RESUMO
The bacterium Bacillus thuringiensis (Bt) produces parasporal crystals containing delta-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.
Assuntos
Bacillus thuringiensis , Proteínas de Bactérias/farmacologia , Toxinas Bacterianas/farmacologia , Sistema Digestório/efeitos dos fármacos , Endotoxinas/farmacologia , Inseticidas/farmacologia , Simuliidae/efeitos dos fármacos , Animais , Toxinas de Bacillus thuringiensis , Sistema Digestório/ultraestrutura , Proteínas Hemolisinas , Larva/efeitos dos fármacos , Larva/ultraestrutura , Microscopia Eletrônica , Controle Biológico de Vetores , Simuliidae/ultraestruturaRESUMO
The bacterium Bacillus thuringiensis (Bt) produces parasporal crystals containing delta-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.
Assuntos
Animais , Simuliidae , Bacillus thuringiensis , Sistema Digestório , Inseticidas , Microscopia Eletrônica , Controle Biológico de Vetores , LarvaRESUMO
Between June 4th and June 20th1996 rotavirus, adenovirus, and astrovirus (HAstrV) were investigated in fecal samples from 27 children under three years old with acute diarrhea, attending the Bertha Lutz day care center, in Rio de Janeiro. All fecal samples were analyzed by polyacrylamide gel electrophoresis (PAGE), reverse transcriptase polymerase chain reaction (RT-PCR), enzyme immunoassays (EIA), and electron microscopy (EM). Nine of them (33 percent) showed positive results for HAstrV by at least one of the employed methodologies. Eight were positive by RT-PCR and EIA, and six by EM. All positive samples were inoculated onto HT-29 (human colon adenocarcinoma) cultured cells for HAstrV isolation and seven were positive after three passages. The sequencing analysis of eight RT-PCR products (449 bp) from gene that codifies VP2 protein, showed a total nucleotide identity among them and 98 percent with HAstrV-1 (strain Oxford type 1). This is the first report of a gastroenteritis outbreak associated with HAstrv-1 in a day care center in Rio de Janeiro and it reinforces the importance of this virus in association with infantile acute gastroenteritis
Assuntos
Humanos , Lactente , Pré-Escolar , Creches , Surtos de Doenças , Gastroenterite , Infecções por Astroviridae/epidemiologia , Mamastrovirus , Brasil , Gastroenterite , Infecções por Astroviridae/complicações , Infecções por Astroviridae/diagnósticoRESUMO
Between June 4th and June 20th 1996 rotavirus, adenovirus, and astrovirus (HAstrV) were investigated in fecal samples from 27 children under three years old with acute diarrhea, attending the Bertha Lutz day care center, in Rio de Janeiro. All fecal samples were analyzed by polyacrylamide gel electrophoresis (PAGE), reverse transcriptase polymerase chain reaction (RT-PCR), enzyme immunoassays (EIA), and electron microscopy (EM). Nine of them (33%) showed positive results for HAstrV by at least one of the employed methodologies. Eight were positive by RT-PCR and EIA, and six by EM. All positive samples were inoculated onto HT-29 (human colon adenocarcinoma) cultured cells for HAstrV isolation and seven were positive after three passages. The sequencing analysis of eight RT-PCR products (449 bp) from gene that codifies VP2 protein, showed a total nucleotide identity among them and 98% with HAstrV-1 (strain Oxford type 1). This is the first report of a gastroenteritis outbreak associated with HAstrv-1 in a day care center in Rio de Janeiro and it reinforces the importance of this virus in association with infantile acute gastroenteritis.
Assuntos
Infecções por Astroviridae/epidemiologia , Creches , Surtos de Doenças , Gastroenterite/epidemiologia , Mamastrovirus/isolamento & purificação , Infecções por Astroviridae/complicações , Infecções por Astroviridae/diagnóstico , Brasil/epidemiologia , Pré-Escolar , Gastroenterite/diagnóstico , Gastroenterite/virologia , Humanos , LactenteRESUMO
This preliminary report describes human and cow cases of poxvirus that recently occurred in the State of Rio de Janeiro. The electron microscopic findings were consistent with parapoxviral and orthopoxviral infection. Orthopoxvirus strains were isolated from human and cow cases. Detailed viral characterization by means of genetical techniques is under investigation. Based on these informations, poxviral diseases should be also considered an emerging viral zoonosis that can affect human beings.
