Leishmaniose visceral em um Pastor Belga: relato de caso / Visceral leishmaniasis in a Belgian Pastor: case report

O presente trabalho tem como objetivo relatar um caso de um Pastor Belga, do município de Ponta Porã, Mato Grosso do Sul, positivo para Leishmaniose Visceral, atendido em 2017 em uma clínica veterinária localizada em Pedro Juan Caballero, Paraguai. O diagnóstico foi confirmado através dos sinais clínicos característicos, e dos exames ELISA e PCR positivos. O animal foi submetido ao tratamento clínico para melhora dos sintomas, cujo tratamento antiparasitário inicial foi realizado com a associação de estibogluconato de sódio 75 mg/kg e alopurinol 100 mg seguido de aloputinol 100mg de uso contínuo e uso da coleira antileishmaniose. Tratamento esse considerado eficiente, com melhora clínica do animal. Após 24 meses o animal foi diagnosticado com tumor de mama e lesão da bolsa escrotal, sendo submetido a tratamento clínico e cirúrgico. Com 30 e 36 meses do diagnóstico inicial repetiu-se os exames ELISA (positivo) e PCR (negativo), e então o animal foi considerado curado clinicamente devido à ausência de sinais clínicos. Tendo em vista a complexidade dos fatores no ciclo de transmissão, conclui-se que as medidas em saúde ainda são insuficientes para o controle efetivo da doença. É importante o papel do Médico Veterinário na saúde pública, devido a obrigatoriedade de notificação de casos de Leishmaniose Visceral Canina, sendo necessários esforços nas diferentes áreas da saúde animal, humana e do meio ambiente, visando medidas de vigilância e controle da doença no país.

The present work aims to report a case of a Belgian Shepherd, from the municipality of Ponta Porã, Mato Grosso do Sul, positive for Visceral Leishmaniasis, treated in 2017 in a veterinary clinic located in Pedro Juan Caballero, Paraguay. The diagnosis was confirmed through the characteristic clinical signs, and the positive ELISA and PCR tests. The animal was submitted to clinical treatment for improvement of symptoms, whose initial antiparasitic treatment was performed with the association of sodium stibogluconate 75 mg/kg and allopurinol 100 mg followed by alloputinol 100mg of continuous use and use of the antileishmaniasis collar. This treatment was considered efficient, with clinical improvement of the animal. After 24 months the animal was diagnosed with a breast tumor and scrotum injury, and was submitted to clinical and surgical treatment. At 30 and 36 months from the initial diagnosis, the ELISA tests (positive) and PCR (negative) were repeated, and then the animal was considered clinically cured due to the absence of clinical signs. Considering the complexity of the factors in the transmission cycle, it is concluded that the health measures are still insufficient for the effective control of the disease. The role of the veterinarian in public health is important, due to the obligatory notification of cases of Canine Visceral Leishmaniasis, being necessary efforts in the different areas of animal health, human and environment, aiming at measures of surveillance and control of the disease in the country.

[Inhibition of Toxoplasma gondii excretory - secretory antigens on growth of murine Lewis lung carcinoma].

