Aracely López-Monteon

Prevalencia de anticuerpos contra Trypanosoma cruzi en donadores de sangre del IMSS, Orizaba, Veracruz, México

OBJETIVO: Determinar la prevalencia de anticuerpos contra Trypanosoma cruzi en donadores del Hospital General Regional del Instituto Mexicano del Seguro Social (IMSS) en la ciudad de Orizaba, Veracruz. MATERIAL Y METODOS: Se examinaron muestras de donadores del banco de sangre del Hospital General Regional (HGRO) del IMSS para la busqueda de antiT. cruzi por ELISA, Western blot e IFI, utilizando una proteina recombinante (MBP::Hsp70) y un extracto crudo de epimastigotes. Las muestras fueron obtenidas entre los meses de octubre de 2001 a enero de 2002. RESULTADOS: Los 420 donadores de sangre analizados fueron seronegativos para HBV, HCV, BrA, VDRL y HIV. Despues del tamizaje de los 420 donadores, se identificaron dos individuos seropositivos por las pruebas de ELISA, Western blot e IFI, con una seroprevalencia de 0.48%. CONCLUSIONES: En este estudio se muestran evidencias de seropositividad para T. cruzi en donadores de sangre del HGRO, lo que sugiere la existencia de riesgo de contaminacion por transfusion sanguinea. Por tal motivo, es necesario aplicar programas para el tamizaje serologico a traves de tecnicas inmunologicas con alta sensibilidad y especificidad.

Identification of a Hyperendemic Area for Trypanosoma cruzi Infection in Central Veracruz, Mexico

The state of Veracruz, Mexico, is a well-recognized endemic region for Chagas disease, but the geographic distribution of the disease and its magnitude are still poorly documented. We evaluated the seroprevalence of Trypanosoma cruzi infection in the sanitary jurisdictions of Cordoba and Cosamaloapan in central Veracruz. A total of 654 serum samples from 19 rural localities were tested by using four tests: two enzyme-linked immunosorbent assays, an indirect immunofluorescent, and Western blotting. Overall, 110 (16.8%) of 654 samples were positive for T. cruzi by >/= 2 tests (95% confidence interval = 14.2-19.9%). The municipality of Tezonapa in the jurisdiction of Cordoba was identified as a potential hyperendemic region with seroprevalence rates </= 45% in young children. No cases were detected in the jurisdiction of Cosamaloapan. Further studies should help clarify T. cruzi transmission dynamics in Tezonapa. The magnitude of T. cruzi infection rate in this region calls for the urgent implementation of extensive epidemiologic surveillance and control programs.

House Infestation Dynamics and Feeding Sources of Triatoma dimidiata in Central Veracruz, Mexico

Chagas disease is endemic in the state of Veracruz, Mexico, and we investigated here the dynamics of house infestation by Chagas disease vectors to understand disease transmission and design effective control interventions. Bug collections in 42 rural villages confirmed the widespread distribution of Triatoma dimidiata in central Veracruz. Unexpectedly, collection data further indicated a clear pattern of seasonal infestation by mostly adult bugs. Analysis of feeding sources with a polymerase chain reaction-heteroduplex assay indicated a frequent feeding on humans, in agreement with the high seroprevalence previously observed. Feeding sources also confirmed a significant dispersal of bugs between habitats. High dispersal capabilities and seasonal infestation may thus be a shared characteristic of several of the T. dimidiata sibling species from this complex. It would thus be critical to adapt vector control interventions to this behavior to improve their efficacy and sustainability, as the control of T. dimidiata has been notoriously challenging.

Extensive diversity of Trypanosoma cruzi discrete typing units circulating in Triatoma dimidiata from central Veracruz, Mexico.

Chagas disease (or American trypanosomiasis) is a parasitic disease of major public health importance, caused by Trypanosoma cruzi, which presents extensive genetic diversity. The parasite has been classified into six lineages or discrete typing units (TcI to TcVI) and we performed here the molecular characterization of the strains present in Triatoma dimidiata, the main vector in central Veracruz, Mexico. Unexpectedly, TcI only represented 9/33 strains identified (27%), and we reported for the first time the presence of TcII, TcIII, TcIV and TcV strains in Mexico, at a relatively high frequency (13-27% each). Our observations indicate a much greater diversity of T. cruzi DTUs than previously estimated in at least part of Mexico. These results have important implications for the understanding of the phylogeography of T. cruzi DTUs and the epidemiology of Chagas disease in North America.

