HPV-16 VARIANTS IN CERVICAL SAMPLES FROM ARGENTINA: A MULTICENTRIC STUDY

BASILETTI, J; DELUCA, G; OVEJERO M; YACHELINI P; MARINIC K; CAEIRO L; LIOTTA, DJ; BADANO, I; SIJVARGER, C; ACUNA M; SUAREZ, A; GONZÁLEZ, JV; ALONIO, LV; PICCONI MA.

San Juan

Conferencia; 28th International Papillomavirus Conference; 2012

International Papillomavirus Society

OBJECTIVES: HPV-16 variants have been clustered in five main branches: European (E), Asian (As), Asian-American (AA) (including the subgroup of North American 1 [NA-1]), African 1 and 2 (Af-1 and Af-2). A multicentre study was performed in order to identify HPV-16 variants in 7 Argentine provinces and analyze the possible association with the severity of the lesions. METHOD: Three hundred and fourteen HPV-16 positive cervical samples were collected from women inhabiting different geographical regions: 170 from the Northeast region; 109 from Northwest region, 26 from the Centre region, and 9 from the South region. A 364 bp fragment of the long control region (LCR) was amplified by PCR and sequenced. Phylogenetic inference was done to determine the grouping of the sequences. In a subgroup of 220 samples which had the cytology results, the analysis of the distribution of variants vs. the severity of the lesions (Normal cytology/LSIL; n=157) vs. (HSIL/cervical cancer; n=63) was performed applying Fisher test. RESULTS: From the 314 analyzed samples, 263 (84%) were successfully amplified and sequenced. Among them, 250 samples (95%) harbored previously known variants: 241(96.4%) E variants, including 59 E-prototypic (E-P), 175 E- G1, 7 E-G10; and 9 (3.6%) AA variants, including 7 IND-8 and 2 B-14. Moreover, 3 new variants were described: Argentina Corrientes-159 (ACor-159) (n=8), similar to E- IND-7, with an additional change (A7636C); Argentina Santiago del Estero-326 (Asgo-326) (n=1), similar to E G-10, with an additional change (G7567A); and Argentina-Cordoba-130 (ACdb-130) (n=3) close to NA-1 variant but exhibiting additional changes: G7507C, A7670G. In the variant ACdb-130, the change observed in the position 7670 is characteristic of Af-2 branch. E variants were predominant in both clinical groups: Normal cytology/LSIL (95.5%) vs. HSIL/cervical cancer (92.1%); although the detection of AA variants was very low, a little trend of increasing the AA rates with the severity of the lesion was observed (4.5% vs. 7.9, respectively) (no statistically significant association) IMPLICATIONS AND IMPACT: The study revealed a low diversity and the vast majority of isolates belonged to the European clade, with non-Prototype predominance, in all geographical regions and clinical categories. In the 3 new variants, mutations were found within or in the vicinity of cellular transcription factors binding sites, which could affect their oncogenic potential. The nt 7670 change (typical of Af-2 branch) found in the new variant ACdb-130, may suggest a possible recombination AA/Af-2; however, due to the lack of cloning and follow-up, it could not be ruled out the presence of a multiple infection. Although non-E variants are considered more oncogenic, these results emphasise that all HPV-16 variant branches are associated with the development of invasive cancer, and that other factors may also be playing a role in cervical carcinogenesis among these women.