Longitudinal measures of human papillomavirus 6 and 11 viral loads and antibody response in children with recurrent respiratory papillomatosis.

OBJECTIVES To measure human papillomavirus (HPV) 6 and 11 viral load and antibody response in longitudinal specimens obtained from children with recurrent respiratory papillomatosis and to examine the association of type-specific viral load with clinical severity of disease. DESIGN Longitudinal pilot study with a median follow-up of 5.4 months. SUBJECTS The study included 15 children undergoing therapy for recurrent respiratory papillomatosis at the Egleston Children's Hospital, Atlanta, GA, between January 22, 1999, and June 13, 2000. MAIN OUTCOME MEASURES The kinetics of HPV-6 and HPV-11 viral load and antibody level were examined over time. Longitudinal HPV-6 and HPV-11 viral loads were analyzed for associations with clinical indicators of disease severity. RESULTS Four children were infected with HPV-11, 4 were infected with HPV-6, and 7 had mixed infections. The HPV-6 and HPV-11 viral loads were stable over time in most of the children. Among children with mixed infections, HPV-6 viral loads were inversely correlated with those of HPV-11 (r = -0.80, P<.001). The HPV-11 infection was significantly associated with more annual surgical procedures (P=.02). Neither HPV-6 nor HPV-11 viral loads were associated with demographic factors or markers of clinical severity. None of the children had detectable antibodies against HPV-6, and only 3 had detectable antibodies against HPV-11 virallike particles. CONCLUSIONS Our data support the association of HPV-11 infection with clinical severity. Measures of HPV-6 and HPV-11 viral loads are relatively stable over time in most children with recurrent respiratory papillomatosis, suggesting that multiple samples may not be necessary. Cytobrush samples may substitute for tissue biopsy specimens in HPV detection and typing, but not for absolute viral load determination.