RESUMO
Abasic sites (AP site) in a DNA duplex have been experimentally used to produce fluorescent Ag nanoclusters (NC) with a small number of atoms (n ≤ 6). These AP-DNA:NC complexes act as biological makers that help to locate genes associated with diseases related to single nucleotide polymorphisms (SNP), for example. Abasic sites are the most common SNP genetic variation, and their detection may help predict a host of genetically determined diseases. In this work, we report a theoretical study of the optical absorption spectra of AP-DNA:Ag4 and AP-DNA:Au4 complexes using a fully ab initio methodology. We consider several different base environments for the noble-metal nanocluster occupying the AP site, and compute the absorption spectra of sixteen AP-DNA:Ag4 and sixteen AP-DNA:Au4 complexes. We find that optical absorption in the AP-DNA:Ag4 complexes tends to concentrate in the green-to-violet range of frequencies (2.50 eV ≤ hω ≤ 3.2 eV) and that AP-DNA:Au4 complexes display absorption peaks in the violet-to-ultraviolet interval (hω ≥ 3.0 eV). An analysis of the optical absorption mechanisms in these complexes shows that they can be of local, charge-transfer, or hybrid nature, i.e., AP-DNA:NC complexes display the full variety of optical absorption processes in molecular systems. In particular, we identify both charge-transfer and hybrid processes involving several DNA bases surrounding the NC. Importantly, we find that even sequences where the Ag4 cluster is not in a guanine rich neighborhood display absorption peaks in the visible-light spectrum. Moreover, we obtain that the maximum intensities of the absorption peaks in complexes with pyrimidine vacancies are generally higher than those in complexes with purine vacancies. Regarding the selectivity of single-vacancy AP-DNA to specific noble-metal nanocluster sizes, our calculations show that the four-atom Ag4 (Au4) species fits naturally and binds into the AP-site in a single-vacancy AP-DNA.
Assuntos
DNA/química , Ouro/química , Nanopartículas Metálicas/química , Prata/química , DNA/efeitos da radiação , Teoria da Densidade Funcional , Luz , Nanopartículas Metálicas/efeitos da radiação , Modelos Químicos , Estrutura Molecular , Análise EspectralRESUMO
Diseases such as leishmaniases are important causes of morbidity and mortality in Brazil, and their diagnoses need to be improved. The use of monoclonal antibodies has ensured high specificity to immunodiagnosis. The development of an immunosensor, coupling a monoclonal antibody to a bioelectronic device capable of quickly detecting Leishmania sp. antigens both qualitatively and quantitatively, is a promising alternative for the diagnosis of leishmaniasis due to its high specificity, low cost, and portability, compared with conventional methods. The present work was aimed at developing an immunosensor-based assay for detecting Leishmania infantum antigens in tissues of infected hosts. Four hybridomas producing monoclonal antibodies against L. infantum had their specificity confirmed by enzyme-linked immunosorbent assay. These antibodies were immobilized on a gold surface, covered with a thin film of 2-aminoethanethiol (cysteamine) and glutaraldehyde, blocked with glycine, and placed into contact with extracts of L. infantum -infected and noninfected control hamster spleens. The assay was able to detect 1.8 × 10(4) amastigotes/g of infected tissue. These results demonstrated that this assay may be useful for quantifying L. infantum amastigotes in organs of experimental animals for studies on pathogenesis and immunity and that it is a promising tool for the development of a diagnostic method, based on antigen detection, of human and dog visceral leishmaniasis.
