Anticorpos contra vírus do grupo da língua azul em caprinos e ovinos do sertão de Pernambuco e inferências sobre sua epidemiologia em regiões semiáridas / Antibodies against bluetongue-virus group in goats and sheep from Pernambuco state and inferences on bluetongue epidemiology under tropical conditions

The prevalence of antibodies against bluetongue virus was investigated in 41 dairy goats and 40 sheep herds in the semi-arid region of Pernambuco state and the conditions for insect Culicoides maintenance, considering climate dynamics and vector competence, were evaluated. The percents of seropositive herds in agar gel immunodiffusion test for bluetongue virus group were 24 for goats and 27.5 for sheep. The estimated prevalences of seropositive animals were 3.9 percent for goats (n = 410) and 4.3 percent for sheep (n = 400). The prevalences of seropositive animals were low in the mesoregion of Sertão Pernambucano (4.8 percent for goats and 4.1 percent for sheep) and São Francisco Pernambucano (1.0 percent for goats and 4.5 percent for sheep). There were no significant differences between species and regions. Considering the social and economic importance of goats and sheep raising in the semi-arid region, it is essential to establish preventive measures to control imports of ruminants from these areas.

Superalimentação e desenvolvimento do esqueleto de cães da raça Dogue Alemão: aspectos clínicos e radiográficos / Overfeeding and skeletal development in Great Dane puppies: clinical and radiographic aspects

Estudou-se o efeito da superalimentação no desenvolvimento do esqueleto de 14 cães da raça Dogue Alemão, utilizando dieta hipercalórica (ração super-premium) associada ao método de alimentação à vontade. Os animais foram distribuídos em dois tratamentos, sendo a ração fornecida à vontade ou restrita. O consumo de alimento foi registrado diariamente e realizaram-se, mensalmente, radiografias do cotovelo e, bimestralmente, do ombro, do quadril e do carpo, visando acompanhar alterações do esqueleto, especificamente quanto ao aparecimento da osteocondrose do ombro e da metáfise distal da ulna, da osteodistrofia hipertrófica e da displasia coxofemoral (DCF). Ao final do experimento, seis cães do grupo que recebeu alimentação à vontade apresentaram-se gordos (87,7 por cento) e um animal obeso (14,3 por cento). Do grupo de alimentação restrita, três filhotes mostraram condição corporal ideal (42,8 por cento), e quatro apresentaram-se magros (57,2 por cento). O exame radiológico revelou alterações compatíveis com o diagnóstico de DCF nos dois grupos; nos alimentados à vontade, a prevalência foi de 51,1 por cento e nos restritos, de 28,6 por cento. A osteocondrose na metáfise distal da ulna, conhecida como retenção do núcleo cartilaginoso, foi observada apenas nos cães alimentados à vontade (57,1 por cento). A superalimentação provocada pelo método de alimentação à vontade, associada com dieta de alta palatabilidade e alta densidade energética em filhotes da raça Dogue Alemão, induziu ao aparecimento de osteocondrose na metáfise distal da ulna e de displasia coxofemoral.

The effects of overfeeding on growing Great Dane puppies were examined by ad libitum feeding of a hypercaloric diet (super premium ration). Fourteen puppies from six litters were divided into two groups, with representation from each litter in each group. The dogs in the overfed group were provided ad libitum access to the diet from 8 AM to 6 PM daily, while the restricted group received the same feed but in amounts recommended by the manufacturer at 7 AM, 12:30 PM and 5 PM. Daily intake was individually recorded. To monitor skeletal changes due to osteochondrosis, hypertrophic osteodystrophy and hip dysplasia, elbow radiographs were taken monthly and shoulder, pelvis and corpus radiographs were taken bi-monthly. Weekly feed consumption and weight gain were greater in ad libitum than in restricted puppies (P<0.01). At the end of the experiment, 85.7 percent of the ad libitum group was over weight and 14.3 percent was obese, whereas 57.2 percent of restricted puppies were slim and 42.8 percent had ideal body weight. None of the dogs had hypertrophic osteodystrophy. Radiographic examination showed alterations compatible with hip dysplasia in both groups, but such observations were more frequent and more severe in the ad libitum group. Osteochondrosis of metaphisis distal ulna, known by the retention of cartiloginous nucleus, was observed only in the ad libitum group, at a rate of 57.1 percent. The thickness of the cortical and diameter of the ulna were greater (P<0.01) in ad libitum dogs than in those fed a restricted amount of the same diet. In summary, overfeeding caused by ad libitum access to a highly palatable and high energy food caused osteochondrosis and hip dysplasia in Great Dane puppies.

