In silico approach for the identification of immunological properties of enolase from Trypanosoma cruzi and its possible usefulness as vaccine in Chagas disease.

Nowadays, Chagas disease is a major health problem in Latin America that has been disseminated also into non-endemic countries. Currently, a vaccine against Chagas disease does not exist. In the present study, the gene encoding Trypanosoma cruzi enolase (TcENO) was amplified, cloned, and sequenced and the recombinant protein was purified. We used in silico and an experimental assay to investigate the immunological role of TcENO. The in silico assays showed that TcENO sequence contains characteristic motifs of enolase; additionally, a transmembranal region was identified, and this could indicate the potential membrane localization of TcENO. Moreover, both B lymphocyte and cytotoxic T lymphocytes (CTL) predicted epitopes were localized; these results suggest the possibility that TcENO can develop both humoral and cellular immune responses. Furthermore, the presence of antibodies was verified by western blot assays, showing that the purified recombinant protein was detected by sera from experimentally infected mice and sera of patients with Chagas disease. These results indicate that TcENO is immunogenic and could be used as a vaccine candidate.

Seroprevalence and major antigens recognized by sera from Trypanosoma cruzi-infected dogs from Jalisco, México.

Chagas disease is a major endemic disease caused by the protozoan parasite Trypanosoma cruzi. This parasitic disease is widely distributed throughout Latin America, affecting 10 million people. There are also reports of canine infection in the southern part of the United States. Dogs are considered the predominant domestic reservoir for T. cruzi in many areas of endemicity. In México, dog infection by this parasite has been poorly studied. In this work 209 dogs from six villages in Jalisco, México, were assessed to detect anti-T. cruzi antibodies by ELISA and Western blot. Seventeen (17) seropositive dogs (8.1 %) were detected by both tests, representing a seropositive value similar to that found in some southern states of México where the infection is present. No statistical differences were observed concerning the age and sex of infected and non-infected dogs. The major antigens recognized by positive sera were 26, 32, 66 and 80kDa. These proteins are candidates to develop a specific diagnostic method for canine Chagas. No antibodies against HSP16 protein were found in T. cruzi seropositive sera. This is the first report of canine serology of Chagas disease in this central part of México. This report will contribute to the knowledge of the infection status of domestic reservoirs in the state of Jalisco, México.

Mycobacterium bovis BCG as immunostimulating agent prevents the severe form of chronic experimental Chagas disease.

Introduction: There is currently no vaccine against Chagas disease (ChD), and the medications available confer multiple side effects. Mycobacterium bovis Bacillus Calmette-Guérin (BCG) produces balanced Th1, Th2, and Th17 modulatory immune responses and has improved efficacy in controlling chronic infections through nonspecific immunity. We aimed to improve the response to infection by inducing a stronger immune response and greater protection against the parasite by trained immunity. Methods: BALB/c mice were immunized with BCG subcutaneously, and 60 days later, they were infected with Trypanosoma cruzi intraperitoneally. An evaluation of the progression of the disease from the acute to the chronic stage, analyzing various aspects such as parasitemia, survival, clinical status, and humoral and cellular immune response, as well as the appearance of visceral megas and the histopathological description of target organs, was performed. Results: Vaccination reduced parasitemia by 70%, and 100% survival was achieved in the acute stage; although the presentation of clinical signs was reduced, there was no increase in the antibody titer or in the differential production of the isotypes. Conclusion: Serum cytokine production indicated a proinflammatory response in infected animals, while in those who received BCG, the response was balanced by inducing Th1/Th2-type cytokines, with a better prognosis of the disease in the chronic stage.

Specific humoral and cellular immunity induced by Trypanosoma cruzi DNA immunization in a canine model.