Assuntos
Anticorpos Monoclonais , Antígenos de Protozoários/isolamento & purificação , Leishmania infantum/imunologia , Leishmaniose Visceral/diagnóstico , Baço/parasitologia , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Antiprotozoários/imunologia , Especificidade de Anticorpos , Técnicas Biossensoriais/métodos , Cricetinae , Ensaio de Imunoadsorção Enzimática , Imunoglobulina G/imunologia , Leishmania infantum/isolamento & purificação , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Organismos Livres de Patógenos Específicos , Baço/imunologiaRESUMO
Infections with Trichuris trichiura and other trichurid nematodes have been reported to display protective effects against atopy, allergic and autoimmune diseases. The aims of the present study were to investigate the immunomodulatory properties of T. trichiura adult worm extract (TtE) and its fractions (TtEFs) on the production of cytokines by peripheral blood mononuclear cells and to identify their proteinaceous components. Fourteen TtEFs were obtained by ion exchange chromatography and tested for effects on cytokine production by peripheral blood mononuclear cells. The molecular constituents of the six most active fractions were evaluated using nano-LC/mass spectrometry. The homology between T. trichiura and the related nematode Trichinella spiralis was used to identify 12 proteins in TtEFs. Among those identified, fructose biphosphate aldolase, a homologue of macrophage migration inhibitory factor and heat-shock protein 70 may contribute to the immunomodulatory effects of TtEFs. The identification of such proteins could lead to the development of novel drugs for the therapy of allergic and other inflammatory diseases.
Assuntos
Citocinas/sangue , Proteínas de Helminto/imunologia , Leucócitos Mononucleares/imunologia , Trichuris/imunologia , Adulto , Animais , Criança , Cromatografia por Troca Iônica , Frutose-Bifosfato Aldolase/química , Frutose-Bifosfato Aldolase/imunologia , Proteínas de Choque Térmico HSP70/imunologia , Proteínas de Helminto/química , Humanos , Proteômica , Trichinella spiralis/química , Tricuríase/imunologia , Tricuríase/parasitologia , Trichuris/química , Adulto JovemRESUMO
1. The vasodilator action of angiotensin (Ang) II has not yet been demonstrated in spontaneously hypertensive rats (SHR), nor have any possible changes in this response during the development of hypertension. 2. In the present study, the vasodilator effect of AngII was evaluated in the rat isolated, preconstricted mesenteric arterial bed (MAB) from 6- (young) and 24-week-old (adult) SHR and compared with effects on MAB from age-matched normotensive rats (control). 3. Angiotensin II (10-300 nmol) induced vasodilation in noradrenaline (NA)-preconstricted MAB that was greater in vessels from young compared with adult rats in both the control and SHR groups. Angiotensin II-induced vasodilation was reduced by the angiotensin AT(2) receptor antagonist PD 123319 (10 micromol/L), the angiotensin-(1-7) receptor antagonist A779 (1 micromol/L) and the bradykinin B(2) receptor antagonist HOE-140 (0.01 micromol/L), but not by the AT(1) receptor antagonist losartan (30 micromol/L). Expression of AT(2) receptors was weak in vessels from adult control rats compared with that in young control rats, whereas in young SHR AT(2) receptor expression was increased compared with that in young control rats. This increased expression of AT(2) receptors was maintained in adult SHR and there was no significant difference in AT(2) receptor expression between young and old SHR. 4. The findings of the present suggest that AngII induces an AT(2) receptor-mediated vasodilator effect in the MAB via activation of angiotensin-(1-7) and bradykinin receptors, an action that is reduced in adult control rats and adult SHR. In adult control rats, the attenuated response of AngII is probably due to endothelial dysfunction and reduced expression of AT(2) receptors, whereas in adult SHR it is associated with endothelial dysfunction alone. Increased expression of AT(2) receptors in SHR may represent a counteracting response for modulating blood pressure.