OBJECTIVE: To investigate the effect of Toxoplasma gondii excretory-secretory antigens (ESA) on CD4+ CD25+ Foxp3+ T (Treg) cells in mice carrying Lewis lung carcinoma, and examine the inhibitory effect of T. gondii ESA on tumor growth. METHODS: C57BL/6 mice were randomly assigned into the PBS group (n = 14) and the Lewis group (n = 34). Mice in the Lewis group were subcutaneously injected with 2 × 105 Lewis lung carcinoma cells in the right axilla, while animals in the PBS group were injected with the same volume of sterile PBS. On day 7 post-injection (D7), mice in the PBS group were further divided into the PBS2 group and the PBS2 + ESA group, of 7 mice in each group, and mice in the Lewis group were further divided into the Lewis2 group and the Lewis2 + ESA group, of 17 mice in each group. Then, mice in the PBS2 + ESA group and the Lewis2 + ESA group were intraperitoneally injected with 100 µL of ESA. The mouse spleen coefficient was calculated in each group 7 days post-injection with ESA, and the changes of Treg cell counts and the long-term tumor growth were measured in tumor-bearing mice. RESULTS: The spleen coefficient was significantly greater in the PBS2 + ESA group and the Lewis2 + ESA group than in the PBS2 (0.66% ± 0.09% vs. 0.30% ± 0.02%, P < 0.05) and Lewis2 groups (0.69% ± 0.07% vs. 0.33% ± 0.03%, P < 0.05) 7 days post-treatment with ESA, respectively, and the percentage of splenic Treg cells in splenocytes was significantly lower in the PBS2 + ESA group and the Lewis2 + ESA group than in the PBS2 (1.28% ± 0.14% vs. 2.06% ± 0.07%, P < 0.05) and Lewis2 groups (1.58% ± 0.14% vs. 2.44% ± 0.23%, P < 0.05), respectively. T. gondii ESA treatment caused a delay in tumor growth, and the tumor size was significantly smaller in the Lewis2 + ESA group than in the Lewis2 group (P < 0.05). CONCLUSIONS: T. gondii ESA may reduce the proportion of splenic Treg cells in splenocytes and inhibit tumor growth in mice carrying Lewis lung carcinoma.

Effect of hydatid cyst antigens on inhibition of melanoma cancer growth in mouse model.

Cancer is the main cause of death in the developed countries. There are some scientific evidences indicating that parasitic infections induce antitumor activity against certain types of cancers. Hydatid cyst is the larval stage of Echinococcus granulosus, which causes hydatidosis in human and livestock. We have already shown that vaccination of mice with hydatid cyst crude antigens and subsequently challenge them with cancer cells, causes inhibition of melanoma cancer growth. In this study, therapeutic effects of hydatid cyst antigens on C57/black mice that had already been challenged with melanoma tumor were investigated. In this experimental study, 6 groups of C57 black mice were subcutaneously inoculated with melanoma cancer cells (line B16F10) in PBS inside their chest site. After 2 weeks case groups were injected with hydatid cyst fluid, a fraction of cyst fluid, live protoscolices or BCG.  control groups were injected with alum alone and other control group was left intact without any intervention. The size of each tumor was measured in all mice. Blood samples were also taken to estimate Interleukin-2 (IL-2), Tumor necrosis factor alpha (TNF-α), Interferon gamma (IFN-γ) and Interleukin-4 (IL-4) levels. Treatment of mice bearing melanoma cancer with hydatid cyst antigens resulted in inhibition of tumor growth and the difference between mean size of tumor in case and control groups was statistically significant. Also, according to our results mean level of measured cytokines between case and control groups was statistically different. Hydatid cyst antigens have anti-melanoma activities and this effect may be related to immune response to parasite antigens.

Resistance to Chronic Toxoplasma gondii Infection Induced by a DNA Vaccine Expressing GRA16.

Toxoplasma gondii can infect all warm-blooded animals including human beings. T. gondii dense granule protein 16 (TgGRA16) as a crucial virulence factor could modulate the host gene expression. Here, a DNA vaccine expressing TgGRA16 was constructed to explore the protective efficacy against T. gondii infection in Kunming mice. The immune responses induced by pVAX-GRA16 were also evaluated. Mice immunized with pVAX-GRA16 could elicit higher levels of specific IgG antibody and strong cellular response compared to those in controls. The DNA vaccination significantly increased the levels of cytokines (IFN-γ, IL-2, IL-4, and IL-10) and the percentages of CD4+ and CD8+ T cells in mice. After lethal challenge, mice immunized with pVAX-GRA16 (8.4 ± 0.78 days) did not show a significant longer survival time than that in controls (7.1 ± 0.30 days) (p > 0.05). However, in chronic toxoplasmosis model (administration of 10 brain cysts of PRU strain orally), numbers of tissue cysts in mice immunized with pVAX-GRA16 were significantly reduced compared to those in controls (p < 0.05) and the rate of reduction could reach 43.89%. The results indicated that the TgGRA16 would be a promising vaccine candidate for further development of effective epitope-based vaccines against chronic T. gondii infection in mice.

