Decreased cruzipain and gp85/trans-sialidase family protein expression contributes to loss of Trypanosoma cruzi trypomastigote virulence

Two cell lines derived from a single Trypanosoma cruzi clone by long-term passaging generated a highly virulent (C8C3hvir) and a low virulent (C8C3lvir) cell line. The C8C3hvir cell line was highly infective and lethal to Balb/c mice, and the C8C3lvir cell line was three- to five-fold less infective to mouse cardiomyocytes than C8C3hvir. The highly virulent T. cruzi cell line abundantly expressed the major cysteine proteinase cruzipain (Czp), complement regulatory protein (CRP) and trans-sialidase (TS), all of which are known to act as virulence factors in this parasite. The in vitro invasion capacity and in vivo Balb/c mouse infectiveness of the highly virulent strain was strongly reduced by pre-treatment with antisense oligonucleotides targeting TS or CRP or with E64d. Based on these results, we conclude that decreased levels of TS, CRP and Czp expression could contribute to loss of T. cruzi trypomastigote virulence.

Diterpenoids from Azorella compacta (Umbelliferae) active on Trypanosoma cruzi

The anti-Trypanosoma cruzi activity of natural products isolated from Azorella compacta was evaluated, with particular emphasis on their effect against intracellular amastigotes. Five diterpenoids from A. compacta derived from mulinane and azorellane were isolated and identified. Only two products, named azorellanol (Y-2) and mulin-11,3-dien-20-oic acid (Y-5), showed trypanocidal activity against all stages of T. cruzi including intracellular amastigotes. At 10 M, these compounds displayed a strong lytic activity. It ranged from 88.4 0.6 to 99.0 1 % for all strains and stages evaluate, with an IC50 /18 h values of 20-84 M and 41-87 M, respectively. The development of intracellular amastigotes was also inhibited by nearly 60% at 25 M. The trypanocidal molecules Y-2 and Y-5 did show different degrees of cytotoxicity depending on the cell line tested, with an IC50 /24 h ranging from 33.2 to 161.2 M. We evaluated the effect of diterpenoids against intracellular T. cruzi forms by immunofluorescent identification of a specific membrane molecular marker (Ssp-4 antigen) of the T. cruzi amastigote forms. The accuracy and reproducibility of the measurements were found to be outstanding when examined by confocal microscopy.

Diterpenoids from Azorella yareta and their trichomonicidal activities

Diterpenoids with trichomonicidal activity were isolated from the aerial parts of Azorella yareta Hauman. One was 13beta-hydroxyazorellane, together with the known constituents mulinolic acid, mulin-11,13-dien-20-oic acid, azorellanol and 13alpha-hydroxyazorellane. Their structures were determined by spectroscopic and chemical methods.

[New cases of Diphyllobothrium pacificum (Nybelin, 1931) Margolis, 1956 human infection in North of Chile, probably related with El Niño phenomenon, 1975-2000]

The effect of El Niño/ENSO on terrestrial atmosphere appears to be extremely clear. However there are outstanding evidences showing its effect on humans and their activities. In fact, prevalence of some parasitic infections have increased during El Niño phenomenon. The reasons for that are the migrations of sylvatic mammals, fishes and birds as well as by environmental contamination. In this report, we show evidence respect of new cases of human infection by Diphyllobothrium pacificum clearly associated with a cyclic manifestation of El Niño in the Chilean Pacific coast during 1975-2000.

[Human diphyllobothriasis by Diphyllobothrium pacificum. A new case in Antofagasta, Chile]

We report a 26 years old asymptomatic female that expelled spontaneously a 39 proglottid strobila. The taxonomic study of proglottids and eggs found in the stool examination concluded that the patient was infected by Diphyllobothrium pacificum. This infection was probably acquired by the ingestion of raw fish (Sciaena deliciosa) with lemon in a traditional plate called "cebiche". She was treated with a single dose of praziquantel in a dose of 10 mg/kg body weight. After 24 h of treatment there were no scolices on feces. The patient did not have anemia. All eight family members studied, did not have the infection. A follow up stool examination three months later remained negative.