Assuntos
Angiotensina II/metabolismo , Regulação da Expressão Gênica/fisiologia , Receptor Tipo 2 de Angiotensina/metabolismo , Vasodilatação/fisiologia , Acetilcolina/farmacologia , Envelhecimento , Angiotensina II/análogos & derivados , Angiotensina II/farmacologia , Animais , Western Blotting , Bradicinina/análogos & derivados , Bradicinina/farmacologia , Imidazóis/farmacologia , Losartan/farmacologia , Artérias Mesentéricas/efeitos dos fármacos , Artérias Mesentéricas/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/metabolismo , Fragmentos de Peptídeos/farmacologia , Piridinas/farmacologia , Ratos , Ratos Endogâmicos SHR , Receptor Tipo 2 de Angiotensina/genéticaRESUMO
The aim of this study was to identify splenic immuno-inflammatory patterns associated with natural infection by Leishmania chagasi. Spleen samples were obtained from 72 stray dogs from an endemic area of visceral leishmaniasis. The animals were grouped into four categories as follows: (i) potentially resistant to visceral leishmaniasis, with a positive leishmanin skin test result, and negative splenic culture for Leishmania parasites (ii) potentially susceptible to visceral leishmaniasis, with a negative leishmanin skin test and positive splenic culture for Leishmania (iii) infected with undefined susceptibility status, with a positive leishmanin skin test and positive splenic culture for Leishmania, and (iv) noninfected, with a negative leishmanin skin test, negative splenic culture for Leishmania, and negative serology for anti-Leishmania antibodies. Histopathological analyses showed that there was a higher frequency of perisplenitis (18/25, P < 0.0001), granuloma (7/25, P = 0.0102), structural disorganization (14/25, P < 0.0001), and atrophy of the lymphoid follicles (20/25, P = 0.0036) and of the marginal zone (15/25, P = 0.0025) in the potentially susceptible group than in the other groups. The data presented here show changes in the white pulp of the spleen that are associated with naturally acquired visceral leishmaniasis.
Assuntos
Doenças do Cão/parasitologia , Leishmania/imunologia , Leishmaniose Visceral/veterinária , Baço/patologia , Baço/parasitologia , Animais , Doenças do Cão/imunologia , Cães , Emaciação/imunologia , Emaciação/parasitologia , Granuloma/parasitologia , Granuloma/patologia , Inflamação/parasitologia , Inflamação/patologia , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/parasitologiaRESUMO
Associations among parameters commonly used as markers of infection by Leishmania sp., or of susceptibility to visceral leishmaniasis, were investigated in 325 stray dogs from an area where this disease is endemic. Evidence of infection (presence of Leishmania in splenic cultures, positive leishmanin skin test (LST) or detection of anti-Leishmania antibody activity in the serum) was found in 57% of the animals. Both evidence of weight loss (chi(2)-test, P=0.0005) and presence of specific antibody activity in the serum (chi(2)-test, P<0.0001) were directly associated with positive splenic culture. The frequencies of animals with positive splenic culture were directly correlated with the intensities of antibody activity in the serum as measured by ELISA (relative risk of 3.4 for animals with moderate antibody levels and relative risk of 8.43 for animals with high-antibody levels). A negative association was observed between positive leishmanin skin test results and emaciation (chi(2), P=0.0089). Furthermore, animals with positive splenic cultures and negative leishmanin skin test results had higher levels of total serum IgG (Kruskal-Wallis test, P=0.001) and IgG2 (Kruskal-Wallis test, P=0.05) than animals with negative splenic cultures, and were more emaciated than animals with negative LST results and positive splenic cultures. The data presented herein suggest that associating these common parameters may improve their performance in predicting susceptibility to canine visceral leishmaniasis.
Assuntos
Anticorpos Antiprotozoários/imunologia , Doenças do Cão/imunologia , Doenças do Cão/parasitologia , Leishmania/imunologia , Leishmaniose Visceral/veterinária , Baço/parasitologia , Animais , Anticorpos Antiprotozoários/sangue , Especificidade de Anticorpos , Antígenos de Protozoários , Cães , Emaciação/imunologia , Emaciação/parasitologia , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/parasitologia , Masculino , Baço/imunologiaRESUMO
Alpinia zerumbet (K. Schum), a medicinal plant originated from West Asia, is used in the northeast and southeast of Brazil as infusions or decoctions as a diuretic, antihypertensive, and antiulcerogenic. Experiments were undertaken to determine whether a hydroalcoholic extract obtained from leaves of Alpinia zerumbet (AZE) induces vasodilation in the mesenteric vascular bed (MVB), and an antihypertensive effect was also assessed in rats with DOCA-salt hypertension. In MVB precontracted with norepinephrine, AZE induces a long-lasting endothelium-dependent vasodilation that is not reduced by indomethacin. Inhibition of NO synthase by NG-nitro-L-arginine methyl ester (L-NAME) and guanylyl cyclase by 1H-[1,2,3]oxadiazolo [4,4-a]quinoxalin-1-one (ODQ) reduces the vasodilator effect of AZE. In vessels precontracted with norepinephrine, the vasodilator effect of AZE was not changed by 4-aminopyridine, glibenclamide, or by charybdotoxin plus apamin. Concentrations of atropine, pyrilamine, and yohimbine that significantly reduced the vasodilator effect of acetylcholine, histamine, and clonidine, respectively, did not change the vasodilator effect of AZE. HOE 140, which significantly reduced the vasodilator effect of bradykinin, induced a slight but significant reduction on the vasodilator effect of AZE. Chronic oral administration of AZE induced a significant reduction in systolic, mean, and diastolic arterial pressure in rats with DOCA-salt hypertension. Probably the vasodilator effect of AZE is dependent on the activation of the NO-cGMP pathway and independent of activation of ATP-dependent, voltage-dependent, and calcium-dependent K+ channels. Bradykinin receptors may also participate in the vasodilator effect of AZE. Finally, the vasodilator and antihypertensive effects of AZE demonstrated in the present study provide experimental support for the indication of Alpinia zerumbet as an antihypertensive medicinal plant.
