RESUMO
In this study we investigated the activity of halogeno-, cyano- and amidino-isoflavenes, isoflavans and flavans on the multiplication of human astroviruses. These are naked small round viruses which have been recognized as causative agents of human gastroenteritis, and whose capsid proteins are similar to those of picornaviruses. Although all drugs tested caused a dose-dependent reduction of viral antigen synthesis as monitored by immunofluorescence, the chloro derivatives were the most effective.
Assuntos
Antivirais/farmacologia , Flavonoides/farmacologia , Isoflavonas/farmacologia , Mamastrovirus/efeitos dos fármacos , Viroses/tratamento farmacológico , Vírus não Classificados/efeitos dos fármacos , Animais , Antígenos Virais/imunologia , Linhagem Celular , Imunofluorescência , Mamastrovirus/crescimento & desenvolvimento , Mamastrovirus/imunologia , CoelhosRESUMO
We investigated the effect of different polyions on the early phases of SA-11 rotavirus infection in susceptible LLC-MK2 cells in order to clarify the influence of electrostatic interactions in rotavirus binding to cell membranes and to select antiviral compounds able to prevent viral attachment. When added during the viral attachment step, polymers having positive charge (protamine, protamine sulphate, DEAE-dextran, histone and poly-L-lysine hydrobromide) enhanced virus infection whereas those having negative charge (mucin, heparin, heparan sulphate, alpha-1-acid glycoprotein and dextran sulphate) inhibited the viral replication. The effect of polyanions on SA-11 rotavirus and on cell membrane receptors has also been examined. Results obtained indicated that while mucin and alpha-1-acid glycoprotein act directly on virus particles, the target of heparin, heparan sulphate and dextran sulphate is the host cell membrane.
Assuntos
Polímeros/farmacologia , Rotavirus/efeitos dos fármacos , Adsorção , Animais , Ânions , Sítios de Ligação , Cátions , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Haplorrinos , Rotavirus/patogenicidade , Rotavirus/fisiologia , Replicação Viral/efeitos dos fármacosRESUMO
The effect of different saturated fatty acids from 10 to 16 carbon atom chains and some derivatives on the infectivity of SA-11 rotavirus was examined. Both fatty acids and derivatives induced an increase of rotavirus infected LLC-MK2 cells when present during viral absorption to host cells. Capric acid and palmitic acid were the most effective with a dose-dependent relationship. These last lipids, in the same experimental conditions, failed to restore the susceptibility to infection of LLC-MK2 cells made resistant by neuraminidase treatment or to allow cell infection by non-infectious single-shelled viral particles. Results obtained suggest that the enhancing effect on viral infectivity by saturated fatty acids requires previous binding of rotaviral outer capsid proteins to sialic acid containing cell receptors.
Assuntos
Ácidos Graxos/farmacologia , Rim/virologia , Rotavirus/efeitos dos fármacos , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Membrana Celular/metabolismo , Relação Dose-Resposta a Droga , Imunofluorescência , Rim/citologia , Macaca , Neuraminidase/farmacologia , Rotavirus/fisiologia , Vírion/metabolismo , Replicação Viral/efeitos dos fármacosRESUMO
During the period May 1987-January 1989, faecal samples from 417 paediatric inpatients admitted to the main paediatric hospital in Rome were screened by direct electron microscopy and rotavirus enzyme-linked immunosorbent assay. Rotaviruses were detected in 18.2% of cases and adenoviruses in 7%, whereas astroviruses were found in 1% of cases. Different percentages of rotavirus excretors were revealed by enzyme-linked immunosorbent assay and electron microscopy. This discrepancy seems to be due to false positive results introduced by enzyme-linked immunosorbent assay. Analysis of electron microscopy-positive samples by rotaviral RNA polyacrylamide gel electrophoresis showed different electropherotypes of rotavirus among which a single, largely predominant long electropherotype (55.4%) was revealed. Short electropherotype subgroup I rotaviruses were demonstrated in about 10.7% of samples.
Assuntos
Diarreia/microbiologia , Viroses/diagnóstico , Infecções por Adenovirus Humanos/diagnóstico , Pré-Escolar , Diarreia Infantil/microbiologia , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Humanos , Lactente , Recém-Nascido , Mamastrovirus/genética , Mamastrovirus/isolamento & purificação , Microscopia Eletrônica , Infecções por Picornaviridae/diagnóstico , RNA Viral/genética , Cidade de Roma/epidemiologia , Infecções por Rotavirus/diagnóstico , Sensibilidade e Especificidade , Viroses/epidemiologiaRESUMO
During the period May 1993-April 1994, an epidemiological survey was conducted on enteric viruses which cause gastroenteritis in infants and young children in Tirana, Albania. Specimens from 321 cases were screened by direct electron microscopy and by an enzyme-linked immunosorbent assay specific for rotavirus group A antigen. By ultrastructural analysis, rotaviruses were detected in 10.3% of cases and adenoviruses in 0.6%, whereas small round structured viruses and small round viruses were found in 2.8% and 2.2% of cases, respectively. Different percentages of rotavirus excretors were revealed by enzyme-linked immunosorbent assay (12.15%) and electron microscopy. Samples rotavirus-positive in at least one of these assays were also analyzed by agglutination of latex particles and electron microscopy results were confirmed. Analysis of electron microscopy-positive samples by rotaviral RNA polyacrylamide gel electrophoresis showed five different long electropherotypes of rotavirus among which a single, largely predominant electropherotype (65.5%) was observed.
