Viral etiology of juvenile- and adult-onset squamous papilloma of the larynx

Juvenile- and adult-onset laryngeal papillomas were examined for the presence of a human papillomavirus (HPV) genome and capsid antigens. DNA was isolated from a portion of tissue removed for therapeutic purposes, and the presence of a papillomavirus genome was detected by Southern transfer analysis. The viral DNA found in the 12 juvenile-onset and the 8 adult-onset laryngeal papillomas examined was identified as HPV-6 on the basis of size, restriction endonuclease digestion patterns, and homology detected under stringent conditions. Restriction endonuclease analysis of the viral genomes revealed at least four different subtypes, designated HPV-6c through HPV-6f. The most common subtype, HPV-6c, was detected in over half of the papillomas studied, including both juvenile and adult types. The remaining tissue was fixed and processed for immunocytochemistry. The immunoperoxidase technique was used with an antiserum that reacts with capsid antigen(s) common to all HPV serotypes. HPV antigen was found in two of the juvenile-onset papillomas and two of the adult-onset papillomas. The antigen was localized to the nucleus and was distributed in the superficial layers of the epithelium. HPV capsid antigen had not previously been detected in cases of adult-onset papilloma, and the HPV genome in both juvenile- and adult-onset laryngeal papillomas had not been characterized. Despite the absence of detectable viral antigen in most of the specimens examined, the presence of the HPV genome provides strong evidence for the papillomavirus etioloty of these tumors.