Assuntos
Alpinia/química , Anti-Hipertensivos/farmacologia , Endotélio Vascular/fisiologia , Vasodilatadores/farmacologia , Acetilcolina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Desoxicorticosterona , Relação Dose-Resposta a Droga , Interações Medicamentosas , Hipertensão/induzido quimicamente , Hipertensão/tratamento farmacológico , Hipertensão/fisiopatologia , Técnicas In Vitro , Masculino , Artérias Mesentéricas/efeitos dos fármacos , Extratos Vegetais/farmacologia , RatosRESUMO
1. The mechanisms involved in the vasodilator actions of angiotensin II (Ang II) have not yet been completely elucidated. We investigated the potential mechanisms that seem to be involved in the Ang II vasodilator effect using rat isolated mesenteric vascular bed (MVB). 2. Under basal conditions, Ang II does not affect the perfusion pressure of MVB. However, in vessels precontracted with norepinephrine, Ang II induces vasodilation followed by vasoconstriction. Vasoconstrictor, but not the vasodilation of Ang II, is inhibited by AT(1) antagonist (losartan). The vasodilator effect of Ang II was not inhibited by AT(2), angiotensin IV and angiotensin 1-7 receptor antagonists alone (PD 123319, divalinal, A 779, respectively). 3. The vasodilator effect of Ang II is significantly reduced by endothelial removal (deoxycholic acid), but not by indomethacin. Inhibition of NO-synthase by N(G)-nitro-l-arginine methyl ester (l-NAME) and guanylyl cyclase by 1H-[1,2,3] oxadiazolo [4,4-a] quinoxalin-1-one (ODQ) reduces the vasodilator effect of Ang II. This effect is also reduced by tetraethylammonium (TEA) or l-NAME, and a combination of l-NAME plus TEA increases the inhibitory effect of the antagonists alone. However, indomethacin does not change the residual vasodilator effect observed in vessels pretreated with l-NAME plus TEA. 4. In vessels precontracted with norepinephrine and depolarized with KCl 25 mm or treated with Ca(2+)-dependent K(+) channel blockers (charybdotoxin plus apamin), the effect of Ang II was significantly reduced. However, this effect is not affected by ATP and voltage-dependent K(+) channel blockers (glybenclamide and 4-aminopyridine). 5. Inhibition of kininase II with captopril significantly potentiates the vasodilator effect of bradykinin (BK) and Ang II in the rat MVB. The inhibitory effect of the B(2) receptor antagonist HOE 140 on the vasodilator effect of Ang II is further enhanced by PD 123319 and/or A 779. 6. The present findings suggest that BK plays an important role in the endothelium-dependent vasodilator effect of Ang II. Probably, the link between Ang II and BK release is modulated by receptors that bind PD 123319 and A 779.
