O coelho é a saúva: a proposta brasileira e o uso do vírus do mixoma (MYXV) contra a praga de coelhos na Austrália, 1896-1952 / Rabbits and leaf-cutting ants: the Brazilian plan to use the myxoma virus (MYXV) against rabbit plagues in Australia, 1896-1952

Resumo O artigo analisa a singularidade dos processos históricos, científicos e políticos que vão da descoberta da doença que passou a ser conhecida como mixomatose infecciosa, causada pelo vírus do mixoma (MYXV), à sua aplicação no controle de uma praga de coelhos na Austrália. A narrativa segue especialmente as pesquisas de Henrique de Beaurepaire Aragão, pesquisador do Instituto Oswaldo Cruz, e posteriormente os esforços da cientista Jean Macnamara para promover pesquisas e implementar o MYXV na Austrália. Foram consultadas notas de pesquisa de cientistas, documentos oficiais que registraram o desenvolvimento dos experimentos, bem como periódicos. Nesse processo, foi considerado o desenvolvimento histórico do campo de estudos da virologia e controle biológico.

Abstract This article analyzes the singularity of historical, scientific, and political processes from the discovery of the disease caused by the myxoma virus (MYXV) that came to be known as infectious myxomatosis to the application of this virus against a plague of rabbits in Australia. This narrative focuses on research by Henrique de Beaurepaire Aragão, a researcher at the Oswaldo Cruz Institute, and later efforts by the scientist Jean Macnamara to promote studies and implement MYXV in Australia. The scientists' research notes were consulted, along with official documents recording the experiments and periodicals. In this process, the historical development of virology and biological controls as a field of study was also considered.

Ultrastructural study of poxvirus causing myxomatosis in rabbits, in São Paulo and Santa Catarina, Brazil / Estudio ultraestructural del poxvirus causal de mixomatosis en conejos, en São Paulo y Santa Catarina, Brasil

The myxomatosis is a contagious worldwide disease caused by poxvirus which infects domestic and wild rabbits. In the present study we present two distinct outbreaks of myxomatosis when raising rabbits, one for commercial purpose of production of meat and skins and, another one for the commercialization of ornamental rabbits. The observed signs were ocular, auricular, nasal, testis lesions and many times scattered throughout the body of the animals. The lesions were characterized by formation of nodules that by palpation disclosed gummy or gelatinous aspect. At the transmission electron microscopy, all the skin and crust samples were analyzed by negative staining technique. A great number of particles with morphology similar to the poxvirus, some enveloped in a brick-shaped and irregular disposition of tubules on the external membrane, measuring 300x240 nm on the average were visualized. Ultra thin sections revealed the presence of intracytoplasmic inclusion bodies surrounded by membrane containing oval particles, measuring 270 x 130 nm, containing nucleus or an internal biconcave (dumbbell-shaped) core. Immature particles (empty), surrounded by membrane were also observed. In addition, intracytoplasmic electron dense inclusion bodies containing viral particles budding of dense amorphous material and intranuclear fibrillar or "digital" inclusions showing a regular striation and arranged in groups were found in the middle of granular material. The nuclei were deformed with densely condensed chromatin forming amorphous and electron dense inclusion bodies. In the immunocytochemistry technique, the antigen-antibody reaction was strongly marked by the particles of colloidal gold, emphasizing the viral particles. The techniques used in this study were important in the diagnosis of the affected animals.

La mixomatosis es una enfermedad contagiosa de distribución mundial, causada por poxvirus que infecta conejos domésticos y salvajes. En este estudio presentamos dos distintos surtos por mixomatosis que ocurrieron en producciones de conejos, una para fines comerciales de producción de carne y pieles y otra para el comercio de conejos domésticos. Las señales observadas fueron afecciones oculares, nasales, testiculares y, a veces, también distribuida por todo el cuerpo de los animales. Estas se caracterizaban por formación de nódulos que a la palpación tenían un aspecto gelatinoso o gomoso. En la microscopía electrónica de transmisión, por la técnica de contrastación negativa, se pudo observar en todas las muestras examinadas de piel y de costras, un gran número de partículas típicas de poxvirus, con envoltura y forma de ladrillo, mostrando disposición irregular de los túbulos sobre la membrana externa, midiendo 300 x 240 nm en el promedio. Cortes ultrafinos de fragmentos de piel y de costras revelaron la presencia de cuerpos de inclusión intracitoplasmáticas, envueltos por membrana y conteniendo partículas ovales, midiendo 270 x 130 nm, conteniendo núcleo o centro interno bicóncavo (forma de mancuernas). Partículas inmaduras (vacías) envueltas por membrana fueron observadas. También fueron analizados cuerpos de inclusión intracitoplasmáticos, electrodensos, conteniendo partículas virales brotando del material denso y amorfo. Fueron observadas inclusiones intranucleares fibrilares o "digitales" mostrando una estriación periódica y disposición en grupos en medio del material granular. Los núcleos estaban deformados con cromatina densamente condensada formando cuerpos de inclusiones electrodensas y amorfas. En la técnica de imunocitoquímica la reacción antígeno-anticuerpo fue intensamente marcada por las partículas de oro coloidal realzando fuertemente las partículas virales.