Expression, Purification and Characterization of GMZ2'.10C, a Complex Disulphide-Bonded Fusion Protein Vaccine Candidate against the Asexual and Sexual Life-Stages of the Malaria-Causing Plasmodium falciparum Parasite.

PURPOSE: Production and characterization of a chimeric fusion protein (GMZ2'.10C) which combines epitopes of key malaria parasite antigens: glutamate-rich protein (GLURP), merozoite surface protein 3 (MSP3), and the highly disulphide bonded Pfs48/45 (10C). GMZ2'.10C is a potential candidate for a multi-stage malaria vaccine that targets both transmission and asexual life-cycle stages of the parasite. METHODS: GMZ2'.10C was produced in Lactococcus lactis and purified using either an immunoaffinity purification (IP) or a conventional purification (CP) method. Protein purity and stability was analysed by RP-HPLC, SEC-HPLC, 2-site ELISA, gel-electrophoresis and Western blotting. Structural characterization (mass analysis, peptide mapping and cysteine connectivity mapping) was performed by LC-MS/MS. RESULTS: CP-GMZ2'.10C resulted in similar purity, yield, structure and stability as compared to IP-GMZ2'.10C. CP-GMZ2'.10C and IP-GMZ2'.10C both elicited a high titer of transmission blocking (TB) antibodies in rodents. The intricate disulphide-bond connectivity of C-terminus Pfs48/45 was analysed by tandem mass spectrometry and was established for GMZ2'.10C and two reference fusion proteins encompassing similar parts of Pfs48/45. CONCLUSION: GMZ2'.10C, combining GMZ2' and correctly-folded Pfs48/45 can be produced by the Lactoccus lactis P170 based expression system in purity and quality for pharmaceutical development and elicit high level of TB antibodies. The cysteine connectivity for the 10C region of Pfs48/45 was revealed experimentally, providing an important guideline for employing the Pfs48/45 antigen in vaccine design.

Antigenicity, Immunogenicity and Protective Efficacy of Three Proteins Expressed in the Promastigote and Amastigote Stages of Leishmania infantum against Visceral Leishmaniasis.

In the present study, two Leishmania infantum hypothetical proteins present in the amastigote stage, LiHyp1 and LiHyp6, were combined with a promastigote protein, IgE-dependent histamine-releasing factor (HRF); to compose a polyproteins vaccine to be evaluated against L. infantum infection. Also, the antigenicity of the three proteins was analyzed, and their use for the serodiagnosis of canine visceral leishmaniasis (CVL) was evaluated. The LiHyp1, LiHyp6, and HRF DNA coding sequences were cloned in prokaryotic expression vectors and the recombinant proteins were purified. When employed in ELISA assays, all proteins were recognized by sera from visceral leishmaniasis (VL) dogs, and presented no cross-reactivity with either sera from dogs vaccinated with a Brazilian commercial vaccine, or sera of Trypanosoma cruzi-infected or Ehrlichia canis-infected animals. In addition, the antigens were not recognized by antibodies from non-infected animals living in endemic or non-endemic areas for leishmaniasis. The immunogenicity and protective efficacy of the three proteins administered in the presence of saponin, individually or in combination (composing a polyproteins vaccine), were evaluated in a VL murine model: BALB/c mice infected with L. infantum. Spleen cells from mice inoculated with the individual proteins or with the polyproteins vaccine plus saponin showed a protein-specific production of IFN-γ, IL-12, and GM-CSF after an in vitro stimulation, which was maintained after infection. These animals presented significant reductions in the parasite burden in different evaluated organs, when compared to mice inoculated with saline or saponin. The decrease in parasite burden was associated with an IL-12-dependent production of IFN-γ against parasite total extracts (produced mainly by CD4+ T cells), correlated to the induction of parasite proteins-driven NO production. Mice inoculated with the recombinant protein-based vaccines showed also high levels of parasite-specific IgG2a antibodies. The polyproteins vaccine administration induced a more pronounced Th1 response before and after challenge infection than individual vaccines, which was correlated to a higher control of parasite dissemination to internal organs.

Experimental Chagas disease in Balb/c mice previously vaccinated with T. rangeli. II. The innate immune response shows immunological memory: reality or fiction?