Assuntos
Angiotensina II/farmacologia , Angiotensina I/fisiologia , Bradicinina/fisiologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Fragmentos de Peptídeos/fisiologia , Receptor Tipo 2 de Angiotensina/fisiologia , Vasodilatação/fisiologia , Animais , Técnicas In Vitro , Masculino , Artérias Mesentéricas/efeitos dos fármacos , Artérias Mesentéricas/fisiologia , Veias Mesentéricas/efeitos dos fármacos , Veias Mesentéricas/fisiologia , Ratos , Ratos Wistar , Receptores de Angiotensina/fisiologia , Vasodilatação/efeitos dos fármacosRESUMO
In this study, the ability of maxadilan and Lutzomyia longipalpis salivary gland lysate to enhance the infection of CBA mice by Leishmania major and of BALB/c mice by L. braziliensis was tested. No difference was observed between sizes of lesion in CBA mice infected with L. major and treated or not with salivary gland lysate or maxadilan, although they were injected in concentrations that induced cutaneous vasodilation. Although parasites were more frequently observed in foot pads and spleens of animals treated with maxadilan than in the animals treated with salivary gland lysate or saline, the differences were small and not statistically significant. The lesions in BALB/c mice infected with L. braziliensis and treated with maxadilan were slightly larger than in animals that received Leishmania alone. Such differences disappeared 14 weeks after infection, and were statistically significant only in one of two experiments.
Assuntos
Proteínas de Insetos/farmacologia , Leishmania/patogenicidade , Leishmaniose Cutânea/parasitologia , Psychodidae/química , Glândulas Salivares/química , Extratos de Tecidos/farmacologia , Vasodilatadores/farmacologia , Animais , Bovinos , Leishmania braziliensis/patogenicidade , Leishmania major/patogenicidade , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/patologia , Camundongos , Camundongos Endogâmicos BALB C , Psychodidae/efeitos dos fármacos , Coelhos , Glândulas Salivares/efeitos dos fármacosRESUMO
Positive Montenegro's skin test is a delayed type hypersensitivity reaction widely used as indicative of previous infection with Leishmania in both humans and dogs. Montenegro's antigen consists of a crude Leishmania antigen solution, usually containing thimerosal as preserving agent. In this work it is shown that a large proportion of dogs (11 out of 56) examined in an endemic area of leishmaniasis presented induration at the site of injection of a diluent containing thimerosal alone. This clearly demonstrates that thimerosal leads to a high number of false positive skin reactions in dogs and that its use in Montenegro's skin test antigenic preparations should be avoided.
Assuntos
Doenças do Cão/diagnóstico , Leishmania/imunologia , Leishmaniose/veterinária , Conservantes Farmacêuticos/efeitos adversos , Pele/efeitos dos fármacos , Timerosal/efeitos adversos , Animais , Brasil/epidemiologia , Doenças do Cão/epidemiologia , Doenças do Cão/imunologia , Cães , Doenças Endêmicas , Reações Falso-Positivas , Hipersensibilidade/imunologia , Hipersensibilidade/veterinária , Leishmaniose/diagnóstico , Leishmaniose/epidemiologia , Pele/imunologia , Pele/patologia , Testes CutâneosRESUMO
To study the role of autoreactive T cells in the pathogenesis of cardiomyopathy in Chagas' disease, we generated a cell line by repeated in vitro antigenic stimulation of purified splenic CD4+ T lymphocytes from a chronically Trypanosoma cruzi-infected mouse. Cells from this line were confirmed to be CD4+ CD8- and proliferated upon stimulation with soluble heart antigens from different animal species, as well as with T. cruzi antigen, in the presence of syngeneic feeder cells. In vitro antigen stimulation of the cell line produced a Th1 cytokine profile, with high levels of IFNgamma and IL-2 and absence of IL-4, IL-5 and IL-10. The cell line also terminated the beating of fetal heart clusters in vitro when cocultured with irradiated syngeneic normal spleen cells. In situ injection of the cell line into well established heart transplants also induced the cessation of heart beating. Finally, adoptive transfer of the cell line to heart-immunized or T. cruzi-infected BALB/c nude mice caused intense heart inflammation.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Doença de Chagas/imunologia , Trypanosoma cruzi , Animais , Linhagem Celular , Doença Crônica , Técnicas de Cocultura , Modelos Animais de Doenças , Rejeição de Enxerto , Transplante de Coração , Interferon gama/análise , Interleucina-2/análise , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Nus , Miocardite/imunologia , Miocárdio/citologia , Miocárdio/imunologia , Coelhos , Ratos , Baço/imunologiaRESUMO
In this study computational analysis was used to compile sequence alignments, construct a dendrogram and calculate physical data in order to predict potential T-cell epitopes of the Leishmania cysteine proteinase. Using multiple alignment of human and Leishmania proteinase sequences deposited on data bank sequences, it was possible to predict that the extreme C-terminus of cysteine proteinase (Cyspep, 355-444) contained three peptides (pI 361-370, pII 415-422 and pIII 431-444) with charge score, hydrophobicity and isoelectric points compatible for human leucocyte-associated antigen (HLA) class II binding. The prediction was confirmed in vitro through the ability of synthetic peptides corresponding to the predicted regions to stimulate peripheral blood mononuclear cells of patients with leishmaniasis.
