Project Summary Human papillomavirus (HPV) is the infectious cause of cervical cancer, one of the leading causes of cancer and cancer-related deaths in women worldwide. Large numbers of women in the US each year are referred to colposcopy / biopsy for abnormal Pap tests and/or positive HPV DNA tests for cervix cancer prevention, however the majority will not have precancerous lesions. Because HPV vaccination will not help everyone and does not prevent all cervical cancer, screening will be needed for the foreseeable future. Thus, there is a critical need to improve the accuracy of cervical cancer screening in general, and the specificity of HR-HPV DNA testing, in particular, to reduce the harms of screening. In this competitive renewal, we will expand upon our recent reports showing that oncogenic HPV epigenetic methylation patterns for HPV16, 18, 31 and 45 have high sensitivity / specificity for detection of prevalent histologically confirmed cervical intraepithelial neoplasia grade 3 or more severe (CIN3+). In other studies, we have defined the genetic heterogeneity of the HPV16-related HR-types (HPV31, 33, 35, 52, 58), established a nomenclature for variant lineages, and shown that HR-HPV variants have different risks for persistence and progression. Overall, our data provide evidence that determining the epigenetic and genetic factors that underlie HPV carcinogenicity is important not only scientifically, but also to enhance and improve screening. Based on the data from this application, we envision a scenario where a HR-HPV DNA+ test could be reflex tested for HR-HPV variant / methylation status. In addition, emerging data implicate the microbiome as a risk factor for a variety of cancers. We have embraced new technology to characterize the cervicovagnial microbiome (CMB) and hypothesize that the CMB is an important determinant explaining, in part, the small minority of HR-HPV infections that do not resolve, but progress to precancer and cancer. We propose to use 4 large, well-characterized NCI cohorts with a total of >2000 histologically confirmed CIN3+ cases to: (1) determine the associations of HR-HPV viral CpG methylation with CIN3+, we will perform case-control studies to evaluate methylation at CpG sites using pyrosequencing and an innovative Next-Gen sequencing protocol of bisulfite treated samples; (2) study the temporal process of HPV genome methylation that precedes and predicts development of incident CIN3+, we will perform a longitudinal study. We will determine the percent methylation as a function of time prior to diagnosis; (3) study the nucleotide variations in HR-HPV genomes associated with risk of precancer/cancer, we will analyze both lineage and variant sites using case-control studies. We will use systems biology approaches and phylogenomics to characterize the genomic determinants of HPV oncogenicity; and, (4) examine the CMB as a cofactor in progression of HR- HPV infections to CIN3, we will determine the microbiome using our recently published methods that employ barcoded primers to the 16S ribosomal RNA gene, Next-Gen sequencing, and a bioinformatics pipeline.