Current epidemiological trends for Chagas disease in Latin America and future challenges in epidemiology, surveillance and health policy

Chagas disease, named after Carlos Chagas, who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, which is transmitted to humans by blood-sucking triatomine bugs and via blood transfusion. Chagas disease has two successive phases: acute and chronic. The acute phase lasts six-eight weeks. Several years after entering the chronic phase, 20-35% of infected individuals, depending on the geographical area, will develop irreversible lesions of the autonomous nervous system in the heart, oesophagus and colon, and of the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980s as a result of the demographically representative cross-sectional studies in countries where accurate information was not previously available. A group of experts met in Brasilia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country programme in the Southern Cone countries, the transmission of Chagas disease by vectors and via blood transfusion was interrupted in Uruguay in 1997, in Chile in 1999 and in Brazil in 2006; thus, the incidence of new infections by T. cruzi across the South American continent has decreased by 70%. Similar multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been reported towards the goal of interrupting the transmission of Chagas disease, as requested by a 1998 Resolution of the World Health Assembly. The cost-benefit analysis of investment in the vector control programme in Brazil indicates that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the programme is a health investment with very high return. Many well-known research institutions in Latin America were key elements of a worldwide network of laboratories that carried out basic and applied research supporting the planning and evaluation of national Chagas disease control programmes. The present article reviews the current epidemiological trends for Chagas disease in Latin America and the future challenges in terms of epidemiology, surveillance and health policy.

Comparison of HPV genotyping by type-specific PCR and sequencing

Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide and there is a strong link between certain high-risk viral types and cervical carcinogenesis. Although there are several typing methods, it is still unclear which test is the best. This study compared the effectiveness of type-specific PCR (TS-PCR) and sequencing, with a focus on their clinical application. A total of 260 cervical samples from HPV-positive patients were tested for types 6, 11, 16, 18, 31, 33 and 35 using TS-PCR and sequencing. The genotype was identified in 36% of cases by TS-PCR and in 75% by sequencing. Sequencing was four times more likely to identify the viral type in positive samples than TS-PCR (p = 0.00). Despite being more effective for virus genotyping, sequencing was unable to identify viral types in multiple infections. Combining both techniques resulted in highly sensitive detection (87% of cases), showing that they are complementary methods. HPV genotyping is an important step in HPV management, helping to identify patients with a higher risk of developing cervical cancer and contributing to the development of type-specific vaccines.

In vivo assessment of antiretroviral therapy-associated side effects

Antiretroviral therapy has been associated with side effects, either from the drug itself or in conjunction with the effects of human immunodeficiency virus infection. Here, we evaluated the side effects of the protease inhibitor (PI) indinavir in hamsters consuming a normal or high-fat diet. Indinavir treatment increased the hamster death rate and resulted in an increase in triglyceride, cholesterol and glucose serum levels and a reduction in anti-oxLDL auto-antibodies. The treatment led to histopathological alterations of the kidney and the heart. These results suggest that hamsters are an interesting model for the study of the side effects of antiretroviral drugs, such as PIs.

Analysis of malaria associated genetic traits in Cabo Verde, a melting pot of European and sub Saharan settlers

Malaria has occurred in the Cabo Verde archipelago with epidemic characteristics since its colonization. Nowadays, it occurs in Santiago Island alone and though prophylaxis is not recommended by the World Health Organization, studies have highlight the prospect of malaria becoming a serious public health problem as a result of the presence of antimalarial drug resistance associated with mutations in the parasite populations and underscore the need for tighter surveillance. Despite the presumptive weak immune status of the population, severe symptoms of malaria are not observed and many people present a subclinical course of the disease. No data on the prevalence of sicklecell trait and red cell glucose-6-phosphate dehydrogenase deficiency (two classical genetic factors associated with resistance to severe malaria) were available for the Cabo Verde archipelago and, therefore, we studied the low morbidity from malaria in relation to the particular genetic characteristics of the human host population. We also included the analysis of the pyruvate kinase deficiency associated gene, reported as putatively associated with resistance to the disease. Allelic frequencies of the polymorphisms examined are closer to European than to African populations and no malaria selection signatures were found. No association was found between the analyzed human factors and infection but one result is of high interest: a linkage disequilibrium test revealed an association of distant loci in the PKLR gene and adjacent regions, only in non-infected individuals. This could mean a more conserved gene region selected in association to protection against the infection and/or the disease.

Predicting the evolution of Kaposi sarcoma, in the highly active antiretroviral therapy era.