Expression, Purification, and Evaluation of Diagnostic Potential and Immunogenicity of a Recombinant NS3 Protein from All Serotypes of Dengue Virus

Dengue is one of the major public health concerns in the world. Since all the four serotypes are actively circulating in Mexico, there is a need to develop an efficient diagnosis system to improve case management of the patients. There exist few studies evaluating the use of the NS3 protein as a protective antigen against dengue virus (DENV). In this paper we show the expression of a recombinant NS3 protein from all serotypes of dengue virus (GST-DVNS3-1-4) and report a reliable “in-house detection system” for the diagnosis of dengue infection which was field-tested in a small village (Tezonapa) in the state of Veracruz, Mexico. The fusion proteins were immunogenic, inducing antibodies to be able to recognize to antigens up to a 1 : 3200 dilution. The purified proteins were used to develop an in-house detection system (ELISA) and were further tested with a panel of 239 serum samples. The in-house results were in excellent agreement with the commercial kits with κ = 0.934 ± 0.064 (95%  CI = 0.808–1.061), and κ = 0.872 ± 0.048 (95%  CI = 0.779–0.965) for IgM and IgG, respectively. The agreement between the NS1 antigen detection versus the rNS3 ELISA, κ = 0.837 ± 0.066 (95%  CI = 0.708–0.966), was very good. Thus, these results demonstrate that recombinant NS3 proteins have potential in early diagnosis of dengue infections.

Seroprevalence of Trypanosoma cruzi and Leishmania mexicana in free-ranging howler monkeys in southeastern Mexico.

Natural infection of wild mammals by protozoa parasites is quite common in nature. For Neotropical Primates different infections of parasites that are etiological agent of disease in human have been identified. In particular, infections by Trypanosoma cruzi and Leishmania sp., have been reported for some New World primate species, but there are no reports of infection with these parasites in any primate species in Mexico. A serological study was conducted on two howler monkey species (Alouatta pigra and A. palliata) from the Mexican states of Campeche and Tabasco. A total of 55 serum samples (20 samples from A. pigra, 20 samples from A. palliata, and 15 samples from semifree ranging A. palliata of Los Tuxtlas, Veracruz as negative controls) were analyzed for the detection of immunoglobulin G antibodies against T. cruzi and Leishmania mexicana through enzyme linked immunosorbent assay test, indirect immunofluorescence assay and Western blot. The overall prevalence of antibodies in howler monkeys was 17.5% for T. cruzi and 30% for L. mexicana. Our results also indicate that A. pigra is more susceptible to develop leishmaniasis than A. palliata. Finally, the finding of positive serology in these primates should be given serious consideration for public health, given the potential role of these primate species as wild reservoirs for these diseases and the increasing contact of monkeys with human populations due to habitat loss and fragmentation. Am. J. Primatol. 75:161‐169, 2013.

A low density microarray method for the identification of human papillomavirus type 18 variants.

We describe a novel microarray based-method for the screening of oncogenic human papillomavirus 18 (HPV-18) molecular variants. Due to the fact that sequencing methodology may underestimate samples containing more than one variant we designed a specific and sensitive stacking DNA hybridization assay. This technology can be used to discriminate between three possible phylogenetic branches of HPV-18. Probes were attached covalently on glass slides and hybridized with single-stranded DNA targets. Prior to hybridization with the probes, the target strands were pre-annealed with the three auxiliary contiguous oligonucleotides flanking the target sequences. Screening HPV-18 positive cell lines and cervical samples were used to evaluate the performance of this HPV DNA microarray. Our results demonstrate that the HPV-18s variants hybridized specifically to probes, with no detection of unspecific signals. Specific probes successfully reveal detectable point mutations in these variants. The present DNA oligoarray system can be used as a reliable, sensitive and specific method for HPV-18 variant screening. Furthermore, this simple assay allows the use of inexpensive equipment, making it accessible in resource-poor settings.