Trypanosoma cruzi is a real challenge to the host's immune system, because it requires strong humoral and cellular immune response to remove circulating trypomastigote forms, and to prevent the replication of amastigote forms in tissues, involving many regulator and effector components. This protozoan is responsible for Chagas disease, a major public health problem in Latinamerica. We have developed a model of vaccination with Trypanosoma rangeli, a parasite closely related to T. cruzi, but nonpathogenic to humans, which reduces the infectiousness in three different species of animals, mice, dogs and guinea pigs, against challenge with T. cruzi. In a previous work, we demonstrated that mice vaccinated with T. rangeli showed important soluble mediators that stimulate phagocytic activity versus only infected groups. The aim of this work was to study the innate immune response in mice vaccinated or not with T. rangeli. Different population cells and some soluble mediators (cytokines) in peritoneal fluid and plasma in mice vaccinated-infected and only infected with T. cruzi were studied. In the first hours of challenge vaccinated mice showed an increase of macrophages, NK, granulocytes, and regulation of IL6, IFNγ, TNFα and IL10, with an increase of IL12, with respect to only infected mice. Furthermore an increase was observed of Li T, Li B responsible for adaptative response. Finally the findings showed that the innate immune response plays an important role in vaccinated mice for the early elimination of the parasites, complementary with the adaptative immune response, suggesting that vaccination with T. rangeli modulates the innate response, which develops some kind of immunological memory, recognizing shared antigens with T. cruzi. These results could contribute to the knowledge of new mechanisms which would have an important role in the immune response to Chagas disease.

Immunological correlates of cure in the first American Cutaneous Leishmaniasis patient treated by immunotherapy in Argentina: A case report. / Correlatos inmunológicos de curación en el primer paciente con Leishmaniasis Cutánea Americana tratado con inmunoterapia en Argentina: Reporte de un caso

A patient with localized cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis infection was treated with an antigen containing heat-killed L. (L.) amazonensis promastigotes plus BCG. Expression of T-cell differentiation, memory and senescence receptors markers were analyzed on T cell subpopulations, in order to establish the correlation between the percentages of expression of these receptors and his clinical status, at different stages of his follow up. The following case reports on the achievement of a successful clinical outcome with complete resolution after receiving immunotherapy. A thorough clinical and immunological follow up supporting the healing process of this patient’s lesion is presented in detail.

Un paciente con leishmaniasis cutánea localizada producida por Leishmania (Leishmania) amazonensis fue tratado con un antígeno compuesto por promastigotes de L. (L.) amazonensis muertos por calor combinado con BCG. Se analizó la expresión de distintos receptores de diferenciación, de memoria y de senescencia en las subpoblaciones de células T, con el fin de establecer una relación entre los porcentajes de expresión de dichos receptores y la clínica del paciente en diferentes momentos del seguimiento. Se reporta en este caso un resultado exitoso, con resolución completa de la lesión después de recibir la inmunoterapia, y se presenta en detalle un seguimiento clínico e inmunológico completo durante el proceso de curación.

Targeting Plasmodium liver stages: better late than never.

The worldwide burden of malaria can be substantially reduced using existing public health interventions. However, elimination of Plasmodium will require fundamentally different approaches. Novel experimental attenuation strategies for active immunization using knockout strains have recently stimulated renewed interest in whole-parasite vaccine approaches. Preventive drug administration during transmission of wild-type sporozoites is a complementary strategy for eliciting protective immune responses. These whole-cell immunization strategies are based on one fundamental principle: inducing protection by blocking parasite conversion from the clinically silent liver phase to the pathogenic intra-erythrocytic replication cycle. Here, we review the basis, evidence and targets for whole-cell-based vaccination strategies against the liver stage bottleneck in Plasmodium infections and discuss preclinical and clinical research opportunities.

Increase of NK cells and proinflammatory monocytes are associated with the clinical improvement of diffuse cutaneous leishmaniasis after immunochemotherapy with BCG/Leishmania antigens.