Chagas disease has a high incidence in Mexico and other Latin American countries. Because one of the most important known methods of prevention is vector control, which has been effective only in certain areas of South America, the development of a vaccine to protect people at risk has been proposed. In this study, we assessed the cellular and humoral immune response generated following immunization with pBCSP and pBCSSP4 plasmids containing the genes encoding a trans-sialidase protein (present in all three forms of T. cruzi) and an amastigote specific glycoprotein, respectively, in a canine model. Thirty-five beagle dogs were divided randomly into 5 groups (n=7) and were immunized twice intramuscularly with 500 µg of pBCSSP4, pBCSP, pBk-CMV (empty plasmid) or saline solution. Fifteen days after the last immunization the 4 groups were infected intraperitoneally with 500,000 metacyclic trypomastigotes. The fifth group was unimmunized/infected. The parasitaemia in the immunized/infected dogs was for a shorter period (14 vs. 29 days) and the parasite load was lower. The concentration of IgG1 (0.612±0.019 O.D.) and IgG2 (1.167±0.097 O.D.) subclasses was measured (absorbance) 15 days after the last immunization with both recombinant plasmids, the majority of which were IgG2. The treatment of parasites using the serum from dogs immunized with pBCSP and pBCSSP4 plasmids produced 54% (±11.8) and 68% (±21.4) complement-mediated lysis, respectively. At 12 h post immunization, an increase in cytokines was not observed; however, vaccination with pBCSSP4 significantly increased the levels of IFN-γ and IL-10 at 9 months post-infection. The recombinant plasmid immunization stimulated the spleen cell proliferation showing a positive stimulatory index above 2.0. In conclusion, immunization using both genes effectively induces a humoral and cellular immune response.

Effectiveness of Nitazoxanide and Electrolyzed Oxiding Water in Treating Chagas Disease in a Canine Model.

Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi, and affects seven million people in Latin America. Side effects and the limited efficacy of current treatment have led to new drug research. The objective of this work was to evaluate the effectiveness of nitazoxanide (NTZ) and electrolyzed oxidizing water (EOW) in a canine model of experimental CD. Náhuatl dogs were infected with the T. cruzi H8 strain and NTZ- or EOW-treated orally for 10 days. Seronegativity was shown at 12 months post-infection (mpi) in the NTZ-, EOW-, and benznidazole (BNZ)-treated groups. The NTZ and BNZ groups had high levels of IFN-γ, TNF-α, IL-6, IL-12B, and IL-1ß at 1.5 mpi and low levels of IL-10. Electrocardiographic studies showed alterations from 3 mpi and worsening at 12 mpi; NTZ treatment produced fewer cardiac pathomorphological changes compared to EOW, similar to BNZ treatment. There was no cardiomegaly in any group. In conclusion, although NTZ and EOW did not prevent changes in cardiac conductivity, they were able to avoid the severity of heart damage in the chronic phase of CD. NTZ induced a favorable proinflammatory immune response after infection, being a better option than EOW as a possible treatment for CD after BNZ.

Nitazoxanide: A Drug Repositioning Compound with Potential Use in Chagas Disease in a Murine Model.

Chagas disease (ChD), caused by Trypanosoma cruzi, is the most serious parasitosis in the western hemisphere. Benznidazole and nifurtimox, the only two trypanocidal drugs, are expensive, difficult to obtain, and have severe side effects. Nitazoxanide has shown to be effective against protozoa, bacteria, and viruses. This study aimed to evaluate the nitazoxanide efficacy against the Mexican T. cruzi Ninoa strain in mice. Infected animals were orally treated for 30 days with nitazoxanide (100 mg/kg) or benznidazole (10 mg/kg). The clinical, immunological, and histopathological conditions of the mice were evaluated. Nitazoxanide- or benznidazole-treated mice had longer survival and less parasitemia than those without treatment. Antibody production in the nitazoxanide-treated mice was of the IgG1-type and not of the IgG2-type as in the benznidazole-treated mice. Nitazoxanide-treated mice had significantly high IFN-γ levels compared to the other infected groups. Serious histological damage could be prevented with nitazoxanide treatment compared to without treatment. In conclusion, nitazoxanide decreased parasitemia levels, indirectly induced the production of IgG antibodies, and partially prevented histopathological damage; however, it did not show therapeutic superiority compared to benznidazole in any of the evaluated aspects. Therefore, the repositioning of nitazoxanide as an alternative treatment against ChD could be considered, since it did not trigger adverse effects that worsened the pathological condition of the infected mice.