Doença crônica da valva mitral em cães: avaliação clínica funcional e mensuração ecocardiográfica da valva mitral / Chronic mitral valvular disease in dogs: assessment of functional clinical stage and echocardiographic measurement of the mitral valve

Foram descritos os achados do exame físico em cães com degeneração mixomatosa crônica da valva mitral e mensurado o comprimento e a espessura das cúspides da valva mitral pelo exame ecocardiográfico. Utilizaram-se 81 cães de diferentes raças de pequeno a médio porte, com idade de 11,12± 2,51 anos e peso de 6,24kg± 3,19, dos quais 20 eram clinicamente normais (grupo-controle) e 61 apresentavam evidências clínicas de cardiopatia. Os animais foram distribuídos em três classes distintas segundo a insuficiência cardíaca congestiva (grupos I, II e III), de acordo com os dados do histórico e dos sinais clínicos apresentados. Ao exame ecocardiográfico, avaliaram-se as medidas das cúspides da valva mitral, que não apresentaram diferença entre os cães do grupo I e II, embora estivessem anormais se comparadas às dos cães do grupo-controle. Nos animais do grupo III, as medidas das valvas avaliadas foram maiores que as dos cães dos grupos I e II. Foram observados nódulos com formato arredondado e, nos cães do grupo III, as cúspides estavam bastante alongadas e espessadas.

Physical and echocardiographic aspects were studied in dogs with chronic mitral valvular disease. The length and thickness of the mitral valve leaflets were echocardiographically measured. Eighty-one dogs of small-medium breeds (mean of 6.24kg± 3.19), older than six years (11.12± 2.51 years) were used. Twenty were clinically normal dogs (control group) and 61 presented myxomatous degeneration of the mitral valve. The diseased dogs were categorized into three classes of congestive heart failure (I, II, and III groups) according to the information on clinical manifestations. On the echocardiographic exam, the measurements of the mitral valve leaflets were evaluated and no diferences between dogs of groups I and II were found, though they were abnormal if compared with control group animals. Group III dogs presented measurements higher than those of animals of groups I and II, as well as leaflets very thick and round-shaped nodules were observed.

Myxomatous stromal changes and necrosis of bone marrow--a retrospective study of 3 years.

Myxomatous stromal changes and bone marrow necrosis (BMN) are uncommon histologic findings. These changes have been found in various conditions like disseminated carcinomatosis, postchemotherapy cases, chronic infections, infiltrative disorders of the marrow etc. The present study is a retrospective study of 3 years (Jan, 1999 to Dec. 2001) from Deptt. Of Hematology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh (India). During this period, 3740 bone marrow samples were examined. Myxomatous stromal changes and bone marrow necrosis were noted in 0.43% (16/3740) and 0.45% (17/3740) samples respectively. In addition to common causes of myxomatous stromal changes and bone marrow necrosis as described in the literature, this study highlights the association of these conditions with some of the rarer entities like hyperoxalosis, leishmaniasis, parvovirus induced marrow aplasia and cryptococcal infection. There is paucity of such associations in the literature.

Achados clínicos e anatomopatológicos em um surto de mixomatose no Rio de Janeiro (relato de caso) / Clinical and anatomopatological findings in a mixomatosis outbreak in Rio de Janeiro (case report)

Relata-se, um surto de Mixomatose atingindo um criatório de coelhos (Oryctolagus cuniculus) no município de Maricá, RJ – Brasil, no ano de 2002, onde foram examinados e necropsiados seis animais. Clinicamente foram observados edema de face, orelhas, pálpebras e genitália externa; blefaro-conjuntivite purulenta, além de deformação naso-labial e presença de nódulos cutâneos principalmente no pavilhão auricular. À necropsia observou-se, além das alterações já encontradas no exame clínico, aumento dos linfonodos retrofaríngeos e submandibulares em dois animais e alterações pneumônicas e esplenomegalia em outros dois. Microscopicamente foram observadas alterações epididérmicas e, na derme, aspecto mixomatoso. Ainda foram observadas pneumonia intersticial com edema, e degeneração testicular.

Lessons in détente or know thy host: the immunomodulatory gene products of myxoma virus.

The poxvirus, myxoma virus, encodes within its genome at least eleven different proteins that compromise, skew, or disable the innate and adaptive responses of its hosts. In the laboratory rabbit, Oryctolagus cuniculus, these effects result in myxomatosis, a fatal condition characterized by skin lesions and systemic immunosuppression. Interestingly, while myxoma infection also causes skin lesions in its natural host and in natural populations of O. cuniculus in Australia where this novel host and the virus have co-evolved, the condition of myxomatosis does not ensue and infection is not fatal. In this review I discuss the biochemical properties of the characterized immunomodulatory proteins of myxoma virus, and their pathogenic effects in laboratory rabbits. Disruption of any one myxoma immunomodulatory gene diminishes the severity of the infection without compromising infectivity. Thus, the characterized immunomodulatory genes appear not to be required for a productive infection in vivo. The differences in the severity of their effects in laboratory-bred versus wild O. cuniculus suggest that the outcome of myxoma infection is a consequence of the interplay between the viral immunomodulatory gene products and the cells and molecules of the host immune system.

Degeneracion mixomatosa de la valvula tricuspide complicada con endocarditis por estafilococo dorado. (Informe de un caso). / Myxomatous degeneration of the tricuspide valve complicated with endocarditis by Staphylococcus aureus

La degeneracion mixomatosa, (DM) de las valvulas cardiacas no es muy frecuente. Se ha descrito sola o acompanando a enfermedades del tejido conectivo, particularmente al sindrome de Marfan, o a su forme frustre. Puede afectar a una o a varias valvulas, pero nunca se ha descrito la lesion anatomopatologica de la valvula tricuspide (VT) aislada. La degeneracion mixomatosa es particularmente susceptible de complicarse con endocarditis infecciosa (EI). Este informe describe un caso de DM de la VT complicada con EI por estafilococo dorado