Diffuse cutaneous leishmaniasis (DCL) is characterized by disseminated lesions and the absence of a specific cellular immune response. Here, the immunochemotherapy outcome of a patient with DCL from Amazonian Brazil infected with Leishmania (Leishmania) amazonensis is presented. After several unsuccessful chemotherapy treatment regimens and many relapses, a monthly immunotherapy scheme of L. amazonensis PH8 plus L. (Viannia) braziliensis M2903 monovalent vaccines associated with Bacillus Calmette-Guerin (BCG) was established, one round of which also included an M2903 vaccine associated with intermittent antimonial treatment. Temporary healing of all lesions was achieved, although Leishmania skin tests were negative and interferon gamma was not detected in mononuclear cell cultures stimulated with Leishmania antigens. The frequencies of CD16 (+)CD56(+) NK cells (approximately 2x) and CD14 (+)CD16(+) proinflammatory monocytes (approximately 8x) increased in peripheral blood, and CD56 (+) lymphocytes were found infiltrating the lesions. An association between the increase of the frequency of innate immune system cells and the healing of lesions is shown, suggesting that this protocol of immunotherapy reduced the parasite load and activated NK cells and monocytes.

Effects of Toxoplasma gondii and Toxocara canis antigens on WEHI-164 fibrosarcoma growth in a mouse model.

Cancer is the main cause of death in developed countries. However, in underdeveloped countries infections and parasitic diseases are the main causes of death. There are raising scientific evidences indicating that parasitic infections induce antitumor activity against certain types of cancers. In this study, the effects of Toxoplasma gondii and Toxocara canis egg antigens in comparison with Bacillus Calmette Guerin (BCG) (known to have anticancer distinctive) on WEHI-164 fibosarcoma transplanted to BALB/c mice was investigated. Groups of 6 male BALB/c mice injected with T. gondii antigen, BCG, or T. canis egg antigen as case groups and alum alone as control groups. All mice were then challenged with WEHI-164 fibrosarcoma cells. The mice were examined for growth of the solid tumor and the tumor sizes were measured every other day up to 4 wk. The mean tumor area in T. gondii, BCG, or alum alone injected mice in 4 different days of measurements was 25 mm(2), 23 mm(2), and 186 mm(2) respectively. Also the mean tumor area in T. canis injected mice in 4 different days was 25.5 mm(2) compared to the control group (alum treated) which was 155 mm(2). T. gondii parasites and T. canis egg antigens induced inhibition of the tumor growth in the fibrosarcoma mouse model. We need further study to clarify the mechanisms of anti-cancer effects.

Immunotherapy as a strategy for treatment of leishmaniasis: a review of the literature.

Leishmaniasis occurs as a spectrum of clinical syndromes divided into cutaneous, mucocutaneous and visceral forms. The epidemiology and clinical features are highly variable owing to the interplay of many factors ranging from parasite species and strains, vectors, host genetics and environment. Currently, there is no effective licensed vaccine for use in humans against leishmaniasis. Most traditional and low-cost treatment options, particularly in poor and endemic areas, are toxic with many adverse reactions and they require a long course of administration. The use of more effective, less toxic drugs is limited because total treatment cost is very high (expensive) and there are fears of development of drug resistance. Recent studies indicate that certain strategies aimed at modulating the host immune response (collectively called immunotherapy) could result in prophylactic and/or therapeutic cure of leishmaniasis under both laboratory and field conditions. In this review, we focus on treatment of leishmaniasis with a particular emphasis on immunotherapy/immunochemotherapy as an alternative to conventional drug treatment.

Immunotherapy for drug-refractory mucosal leishmaniasis.

BACKGROUND: Pentavalent antimony (Sb(v)) is the mainstay therapy for mucosal leishmaniasis (ML), but it is toxic, and relapses are common. Immunotherapy using a mixture of killed parasites, with or without bacille Calmette-Guerin, is an alternative but is used sporadically because of inconsistent results. METHODS: We developed a defined immunotherapeutic antigen preparation for use in an observational, open-label trial to treat 6 patients with ML with a history of Sb(v) therapy failure. All patients were treated with the antigens thiol-specific antioxidant, Leishmania major stress inducible protein 1, Leishmania elongation initiation factor, and Leishmania heat shock protein 83, plus granulocyte-macrophage colony-stimulating factor. Patients underwent clinical and pathological evaluations before the initiation of immunotherapy and at 3, 6, 9, 12, 18, 24, and 60 months after. RESULTS: One month after the third injection, 1 patient showed complete clinical remission (CC) and remained disease free for the duration of the study. At the 9-month follow-up examination, 5 patients showed CC, and all patients were asymptomatic at a subsequent 5-year follow-up examination. CONCLUSIONS: These data support the concept that vaccine therapy with a defined antigen combination, used with standard chemotherapy, is a safe and effective approach to treat drug-refractory ML.

