, using the clinical 1.0 pg/ml cut point, differentiated cytologically normal women from women with any level of cytological abnormality (normal versus >/=LSIL) but did not change as lesion severity increased. There was no evidence for plateau of HC 2 at high copy numbers, nor was significant variability in total specimen cellularity observed. However, cumulative viral load measurements by HC 2, in the presence of multiple coinfections, overestimated type-specific viral load. Multiple infections were more common among women with no (32%) or LSIL (51%) [versus 23% in high-grade SIL/cancer], partially explaining the lack of a dose response using a cumulative HC2 viral load measure. The nonrandom distribution of multiple infections by case-control status and the apparent differential effect of viral load by genotype warrant caution when using HC 2 measurements to infer viral load associations with SIL and cancer.
Gravitt
Patti E
PE
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland 20892, USA. pgravitt@jhsph.edu
Burk
Robert D
RD
Lorincz
Attila
A
Herrero
Rolando
R
Hildesheim
Allan
A
Sherman
Mark E
ME
Bratti
Maria Concepcion
MC
Rodriguez
Ana Cecilia
AC
Helzlsouer
Kathy J
KJ
Schiffman
Mark
M
D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000821:virology; D016022:Case-Control Studies; D015331:Cohort Studies; D003199:Computer Systems; D003364:Costa Rica / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000032:analysis* / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D006801:Humans; D009693:Nucleic Acid Hybridization; D009856:Oncogene Proteins, Viral / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification; D027383:Papillomaviridae / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods; D011237:Predictive Value of Tests; D015995:Prevalence; D012720:Severity of Illness Index; D013223:Statistics as Topic; D014412:Tumor Virus Infections / Q000235:genetics / Q000821:virology; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000821:virology; D019562:Viral Load; D016387:Women's Health; D002578:Uterine Cervical Dysplasia / Q000235:genetics / Q000821:virology
D004279:DNA, Viral; D009856:Oncogene Proteins, Viral