ABSTRACT
Objective To research the homology and cross reaction characteristics of human papillomavirus(HPV)16 type L2 N-terminal(1-200)protein in clinical common HPV infection types.Methods The amino acid sequences of the common HPV infection types(6,11,16,18 ,etc.)were blasted and it was found that 1-200 N-terminal sequence of L2 protein was highly homologous.The gene of HPV16 L2(1-200)was amplificated from tissue sample of cervical cancer patient and inserted into the prokaryotic expression vector PGEX-4T-1 to construct the recombinant plasmid PGEX-4T-1-HPV16 L2(1-200).After sequencing identification,the recombinant plasmid was tranformed into E.coli BL21(DE3).Induced by IPTG,the fusion protein containing HPV16 L2(1-200)was expressed and analyzed by both SDS-PAGE and Western blot.Furthermore,the specific binding capacity of the fusion protein to the HPV 6,11,16 and 18 DNA positive patient serums were analyzed by Western blot.The fusion protein was purified with Ni-NTA Agarose Kit and coated with ELISA reaction plates.The specific serum IgG of 98 condyloma acuminatum patients,135 cervix cancer patients and 96 healthy control subjects were detected respectively by indirect ELISA.Results After comparing the amino acid sequences of the common HPV infection types(HPV6,11,16,18,etc.),We found that the homology of HPV L2(1-200)reached 52.7%-74.3%.The recombinant plasmid PGEX-4T-1-HPV 16 L2(1-200)was constructed successfully.Highly expressed HPV16 L2(1-200)fusion protein was obtained and the expression level was account for up to about 22.6% of total bacterial protein.The relative molecular mass(Mr)of the fusion protein is about 49×103,which matches up to the expected Mr Meanwhile,the serums of HPV 6,11,16,18 DNA positive patients were used as the first antibody and the specific band was detected respectively at about 49 × 103 by Western blot.Indirect ELISA showed that the A490 values of the specific IgG of condyloma acuminatum group,cervical cancer group and healthy control subjects were 0.753 ± 0.262,0.756 ± 0.274 and 0.178 ± 0.157 with the positive rate were 89.8%,88.9% and 9.4% respectively.There was no significance of the specific IgG between condyloma acuminatum group and cervical cancer group(P＞0.05),but it was significant among the three groups(P＜0.001).Conclusion The N-terminal 1-200 amino acids of HPV L2 has high homology and there exits cross reaction among the most common HPV infection types.