Dendritic cell-based immunotherapy combined with antimony-based chemotherapy cures established murine visceral leishmaniasis.

Dendritic cells (DCs) have been proposed to play a critical role as adjuvants in vaccination and immunotherapy. In this study we evaluated the combined effect of soluble Leishmania donovani Ag (SLDA)-pulsed syngeneic bone marrow-derived DC-based immunotherapy and antimony-based chemotherapy for the treatment of established murine visceral leishmaniasis. Three weekly injections of SLDA-pulsed DCs into L. donovani-infected mice reduced liver and splenic parasite burden significantly, but could not clear parasite load from these organs completely. Strikingly, the conventional antileishmanial chemotherapy (sodium antimony gluconate) along with injections of SLDA-pulsed DCs resulted in complete clearance of parasites from both these organs. Repetitive in vitro stimulation of splenocytes from uninfected or L. donovani-infected mice with SLDA-pulsed DCs led to the emergence of CD4(+) T cells with characteristics of Th1 cells. Our data indicate that DC-based immunotherapy enhances the in vivo antileishmanial potential of antimony or vice versa.

Successful use of a defined antigen/GM-CSF adjuvant vaccine to treat mucosal Leishmaniasis refractory to antimony: A case report.

Immunotherapy has been proposed as a method to treat mucosal leishmaniasis for many years, but the approach has been hampered by poor definition and variability of antigens used, and results have been inconclusive. We report here a case of antimonial-refractory mucosal leishmaniasis in a 45 year old male who was treated with three single injections (one per month) with a cocktail of four Leishmania recombinant antigens selected after documented hypo-responsiveness of the patient to these antigens, plus 50 microg of GM-CSF as vaccine adjuvant. Three months after treatment, all lesions had resolved completely and the patient remains without relapse after two years. Side effects of the treatment included only moderate erythema and induration at the injection site after the second and third injections. We conclude that carefully selected microbial antigens and cytokine adjuvant can be successful as immunotherapy for patients with antimonial-refractory mucosal leishmaniasis.

Vaccination of BALB/c mice with Leishmania major amastigote-specific cysteine proteinase.

Cellular immune mechanisms resulting in interferon-gamma (IFN-gamma) production are essential for protection against cutaneous leishmaniasis. Antigens of the intracellular amastigote form of the parasite, found in mammalian hosts, are likely to be good candidates for the induction of T cell response and protection from development of leishmaniasis. We purified a stage-specific antigen from amastigote soluble antigen (A-SLA) of Leishmania major by immunoaffinity chromatography. The purified protein was characterized as a cysteine proteinase with enzymatic activity which is inhibited by E-64, and it was named the amastigote cysteine proteinase (ACP). BALB/c mice were immunized by two intraperitoneal injections, at a month interval, of 5 microg of ACP or A-SLA in Freund's complete adjuvant (FCA). Animals were challenged 4 weeks later with 106 L. major promastigotes and examined 4 months after the last injection. The immunized animals developed significantly smaller or no lesions compared with controls. Spleen cells from immunized mice showed a significant proliferative response and produced a high level of IFN-gamma in response to ACP, suggesting the induction of Th1 cells after immunization. These results make 24-kD ACP a possible component for an eventual cocktail vaccine against L. major infection.

Protective immune mechanisms against Theileria parva: evolution of vaccine development strategies.

Theileria parva is an intracellular sporozoan parasite that infects and transforms bovine lymphocytes, causing a severe lymphoproliferative disease known as East Coast fever in eastern, central and southern Africa. In this article, Declan McKeever and colleagues summarize the current understanding of immune mechanisms provoked by the parasite with regard to their role in both pathogenesis and protection. In particular, the influence of genomic polymorphism in parasite and host on the development of immunity is discussed, along with the evolution of current vaccine development strategies as a result of immunological research on the disease.