The Low Variability of Tc24 in Trypanosoma cruzi TcI as an Advantage for Chagas Disease Prophylaxis and Diagnosis in Mexico.

(1) Background: Chagas disease is the main neglected tropical disease in America. It is estimated that around 6 million people are currently infected with the parasite in Latin America, and 25 million live in endemic areas with active transmission. The disease causes an estimated economic loss of USD 24 billion dollars annually, with a loss of 75,200 working years per year of life; it is responsible for around ~12,000 deaths annually. Although Mexico is an endemic country that recorded 10,186 new cases of Chagas disease during the period of 1990-2017, few studies have evaluated the genetic diversity of genes that could be involved in the prophylaxis and/or diagnosis of the parasite. One of the possible candidates proposed as a vaccine target is the 24 kDa trypomastigote excretory-secretory protein, Tc24, whose protection is linked to the stimulation of T. cruzi-specific CD8+ immune responses. (2) Methods: The aim of the present study was to evaluate the fine-scale genetic diversity and structure of Tc24 in T. cruzi isolates from Mexico, and to compare them with other populations reported in the Americas with the aim to reconsider the potential role of Tc24 as a key candidate for the prophylaxis and improvement of the diagnosis of Chagas disease in Mexico. (3) Results: Of the 25 Mexican isolates analysed, 48% (12) were recovered from humans and 24% (6) recovered from Triatoma barberi and Triatoma dimidiata. Phylogenetic inferences revealed a polytomy in the T. cruzi clade with two defined subgroups, one formed by all sequences of the DTU I and the other formed by DTU II-VI; both subgroups had high branch support. Genetic population analysis detected a single (monomorphic) haplotype of TcI throughout the entire distribution across both Mexico and South America. This information was supported by Nei's pairwise distances, where the sequences of TcI showed no genetic differences. (4) Conclusions: Given that both previous studies and the findings of the present work confirmed that TcI is the only genotype detected from human isolates obtained from various states of Mexico, and that there is no significant genetic variability in any of them, it is possible to propose the development of in silico strategies for the production of antigens that optimise the diagnosis of Chagas disease, such as quantitative ELISA methods that use this region of Tc24.

Plasmid DNA immunization with Trypanosoma cruzi genes induces cardiac and clinical protection against Chagas disease in the canine model.

The only existing preventive measure against American trypanosomosis, or Chagas disease, is the control of the transmitting insect, which has only been effective in a few South American regions. Currently, there is no vaccine available to prevent this disease. Here, we present the clinical and cardiac levels of protection induced by expression to Trypanosoma cruzi genes encoding the TcSP and TcSSP4 proteins in the canine model. Physical examination, diagnostic chagasic serology, and serial electrocardiograms were performed before and after immunization, as well as after experimental infection. We found that immunization with recombinant plasmids prevented hyperthermia in the acute phase of experimental infection and produced lymphadenomegaly as an immunological response against the parasite and additionally prevented heart rate elevation (tachycardia) in the acute and/or chronic stages of infection. Immunization with T. cruzi genes encoding the TcSP and TcSSP4 antigens diminished the quality and quantity of the electrocardiographic abnormalities, thereby avoiding progression to more severe developments such as right bundle branch block or ventricular premature complexes in a greater number of dogs.

Consensus Enolase of Trypanosoma Cruzi: Evaluation of Their Immunogenic Properties Using a Bioinformatics Approach.