Assuntos
Diarreia Infantil/epidemiologia , Gastroenterite/epidemiologia , Infecções por Rotavirus/epidemiologia , Viroses/epidemiologia , Adenoviridae/isolamento & purificação , Albânia/epidemiologia , Antígenos Virais/isolamento & purificação , Pré-Escolar , Diarreia Infantil/virologia , Ensaio de Imunoadsorção Enzimática , Fezes/virologia , Gastroenterite/virologia , Inquéritos Epidemiológicos , Humanos , Lactente , Recém-Nascido , RNA Viral/isolamento & purificação , Rotavirus/isolamento & purificação , Vírus/isolamento & purificaçãoRESUMO
The effect of a mixed poliovirus-rotavirus infection in HT-29 cells, a gut tumour derived cell line highly susceptible to both viruses, has been analyzed. The obtained results showed an increase of poliovirus multiplication in cells super-infected or co-infected with rotavirus, whereas the pre-infection with poliovirus had an interfering effect on rotavirus replication.
Assuntos
Poliovirus/fisiologia , Rotavirus/fisiologia , Antígenos Virais/biossíntese , Humanos , Poliovirus/imunologia , Rotavirus/imunologia , Células Tumorais Cultivadas , Replicação ViralRESUMO
Astroviruses are intestinal pathogens associated with gastroenteritis in man and animals. The mechanism of internalization into host cells has not been reported previously. The cell entry pathway of serotype 1 human astrovirus into 293 cell line was studied biochemically and morphologically. Viral infection was monitored by indirect immunofluorescence. Infected cells were treated with the lysosomotropic agents ammonium chloride, methylamine, and dansylcadaverine or the ionophore monensin to raise the intraendosomal and intralysosomal pH. All drugs tested inhibited the early stages of infection whereas they did not interfere with the viral binding to the plasma membrane. The presence of astrovirus particles was detected by electron microscopy in coated pits and later in coated vesicles. The data indicate adsorptive endocytosis as the most probable mechanism by which astroviruses enter susceptible cells.
Assuntos
Cloreto de Amônio/farmacologia , Cadaverina/análogos & derivados , Imunossupressores/farmacologia , Mamastrovirus/fisiologia , Metilaminas/farmacologia , Monensin/farmacologia , Replicação Viral/efeitos dos fármacos , Cadaverina/farmacologia , Linhagem Celular , Relação Dose-Resposta a Droga , Humanos , Mamastrovirus/efeitos dos fármacos , Microscopia EletrônicaRESUMO
An investigation of SA-11 rotavirus binding to human serum lipoproteins was carried out. Various subclasses of lipoproteins, purified by ultracentrifugal flotation, and apoproteins were tested for their activity in inhibiting viral infectivity and hemagglutination. All tested lipoprotein subclasses (very low, low and high density, lipoproteins; VLDL, LDL, HDL, HDL1) were shown to interact with SA-11 rotavirus: VLDL and LDL were the most active in preventing rotavirus replication, whereas HDL and HDL1 inhibited viral hemagglutination to a greater extent. Moreover, A1 and A2 apoproteins were effective towards both viral infectivity and hemagglutination. Results obtained are in agreement with a preferential interaction of VP7 or VP4 proteolytic products with low density lipoproteins and of VP8* with high density lipoproteins. Binding of SA-11 to lipoproteins or apoproteins was also quantified by an enzyme-linked immunosorbent assay procedure and lipoproteins-virus interaction was visualized by electron microscopy.