Use of a recombinant antigen, SAG2, expressed as a glutathione-S-transferase fusion protein to immunize mice against Toxoplasma gondii.

The capacity of Toxoplasma gondii surface protein SAG2 to induce protective immunity against the parasite in mice was studied using recombinant SAG2 expressed as a glutathione-S-transferase (GST) fusion protein incorporated into immune stimulating complexes (iscoms). Immunization with the iscoms resulted in the production of antibodies recognizing SAG2 as well as GST. After oral challenge infection with T. gondii oocysts or tissue cysts, no protective effect was observed. On the contrary, mice immunized with fusion SAG2 or with GST iscoms died earlier than non-immunized control mice.

Evaluación de las pérdidas económicas debidas a toxoplasmosis en ovinos en el Uruguay / Evaluation of economic losses due to sheep toxoplasmosis in Uruguay

Se determinó la presencia de anticuerpos contra Toxoplasma gondii, antes y después de la gestación, con la reacción de aglutinación directa para toxoplasmosis (AD), en 1613 ovejas de 18 establecimientos de diferentes Departamentos del Uruguay, de 1992 a 1994. La prevalencia total de la infección ascendió de 28,7 por ciento antes de la gestación a 38,5 por ciento, luego de la misma. La incidencia fue, por lo tanto de 9,8 por ciento. Las pérdidas debidas a la infección toxoplásmica durante la gestación se estimaron teóricamente con una fórmula que contempla el nivel de incidencia así como algunos factores de la patogénesis de la enfermedad en el ovino. Sobre esta base, de 1,4 a 3,9 por ciento del total de las ovejas investigadas pudieron haber perdido sus corderos debido a la toxoplasmosis. Esto representa una pérdida económica anual para la industria ovina en el Uruguay de 1,9 a 5,2 millones de dólares americanos. En la estación de parición de 1993, de 562 ovejas y borregas que fueron servidas en uno de los establecimientos. 154 tuvieron corderos y 125 abortaron. Se aisló Toxoplasma mediante bioensayos, a partir de los fetos abortados. Veintiocho sueros de ovejas que abortaron presentaron títulos de 1:16.384 o mayores con el test de AD. Se apreciaron puntos blancos de necrosis del tamaño de la cabeza de un alfiler sobre la superficie de los cotiledones placentarios de las ovejas que abortaron. Los hallazgos histopatológicos fueron necrosis y calcificación de las vellosidades cotiledonarias y encefalitis, hepatitis y neumonía. Seis meses luego de los abortos, 55,6 por ciento de 300 ovejas presentaron títulos de 1:1.024 o mayores, reflejando la extensión de la infección. Se detectaron abortos toxoplásmicos en otros establecimientos, el mismo año. Se destaca la situación de subdiagnóstico de la toxoplasmosis ovina, al quedar enmascarada por otras causas de pérdidas de corderos más extensivos, salvo que adopte la magnitud inusual del caso relatado

Safety, immunogenicity, and efficacy of Plasmodium falciparum repeatless circumsporozoite protein vaccine encapsulated in liposomes.

Seventeen malaria-naive volunteers received a recombinant Plasmodium falciparum vaccine (RLF) containing the carboxy- and the amino-terminal of the circumsporozoite protein (CSP) antigen without the central tetrapeptide repeats. The vaccine was formulated in liposomes with either a low or high dose of 3-deacylated monophosphoryl lipid A (MPL) and administered with alum by intramuscular injection. Both formulations were well tolerated and immunogenic. MPL increased sporozoite antibody titers measured by ELISA, Western blot, and immunofluorescence assay. One high-dose MPL vaccine formulation recipient developed a CSP-specific cytotoxic T lymphocyte response. After homologous sporozoite challenge, immunized volunteers developed patent malaria. There was no correlation between prepatent period and antibody titers to the amino- or carboxy-terminal. The absence of delay in patency argues against inclusion of the amino-terminal in future vaccines. A significant cytotoxic T lymphocyte response may have been suppressed by the inclusion of alum as an adjuvant.