There is currently no vaccine against American trypanosomiasis, caused by the parasite Trypanosoma cruzi. This is due to the genomic variation observed in the six DTUs of T. cruzi. This work aims to propose a consensus sequence of the enolase protein from different strains of T. cruzi and mainly evaluate its immunogenic properties at the bioinformatic level. From specialized databases, 15 sequences of the enolase gene were aligned to obtain a consensus sequence, where this sequence was modeled and then evaluated and validated through different bioinformatic programs to learn their immunogenic potential. Finally, chimeric peptides were designed with the most representative epitopes. The results showed high immunogenic potential with six epitopes for MHC-I, and seven epitopes for MHC-II, all of which were highly representative of the enolase present in strains from the American continent as well as five epitopes for B cells. Regarding the computational modeling, molecular docking with Toll-like receptors showed a high affinity and low constant of dissociation, which could lead to an innate-type immune response that helps to eliminate the parasite. In conclusion, the consensus sequence proposed for enolase is capable of providing an ideal immune response; however, the experimental evaluation of this enolase consensus and their chimeric peptides should be a high priority to develop a vaccine against Chagas disease.

Chagas Heart Disease: Beyond a Single Complication, from Asymptomatic Disease to Heart Failure.

Chagas cardiomyopathy (CC), caused by the protozoan Trypanosoma cruzi, is an important cause of cardiovascular morbidity and mortality in developing countries. It is estimated that 6 to 7 million people worldwide are infected, and it is predicted that it will be responsible for 200,000 deaths by 2025. The World Health Organization (WHO) considers Chagas disease (CD) as a Neglected Tropical Disease (NTD), which must be acknowledged and detected in time, as it remains a clinical and diagnostic challenge in both endemic and non-endemic regions and at different levels of care. The literature on CC was analyzed by searching different databases (Medline, Cochrane Central, EMBASE, PubMed, Google Scholar, EBSCO) from 1968 until October 2022. Multicenter and bioinformatics trials, systematic and bibliographic reviews, international guidelines, and clinical cases were included. The reference lists of the included papers were checked. No linguistic restrictions or study designs were applied. This review is intended to address the current incidence and prevalence of CD and to identify the main pathogenic mechanisms, clinical presentation, and diagnosis of CC.

Risk of COVID-19 in Chagas Disease Patients: What Happen with Cardiac Affectations?

BACKGROUND: Chagas disease is considered a neglected tropical disease. The acute phase of Chagas disease is characterized by several symptoms: fever, fatigue, body aches, headache and cardiopathy's. Chronic phase could be asymptomatic or symptomatic with cardiac compromise. Since the emergence of the pandemic caused by the SARS-CoV-2 virus, the cardiovascular involvement has been identified as a complication commonly reported in coronavirus disease 2019 (COVID-19). Due to the lack of knowledge of the cardiac affectations that this virus could cause in patients with Chagas disease, the aim of this review is to describe the possible cardiac affectations, as well as the treatment and recommendations that patients with both infections should carry out. METHODS: The authors revised the recent and relevant literature concerning the topic and discussed advances and limitations of studies on COVID-19 and their impact in Chagas disease patients, principally with cardiac affectations. RESULTS: There currently exists little information about the consequences that Chagas disease patients can suffer when they are infected with COVID-19. CONCLUSIONS: This review highlights the emerging challenges of access to medical care and future research needs in order to understand the implications that co-infections (SARS-CoV-2 or other viruses) can generate in Chagas disease-infected people.

Echocardiographic Findings in Canine Model of Chagas Disease Immunized with DNA Trypanosoma cruzi Genes.