How are antibodies involved in the protective mechanism of susceptible mice infected with T. cruzi?

Host resistance to Trypanosoma cruzi is dependent on both natural and acquired immune responses. During the acute phase of the infection the presence of IFN-gama, TNF-alpha, IL-12 and GM-CSF has been closely associated with resistance, whereas TGF-beta and IL-10 have been associated with susceptibility. Several investigators have demonstrated that antibodies are responsible for the survival of susceptible animals in the initial phase of infection and for the maintenance of low levels of parasitemia in the chronic phase. However, how this occurs is not yet understood. Our results and other data in the literature support the hypothesis that the protective role of antibodies in the acute phase of infection is dependent mostly on their ability to induce removal of bloodstream trypomastigotes from the circulation in addition to other concomitant cell-mediated events.

Clearance-inducing antibodies are responsible for protection against the acute phase of Trypanosoma cruzi infection in mice

A study was conducted on mice infected with strains Y and CL of Trypanosoma cruzi. The ability of anti-Y and anti-CL sera to induce complement-mediated lysis, immune clearance and protection against the acute phase of the infection was studied using homologous anti-Y or anti-CL serum tested with the Y or CL strain, or heterologous anti-Y serum tested with the CL strain or anti-CL serum tested with the Y strain. Complement-mediated lysis was induced by both homologous and heterologous antisera but protection was afforded only by homologous antisera. Immune clearance was induced by homologous but not by heterologous antisera. Antisera with high clearance ability were able to confer protection whereas antisera with high lytic ability were not. These results show a high correlation between the antibody ability to induce clearance and to confer protection and suggest that clearance rather than lysis is responsible for protection against the acute phase of the infection. The mechanisms of antibody protection against the acute phase of the infection is discussed.

Identification and neutralization of biological activities in the venoms of Loxosceles spiders

The biological activities of the venom of three species of spiders of the genus Loxosceles were studied (L. gaucho, L. laeta and L. intermedia). The dermonecrotic and lethal activities are shared by all three Loxosceles venoms. Only low levels of proteolytic, myotoxic and phospholipase A2 activities were demonstrable even when a large amount of venom was used. No direct hemolytic activitiy was detected. L. intermedia venom was the most lethal (LD50 0.48 mg/kg), the L. laeta venom was the least lethal (LD50 1.45 mg/kg) whereas L. gaucho venom showed an intermediate value (LD50 0.74 mg/kg). The anti-Loxosceles serum used (anti-arachnidic serum) was able to neutralize the most important activities (i.e., dermonecrotic and lethal activities) of the three venoms. SDS-PAGE and immunoblotting using the anti-arachnidic serum showed that almost all venom antigens were recognized by this antiserum. The possible mechanisms of action of the Loxosceles venom are discussed.

Specificity and role of anti-Trypanosoma cruzi clearance antibodies

Two strains of Trypanosoma Cruzi (Y and CL) were used to study the specificity and role of anti-T. cruzi clearance antibodies. Clearance antibodies were only induced after immunization with living blood-stream trypomastigotes (Btrys) but not with dead parasites. Btrys of either strain were readily cleared from the circulation after passive immunization with anti-Y or anti-CL scrum provided that the homologous strain was used. CL or Y Btrys sensitized in vitro with the homologous or heterologous antiserum and transferred to normal mice were cleared from the circulation only when the homologous antiserum was used. Clearance antibodies were removed from serum by absorption with the homologous but not with the heterologous strain. Clearance antibodies were removed from serum by absorption with living Btrys but not with fixed parasites. These results suggest that: a) the parasite epitopes involved in the clearance are peculiar to each strain, b) the clearance antibodies are specific to these epitopes, and c) a proper conformation of the parasite antigens is required for the induction and effector activity of the clearance antibodies.