Assuntos
Cisteína Endopeptidases/imunologia , Epitopos de Linfócito T/química , Leishmania/enzimologia , Algoritmos , Sequência de Aminoácidos , Animais , Bases de Dados Factuais , Humanos , Leishmania/imunologia , Leishmaniose/imunologia , Leishmaniose/patologia , Ativação Linfocitária/efeitos dos fármacos , Peptídeos/síntese química , Peptídeos/imunologia , Peptídeos/farmacologia , Alinhamento de SequênciaRESUMO
Pharmacological aspects of mouse hind-paw oedema induced by subplantar injections of Lachesis muta rhombeata (LMR) venom were investigated. The oedema induced by subplantar injections of 10 to 50 ng/g of LMR venom is dose dependent, with onset, peak and duration at 30, 60 and 180 min, respectively. Subplantar injection of 30 ng/g of Bothrops jararaca (BJ) venom induced oedema that has the same intensity as 30 ng/g of LMR venom but lasts for more than 4 h suggesting different time course. Systemic effects or haemorrhage were not observed with doses less than 50 ng/g. Oedema is not due to the presence of oedematogenic amines since dialysis did not change the oedema induced by 30 ng/g of LMR venom. Part of the oedema induced by LMR venom is due to a thermolabile fraction since pre-heating the venom at 100 degrees C for 15 min induced a significant reduction (56.19 +/- 6.8%) of the oedematogenic activity. The oedema induced by LMR venom is possibly induced by release of a pharmacological active substance at the site of injection. Histamine, arachidonate metabolites, nitric oxide and serotonin may play important roles in the oedematogenic effect of LMR venom since pre-treatment of mice with pyrilamine, indomethacin, dexamethasone, L-NAME and methysergide induced a significant reduction (49.86 +/- 10%; 51.06 +/- 5.9%; 77.66 +/- 3.6%; 73.30 +/- 6.1% and 93.77 +/- 2.8%, respectively) of the oedema formation. The present results demonstrate that the oedema induced by LMR and BJ venoms may be triggered and maintained by different pharmacological mechanisms. Since methysergide and L-NAME were the most active inhibitors of the oedema we can suggest that a link between serotonin release by the venom and a NO synthase activation may be an important step in the oedema formation induced by LMR venom.
Assuntos
Bothrops , Venenos de Crotalídeos/toxicidade , Edema/etiologia , Endopeptidases/toxicidade , Antagonistas dos Receptores Histamínicos H1/uso terapêutico , Animais , Anti-Inflamatórios/uso terapêutico , Inibidores de Ciclo-Oxigenase/uso terapêutico , Edema/tratamento farmacológico , Inibidores Enzimáticos/uso terapêutico , Membro Posterior , Temperatura Alta , Masculino , Camundongos , Óxido Nítrico Sintase/antagonistas & inibidores , Antagonistas da Serotonina/uso terapêutico , EsteroidesRESUMO
American visceral leishmaniasis is a main public health matter in Brazil. Since dogs have been incriminated as the main urban reservoir of AVL agent Leishmania chagasi, a cohort study aimed at understanding the dynamics of the canine infection was carried out in Jequié--an endemic community in the Northeast of Brazil. The inhabited urban and periurban areas of Jequié were divided into 140 clusters of 0.25 km2. All 1681 dogs domiciled in 34 randomly selected clusters were screened for Leishmania antibodies in an enzyme-linked immunosorbent assay. After the seropositive dogs were painlessly eliminated, a cohort of 1286 seronegative dogs was followed up for 18 months, yielding a total of 1739.7 dog-years. The overall incidence of Leishmania infection, as assessed by the detection of Leishmania antibodies in blood samples collected every six months, was 6.55 cases/100 dog-years (95% confidence interval; CI 6.04-7.26). Two subsets of clusters, with 0.70 and 1.35 relative risks of infection, were identified. The annual emigration rate was 2.26 cases/100 dog-years (95% CI 1.86-2.66). The implications of these findings for the control of American visceral leishmaniasis are discussed.