Chagas disease (ChD) is considered an emerging disease in the USA and Europe. Trypanosoma cruzi genes encoding a trans-sialidase protein and an amastigote-specific glycoprotein were tested as vaccines in canine model. The aim for this study was determining the prophylactic effect of these genes in experimentally infected dogs by echocardiography evaluation to compare with our findings obtained by other techniques published previously. Low fractional-shortening values of non-vaccinated dogs suggested an impairment in general cardiac function. Low left ventricular ejection fraction values found in infected dogs suggested myocardial injury regardless of whether they were vaccinated. Low left ventricular diastolic/systolic diameters suggested that progressive heart damage or heart dilation could be prevented by DNA vaccination. Systolic peak time was higher in non-vaccinated groups, increasing vulnerability to malignant arrhythmias and sudden death. High left ventricular volume suggested a decrease in wall thickness that might lead to increased size of the heart cavity, except in the pBCSP plasmid-vaccinated dogs. There was an echocardiographic evidence of left ventricular dilation and reduction in systolic function in experimental chagasic dogs. Echocardiography allowed a more complete follow-up of the pathological process in the living patient than with other techniques like electrocardiography, anatomopathology, and histopathology, being the method of choice for characterizing the clinical stages of ChD.

DNA Vaccine Treatment in Dogs Experimentally Infected with Trypanosoma cruzi.

Chagas disease is a chronic and potentially lethal disorder caused by the parasite Trypanosoma cruzi, and an effective treatment has not been developed for chronic Chagas disease. The objective of this study was to determine the effectiveness of a therapeutic DNA vaccine containing T. cruzi genes in dogs with experimentally induced Chagas disease through clinical, pathological, and immunological analyses. Infection of Beagle dogs with the H8 T. cruzi strain was performed intraperitoneally with 3500 metacyclic trypomastigotes/kg body weight. Two weeks after infection, plasmid DNA immunotherapy was administered thrice at 15-day intervals. The clinical (physical and cabinet studies), immunological (antibody and cytokine profiles and lymphoproliferation), and macro- and microscopic pathological findings were described. A significant increase in IgG and cell proliferation was recorded after immunotherapy, and the highest stimulation index (3.02) was observed in dogs treated with the pBCSSP4 plasmid. The second treatment with both plasmids induced an increase in IL-1, and the third treatment with the pBCSSP4 plasmid induced an increase in IL-6. The pBCSP plasmid had a good Th1 response regulated by high levels of IFN-gamma and TNF-alpha, whereas the combination of the two plasmids did not have a synergistic effect. Electrocardiographic studies registered lower abnormalities and the lowest number of individuals with abnormalities in each group treated with the therapeutic vaccine. Echocardiograms showed that the pBCSSP4 plasmid immunotherapy preserved cardiac structure and function to a greater extent and prevented cardiomegaly. The two plasmids alone controlled the infection moderately by a reduction in the inflammatory infiltrates in heart tissue. The immunotherapy was able to reduce the magnitude of cardiac lesions and modulate the cellular immune response; the pBCSP treatment showed a clear Th1 response; and pBCSSP4 induced a balanced Th1/Th2 immune response that prevented severe cardiac involvement. The pBCSSP4 plasmid had a better effect on most of the parameters evaluated in this study; therefore, this plasmid can be considered an optional treatment against Chagas disease in naturally infected dogs.

Electrolyzed Oxidizing Water Modulates the Immune Response in BALB/c Mice Experimentally Infected with Trypanosoma cruzi.

Chagas disease is a major public health problem in Latin America. The mixed Th1/Th2 immune response is required against Trypanosoma cruzi. Electrolyzed oxidizing water (EOW) has been shown to have germicidal efficacy. The objective of this study was to evaluate the EOW effectiveness in T. cruzi-infected BALB/c mice clinically, immunologically, and histologically. The severity of the infection was assessed by parasitaemia, general health condition, mortality, mega syndromes, and histological lesions. IgG, TNF-alpha, IFN-gamma, and IL-1 beta levels were quantified. The EOW administration showed a beneficial effect on parasitaemia, general physical condition, and mortality. High levels of IgG1 at 50 days postinfection were observed. Prophylactic EOW treatment was able to induce a predominantly TH1 immune response based on an IgG2a levels increase at the late acute phase, and a 10-fold increase of INF-gamma in whole acute phase. EOW was able to control the acute phase infection as effectively as benznidazole. Splenomegaly was caused by EOW treatment and lymphadenopathy was stimulated by T. cruzi infection in all groups. Severe tissue damage was not prevented by EOW treatments. Moderate efficacy may be due to immunomodulatory properties and not to a direct toxic effect on the parasite.