Codetection of Trichomonas vaginalis and Candida albicans by PCR in Urine Samples in a Low-Risk Population Attended in a Clinic First Level in Central Veracruz, Mexico

The aim of this study is to estimate the prevalence of Trichomonas vaginalis and Candida albicans in low-risk patients treated at a first level clinic (primary health care represents the first level of contact of individuals, families, and the community with the system national health). Using a cross-sectional study in patients treated in clinical laboratory of the Sanitary District no. 7 of the city of Orizaba during the months June-July, 252 urine samples were collected for the identification of T. vaginalis and C. albicans by PCR. Furthermore, we analyzed the sociodemographic characteristics of the studied population. We observed an overall prevalence of 23.41% (95% CI 22.10–24.72) for T. vaginalis and 38.88% (95% CI 37.73–40.03) for C. albicans. There was also presence of coinfection in 14.28% (95% CI 13.10–15.46), which was associated with the presence of pain. Most of the positive cases were observed in women house-maker (80%, 95% CI 50.36–48.98). The results of this study provide evidence that the majority of positive cases observed in the studied population are presented in an asymptomatic form and usually are not associated with any risk factor.

Differential humoral and cellular immunity induced by vaccination using plasmid DNA and protein recombinant expressing the NS3 protein of dengue virus type 3

BackgroundThe dengue non-structural 3 (NS3) is a multifunctional protein, containing a serine-protease domain, located at the N-terminal portion, and helicase, NTPase and RTPase domains present in the C-terminal region. This protein is considered the main target for CD4+ and CD8+ T cell responses during dengue infection, which may be involved in protection. However, few studies have been undertaken evaluating the use of this protein as a protective antigen against dengue, as well as other flavivirus. In the present work we evaluated the potential of the NS3 (protease domain) as a protective antigen by comparing the administration of a recombinant protein versus a DNA vaccine in the mouse model.ResultsBALB/c mice were immunized with the recombinant protein NS3-DEN3 via intraperitoneal and with plasmid pcDNA3/NS3-DEN3 intramuscularly and the immune response was evaluated. The activity of T lymphocytes was analyzed by the MTT assay, and cells of mice immunized with the recombinant protein showed no activity when stimulated with the homologous protein. However, cells from mice immunized with DNA, responded to stimulation with the recombinant protein. When the expression (RT-PCR) and cytokine production (ELISA) was evaluated in the splenocytes, different behavior depending on the type of immunization was observed, splenocytes of mice immunized with the recombinant protein expressed cytokines such as IL-4, IL-10 and produced high concentrations of IL-1, IL-6 and TNFα. Splenocytes from mice immunized with DNA expressed IL-2 and IFNγ and did not produce IL-6. In addition, immunization with the recombinant protein induced the production of antibodies that are detected up to a dilution 1:3200 by ELISA and Western blot assays, however, the serum of mice immunized with DNA presented no detectable antibody titers.ConclusionThe results obtained in this study show that administration of pcDNA3/NS3-DEN3 induces a favorable response in the activation of T lymphocytes with low production of specific antibodies against NS3-DEN3.

Prevalence of Trichomonas vaginalis and Human papillomavirus in female sex workers in Central Veracruz, Mexico

Female sex workers (FSWs) have been considered a key population for sexually transmitted infections (STIs); therefore, they are periodically screened as a requirement to obtain a work card. However, there is insufficient epidemiological data on STIs among FSWs in Mexico. The detection of Trichomonas vaginalis is limited to microscopic studies and the molecular screening of Human papillomavirus (HPV) is only done to women 35 years of age and older. The objective of this study was to determine the prevalence of T. vaginalis and HPV infections in FSWs in the city of Orizaba, Veracruz, Mexico. Samples from 105 FSWs were obtained by cervical swab and analyzed. The identification of T. vaginalis and HPV was performed by molecular methods. HPV DNA was identified in 5.71% of the samples with the presence of HPV16, HPV18, and HPV58. A percentage of 25.7% samples were positive for T. vaginalis for optical microscopy and 23.8% for PCR. The results of the study indicate the need to incorporate more sensitive methods for the timely diagnosis of STIs as well as comprehensive health promotion programs directed to the most vulnerable groups among FSWs.