BACKGROUND: The outcome of Kaposi sarcoma varies. While many patients do well on highly active antiretroviral therapy, others have progressive disease and need chemotherapy. In order to predict which patients are at risk of unfavorable evolution, we established a prognostic score. METHOD: The survival analysis (Kaplan-Meier method; Cox proportional hazards models) of 144 patients with Kaposi sarcoma prospectively included in the Swiss HIV Cohort Study, from January 1996 to December 2004, was conducted. OUTCOME ANALYZED: use of chemotherapy or death. VARIABLES ANALYZED: demographics, tumor staging [T0 or T1 (16)], CD4 cell counts and HIV-1 RNA concentration, human herpesvirus 8 (HHV8) DNA in plasma and serological titers to latent and lytic antigens. RESULTS: Of 144 patients, 54 needed chemotherapy or died. In the univariate analysis, tumor stage T1, CD4 cell count below 200 cells/microl, positive HHV8 DNA and absence of antibodies against the HHV8 lytic antigen at the time of diagnosis were significantly associated with a bad outcome.Using multivariate analysis, the following variables were associated with an increased risk of unfavorable outcome: T1 [hazard ratio (HR) 5.22; 95% confidence interval (CI) 2.97-9.18], CD4 cell count below 200 cells/microl (HR 2.33; 95% CI 1.22-4.45) and positive HHV8 DNA (HR 2.14; 95% CI 1.79-2.85).We created a score with these variables ranging from 0 to 4: T1 stage counted for two points, CD4 cell count below 200 cells/microl for one point, and positive HHV8 viral load for one point. Each point increase was associated with a HR of 2.26 (95% CI 1.79-2.85). CONCLUSION: In the multivariate analysis, staging (T1), CD4 cell count (<200 cells/microl), positive HHV8 DNA in plasma, at the time of diagnosis, predict evolution towards death or the need of chemotherapy.

Submicroscopic deletion in patients with Williams-Beuren syndrome influences expression levels of the nonhemizygous flanking genes.

Genomic imbalance is a common cause of phenotypic abnormalities. We measured the relative expression level of genes that map within the microdeletion that causes Williams-Beuren syndrome and within its flanking regions. We found, unexpectedly, that not only hemizygous genes but also normal-copy neighboring genes show decreased relative levels of expression. Our results suggest that not only the aneuploid genes but also the flanking genes that map several megabases away from a genomic rearrangement should be considered possible contributors to the phenotypic variation in genomic disorders.

Williams-Beuren syndrome TRIM50 encodes an E3 ubiquitin ligase.

Williams-Beuren syndrome (WBS) is a neurodevelopmental and multisystemic disease that results from hemizygosity of approximately 25 genes mapping to chromosomal region 7q11.23. We report here the preliminary description of eight novel genes mapping within the WBS critical region and/or its syntenic mouse region. Three of these genes, TRIM50, TRIM73 and TRIM74, belong to the TRIpartite motif gene family, members of which were shown to be associated to several human genetic diseases. We describe the preliminary functional characterization of these genes and show that Trim50 encodes an E3 ubiquitin ligase, opening the interesting hypothesis that the ubiquitin-mediated proteasome pathway might be involved in the WBS phenotype.

cis- and trans-acting elements of the estrogen-regulated vitellogenin gene B1 of Xenopus laevis.

Vitellogenin genes are expressed under strict estrogen control in the liver of female oviparous vertebrates. Gene transfer experiments using estrogen-responsive cells have shown that the 13 bp perfect palindromic element GGTCACTGTGACC found upstream of the Xenopus laevis vitellogenin gene A2 promoter mediates hormonal stimulation and thus, was called the estrogen-responsive element (ERE). In the Xenopus vitellogenin genes B1 and B2 there are two closely adjacent EREs with one or more base substitutions when compared to the consensus ERE GGTCANNNTGACC. On their own, these degenerated elements have only a low or no regulatory capacity at all but act together synergistically to form an estrogen-responsive unit (ERU) with the same strength as the perfect palindromic 13 bp element. Analysis of estrogen receptor binding to the gene B1 ERU revealed a cooperative interaction of receptor dimers to the two adjacent imperfect EREs which most likely explains the synergistic stimulation observed in vivo. Furthermore, a promoter activator element located between positions --113 and --42 of the gene B1 and functional in the human MCF-7 and the Xenopus B3.2 cells has been identified and shown to be involved in the high level of induced transcription activity when the ERE is placed at a distance from the promoter. Finally, a hormone-controlled in vitro transcription system derived from Xenopus liver nuclear extracts was exploited to characterize two additional novel cis-acting elements within the vitellogenin gene B1 promoter. One of them, a negative regulatory element (NRE), is responsible for repression of promoter activity in the absence of hormone. The second is related to the NF-I binding site and is required, together with the ERE, to mediate hormonal induction. Moreover, we detected three trans-acting activities in Xenopus liver nuclear extracts that interact with these regions and demonstrated that they participate in the regulation of the expression of the vitellogenin promoter in vitro.

