WHAT IS HUMAN PAPILLOMAVIRUS (HPV) IN SITU HYBRIDIZATION TEST?
Human papillomaviruses are DNA viruses that are known to cause Bowen’s extragenital disease, warts, condyloma acuminatum, intraepithelial neoplasia, and anogenital, cervical, or oropharyngeal cancers. There are more than 70 different types of HPV, with about 20 of these types being associated with genital warts. Most genital warts are associated with the “low-risk” HPV types 6 and 11. Invasive carcinoma of the cervix, vulva, anus, and penis is associated with HPV types 16, 18, 33, 35, and 39. Endocervical carcinoma is associated with HPV 18. Although these specific associations exist, only a small proportion of HPV 16 and 18 lesions actually progress to malignancy. In situ hybridization is a technique used to both confirm the presence of the HPV virus in a specimen and to type the HPV. DNA from the specimen is placed on a nitrocellulose membrane and fixed. The membrane can then be hybridized to a DNA sample of known sequence that is radioactively labelled. If the pathogenic DNA is present in the sample (such as HPV type 18), the sample DNA will hybridize to the known DNA, producing a double-stranded DNA segment. The radioactive label is incorporated into the double-stranded DNA segment, allowing this segment to be detected by autoradiography.