The mast cell revisited

The role of mast cells in allergic reactions is reviewed and the origin, distribution and properties of mast cells are reported. The characteristics of two phenotypically distinct mast cell populations are described. The function and properties of the IgE molecule as an antigen receptor on mast cells is discussed. The participation of mast cells in the acute and late phase of the allergic reaction is pointed out. A double role for mast cells in allergic reactions is suggested: they may be responsible for the acute phase reaction through the release of mediators such as histamine and leukotrienes and for the late phase reaction through the release of pro-inflammatory cytokines.

A rapid and efficient purification method for horse IgG(T) usin a rat monoclonal antibody

1. Louvain rats (IgK-1a) were immunized with horse IgG(T). To generate mAb to IgG(T), popliteal lymph node cells taken from the immunized animals were fused to a non-secreting LOU/C immunocytoma (IR983F). The hybridomas were cultured in HAT -containing medium and cloned under limiting dilution conditions. Supernatants from the growing hybrids were screened by ELISE using plates coated with horse IgG(T) or IgGa+b+c. 2. The anti-IgG(T) mAb obtained was named LO-HoGT-1 (LOU anti-horse IgG(T)). It is an IgG2a rat antibody whose light chain allotype is IgK-1a, and with an affinity constant of 2.9 x 1010 M-1. 3. Ascites was isnduced in LOU (IgK-1b) rats by injecting the hybridoma cells and incomplete Freund's adjuvant ip. To obtain purified mAb, ascitic fluid was applied to a Sepharose anti-rat LOU IgK-1 a chain column. 4. The purified mAb was then coupled to Sepharose. Immunoelectrophoretically pure IgG(T) was obtained by passage of horse serum through this column. The entire procedure took less than 30 min and resulted in a highly purified IgG(T)

Detection and neutralization of B. jararaca venom in mice

1. Bothrops jararaca venom was detected by ELISA at different times in the skin, muscle, blood, liver, lung, heart, kidney and spleen of mice injected with venom im or id. 2. The results showed that even 10 min after im injection the venom is detected mostly in skin rather than in the muscle of the venom injection site. A small amount of venom was detected in the kidney up to 12 h after im venom injection, and none was detected in tissues of lung, heart, liver or spleen. 3. However, in mice injected id, the venom could be detected in the skin up to 24 h after injection. Local necrosis and haemorrhage could be neutralized by antivenom injected by the id or iv routes only if the antivenom was given a short time after venom injection, even when antivenom is adminsitered in high concentration. 4. In contrast, experiments performed in mice receiving venom id and treated by id or iv routes with antivenom injected at different times after envenoming showed that the effect of venom on blood coagulation could be counteracted by antivenom administered by either route up to 2 h after venom injection 5. We suggest that a feasible amount of antivenom administered id could be given as a first aid measure after a snake bite accident. However, further experimental studies using the id route for antivenom administration are essential to confirm this possibility

Role of platelets and complement in the clearance of epimastigote forms of Trypanosoma cruzy

1. Trypanosoma cruzi epimastigote forms are very rapidly removed from the circulation of normal and C5-deficient mice. Depletion of C3 by cobra venom factor results in a significant delay in parasite clearance. 2. During parasite clearance there is a significant decrease in the number of circulating platelets and parasite clearance is considerably delayed in thrombocytopenic animals. 3. In vitro incubation of epimastigote forms with normal mouse serum leads to the formation of parasite clumps provided that platelets are present. Innactivation of factor B or depletion of C3 prevents this phenomenon. 4. When epimastigotes are incubated with normal mouse serum they absorb one or more factors required for their aggregation with platelets. 5. It is suggested that in mice T. cruzi epimastigote forms are removed from circulation by the alternative pathway of complement activation and that both C3 and platelets are required for parasite clearance