Inverted ductal papilloma of the oral cavity secondary to lower lip trauma. A case report and literature review

Inverted ductal papilloma of the oral cavity is an infrequent benign neoplasm of papillary appearance that originates in the secretory duct of a salivary gland. The etiology is unknown, though some authors have related it to human papillomavirus (HPV) infection. We present the case of a 40-year-old woman with a tumor of the lower lip mucosa. Histopathological study of the lesion diagnosed inverted ductal papilloma of the oral cavity. Human papillomavirus DNA detection and typing based on tumor lesion DNA amplification and posterior hybridization, revealed no presence of viral DNA. The antecedents of trauma reported by the patient could have played an important role in the development of this tumor

Genome-wide enrichment analysis between endometriosis and obesity-related traits reveals novel susceptibility loci.

Endometriosis is a chronic inflammatory condition in women that results in pelvic pain and subfertility, and has been associated with decreased body mass index (BMI). Genetic variants contributing to the heritable component have started to emerge from genome-wide association studies (GWAS), although the majority remain unknown. Unexpectedly, we observed an intergenic locus on 7p15.2 that was genome-wide significantly associated with both endometriosis and fat distribution (waist-to-hip ratio adjusted for BMI; WHRadjBMI) in an independent meta-GWAS of European ancestry individuals. This led us to investigate the potential overlap in genetic variants underlying the aetiology of endometriosis, WHRadjBMI and BMI using GWAS data. Our analyses demonstrated significant enrichment of common variants between fat distribution and endometriosis (P = 3.7 × 10(-3)), which was stronger when we restricted the investigation to more severe (Stage B) cases (P = 4.5 × 10(-4)). However, no genetic enrichment was observed between endometriosis and BMI (P = 0.79). In addition to 7p15.2, we identify four more variants with statistically significant evidence of involvement in both endometriosis and WHRadjBMI (in/near KIFAP3, CAB39L, WNT4, GRB14); two of these, KIFAP3 and CAB39L, are novel associations for both traits. KIFAP3, WNT4 and 7p15.2 are associated with the WNT signalling pathway; formal pathway analysis confirmed a statistically significant (P = 6.41 × 10(-4)) overrepresentation of shared associations in developmental processes/WNT signalling between the two traits. Our results demonstrate an example of potential biological pleiotropy that was hitherto unknown, and represent an opportunity for functional follow-up of loci and further cross-phenotype comparisons to assess how fat distribution and endometriosis pathogenesis research fields can inform each other.

Presence of Leishmania RNA Virus 1 in Leishmania guyanensis Increases the Risk of First-Line Treatment Failure and Symptomatic Relapse.

Treatment failure and symptomatic relapse are major concerns in American tegumentary leishmaniasis (TL). Such complications are seen frequently in Leishmania guyanensis infections, in which patients respond variously to first-line antileishmanials and are more prone to develop chronic cutaneous leishmaniasis. The factors underlying this pathology, however, are unknown. Recently, we reported that a double-stranded RNA virus, Leishmania RNA virus 1 (LRV1), nested within L. guyanensis parasites is able to exacerbate experimental murine leishmaniasis by inducing a hyperinflammatory response. This report investigates the prevalence of LRV1 in human L. guyanensis infection and its effect on treatment efficacy, as well as its correlation to symptomatic relapses after the completion of first-line treatment. In our cohort of 75 patients with a diagnosis of primary localized American TL, the prevalence of LRV1-positive L. guyanensis infection was elevated to 58%. All patients infected with LRV1-negative L. guyanensis were cured after 1 dose (22 of 31 [71%]) or 2 doses (31 of 31 [100%]) of pentamidine. In contrast, 12 of 44 LRV1-positive patients (27%) presented with persistent infection and symptomatic relapse that required extended therapy and the use of second-line drugs. Finally, LRV1 presence was associated with a significant increase in levels of intra-lesional inflammatory markers. In conclusion, LRV1 status in L. guyanensis infection is significantly predictive (P = .0009) of first-line treatment failure and symptomatic relapse and has the potential to guide therapeutic choices in American TL.