[Activity of Dipernoids isolated from Azorella compacta (Llareta) on Trypanosoma cruzi amastigotes]

The trypanocidad activity against amastigote forms of SPA-14, Tulahuen and G strains and CL Brener clone of Trypanosoma cruzi of diterpenoids isolated from Azorella compacta, Phil. (Llareta), a plant with ethnomedicinal prestige from prespanish age, was investigated. Amastigocidal activity was shown in azorellanol (2), diterpene isolated by first time, with an inhibitory concentration 50 (IC50) that varied between 60 M (CL Brener clone) and 84 M (SPA-14 strain), and in mulin -11,13 -dien-20-oico acid (5) with IC50 between 41 microM (G strain) and 87 mM (CL Brener clone). The cytotoxicity levels of both compounds against Hela and Vero cells and macrophages J144 are lower than nifurtimox and similar to gentian violet.

[Epidemiological study of pediculosis capitis and scabies in schoolchildren from Antofagasta, Chile, 1995]

In order to contribute to a better knowledge of the pediculosis capitis and scabies during March-December 1995, 1122 primary schoolchildren under 14 years of age in the city-port of Antofagasta in northern Chile (20 degrees South lat.), were examined. A total of 285 (25.4%) were found to be infested with Pediculus humanus capitis and only 20 (1.8%) with Sarcoptes scabiei. In general the rates of infestation to both ectoparasitic diseases were higher in groups of younger schoolchildren, also higher in women than in men and in those groups with high indexes of crowding and ignorance of the transmission mechanism of pediculosis capitis and scabies.

[Current human and canine seroprevalence of Chagasic infection in San Pedro de Atacama County, II Region of Antofagasta, Chile, 1995]

In order to assess the impact of a control program against Triatoma infestans launched in 1988, based on insecticide spraying of dwellings, a serological survey for chagasic infection was carried out during 1995 in three localities from San Pedro de Atacama County (22 degrees 55' South lat., 68 degrees 12' West long.), II Region of Antofagasta in northern Chile. Blood samples from 531 children and adolescents and 65 dogs were subjected to ELISA test and indirect immunofluorescent test for Chagas' disease respectively. Tests resulted positive in 12 (2.3%) persons, all above 5 years old, in contrast with the 16.8% serological positivity observed in 1985. Three (4.6%) dogs (two 0-12 months old) resulted positive. These results indicate that dwelling sprayings with long-term activity insecticides against T. infestans is a good tool to prevent new human infections with T. cruzi. However, active vector transmission among domestic animals (canines) could be recently acquired.

Serum antibodies to Trypanosoma cruzi antigens in Atacameños patients from highland of northern Chile

In the present work we have investigated the serum antibody spectrum to parasite antigens involved in human T. cruzi infection. Analysis was performed by conventional serology (IHA, IFAT and ELISA), complement-mediated lysis, anti-gal antibody assay and reactivity against recombinant and synthetic peptides and metacyclic antigens by immunowestern-blotting. All the sera showed a significant reactivity in IHA, IFAT and ELISA. We found that 84.2% of the sera showed lytic activity and thirty serum samples (78.9%) which showed a lytic activity higher than 50%, also showed anti-gal antibodies at serum dilutions higher than 1:1,600. Ninety-four percent of sera reacted with one or more of the recombinant DNA clones and 97.3% reacted with one or more of the synthetic peptides. A pool of serum samples with a lytic activity higher than 75% were able to produce 60% to 78% inhibition of cell invasion. Thirty-six of the serum samples (94.7%) were able to react by immunowestern blotting with a T. cruzi metacyclic antigen with molecular size of 70 kDa. The results obtained give preliminary information about the humoral immune response and the possible role of antibodies in protection against T. cruzi infection of chronic patients from the highlands of Chile.