Suppresion of the antivenom antibody response by serum therapy

1. The antivenom antibody response of mice injected with Bathrops jararaca venom and receiving specific serum therapy was studied under different experimental conditions. Balb/c mice (18-22g) injected with venom (1.75 mg/kg) presented the clinical symptoms observed in patients bitten by B. jararaca and a high and long-lasting antivenom antibody response. 2. Injection of 0.1 ml of horse antiserum to venom 15 min after venom administration abolished the symptoms induced by the venom and induced an almost completely suppressed production of mouse antivenom antibodies. The extent of suppression of the antivenom antibody response depended on the dose of horse antiserum administered and was greater the sooner the serum therapy was applied after envenomation. 3. Injection of antiserum into envenomed mice that received an unrelated antigen (KLH) did not suppress the antibody response to KLH antigen though it inhibited production of antivenom antibodies. 4. Envenomed mice receiving an equivalent dose of F(ab')2 fragments obtained by pepsin digestion of horse antiserum presented the same extent of suppression of the antivenom antibody response as mice injected with the non-treated antiserum. 5. Mice whose antibody response was suppressed, when rechallenged with venom, presented a primary antibody response. 6. These results suggest that suppression of the antivenom antibody response presented by envenomed patients submitted to serum therapy is due to the masking of the venom epitopes by horse antibodies as well as to the rapid elimination of the venom epitopes

Decrease in passive cutaneous anaphylaxis reactions in rats secondary to stress

Anaphylaxis was assayed by the passive cutaneous anaphylaxis (PCA) test in male Wistar rats (250 g body weight). Three experimental groups were used: animals restrained in an electric chamber and submitted to electric shock immediately after sensitization and 24 h before anaphylaxis (31 animals), animals restrained in the electric chamber for the same time but receiving no electric shock (23 animals), and non-manipulated, home-cage control animals (24 animals). The frequency of PCA reactions was decreased in the group of animals submitted to restraint when compared with the home-cage control group. However, the group of animals submitted to both restraint and electric shock showed no decrease in the frequency of PCA reactions. It is suggested that, in rats, stress induced by restraint decreases PCA reactions and that this decrease is counteracted by a simultaneous stress induced by electric shock

Effect of purified components of Ascaris suum extracts on IgE antibody response in guinea pigs

The effect of components P530 and P29, isolated from Ascaris suum adult worm extract (ASC), on the heterologous IgE antibody response was studied in guinea pigs. Groups of 7 guinea pigs were immunized ip with 50 micrograms of ovalbumin (OA) alone or mixed with 200 micrograms of each component precipitated in an alum gel. The primary and secondary IgE antibody response was evaluated by passive cutaneous anaphylaxis reaction (PCA). Immunization of guinea pigs with P29 plus ovalbumin (OA) resulted in a significant increase in the level of serum IgE anti-OA antibodies, especially in the secondary response (almost 8-fold higher when compared with control group). This potentiated response was not observed when the animals received OA plus P530 or the crude extract. Indeed, the P530 component, as well as the crude extract, induced a depression of the anti-OA IgE antibody response (2-3 fold decrease when compared with OA-immunized animals). It was also shown that P29, but not P530 or ASC, was capable of eliciting a strong anti-ASC IgE antibody response. These results demonstrate that in guinea pigs these two Ascaris suum components have antagonistic biological effects, one inducing potentiation and the other suppression of the heterologous IgE antibody response

Suppression of the IgE antibody response by Ascaris suum components: effect of x-irradiation

The effect of X-irradiation on the supperession of IgE antibody responses induced by some of the Ascaris suum (ASC) components was analyzed in mice (7-week old A?Sn females). Treatment with 300 R 24h before immunization with 50 *g OVA and 200 *g ASC suppressive components abolished the damping effect on ati-OVA IgE antibody levels. The same effect was observed on the anti-ASC IgE antibody response obtained in mice injected with 200 *g ASC immunogenic plus 200 *g ASC suppressive components. Moreover, the failure of suppressive components to induce an IGE anti-ASC antibody response on their own was also abolished by X-irradiation. These results indicate that the suppressive components are able to elicit an IgE antibody response, but simultaneously activate a regulatory mechanism which suppressive both the homologous (anti-ASC) and heterologous (anti-OVA) antibody formation

The possible mechanism of action of IgG antibodies and platelets protecting against Trypanosoma cruzi infection

1. The role of IgG antibody and platelets in the mechanism of defense against Trypanosoma cruzi infection is reviewed. 2. Experimental data showing the participation of the different IgG subclasses in the immune lysis and immune clearance of the parasites are discussed. 3. The involvement of the platelets in the removal of the parasites from the circulation is considered. 4. It is suggested that IgG anti-T. cruzi antibodies interact with circulating parasites leading to formation of microaggregates, activation of C3 and deposition of C3 and deposition of C3b on the immune aggregates followed by adherence of platelets through C3b receptors. The immune aggregates would then be taken up by cells of the mononuclear phagocytic system