Assuntos
Doenças do Cão/epidemiologia , Leishmaniose/veterinária , Animais , Anticorpos Antiprotozoários/sangue , Brasil/epidemiologia , Reservatórios de Doenças , Doenças do Cão/imunologia , Doenças do Cão/parasitologia , Cães , Ensaio de Imunoadsorção Enzimática , Feminino , Incidência , Leishmaniose/epidemiologia , Leishmaniose/imunologia , Leishmaniose/parasitologia , MasculinoRESUMO
The humoral antibody response to Cryptosporidium was investigated in mice genetically selected for high (H) and low (L) antibody responsiveness. Groups of 4-5 mice from two different selections, general primary (GP) and general secondary (GS), were studied. Following immunization with Cryptosporidium parvum antigens, the maximum levels of IgG in the HGP (X +/- SD = 1.13 +/- 0.35, N = 5) in the HGS (0.42 +/- 0.15, N = 4) lines, and of IgM in the HGP line (0.86 +/- 0.53, N = 5) were significantly higher than those in their L counterparts (0.04 +/- 0.02, N = 5; 0.05 +/- 0.02, N = 4 and 0.24 +/- 0.07, N = 5, respectively). These findings were similar to those reported for other immunogens. However, the IgG (0.22 +/- 0.05, N = 4) and the IgM (0.33 +/- 0.08, N = 4) responses to immunization of F1 (LGP x HGP) hybrids indicated an incomplete dominance of the low response, in contrast to the incomplete dominance of the high response described for many other antigens and representing an important exception. In addition, the H, L and F1 mice did not develop detectable infections when inoculated with live Cryptosporidium oocysts, supporting the view that a reduced or zero antibody production itself is not enough to permit the establishment of Cryptosporidium infection in adult mice.
Assuntos
Afinidade de Anticorpos/imunologia , Cryptosporidium parvum/imunologia , Animais , Afinidade de Anticorpos/genética , Criptosporidiose/imunologia , Criptosporidiose/parasitologia , Suscetibilidade a Doenças , Genes Dominantes , Genes Recessivos , CamundongosRESUMO
Jequie, a community of about 144,500 inhabitants located in the State of Bahia, Brazil, is endemic for both visceral and cutaneous leishmaniases. In the present epidemiologic study, the urban and inhabited periurban areas of the town were divided into 140 clusters of 0.25 km2 each. The seroprevalence of canine Leishmania antibodies was investigated using an enzyme-linked immunosorbent assay as a screening test since its sensitivity was significantly higher than that of an indirect immunofluorescence assay. A total of 1,681 dogs was surveyed in 34 randomly sampled clusters. The overall prevalence of Leishmania antibodies in the dog population was 23.5%, with intracluster prevalences ranging from 0% to 67%. There was no correlation of these seroprevalences with the intracluster densities of canine populations, or with the distances from individual clusters to the town center. Moreover, the Leishmania transmission did not seem to follow any clear-cut spatial pattern, since large disparities in the seroprevalences of contiguous clusters were found. Curiously, human cases of visceral leishmaniasis have never been observed in some clusters with a relatively high prevalence of canine seroprevalences. Eight parasite isolates from seropositive dogs were found to belong to the same serodeme and zymodeme as Leishmania (L.) chagasi. The implications of these findings with respect to the epidemiology and control of American visceral leishmaniasis are discussed.