Biochemical, immunological, and biological characterization of Trypanosoma cruzi populations of the Andean north of Chile

Twenty-one Trypanosoma cruzi stocks isolated from Triatoma infestans and humans of the Chilean Andean highlands were studied at the genotypic level by schizodeme and molecular karyotype analyses, which allowed a clear distinction of the parasites from those hosts. A phenotypical characterization was performed by proteolytic activity after electrophoretic fractionation without discrimination among the stocks. Metacyclic trypomastigotes obtained in vitro proved to be infective to Swiss mice and the study of immune response and biological behavior was assessed. Of a total of 21 T. cruzi stocks, only 11 proved to be infective in mice due to difficulties in obtaining metacyclic trypomastigotes with the parasite populations isolated from humans. Western blot analysis revealed a complex immune response even in the first days postinfection with each T. cruzi strain studied. Antigenic recognition by each immune serum is characteristic, although several major and common antigens were detected. Lytic antibodies were studied by the in vitro complement-mediated lytic assay using purified metacyclic trypomastigotes as target cells. All the T. cruzi isolates tested induced lytic antibodies in this experimental model. Parasitemias were moderate and characteristic for each T. cruzi strain. Results are compared with metacyclic forms of the infective and pathogenic Tulahuen strain.

[Levels of anti-Gal antibodies in persons infected and non-infected with Trypanosoma cruzi. Probably induced by bacteria and by the parasite]

Antibodies levels against Gal alpha 1,3 Gal epitopes were studied in 407 human sera (92 chagasic and 315 non-chagasic), by means of hemagglutination with rabbit erytrocytes reactivity of serum having high titres of anti-Gal antibodies in presence of Escherichia coli and Serratia marcescens antigen was studied by immunoelectrotransference. Finally, using a purified anti-Gal antibody, Gal alpha 1,3 Gal epitopes were identified in metacyclic forms from 12 high Andean Chilean strains of Trypanosoma cruzi. Among the chagasic sera, it was demonstrated that in 63 (68.5%) were detected antibodies anti-Gal at the same or higher titer than 1:1,600; while i the non chagasic sera only 49 (15.6%) showed and anti-Gal response at similar titers. Immunoelectrotransference showed that the sera of people infected with T. cruzi recognize antibodies present in E. coli and S. marcescens, which reinforces the idea that at least in part, these bacterias would be capable of stimulating these responses. The autoradiographic analysis using purified anti-Gal antibodies, showed differences in the Gal alpha 1,3 Gal epitopes expressed in the different strains of T. cruzi. These results suggest that anti-Gal antibodies could have a real significance on the natural immunity mechanisms and protection of human infection with T. cruzi.

[Chagas disease in northern Chile. Serological prevalence in pregnant women of the city of Antofagasta, 1991-1993]

Antofagasta, the big city-port in North Chile is a triatomines free locality. Chagas infection was serologically diagnosed in 44 out of 2063 (2.1%) pregnant women from Antofagasta, studied by means of an indirect immunoflourescence test (IIFT), during 1991-1993. Out of the 44 seropositive mothers, 31 and 10 were born in the II (moderate endemic area) and IV Región (hiperendemic area), respectively. The usefulness of a screening programme for congenital Chagas' disease at primary health care in Chile is discussed.

[Chronic Chagas cardiomyopathy. Serologic and anatomopathologic study]

In order to contribute to a better knowledge of the chronic chagasic myocardiopathy, a post-mortem serological and anatomopathological study of Chagas' disease was carried out in 40 corpses. Between november 1987 and august 1988, autopsies were performed at the Pathological Anatomy Service of Antofagasta Regional Hospital and the Legal Medicine Section of the Ministry of Justice in Antofagasta. Positive postmortem chagasic serology, by using an indirect immunofluorescence test in pericardial fluid, was confirmed in three cases, among which the study of the histopathology of the cardiac muscle showed "Trypanosoma cruzi type" elements of the damage. The macroscopic morphological study did not show relevant findings. Results reveal the need to implement anatomopathological study systems for routines which contribute to evaluate the chagasic etiology as a cause of death among population of the endemic Chilean area.