Recombinant Enolase of Trypanosoma cruzi as a Novel Vaccine Candidate against Chagas Disease in a Mouse Model of Acute Infection.

Trypanosoma cruzi is the protozoan parasite that causes Chagas disease, which is considered by the World Health Organization to be a neglected tropical disease. Two drugs exist for the treatment of Chagas disease, nifurtimox and benznidazole; they are only effective in the acute phase, and a vaccine is currently not available. In this study, we used the recombinant enolase from T. cruzi H8 strain (MHOM/MX/1992/H8 Yucatán) (rTcENO) and its encoding DNA (pBKTcENO) to immunize mice and evaluate their protective effects in an experimental murine model of acute phase infection. Our results showed that mice vaccinated with rTcENO or its encoding DNA were able to generate typical specific antibodies (IgG1, IgG2a, and IgG2b), suggesting that a mixed Th1/Th2 immune response was induced. The parasite burden in the blood was reduced to 69.8% and 71% in mice vaccinated with rTcENO and pBKTcENO, respectively. The group vaccinated with rTcENO achieved 75% survival, in contrast to the group vaccinated with pBKTcENO that showed no survival in comparison to the control groups. Moreover, rTcENO immunization elevated the production of IFN-γ and IL-2 after the parasite challenge, suggesting that the Th1-type immune response was polarized. These results indicated that rTcENO could be used as a vaccine against Chagas disease.

Palmitic acid in HDL is associated to low apo A-I fractional catabolic rates in vivo.

BACKGROUND: HDL becomes enriched with non-esterified fatty acids (NEFAs) in some pathologies, such as nephrotic syndrome, as well as after aerobic exercise. However, little is known about the impact of NEFAs on HDL metabolism. We investigated the effects of one NEFA, the palmitic acid, on HDL structure and catabolism. METHODS: HDL enrichment with palmitic acid (HDLPal) was performed by fusing phosphatidyl choline small unilamellar vesicles containing the NEFA with human HDL isolated from a pool of 5 normolipidemic plasma. HDL enriched only with phosphatidyl choline (HDLPhl) and native HDL (HDLCtrl) were included as controls. RESULTS: As expected, HDLPal surface charge density was higher than HDLPhl and HDLCtrl (2014.4+/-164.8 vs. 1682.7+/-149.5 and 1758.2+/-124.3-esu/cm2, respectively, p<0.05). Both, HDLPal and HDLPhl were better substrates for cholesteryl esters transfer protein (CETP) than HDLCtrl (% of transfer, 13.02+/-3.8 and 12.7+/-4.5 vs. 7.8+/-2.7% in 16 h, respectively, p<0.05). HDLPal apo A-I catabolism in vivo, as performed in New Zealand white rabbits by exogenous radiolabeling, was markedly lower than that of HDLPhl and HDLCtrl (fractional catabolic rate, 0.019+/-0.008 vs. 0.030+/-0.005 and 0.047+/-0.003 h-1, respectively, p<0.001), suggesting that negative charge is inversely related to HDL-apo A-I catabolism. CONCLUSIONS: Enrichment with palmitic acid increases the negative electric charge of HDL at physiological pH, contributes to decrease their catabolism, and is associated to an enhanced lipid transfer by CETP that has been related to the atherogenic process.

[Antithrombotic regulation by fibrinolytic system]. / Regulación antitrombótica por la fibrinólisis.

In this work it is emphasized the presence of the fibrinolitico system in different physiological mechanisms, specially in the antithrombotic regulation of the hemostasis. It is described: the mechanism of activation of plasminogen by their activators as much on the fibrin as in the cells surface; the inhibition of the activators in different metabolic alterations.