Assuntos
Doenças do Cão/epidemiologia , Leishmania infantum/isolamento & purificação , Leishmaniose Visceral/veterinária , Animais , Anticorpos Antiprotozoários/sangue , Brasil/epidemiologia , Estudos Transversais , Doenças do Cão/imunologia , Doenças do Cão/parasitologia , Cães , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Imunofluorescência/veterinária , Leishmania infantum/classificação , Leishmania infantum/imunologia , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/parasitologia , Masculino , Prevalência , Sensibilidade e EspecificidadeRESUMO
Parasite-derived trans-sialidase (TS) activity was demonstrated in the serum and blood of Trypanosoma cruzi-infected mice. Serum TS activity levels correlated well with parasitemia in BALB/c and Swiss mice during the initial stages of the infection. However, in later stages the TS activity levels decreased despite increasing parasitemia. This coincided with the appearance of circulating TS antibodies. On the other hand, there was always a good correlation between TS activity and parasitemia in athymic nude mice. Sera from mice with high parasitemia and low TS activity inhibited TS activity in vitro. The inhibition was also observed with purified serum IgG, and it was absorbed by staphylococcal protein A, indicating that it was caused by anti-TS IgG antibodies. These antibodies inhibited the enzymatic activity of insolubilized TS, indicating that they act by interfering with the catalytic site rather than by aggregating the enzyme. The presence of inhibitory antibodies, however, did not prevent the progression of parasitemia in BALB/c mice.
Assuntos
Anticorpos Antiprotozoários/sangue , Doença de Chagas/sangue , Glicoproteínas/sangue , Neuraminidase/sangue , Trypanosoma cruzi/enzimologia , Animais , Western Blotting , Doença de Chagas/enzimologia , Doença de Chagas/imunologia , Eletroforese em Gel de Poliacrilamida , Feminino , Glicoproteínas/antagonistas & inibidores , Glicoproteínas/imunologia , Imunoglobulina G/sangue , Imunoglobulina G/isolamento & purificação , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neuraminidase/antagonistas & inibidores , Neuraminidase/imunologia , Parasitemia/sangue , Parasitemia/enzimologia , Parasitemia/imunologia , Fatores de Tempo , Trypanosoma cruzi/imunologiaRESUMO
trans-Sialidase isolated from trypomastigote forms of Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, is multimeric and heterogeneous in size. We show here that limited proteolysis of tans-sialidase with papain yields a single monomeric polypeptide chain of 70 kDa that conserves full enzymatic activity on soluble and membrane-bound substrates. The papain fragment lacks most of the 12-amino acid repeats of the carboxyl-terminal domain that comprises about 50% of the native trans-sialidase. When injected into rabbits, the papain-generated fragment induces antibodies that inhibit trans-sialidase activity and trypomastigote sialylation. The repeats are also not required for the stability of the enzyme or for the correct folding during the biosynthesis in Escherichia coli, but seem essential for trans-sialidase oligomerization. We conclude that trans-sialidase is composed of two structurally and functionally independent domains.
Assuntos
Anticorpos/farmacologia , Neuraminidase/antagonistas & inibidores , Neuraminidase/metabolismo , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/metabolismo , Trypanosoma cruzi/enzimologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Cromatografia de Afinidade , Primers do DNA , Immunoblotting , Cinética , Dados de Sequência Molecular , Neuraminidase/isolamento & purificação , Peptídeos/síntese química , Peptídeos/imunologia , Plasmídeos , Coelhos/imunologia , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Mapeamento por Restrição , Deleção de SequênciaRESUMO
Salivary gland lysates of the sand fly Lutzomia longipalpis have been shown to enhance the infectivity of Leishmania in mice. As shown herein, the simultaneous inoculation of Leishmania chagasi stationary-phase promastigotes and L. longipalpis salivary gland lysate by the intradermal route in a group of mongrel dogs induced a statistically significant eosinophilia, in relation to dogs inoculated with Leishmania or with salivary gland lysate only. These dogs had no evidence of infection, in spite of the high infectivity of the promastigotes when inoculated by the intravenous route.