RESUMEN
Coxsackievirus B4 (CV-B4), in presence of antibodies and through a specific viral receptor CAR and Fcγ receptors II and III, can infect monocytes which results in interferon-α synthesis. The antibody-dependent enhancement of CV-B4 infection in the human monocytic-like THP-1 cell line has been investigated. The preincubation of CV-B4 with human plasma or human polyvalent immunoglobulins enhanced the infection of phorbol-myristate-acetate (PMA)-activated THP-1 cell cultures. CV-B4 replicated in these cells as demonstrated by the intracellular detection of infectious particles, viral protein VP1 (immunofluorescence), positive and negative viral RNA (RT-PCR). The viability of infected and control cell cultures was not different up to 20 days post-infection. Activated cell cultures inoculated with CV-B4 harbored intracellular RNA up to 14 days post-infection and produced IFNα that was detected by intracellular immunofluorescence staining as soon as 4 h post-infection with a maximum at 48 h post-infection and by RT-PCR all along the experiment. Together, these data demonstrate that PMA-activated THP-1 cells can be infected with CV-B4, can produce IFNα as a result of interactions between the virus, antibodies and specific receptors. This cellular model can be used to investigate further the mechanism and the result of the antibody-dependent enhancement of CV-B4 infection.
Asunto(s)
Enterovirus Humano B/inmunología , Inmunoglobulinas/farmacología , Monocitos/inmunología , Monocitos/virología , Células Cultivadas , Proteína de la Membrana Similar al Receptor de Coxsackie y Adenovirus/inmunología , Infecciones por Coxsackievirus/inmunología , Infecciones por Coxsackievirus/virología , Enterovirus Humano B/patogenicidad , Interacciones Huésped-Patógeno/efectos de los fármacos , Humanos , Interferón-alfa/biosíntesis , Interferón-alfa/inmunología , Espacio Intracelular/metabolismo , Espacio Intracelular/virología , Monocitos/efectos de los fármacos , Monocitos/metabolismo , Receptores de IgG/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Acetato de Tetradecanoilforbol/análogos & derivados , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
We studied the role of viruses and atypical bacteria in children hospitalized with exacerbated asthma by a prospective study of children with acute asthma admitted to the Department of Pediatrics in Lille, and to 15 hospitals in the Nord-Pas de Calais region, from October 1, 1998-June 30, 1999. We included children aged 2-16 years with active asthma, defined as three or more recurrent episodes of reversible wheezing. The severity of asthma and of asthmatic exacerbations was recorded. Immunofluorescence assays (IFA) on nasopharyngeal secretions (NPS), serological tests, or both, were used for detection of influenza virus, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, and coronavirus. Polymerase chain reaction (PCR) assays on NPS were used for rhinovirus and enterovirus. Serological tests for Chlamydia pneumoniae and Mycoplasma pneumoniae were performed. A control group of asymptomatic asthmatic outpatients was examined for respiratory viruses (using IFA and PCR). Eighty-two symptomatic children (mean age, 7.9 years) were examined. Viruses were detected in 38% (enterovirus, 15.8%; rhinovirus, 12%; RSV, 7.3%). Serological tests for atypical bacteria were positive in 10% of patients (C. pneumoniae, 5%; M. pneumoniae, 5%). Among the 27 control subjects (mean age, 7.9 years), one PCR was positive for enterovirus. There was no correlation between severity of chronic asthma or asthmatic exacerbations and the diagnosis of infection. Atypical bacterial pathogen infections were linked with prolonged asthmatic symptoms. In conclusion, we confirmed the high incidence of viral infection in acute exacerbations of asthma, especially enteroviruses or rhinoviruses. Persistent clinical features were more frequently associated with atypical bacterial infections, suggesting that these infections should be investigated and treated in cases of persistent asthmatic symptoms.
Asunto(s)
Asma/microbiología , Asma/virología , Chlamydophila pneumoniae/aislamiento & purificación , Chlamydophila pneumoniae/fisiología , Hospitalización , Mycoplasma pneumoniae/aislamiento & purificación , Mycoplasma pneumoniae/fisiología , Virus ARN/aislamiento & purificación , Virus ARN/fisiología , Adolescente , Factores de Edad , Asma/fisiopatología , Niño , Preescolar , Femenino , Francia , Humanos , Masculino , Estudios Prospectivos , Índice de Severidad de la EnfermedadRESUMEN
A Herpes Consensus allows the simultaneous detection of 6 human herpesviruses: herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), human cytomegalovirus (HCMV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and human herpes virus 6 (HHV-6). This technique was used first to examine retrospectively 100 DNA extracts from 95 CSF and 5 aqueous fluids, prepared by treatment by saturated NaCl followed by ethanol precipitation (n = 63) or by simple boiling (n = 37) and stored at -80 degrees C, and secondly to test prospectively 38 CSF samples for which two DNA extracts were prepared with commercially available DNA extraction kits. In all cases, the results were compared with those of an "in-house" PCR. Concordant results between both PCR and the Herpes Consensus techniques were obtained in 61 of 63 DNA extracts prepared by treatment by saturated NaCl (97%) and in only 31 of 37 boiled samples (84%). Both commercially available methods of DNA extraction examined appear to be suitable for Herpes Consensus PCR, although they cannot remove completely PCR inhibitors that must be sought in case of negative results. This preliminary study shows that the Herpes Consensus method should be of value for rapid diagnosis of herpesvirus infections on condition that it is performed on purified DNA extracts.