E6 and E7 variants of human papillomavirus-16 and -52 in Japan, the Philippines, and Vietnam.

Human papillomavirus (HPV) has several intragenotypic variants with different geographical and ethnic distributions. This study aimed to elucidate the distribution patterns of E6 and E7 (E6/E7) intragenotypic variants of HPV type 16 (HPV-16), which is most common worldwide, and HPV-52, which is common in Asian countries such as Japan, the Philippines, and Vietnam. In previous studies, genomic DNA samples extracted from cervical swabs were collected from female sex workers in these three countries and found to be positive for HPV-16 or HPV-52. Samples were amplified further for their E6/E7 genes using type-specific primers and analyzed genetically. Seventy-nine HPV-16 E6/E7 genes were analyzed successfully and grouped into three lineages: European (Prototype), European (Asian), and African-2. The prevalences of HPV-16 European (Prototype)/European (Asian) lineages were 19.4%/80.6% (n = 31) in Japan, 75.0%/20.8% (n = 24) in the Philippines, and 0%/95.8% (n = 24) in Vietnam. The 109 HPV-52 E6/E7 genes analyzed successfully were grouped into four lineages, A-D; the prevalences of lineages A/B/C/D were, respectively, 5.1%/92.3%/0%/2.6% in Japan (n = 39), 34.4%/62.5%/0%/3.1% in the Philippines (n = 32), and 15.8%/73.7%/7.9%/2.6% in Vietnam (n = 38). The distribution patterns of HPV-16 and HPV-52 lineages in these countries differed significantly (P < 0.000001 and P = 0.0048, respectively). There was no significant relationship between abnormal cervical cytology and either HPV-16 E6/E7 lineages or specific amino acid mutations, such as E6 D25E, E6 L83V, and E7 N29S. Analysis of HPV-16 and HPV-52 E6/E7 genes can be a useful molecular-epidemiological tool to distinguish geographical diffusion routes of these HPV types in Asia.

Infection with high-risk HPV types among female sex workers in northern Vietnam.

Vaccines against two high-risk human papillomavirus (HPV) types, HPV-16, and HPV-18, are in use currently, with high efficacy for preventing infections with these HPV types and consequent cervical cancers. However, circulating HPV types can vary with geography and ethnicity. The aim of this study was to investigate the prevalence of HPV types and the association between HPV types and abnormal cervical cytology among female sex workers in Northern Vietnam. Cervical swabs and plasma samples were collected from 281 female sex workers at two health centers in Hanoi and Hai Phong in 2009. The HPV L1 gene was amplified by PCR using original and modified GP5(+)/6(+) primers. Amplified PCR products were genotyped by the microarray system GeneSquare (KURABO) and/or clonal sequencing. Of the 281 women, 139 (49.5%) were positive for HPV DNA. Among the HPV-positive samples, 339 strains and 29 different types were identified. Multiple-type and high risk-type HPV infections were found in 85 (61.2%) and 124 (89.2%) women, respectively. The most common genotype was HPV-52, followed by HPV-16, HPV-18, and HPV-58. Abnormal cervical cytology was detected in 3.2% (9/281) of the women, and all of these samples were positive for HPV-DNA. Age ≤25 years and infection with human immunodeficiency virus were associated positively with HPV infection among the women while ever smoking was associated negatively. These results show that HPV-52 is most prevalent among female sex workers in Northern Vietnam, most of whom had normal cervical cytology. This information may be important for designing vaccination strategies in Vietnam.

Oral and cervical human papillomavirus infection among female sex workers in Japan.

It has been reported recently that oral human papillomavirus (HPV) infection is associated with oropharyngeal squamous cell carcinomas. The aim of this study was to determine the prevalence of HPV infection and HPV types in the oral cavity and cervix of female sex workers in Japan. Oral and cervical swabs were taken from 196 female sex workers who visited a clinic for regular medical checkups in 2007, and genomic DNA was extracted from those specimens. The HPV L1 gene was amplified by polymerase chain reaction (PCR) using original and modified GP5(+)/6(+) primers, and genotyping was performed using the Kurabo GeneSquare Microarray or by sequencing cloned PCR products. HPV DNA was detected in the oral cavity of 12 (6.1%) women, with HPV-56 being the most common type (7/12). Likewise, HPV DNA was detected in the cervix of 103 (52.6%) women, with HPV-52 (30/103, 29.1%), followed by HPV-16 (24.3%) and HPV-56 (18.4%), being the most common. Of the 12 women with oral HPV infection, only two were infected with the concordant HPV genotype in the cervix. These findings suggest that oral HPV infection occurs independently of cervical HPV infection in this population, and that oral HPV infection may play a role in HPV transmission in Japan.

High-risk HPV types in lesions of the uterine cervix of female commercial sex workers in the Philippines.

In order to prevent cervical cancer, vaccines against human papilloma virus types 16 (HPV-16) and 18 (HPV-18) have been implemented worldwide. However, the HPV types that cause cancer can differ according to geographical area and ethnicity. In this new era of the HPV vaccine, it is important to elucidate the prevalent HPV types in each area. Therefore, the prevalence of HPV infection and cervical abnormalities among 369 female commercial sex workers in the Philippines were examined. HPV L1 gene was amplified by polymerase chain reaction (PCR) using modified GP5+/6+ primers, and genotyping was performed by sequencing cloned PCR products. HPV DNA was detected in 211 (57.2%) women, among whom 46 HPV types were identified. HPV-52 was most common and multiple-type infection was observed in 44.5%. Among 56 women with abnormal cervical cytology (low- and high-grade squamous intraepithelial lesions and adenocarcinoma in situ), HPV-52 was most common (23.2%), followed by HPV-16 (19.6%), -58 (10.7%), and -67 (10.7%). Only 27% of these women were positive for HPV-16 and -18. Multivariate analysis revealed that HPV-16, -39, -52, -67, and -82 were significantly associated with abnormal cytology. Repeated analysis of HPV-52 single-positive samples using the original GP5+/6+ PCR primers produced negative results in 57% of cases, suggesting that the prevalence of HPV-52 infection may have been underestimated in previous studies, and the current vaccines may not be sufficient for preventing infection and the development of premalignant lesions of the cervix in women in the Philippines.

Involvement of Ras in extraembryonic endoderm differentiation of embryonic stem cells.

Embryonic stem (ES) cells, derived from the inner cell mass of blastocyst can differentiate into multiple cell lineages. In this study, we examined the possible involvement of Ras in ES cell differentiation. We found that Ras was activated upon formation of embryoid bodies (EBs), an initial step in ES cell differentiation. When expressed during EB differentiation, a dominant-negative mutant of Ras suppressed induction of marker genes for extraembryonic endoderm differentiation, including GATA-4, GATA-6, alpha-fetoprotein, and hepatocyte nuclear factor 3beta, while an activated mutant promoted their induction. Expression of a Ras mutant that selectively activates the Raf/MEK/Erk pathway also enhanced induction of extraembryonic endoderm markers, and treatment with a MEK inhibitor resulted in their decreased expression. In addition, Ras stimulated downregulation of Nanog, a suppressor of endoderm differentiation in ES cells. These data suggest that Ras activation during EB differentiation plays a crucial role in initiation of extraembryonic endoderm differentiation.