Assuntos
Lipoproteínas/metabolismo , Rotavirus/metabolismo , Animais , Apolipoproteínas/sangue , Apolipoproteínas/metabolismo , Linhagem Celular , Hemaglutinação por Vírus , Humanos , Técnicas In Vitro , Lipoproteínas/sangue , Lipoproteínas/classificação , Microscopia Eletrônica , Ligação Proteica , Receptores Virais/metabolismo , Rotavirus/ultraestrutura , Infecções por Rotavirus/etiologia , Infecções por Rotavirus/prevenção & controleRESUMO
Rotavirus infections were detected in 210 of 675 children with acute diarrhea admitted to a major pediatric hospital in Rome from January 1982 through December 1985. Most of the patients with rotavirus infections were admitted during the winter season in both 1982 and 1985, whereas during the two intermediate years, cases occurred in all months. Among 84 rotavirus samples examined, 14 different electropherotypes were recognized, 2 of which largely predominated over the others. The two electropherotypes were particularly frequent in the 2 epidemic years, altogether accounting for 70.2% of the samples typed, and circulated in distinct periods. None of the viruses showed a short pattern of electrophoretic migration of the genome, indicating a minor involvement of subgroup I rotaviruses in hospitalization-requiring diarrheas occurring in the area surveyed.
Assuntos
Diarreia Infantil/microbiologia , RNA Viral/análise , Infecções por Rotavirus/microbiologia , Rotavirus/classificação , Doença Aguda , Pré-Escolar , Diarreia Infantil/epidemiologia , Eletroforese em Gel de Poliacrilamida , Fezes/microbiologia , Humanos , Lactente , Recém-Nascido , RNA de Cadeia Dupla/análise , Cidade de Roma , Rotavirus/genética , Infecções por Rotavirus/epidemiologia , Estações do AnoRESUMO
The effect of a nonsteroidal antiinflammatory drug commercially available in eye drop form (sodium diclofenac) was assayed for its ability to affect biofilms formed by clinical Staphylococcus epidermidis isolates. Biofilms produced by one strain positive for a slime-associated antigen, suggested to be expressed by more virulent strains, was not affected by sodium diclofenac treatment. On the other hand, biofilm produced by the slime-positive, antigen-negative strain showed dramatic alterations already after short treatments with sodium diclofenac as reported for salicylate and other nonsteroidal drugs. Such results suggest further investigation of the possible use of sodium diclofenac drops in the treatment of ophthalmic infections in soft contact lens wearers.
Assuntos
Antibacterianos/farmacologia , Biofilmes , Lentes de Contato Hidrofílicas/microbiologia , Diclofenaco/farmacologia , Staphylococcus epidermidis/crescimento & desenvolvimento , Anti-Inflamatórios não Esteroides/farmacologia , Antígenos de Bactérias/análise , Aderência Bacteriana/efeitos dos fármacos , Microscopia Eletrônica de Varredura , Staphylococcus epidermidis/efeitos dos fármacosRESUMO
Rotavirus infection was demonstrated in 168 (29.3%) of 573 children hospitalized for acute diarrhoea in Rome between January 1982 and December 1984. Laboratory diagnosis of these infections was made by transmission electron microscopy and enzyme immunoassay techniques with an overall agreement of 91.3%. Astroviruses, adenoviruses and small round viruses were detected in the faeces of 36 patients (6.4%). Whereas in 1982 rotavirus positive patients were clustered in the winter and following spring, in the following years cases were recorded all year round. The median age of patients with rotavirus infections was 17, 10 and 11.5 months in 1982, 1983 and 1984, respectively. In addition, a smaller number of rotavirus positive cases were admitted in 1983 when compared to those admitted during the previous as well as the subsequent years. It is suggested that a herd immunity was induced in the population by epidemic spread of rotavirus in the first half of 1982.
Assuntos
Diarreia Infantil/epidemiologia , Infecções por Rotavirus/epidemiologia , Infecções por Adenovirus Humanos/diagnóstico , Infecções por Adenovirus Humanos/epidemiologia , Adenovírus Humanos/isolamento & purificação , Fatores Etários , Pré-Escolar , Diarreia/diagnóstico , Diarreia/epidemiologia , Diarreia/etiologia , Diarreia Infantil/diagnóstico , Diarreia Infantil/etiologia , Ensaio de Imunoadsorção Enzimática , Fezes/microbiologia , Humanos , Lactente , Mamastrovirus/isolamento & purificação , Cidade de Roma , Rotavirus/isolamento & purificação , Infecções por Rotavirus/diagnóstico , Estações do Ano , Viroses/diagnóstico , Viroses/epidemiologiaRESUMO
One hundred stool samples from children with acute diarrhoea were examined by six commercial latex and immunoenzymatic assays for the diagnosis of rotavirus infection in four different laboratories. Samples were also analyzed by solid-phase immune electron microscopy using a rabbit anti-group A rotavirus antiserum. With electron microscopy as a basis for comparison, sensitivity and specificity for the latex and ELISA assays varied from 91.1 to 92.9% and from 94.2 to 99.4%, respectively. Statistically significant differences were revealed in the confirmation rate of electron microscopy-negative samples between different commercial assays. Significant variability was also found between results obtained by the laboratories taking part in the study.