Study on the frequency of human papillomavirus type 6 and type 11 infection and L1 gene expression of the virus in biopsy samples of pointed condyloma patients / 中华流行病学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To determine the different rates of human papillomavirus types 6 (HPV-6) and 11 (HPV-11) infection in biopsy samples from pointed condyloma patients, and to construct prokaryotic expression system of the major capsid protein L1 of the virus so as to establish an ELISA for detecting the expression of L1 gene in the biopsy samples.</p><p><b>METHODS</b>Using a double PCR based on the L1 gene of HPV-6 and HPV-11, the infection rates of HPV-6 and HPV-11 in the biopsy samples were determined. The whole length of HPV-6 L1 gene was amplified using PCR and the target amplification fragment was sequenced after T-A cloning. The prokaryotic expression system pET32a-L1-E. coli BL21 (DE3) was constructed and SDS-PAGE was used to measure the expression of the target recombinant protein rL1. Rabbit anti-rL1 serum was prepared and immuno-diffusion assay was applied to examine the antiserum titer. ELISA was established to detect the expression of L1 gene in the biopsy samples.</p><p><b>RESULTS</b>In the biopsy samples from 116 pointed condyloma patients, 92.2% (107/116) were detectable for HPV-6 and/or HPV-11. Of the 107 positive samples, 70.1% (75/107) and 23.4% (25/107) were positive for HPV-6 or HPV-11 alone and 6.5% (7/107) were coinfected with both HPV-6 and HPV-11 respectively. When compared with the reported corresponding sequences, the homology of nucleotide and sequence of the cloned HPV-6 L1 gene was from 99.20% - 99.93% while its putative amino acid sequence homology was from 99.80% - 100%, suggesting IPTG could induce the expression of rL1. The immuno-diffusion titer of the rabbit anti-rL1 serum was 14. 88.8% (103/116) of the biopsy samples were the major capsid protein L1 detectable.</p><p><b>CONCLUSION</b>A prokaryotic expression system of HPV-6 L1 gene, a double PCR assay for HPV-6 and HPV-11 genotyping, and an ELISA assay for detecting the major capsid protein L1 were successfully established in this study. The pointed condyloma patients in Zhejiang area mainly infected with HPV-6. The HPV in the focus frequently expressed major capsid protein L1.</p>