Introduction In cervical cancer, human papillomavirus (HPV) 18 is predominantly related to adenocarcinomas. Variant lineages of HPV type 16 have been well characterized, whereas the knowledge about HPV 18 variants is limited in Northeast China.

Methods To identify prevalent and novel HPV 18 variants in Northeast China, the E6, E7, and L1 genes of HPV 18 from patients with cervical lesion were amplified and sequenced, and intratypic variants were analyzed by comparing to the known phylogenetic branches.

Results The HPV-18 E6 variants of our studied strains belong to 2 main branches: Asian-American (AA) variants in 81.5% and European (E) variants in 18.5%. Strains with variations of C287G, T482C, and C519A in E6 and C751T in E7 were novel variants. All the L1 genes of the analyzed HPV 18 strains had 4 C-G transversions at nucleotide positions of 5701, 6460, 6625, and 6842 and one G-A transition at position 5503. Moreover, strains with L1 nucleotide variations of A5920T, A6431T, and G6987A leading to amino acid substitutions of A164V, Q334P/H, and D520N are novel variants.

Conclusions Based on the E6 gene, the prevalent HPV 18 in Northeast China was AA and E variants. Besides some common variations reported before, some new variations in the E6, E7, and L1 genes were found. Data about the novel variations found in the L1 gene of HPV 18 variants may be helpful to design the diagnostic reagents and vaccine for naturally infected HPV 18 in Northeast China.