[Electro-histological comparison in a case of Chagasic chronic cardiomyopathy]. / Cotejo electro-histológico en un caso de miocardiopatía chagásica crónica.

The case of a 50 years old man, coming from an endemic Chagas' disease zone, is reported. This patient came with a dilated cardiomyopathy, likely of Chagasic etiology, and heart failure. He died in our Institute, were it was possible to register an ECG, and perform the necropsy, on the same day of his death. The ECG showed signs of heart chambers dilatation, inactive myocardium in subendocardial anterolateral regions of the left ventricle, and extensive subepicardial injury. The anatomical study demonstrated the four heart chambers dilatation, and a subendocardial fibrosis essentially located in anterolateral portions of the left ventricle. The histological examination proved that the distribution of injured zones corresponded to location of the inflammatory foci. Furthermore, Trypanosoma cruzi inoculation in mice produced inflammatory foci, predominantly located in the ventricular epicardial and subepicardial regions.

Seropositivity for Trypanosoma cruzi in domestic dogs from Sonora, Mexico.

BACKGROUND: Chagas disease is an important health problem in Latin America due to its incapacitating effects and associated mortality. Studies on seropositivity for Trypanosoma cruzi in Mexican dogs have demonstrated a direct correlation between seropositivity in humans and dogs, which can act as sentinels for the disease in this region. The objective of this study was to determine the seropositivity for T.cruzi infection in dogs from Sonora, a northern borderstate of Mexico. METHODS: Responsible pet owners were selected at random from an urban area of Empalme municipality, Sonora, Mexico, and from there, 180 dog samples were collected. Anti-T. cruzi antibodies were determined using the enzyme-linked immunosorbent assay (ELISA) method. Reactive ELISA sera were processed by indirect immunofluorescence to confirm the presence of anti-T. cruzi antibodies. For the statistical analysis, chi-square tests were conducted. RESULTS: Dogs' sera showed a seropositivity rate of 4.44%. The rate of seropositivity was not associated with the dogs' age, sex, or socioeconomics pertaining to the geographical area. One sample (1/180, 0.55%) showed the acute state of the disease. CONCLUSIONS: The study found a presence of anti-T. cruzi antibodies in dogs in this area, which suggests vector transmission. There is a need for active surveillance programs throughout the state of Sonora and vector control strategies should also be implemented in endemic regions.

Autoantibodies to human heart conduction system in Chagas' disease.

Destruction of heart tissue in chronic chagasic cardiopathy may be caused by autoimmune recognition of heart tissue. Indirect evidence suggests that there is antigenic cross-reactivity between Trypanosoma cruzi and heart tissue. The objective of this study was to determine whether seric autoantibodies against atrio-ventricular (AV) node and sinus auricular node tissues are markers of chronic cardiopathy condition. We searched for the presence of seric autoantibodies against AV node and sinus auricular node tissues in 25 sera from chronic chagasic cardiopathy patients, 20 sera from non-chagasic cardiopathy patients, 20 sera from indeterminate chagasic subjects, and 20 sera from healthy blood donors as controls. Diagnosis of dilated cardiopathy was established based on the left-ventricular end systolic dimension and cardiothoracic ratio on chest x-radiography and impaired contracting ventricle, and chagasic etiology by demonstration of circulating antibodies using ELISA and IIF. Autoantibody detection against conduction heart tissue was carried out by immunohistochemical test. The tissues were obtained from non-cardiopathy necropsy case. Human sera were diluted at 1:10 in PBS-FSB. Goat antihuman laminin was used as positive control. Autoantibodies were more frequently found in chronic chagasic cardiopathy (20%) compared to non-chagasic cardiopathy (5%) and indeterminate chagasic subjects (5%), pattern staining define interstitial and membrane targets on rich conduction system tissue. In conclusion seric autoantibodies against heart conduction system are not a good markers for chagasic cardiopathy group. Their presence showed no clear association with complex rhythm/conduction aberrations.