RESUMO
BACKGROUND: The association of human papillomavirus (HPV) types to neoplastic lesions increase as a function of their oncogenicity and the duration of the infection since lesion severity progresses from low-grade to high-grade and cancer. In an outbreak, the prevalence of the HPV type involved would increase and the proportion of the associated low-grade lesions would predominate over severe lesions. In this study, the prevalence of HPV types and their association to neoplastic lesions was determined in women subjected to colposcopy in San Luis Potosí, Mexico. METHODS: DNA from high-risk (HR) and low-risk (LR) HPV types was identified by E6 nested multiplex PCR in cervical scrapes from 700 women with normal cytology, atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL) or invasive cervical cancer (CC). RESULTS: Overall HPV-DNA prevalence was 67.7 %, that of HR-HPV was 63.1 %, and that of LR-HPV was 21.3 %. The highest prevalence (78.2 %) occurred in the 15-24 year group, whereas that of single infections was 52 % and that of multiple infections (i.e., by 2-6 HPV types) was 48 %. The most prevalent HR types were HPV33 (33.1 %), HPV16 (16.6 %), HPV18 and HPV51 (6.7 % each). HR-HPV prevalence was 29.6 % in normal cytology, 26.7 % in ASCUS, 63.3 % in LSIL, 68.2 % in HSIL, and 90.5 % in CC. Three prevalence trends for HR-HPV types were found in neoplastic lesions of increasing severity: increasing (LSIL < HSIL < CC) for HPV16, HPV39, HPV18, HPV58, HPV31 and HPV35; asymptotic (LSIL < HSIL ≈ CC) for HPV51 and HPV68; U-shaped (LSIL < HSIL > CC) for HPV33. CONCLUSIONS: Two-thirds of the women subjected to colposcopy from 2007 to 2010 in San Luis Potosí have HPV infections which predominate in the 15-24 years group. Around half of the infections are by one viral type and the rest by 2-6 types. HPV33 is the most prevalent type, followed by HPV16. Overall HR-HPV prevalence increases with the severity of neoplastic lesions. HPV33 prevalence is highest in LSIL and its U-shaped trend with progressing neoplastic lesions differs from the growing/asymptotic trends of other HR-HPV types. An ongoing or recent HPV33 outbreak is consistent with its high prevalence and anomalous association to LSIL.
RESUMO
BACKGROUND: In San Luis Potosí City cervical infection by human papillomavirus type 16 (HPV16) associated to dysplastic lesions is more prevalent in younger women. In this work HPV16 subtypes and variants associated to low-grade intraepithelial lesions (LSIL), high-grade intraepithelial lesions (HSIL) and invasive cervical cancer (ICC) of 38 women residing in San Luis Potosí City were identified by comparing their E6 open reading frame sequences. RESULTS: Three European (E) variants (E-P, n = 27; E-T350G, n = 7; E-C188G, n = 2) and one AA-a variant (n = 2) were identified among the 38 HPV16 sequences analyzed. E-P variant sequences contained 23 single nucleotide changes, two of which (A334G, A404T) had not been described before and allowed the phylogenetic separation from the other variants. E-P A334G sequences were the most prevalent (22 cases, 57.9%), followed by the E-P Ref prototype (8 cases, 21.1%) and E-P A404T (1 case, 2.6%) sequences. The HSIL + ICC fraction was 0.21 for the E-P A334G variants and 0.00 for the E-P Ref variants. CONCLUSION: We conclude that in the women included in this study the HPV16 E subtype is 19 times more frequent than the AA subtype; that the circulating E variants are E-P (71.1%) > E-T350G (18.4%) > E-C188G (5.3%); that 71.0% of the E-P sequences carry the A334G single nucleotide change and appear to correspond to a HPV16 variant characteristic of San Luis Potosi City more oncogenic than the E-P Ref prototype.
RESUMO
BACKGROUND: Prevalence of high risk (HR) human papillomavirus (HPV) types in the states of San Luis Potosí (SLP) and Guanajuato (Gto), Mexico, was determined by restriction fragment length-polymorphism (RFLP) analysis on the E6 ~250 bp (E6-250) HR-HPV products amplified from cervical scrapings of 442 women with cervical intraepithelial neoplasia and invasive carcinoma (280 from SLP and 192 from Gto). Fresh cervical scrapings for HPV detection and typing were obtained from all of them and cytological and/or histological diagnoses were performed on 383. RESULTS: Low grade intraepithelial squamous lesions (LSIL) were diagnosed in 280 cases (73.1%), high grade intraepithelial squamous lesions (HSIL) in 64 cases (16.7%) and invasive carcinoma in 39 cases (10.2%). In the 437 cervical scrapings containing amplifiable DNA, only four (0.9%) were not infected by HPV, whereas 402 (92.0%) were infected HR-HPV and 31 (7.1%) by low-risk HPV. RFLP analysis of the amplifiable samples identified infections by one HR-HPV type in 71.4%, by two types in 25.9% and by three types in 2.7%. The overall prevalence of HR-HPV types was, in descending order: 16 (53.4%) > 31 (15.6%) > 18 (8.9%) > 35 (5.6) > 52 (5.4%) > 33 (1.2%) > 58 (0.7%) = unidentified types (0.7%); in double infections (type 58 absent in Gto) it was 16 (88.5%) > 31 (57.7%) > 35 (19.2%) > 18 (16.3%) = 52 (16.3%) > 33 (2.8%) = 58 (2.8%) > unidentified types (1.0%); in triple infections (types 33 and 58 absent in both states) it was 16 (100.0%) > 35 (54.5%) > 31 (45.5%) = 52 (45.5%) > 18 (27.3%). Overall frequency of cervical lesions was LSIL (73.1%) > HSIL (16.7%) > invasive cancer (10.2%). The ratio of single to multiple infections was inversely proportional to the severity of the lesions: 2.46 for LSIL, 2.37 for HSIL and 2.15 for invasive cancer. The frequency of HR-HPV types in HSIL and invasive cancer lesions was 16 (55.0%) > 31 (18.6%) > 35 (7.9%) > 52 (7.1%) > 18 (4.3%) > unidentified types (3.6%) > 33 (2.9%) > 58 (0.7%). CONCLUSION: Ninety percent of the women included in this study were infected by HR-HPV, with a prevalence 1.14 higher in Gto. All seven HR-HPV types identifiable with the PCR-RFLP method used circulate in SLP and Gto, and were diagnosed in 99.3% of the cases. Seventy-one percent of HR-HPV infections were due to a single type, 25.9% were double and 2.7% were triple. Overall frequency of lesions was LSIL (73.1%) > HSIL (16.7%) > invasive cancer (10.2%), and the ratio of single to multiple infections was inversely proportional to severity of the lesions: 2.46 for LSIL, 2.37 for HSIL and 2.15 for invasive cancer. The frequency of HR-HPV types found in HSIL and invasive cancer was 16 (55.0%) > 31 (18.6%) > 35 (7.9%) > 52 (7.1%) > 18 (4.3%) > unidentified types (3.6%) > 33 (2.9%) > 58 (0.7%). Since the three predominant types (16, 31 and 18) cause 77.9% of the HR-HPV infections and immunization against type 16 prevents type 31 infections, in this region the efficacy of the prophylactic vaccine against types 16 and 18 would be close to 80%.
