Detection of human papillomavirus from self-collected vaginal samples of women in Chiang Mai, Thailand.

IT HAS BEEN SHOWN THAT some types of human papillomavirus (HPV) are the major risk factor for high-grade squamous intraepithelial lesion and invasive cervical carcinoma.1,2 The detection of HPV has been used as an adjunct to cervical cytology to identify women who are at risk of developing cervical cancer.2 Currently, the most widely used method to detect HPV DNA is by obtaining a specimen from cervix. However, some studies have shown that HPV detection by self-collected vaginal swab is comparable to virus detection in swabs obtained directly from the cervix.3,4 The self-collected vaginal samples also offer advantages over endocervical swabs in term of acceptability to clients and in reducing the need for trained personnel and clinical materials required for a cervical sample collection.4,5 The self-collected sample for HPV detection seems to offer a potential opportunity for more widely accessible cancer prevention and for populationbased molecular epidemiologic research. We conducted the study of HPV infection among women from communities in Chiang Mai, Thailand, using self-collected vaginal samples. Five hundred thirty-one sexually active women aged 20 to 65 years participated in the study. They were selected by nonprobability sampling method from 8 communities located within 50 km of Chiang Mai city. Written informed consent was obtained from all women; the protocol was reviewed and approved by the relevant Institutional Review Boards. The women were asked to provide their vaginal sample for HPV testing. The women were given a sample collection kit (swab specimen collection kit, Digene Corp, Beltsville, MD) that was composed of a sterile Dacron swab in a wrapper and a plastic vial containing specimen transport media. Verbal and written instructions for cell collection were provided. In brief, women were asked to insert a collection swab gently into the vagina about halfway in or until meeting with resistance; then they were to rotate the swab 3 turns in the same direction, take the swab out, and put it in the transport vial. The samples were transported to the laboratory and tested for HPV DNA and HPV typing. The DNA of vaginal samples was extracted and amplified using PGMY09-PGMY11 biotinylated L1 consensus primers, generating a 450-base pair amplicon.6 To determine specimen adequacy, the biotinylated -GH20/ -PC04 human -globin target was coamplified, generating a 250-base pair amplicon. The results of amplification were confirmed by agarose gel electrophoresis. The genotypes of HPV were determined by the reverse line blot hybridization method.7 The HPV genotyping strip detects 2 -globin concentrations (high and low) and 38 HPV types: 22 putative high-risk types (16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56,58, 59, 66, 67, 68, 69, 70, 73, 82, IS39) and 16 low-risk types (6, 11, 40, 42, 54, 55, 57, 61, 62, 64, 71, 72, 81, 83, 84, CP6108). The classification of highand low-risk types was primarily based on International Agency for Research on Cancer (IARC)8 and also referred to the HPV reference guide provided by Roche. All of the women we approached were interested in collecting their vaginal samples for HPV testing. About 9.4% (50 of 531) of the samples lacked -globin control amplification. We therefore diluted the DNA template of these 50 samples with TE buffer (1:10) (TE 20 mM Tris-HC1, 1 mM EDTA [pH 8.0]) and repeated the polymerase chain reaction (PCR), and subsequently every sample could be amplified and produced a -globin PCR product. Of 531 women tested, 61 were positive for HPV DNA, and the overall HPV prevalence was 11.5% (Table 1). The prevThe authors gratefully acknowledge the Roche Molecular System, USA, for the donation of reagents and supplies for HPV detection and HPV typing. This work was supported, in part, by a fellowship/grant from the Fogarty International Center/USNIH, Johns Hopkins University, Grant 2 D 43 TW000010-18-AITRP. Correspondence: Kanlaya Wongworapat, MSc, 110 Intavaroros Road, Tambol Sriphum, Chiang Mai 50202 Thailand. E-mail: kanlaya@ chiangmai.ac. th. Received for publication November 10, 2006, and accepted August 16, 2007. From the *Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, Thailand; and †Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Sexually Transmitted Diseases, February 2008, Vol. 35, No. 2, p.172–173 DOI: 10.1097/OLQ.0b013e318158af65 Copyright © 2008, American Sexually Transmitted Diseases Association All rights reserved.