HPV & head and neck cancer: a descriptive update

The incidence of head and neck squamous cell carcinoma (HNSCC) has been gradually increasing over the last three decades. Recent data have now attributed a viral aetiology to a subset of head and neck cancers. Several studies indicate that oral human papillomavirus (HPV) infection is likely to be sexually acquired. The dominance of HPV 16 in HPV+ HNSCC is even greater than that seen in cervical carcinoma of total worldwide cases. Strong evidence suggests that HPV+ status is an important prognostic factor associated with a favourable outcome in head and neck cancers. Approximately 30 to 40% of HNSCC patients with present with early stage I/II disease. These patients are treated with curative intent using single modality treatments either radiation or surgery alone. A non-operative approach is favored for patients in which surgery followed by either radiation alone or radiochemotherapy may lead to severe functional impairment. Cetuximab, a humanized mouse anti-EGFR IgG1 monoclonal antibody, improved locoregional control and overall survival in combination with radiotherapy in locally advanced tumours but at the cost of some increased cardiac morbidity and mortality. Finally, the improved prognosis and treatment responses to chemotherapy and radiotherapy by HPV+ tumours may suggest that HPV status detection is required to better plan and individualize patient treatment regimes.

Impairment of cytomegalovirus-specific cellular immune response as a risk factor for cytomegalovirus disease in transplant recipients

Human cytomegalovirus (CMV) infection is common in most people but nearly asymptomatic in immunocompetent individuals. After primary infection the virus persists throughout life in a latent form in a variety of tissues, particularly in precursor cells of the monocytic lineage. CMV reinfection and occurrence of disease are associated with immunosuppressive conditions. Solid organ and bone marrow transplant patients are at high risk for CMV disease as they undergo immunosuppression. Antiviral treatment is effective in controlling viremia, but 10-15% of infected patients can experience CMV disease by the time the drug is withdrawn. In addition, long-term antiviral treatment leads to bone marrow ablation and renal toxicity. Furthermore, control of chronic CMV infection in transplant recipients appears to be dependent on the proper recovery of cellular immunity. Recent advances in the characterization of T-cell functions and identification of distinct functional signatures of T-cell viral responses have opened new perspectives for monitoring transplant individuals at risk of developing CMV disease.

Immunodominance: a new hypothesis to explain parasite escape and host/parasite equilibrium leading to the chronic phase of Chagas' disease?

Intense immune responses are observed during human or experimental infection with the digenetic protozoan parasite Trypanosoma cruzi. The reasons why such immune responses are unable to completely eliminate the parasites are unknown. The survival of the parasite leads to a parasite-host equilibrium found during the chronic phase of chagasic infection in most individuals. Parasite persistence is recognized as the most likely cause of the chagasic chronic pathologies. Therefore, a key question in Chagas' disease is to understand how this equilibrium is established and maintained for a long period. Understanding the basis for this equilibrium may lead to new approaches to interventions that could help millions of individuals at risk for infection or who are already infected with T. cruzi. Here, we propose that the phenomenon of immunodominance may be significant in terms of regulating the host-parasite equilibrium observed in Chagas' disease. T. cruzi infection restricts the repertoire of specific T cells generating, in some cases, an intense immunodominant phenotype and in others causing a dramatic interference in the response to distinct epitopes. This immune response is sufficiently strong to maintain the host alive during the acute phase carrying them to the chronic phase where transmission usually occurs. At the same time, immunodominance interferes with the development of a higher and broader immune response that could be able to completely eliminate the parasite. Based on this, we discuss how we can interfere with or take advantage of immunodominance in order to provide an immunotherapeutic alternative for chagasic individuals.

Production of L1 protein from different types of HPV in Pichia pastoris using an integrative vector

Human papillomavirus (HPV) infection is the most common sexually transmitted disease in the world and is related to the etiology of cervical cancer. The most common high-risk HPV types are 16 and 18; however, the second most prevalent type in the Midwestern region of Brazil is HPV-33. New vaccine strategies against HPV have shown that virus-like particles (VLP) of the major capsid protein (L1) induce efficient production of antibodies, which confer protection against the same viral type. The methylotrophic yeast Pichia pastoris is an efficient and inexpensive expression system for the production of high levels of heterologous proteins stably using a wild-type gene in combination with an integrative vector. It was recently demonstrated that P. pastoris can produce the HPV-16 L1 protein by using an episomal vector associated with the optimized L1 gene. However, the use of an episomal vector is not appropriate for protein production on an industrial scale. In the present study, the vectors were integrated into the Pichia genome and the results were positive for L1 gene transcription and protein production, both intracellularly and in the extracellular environment. Despite the great potential for expression by the P. pastoris system, our results suggest a low yield of L1 recombinant protein, which, however, does not make this system unworkable. The achievement of stable clones containing the expression cassettes integrated in the genome may permit optimizations that could enable the establishment of a platform for the production of VLP-based vaccines.