Isolation of horse IgG with protein A

Horse immunoglobulins were obtained from normal defatted with dextran sulfate and precipitated with ammonium sulfate. Eight mg of this preparation was submitted to affinity chromatography with protein A-Sepharose CL-4B. Low temperature (4-C) and a starting buffer at pH 8.0 were conditions required for all IgG subclasses to bind to protein A, even those with low affinity. The IgGs bound to protein A were eluted with glycine buffer at pH 2.8. The yield was about 90%. Its suggested that isolated IgG, instead of whole Igs, be used in serum therapy, reducing the amount of Igs and diminishing serum-related reactions

Further characterization of ascaris suum component(s) with supressive activity on the IgE antibody response

In order to characterize the component(s) of Ascaris suum reponsible for damping of the IgE antibody production we demonstrated that the extract incubated in sodium acetate buffer, pH 4.5, maintained its suppressive effect and the same protein banding pattern by SDS-PAGE. Elimination of the lipoprotein components of the extract also left its damping properties unchanged. SDS-PAGE of the lipoprotein-free extract revealed practically the same pattern as shown by the whole extract, except for the high molecular weight polupeptides. These results indicate that the suppressive component(s) of A. suum did not precipitate and retained their activity at low pH. In addition, they appear not to be lipoproteins

Role of platelets in the in vivo removal of T. cruzi from circulation

The possible role of platelets in the clearance of Trypanosoma cruzi was studied in vivo in A/sn female mice. Platelet depletion achieved by anti-platelet IgG antibodies induced a significant, though not total, reduction in the rate of removal of T. cruzi bloodstream trypomastigotes (BTRYS) from the circulation. Furthermore, during removal of T. cruzi BTRYS from the circulation of normal mice there was a simultaneous decrease in the number of platelets. These results suggest that platelets play a role in the in vivo mechanism of defense against T. cruzi infection

Role of the mononuclear phagocytic system in the immune and nonspecific clearance of Trypanosoma cruzi bloodstream trypomastigotes

The removal of T. cruzi bloodstream trypomastigotes (BTRYS) from the circulation is mediated mostly by the mononuclear phagocytic system (MPS). In the present study we investigated the the nonspecific and the immune clearance of BTRYS in groups of 4 mice whose MPS activity was either enhanced by BCG treatment or depressed by silica treatment. Treatment with BCG resulted in a significant increase in the nonspecific clearance of both carbon particles (100% after 6 min) and BTRYS (60% after 5 min) 28 days after BCG treatment but there was no change in the immune clearance of the parasites. Pretreatment of the animals with silica induced a significant reduction of the colloidal carbon clearance (80% less than control 15 min later) but did not alter the nonspecific or the immune clearance of BTRYS. We conclude that the removal of the opsonized parasites from the circulation is due to a mechanism different from that of the nonspecific clearance

Lytic antibodies elicited by trypanosoma cruzi infection recognize epitopes present on both blood stream trypomastigote and epimastigote forms of parasite

Soro de pacientes com doença de Chagas na fase crônica foram submetidos a cromatografia de afinidade com Sepharose 4B conjugada com um extrato antigênico obtido de formas epimastigotas ou tripomastigotas de T. cruzi: os epimastigotas foram obtidos de cultura na fase exponencial de crescimento e os tripomastigotas de sangue de camundongos infectados e imunossuprimidos. Os antígenos de ambas formas parasitárias foram obtidos por tratamento dos parasitas por ultra-som, de centrifugaçäo. A cromatografia de afinidade foi feita passando-se os soros chagásicos através de uma coluna de imunoadsorvente contendo antígenos de pimastigotas ou tripomastigotas. Os anticorpos foram eluídos da coluna com tampäo glicina 0,2 M pH 2,8 a 4-C. Os anticorpos eluidos foram analisados quanto ao seu isotipo e atividade lítica. Os resultados mostraram que os anticorpos anti-T. cruzi com atividade lítica presentes em soros chagásicos estäo localizados no isotipo gG e reconhecem epitopos presentes tanto nos tripomastigotas quanto nos epimastigotas.