Multiple human papillomavirus infections are highly prevalent in the anal canal of human immunodeficiency virus-positive men who have sex with men.

BACKGROUND: Anal cancer has become one of the most common non-AIDS-defined tumors among Human Immunodeficiency Virus-positive (HIV+) individuals, and a rise in its incidence among HIV+ Men who have Sex with Men (MSM) has been shown, despite the introduction of Highly Active Anti-Retroviral Therapy (HAART). Human Papillomavirus (HPV) infections are highly prevalent among HIV+ MSM and recent studies have shown high rates of HPV-associated anal intraepithelial neoplasia (AIN) and anal cancer among this population. METHODS: In the present study we determined the prevalence and nature of HPV co-infections in the anal canal of 324 HIV+ MSM attending a high specialty medical center in Mexico City, DNA extraction and amplification with generic primers for HPV was performed, followed by detection of specific types and co-infections with INNO-Lipa, and identification of variants by amplification and sequencing of the E6 and LCR region of HPV 16. RESULTS: We found a very high prevalence of HPV infections among this cohort (86%), with more than one fourth of them (28%) positive for type 16. Among HPV16-positive patients, European variants were the most prevalent, followed by Asian-American ones. Among these individuals (HPV-16+), we identified co-infections with other 21 HPV types namely; 11, 51, 52, 6, 66, 68, 74, 18, 45, 35, 26, 44, 70, 53, 54, 82, 31, 33, 56, 58, 59. CONCLUSIONS: HIV+ MSM show a very high rate of HPV infections in the anal canal and those with type 16 exhibited a multiplicity of associated types. This study emphasizes the need for an early detection of HPV infections among HIV+ MSM in order to establish its utility to prevent anal neoplasia and cancer.

Analysis of CpG methylation sites and CGI among human papillomavirus DNA genomes.

BACKGROUND: The Human Papillomavirus (HPV) genome is divided into early and late coding sequences, including 8 open reading frames (ORFs) and a regulatory region (LCR). Viral gene expression may be regulated through epigenetic mechanisms, including cytosine methylation at CpG dinucleotides. We have analyzed the distribution of CpG sites and CpG islands/clusters (CGI) among 92 different HPV genomes grouped in function of their preferential tropism: cutaneous or mucosal. We calculated the proportion of CpG sites (PCS) for each ORF and calculated the expected CpG values for each viral type. RESULTS: CpGs are underrepresented in viral genomes. We found a positive correlation between CpG observed and expected values, with mucosal high-risk (HR) virus types showing the smallest O/E ratios. The ranges of the PCS were similar for most genomic regions except E4, where the majority of CpGs are found within islands/clusters. At least one CGI belongs to each E2/E4 region. We found positive correlations between PCS for each viral ORF when compared with the others, except for the LCR against four ORFs and E6 against three other ORFs. The distribution of CpG islands/clusters among HPV groups is heterogeneous and mucosal HR-HPV types exhibit both lower number and shorter island sizes compared to cutaneous and mucosal Low-risk (LR) HPVs (all of them significantly different). CONCLUSIONS: There is a difference between viral and cellular CpG underrepresentation. There are significant correlations between complete genome PCS and a lack of correlations between several genomic region pairs, especially those involving LCR and E6. L2 and L1 ORF behavior is opposite to that of oncogenes E6 and E7. The first pair possesses relatively low numbers of CpG sites clustered in CGIs while the oncogenes possess a relatively high number of CpG sites not associated to CGIs. In all HPVs, E2/E4 is the only region with at least one CGI and shows a higher content of CpG sites in every HPV type with an identified E4. The mucosal HR-HPVs show either the shortest CGI size, followed by the mucosal LR-HPVs and lastly by the cutaneous viral subgroup, and a trend to the lowest CGI number, followed by the cutaneous viral subgroup and lastly by the mucosal LR-HPVs.

Vaccines against human papillomavirus: perspectives for controlling cervical cancer.

Prophylactic vaccines against human papillomavirus (HPV) are on the market and will certainly reduce the incidence of genital warts and the risk of developing cervical cancer. In addition, they will contribute to reducing anal as well as head and neck cancers. However, effort should be made in the short term in order for these vaccines to have a real impact in the developing world, where almost 80% of cervical cancer cases occur. Since the available vaccines include only two of the HPV types found in cancers (approximately 70%), improvements in current mass screening programs - with the use of molecular techniques - must be made, particularly in developing countries. Therapeutic vaccines have been designed to control advanced lesions and residual illness and, although success has usually been obtained in animal models, clinical studies have not yet provided the anticipated results. Finally, the next generations of prophylactic HPV vaccines will probably include subunit vaccines, transgenic bacteria and plants, among others, and could represent useful and cheaper alternatives for reducing cervical cancer, particularly in the developing world.

[Phylogenetic distance between Giardia intestinalis isolates from symptomatic and asymptomatic children]. / Distancia filogenética de aislados de Giardia intestinalis de niños sintomáticos y asintomáticos.

The purpose of the present investigation, was to analyze the sequences of 16S ribosomal genes partially amplified from 17 isolated Giardia intestinalis obtained from faces of 13 children with intestinal pathology and four symptoms-free children with intestinal pathology. Analysis was made also with Giardia Portland-I and four Giardias isolated from dogs. Children ages in both groups ranged from six to twelve years. Genomic DNA was isolated using the phenol-chloroform-isoamyl alcohol technique, and partial amplification of 16S rRNA ribosomal gene was carried out by the Polymerase Chain Reaction. Sequences of rDNA were compared with Portland-I by using CLUSTAL-W (1.81) and PHYLIP (3.6) software in order to determine phylogenic associations. Our results showed that only one isolate from symptoms-free children and three from the symptomatic children were associated with Portland I. The other isolated Giardias were associated between them and with two samples obtained from dogs that are phylogenetically distant from Portland-I. Two isolates from dog constituted a different group. These results suggest a zoonotic infection and presence of symptoms in children from the present investigation; probably it was associated with host or special characteristics of Giardia strains. The last two situations have a special epidemiological and public health interest.

Distancia filogenética de aislados de Giardia intestinalis de niños sintomáticos y asintomáticos / Phylogenetic distance between Giardia intestinalis isolates from symptomatic and asymptomatic children

The purpose of the present investigation, was to analyze the sequences of 16S ribosomal genes partially amplified from 17 isolated Giardia intestinalis obtained from faces of 13 children with intestinal pathology and four symptoms-free children with intestinal pathology. Analysis was made also with Giardia Portland-I and four Giardias isolated from dogs. Children ages in both groups ranged from six to twelve years. Genomic DNA was isolated using the phenol-chloroform-isoamyl alcohol technique, and partial amplification of 16S rRNA ribosomal gene was carried out by the Polymerase Chain Reaction. Sequences of rDNA were compared with Portland-I by using CLUSTAL-W (1.81) and PHYLIP (3.6) software in order to determine phylogenic associations. Our results showed that only one isolate from symptoms-free children and three from the symptomatic children were associated with Portland I. The other isolated Giardias were associated between them and with two samples obtained from dogs that are phylogenetically distant from Portland-I. Two isolates from dog constituted a different group. These results suggest a zoonotic infection and presence of symptoms in children from the present investigation; probably it was associated with host or special characteristics of Giardia strains. The last two situations have a special epidemiological and public health interest.