Assuntos
Doenças dos Bovinos/virologia , Bovinos/virologia , Orthopoxvirus/isolamento & purificação , Parapoxvirus/isolamento & purificação , Infecções por Poxviridae/veterinária , Adolescente , Adulto , Animais , Brasil , Humanos , Microscopia Eletrônica , Pessoa de Meia-Idade , Infecções por Poxviridae/transmissão , Infecções por Poxviridae/virologiaRESUMO
Viral replication, histopathological and ultrastructural changes were observed for a period of nine days in the small intestine of suckling mice infected with a simian rotavirus (SA11). Samples taken from duodenum, jejunum and ileum were prepared for light microscopy, transmission and scanning electron microscopy analysis. Histopathologic effect could be detected within 8 hr post-infection, when only a few altered cells were observed. Damage was extensive after 16 hr post-infection, showing swollen enterocytes and reduced and irregularly oriented microvilli at intestinal villi tips. Virus particles were detected at 16 and 48 hr post-infection, budding from the viroplasm into the rough endoplasmic reticulum cisternae in ileum enterocytes. Clear evidence of viral replication, observed by electron microscopy was not described before in heterologous murine models. Regeneration of the intestinal villi began at the third day post-infection. Despite some differences observed in clinical symptoms and microscopic analysis of homologous and heterologous rotavirus infections, we concluded that mechanisms of heterologous rotavirus infection in mice follow similar patterns to those observed in the homologous models.
Assuntos
Intestinos/virologia , Retrovirus dos Símios/ultraestrutura , Infecções por Rotavirus/virologia , Animais , Intestinos/fisiopatologia , Intestinos/ultraestrutura , Camundongos , Retrovirus dos Símios/crescimento & desenvolvimento , Retrovirus dos Símios/isolamento & purificação , Infecções por Rotavirus/patologia , Replicação ViralRESUMO
A presença de antígeno viral em cortes de tecidos humanos fixados em formol e emblocados em parafina foi demonstrada pela digestäo com tripsina foi demonstrada pela ingestäo com tripsina seguida de imunofluorescência direta ou indireta. Os espécimens podem ser utilizados para diagnoses retrospectivas. A técnica da imunofluorescência deve ser adaptada à infecçäo viral suspeita segundo diagnosie histopatológica prévia. Os parâmetros para a digestäo do tecido pela tripsina, relacionados à concentraçäo, duraçäo de atuaçäo e temperatura, expöem diferentes antígenos virais e devem ser previamente testados para cada sistema a ser estabelecido. Uma digestäo mais intensa deve ser aplicada para a detecçäo do vírus do sarampo em tecido pulmonar do que para adenovírus ou vírus respiratório sincicial no mesmo tecido. Por outro lado, o vírus da febre amarela em tecido de fígado necessita de uma digestäo mais fraca
Assuntos
Humanos , Imunofluorescência , Tripsina/metabolismo , Viroses/diagnóstico , Cultura de VírusRESUMO
Transmission electron microscopy has been employed for the rapid detection of mycoplasma in sera and cell cultures. High speed centrifugation of sera or low speed centrifugation of cell debris, followed by negative staining of the resuspended pellet, detected mycoplasma contamination more frequently than a culture method followed by direct fluorescence (DAPI), which was used as a control procedure. The appearance of the mycoplasma cell border and content gives some information about particle viability.
Assuntos
Sangue/microbiologia , Células Cultivadas/microbiologia , Mycoplasma/isolamento & purificação , Meios de Cultura , Microscopia EletrônicaRESUMO
The presence of viral antigen in sections from formalin-fixed and paraffin-embedded human tissues was demonstrated by trypsin digestion followed by direct or indirect immunofluorescence. The specimens may be used for retrospective diagnosis. The immunofluorescence technique has to be adapted to the suspected virus infection on the basis of previous histopathologic study. Variations of trypsin concentration time and temperature of incubation, expose different viral antigens and have to be previously tested for each unknown system. For measles virus detection in lung a stronger digestion has to be applied as compared to adenovirus or respiratory disease viruses in the same tissue. Flavivirus in liver tissue needs a weaker digestion. The reproducibility of the method makes it useful as a routine technique in diagnosis of virus infection.
Assuntos
Imunofluorescência , Tripsina/metabolismo , Viroses/diagnóstico , Humanos , Cultura de VírusRESUMO
Oral inoculation of newborn mice with the MET strain of human rotavirus produced transient diarrhoeal disease. Light and scanning electron microscopy showed typical rotavirus-induced morphological lesions in the villous epithelium of the small intestine consisting of extensive cytoplasmic vacuolation, villous necrosis and atrophy. Virus recovered from intestinal suspensions of infected mice showed the typical electrophoretic profile of the genome of the inoculated strain. Rotavirus antibody appeared in infected mice 10 to 20 days after inoculation but not in controls or nursing dams. The availability of a small animal model for experimental infection with human rotaviruses should prove useful for virulence and protection studies.