Infecções humanas causadas por poxvirus relacionados ao vírus vaccinia no Brasil / Human infections caused by vaccinia-like poxviruses in Brazil

A partir de 1999, infecções humanas por Orthopoxvirus vem sendo observadas em pelo menos oito estados no país, com a formação de vesículas as quais evoluem para pústulas e crostas, principalmente nos membros superiores e face, após contacto com bovinos apresentando lesões semelhantes no úbere. Alem das lesões na pele, foram descritas nos pacientes reações ganglionares axilares por vezes dolorosas, febre, cefaléia, fadiga, desidratação, anorexia, sudorese, artralgia e mialgia, evoluindo o quadro por três a quatro semanas. Lesão vulvar bem como transmissão intrafamiliar foram igualmente descritas. Estudos moleculares demonstraram que os poxvirus identificados são geneticamente relacionados a amostras do vírus vaccinia utilizadas no passado, nas campanhas de vacinação. Especimens clínicos de 80 infecções humanas foram estudados no laboratório e a infecção por orthopoxvirus confirmada em 68 casos. São apresentadas lesões observadas em pacientes bem como discutidas as implicações desta zoonose no Brasil.

Since 1999, human infection caused by Orthopoxvirus has been observed in at least eight Brazilian states, with the presence of vesicles that evolve to pustules and crusts, especially on the hands, arms and face, after contact with cows showing comparable lesions on the udder. In addition to the skin lesions, there have been descriptions of patients with axillary ganglionic reactions that are sometimes painful, along with fever, headache, fatigue, dehydration, anorexia, sudoresis, arthralgia and muscle pain. The condition evolves over a three to four-week period. Vulvar lesions and transmission within families have also been described. Molecular studies have shown that the poxviruses identified are genetically related to vaccinia virus samples that were used in vaccination campaigns in the past. Clinical specimens from 80 human infections were studied in the laboratory, and orthopoxvirus infections were confirmed in 68 cases. The lesions observed in these patients are presented and the implications of this zoonosis in Brazil are discussed.

Análises histopatológicas e ultra-estruturais de tecidos de camundongos BALB/c infectados experimentalmente pelos vírus dengue / Histopathological and ultrastructural analyses of tissues of mice BALB/c mice experimentally infected for the dengue virus

Uma das maiores dificuldades no estudo da infecção de dengue em humanos e no desenvolvimento de uma vacina é a ausência de um modelo animal susceptível para o estudo de infecções pelos vírus dengue. Na presente tese apresentamos e discutimos aspectos morfológicos de um modelo animal que demonstra muitas semelhanças com a infecção de dengue em humanos. São analisados aspectos histopatológicos e ultra-estruturais de pulmão e fígado de camundongos BALB/c em uma infecção primária e em infecção secundária por sorotipo heterólogo de vírus dengue. Os animais foram infectados com vírus não neuro-adaptado. As amostras de vírus dengue sorotipos 1 e 2 foram isoladas de soro de paciente e propagadas em culturas de linhagem de mosquito Aedes albopictus. Os fragmentos dos tecidos foram processados seguindo técnicas padrão para análises em microscopia de luz fotônica e microscopia eletrônica de transmissão. Na infecção primária pelos vírus dengue sorotipos 1 e 2, análises morfológicas e morfométricas revelaram alterações focais em tecido hepático tais como hepatócitos alterados, presença de células inflamatórias nos capilares sinusoidais e no espaço perivascular da veia portal, recrutamento de plaquetas e hemorragia interstical. Em animais infectados com vírus dengue sorotipo 2, o antígeno do vírus dengue foi detectado em hepatócitos e no endotélio dos capilares da área da veia centrolobular e em animais infectados com vírus dengue sorotipo 1, partículas semelhantes ao vírus dengue foram observadas no citoplasma das células de Kupffer. Testes de função hepática demonstraram altos níveis das aminotransferases aspartato e alanina. Análises do tecido pulmonar evidenciaram pneumonia interstical caracterizada pela presença de células inflamatórias e plaquetas nos capilares, focos de hemorragia, fibroblastos produzindo elastina, células endoteliais exibindo numerosas vesículas citoplasmáticas e filopódios na membrana citoplasmática. O vírus dengue foi detectado em células...dengue.

Histopathological and ultrastructural aspects of mice lungs experimentally infected with dengue virus serotype 2

Histological and ultrastructural alterations in lung tissue of BALB/c mice infected with dengue virus serotype 2 (non-neuroadapted), by intraperitoneal and intravenous routes were analyzed. Lung tissues were processed following the standard techniques for photonic and electron transmission microscopies. Histopathological and ultrastructural studies showed interstitial pneumonia, characterized by the presence of mononuclear cells. In the mouse model, the dengue virus serotype 2 seems to led to a transient inflammatory process without extensive damage to the interalveolar septa, but caused focal alterations of the blood-exchange barrier. Endothelial cells of blood capillaries exhibited phyllopodia suggesting activation by presence of dengue virus. Morphometrical analysis of mast cells showed an expressive increase of the number of these cells in peribronchiolar spaces and adjacent areas to the interalveolar septa. Alveolar macrophages showed particles dengue virus-like inside rough endoplasmic reticulum and Golgi complex, suggesting viral replication. The tissue alterations observed in our experimental model were similar to the observed in human cases of dengue fever and dengue hemorrhagic fever. Our results show that BALB/c mice are permissive host for dengue virus serotype 2 replication and therefore provides an useful model to study of morphological aspects of dengue virus infection.

Morphological studies in a model for dengue-2 virus infection in mice

One of the main difficulties in studying dengue virus infection in humans and in developing a vaccine is the absence of a suitable animal model which develops the full spectrum of dengue fever, dengue haemorrhagic fever, and dengue shock syndrome. It is our proposal to present morphological aspects of an animal model which shows many similarities with the dengue infection in humans. BALB/c mice were intraperitoneally infected with non-neuroadapted dengue virus serotype 2 (DENV-2). Histopathological and morphometrical analyses of liver tissue revealed focal alterations along the infection, reaching wide-ranging portal and centrolobular veins congestion and sinusoidal cell death. Additional ultrastructural observations demonstrated multifocal endothelial injury, platelet recruitment, and alterated hepatocytes. Dengue virus antigen was detected in hepatocytes and in the capillar endothelium of the central lobular vein area. Liver function tests showed high levels of aspartate transaminase and alanine transaminase enzyme activity. Lung tissue showed interstitial pneumonia and mononuclear cells, interseptal oedema, hyperplasia, and hypertrophy of the bronchiolar epithelial cells. DENV-2 led to a transient inflammatory process, but caused focal alterations of the blood-exchange barrier. Viremia was observed from 2nd to 11th day p.i. by isolation of DENV-2 in C6/36 mosquito cell line inoculated with the supernatant of macerated liver, lung, kidney, and cerebellum tissues of the infected mice.