[Investigation of HPV-DNA in cervical smear samples by two different methods: MY09/11 consensus PCR and type-specific...

Cervical cancer that has been proven to be associated with human papillomavirus (HPV) is the second most common cancer in women worldwide and is a leading cause of cancer deaths in women in developing countries. Cervical cancers can be detected in the early stages by screening programs since a long latency period exists between the beginning of HPV infection and the development of cervical cancer. HPV-DNA testing is widely used throughout the world and today is an important part of cervical cancer screening programs. In this study, we analyzed the presence of HPV-DNA in 356 cervical smear samples by two different methods which are MY09/11 consensus real-time polymerase chain reaction (Rt-PCR) and type-specific Rt-PCR. All samples were also tested by type-specific PCR, regardless of consensus PCR results. PCR analysis were performed using the type- specific primers and TaqMan probes that were designed for a total of 13 different HPV types; two low risk HPV and 11 high risk HPV types. A total of 142 different isolates, 95 being high risk HPV isolates, 39 low risk HPV isolates and eight unidentified isolates, were determined in 109 (30.6%) smear samples that were defined as HPV-DNA positive by at least one of the two methods. Frequencies of detection of high risk HPV types in HPV-positive samples were as follows respectively: HPV-16; 32 (33.7%), HPV-52; 12 (12.6%), HPV-58; 11 (11.6%), HPV-18; 7 (7.4%), HPV-31; 7 (7.4%), HPV-35; 7 (7.4%), HPV-68; 6 (6.3%), HPV-33; 4 (4.2%), HPV-82; 4 (4.2%), HPV-39; 3 (3.2%) and HPV-45; 2 (2.1%). Various cytologic atypia were reported in 84 (23.6%) smear samples according to the simultaneously performed cytopathologic examination. Single HPV type was detected in 72 (71.3%) and multiple HPV types were detected in 29 (28.7%) of 101 smear samples with the exception of the unidentified isolates by type-specific RtPCR. HPV-18, HPV-33 and HPV-35 had higher detection rates of 7.4, 3.7 and 3.0 fold in mixed infections than single ones, respectively. HPV-DNA could not be detected by MY09/11 consensus primers in 24 (23.8%) of 101 cervical smear samples that were accepted as HPV-DNA positive by type-specific PCR. Thus, investigation of the presence of HPV-DNA by only consensus primers would be insufficient for the diagnosis, treatment and follow-up of HPV infections. Initial assessment of smear samples by using consensus primers and genotyping only positive samples seem to be the most practical strategy for the diagnosis and screening of HPV infections throughout the world. When this situation is taken into consideration, we think that the current prevalence data in our country and around the world must be updated by using large-scale studies that apply new generation screening and diagnostic tests.