RESUMO
A combined non-selective enrichment-filtration technique was investigated for the isolation of Campylobacter spp. from clinical samples. In total, 479 samples were tested by direct culture, enrichment subculture and enrichment-filtration. The enrichment-filtration technique was used with both selective and non-selective media. Direct culture and enrichment subculture yielded 13 and seven isolates, respectively, while enrichment-filtration yielded 18 and 14 isolates on selective and non-selective agar, respectively. Thus, the combination of enrichment-filtration with selective agar produced a 38.5% increase in the number of isolates (p <0.05). All isolates were identified as Campylobacter jejuni.
Assuntos
Técnicas Bacteriológicas/métodos , Infecções por Campylobacter/microbiologia , Campylobacter/isolamento & purificação , Filtração/métodos , Secreções Corporais/microbiologia , Campylobacter/crescimento & desenvolvimento , Meios de Cultura , HumanosRESUMO
BACKGROUND: Identification of possible transmission of variant Creutzfeldt-Jakob disease (vCJD) via blood transfusion has caused concern over spread of the disease within the human population. We aimed to model iatrogenic spread to enable a comparison of transmission efficiencies of vCJD and bovine spongiform encephalopathy (BSE) and an assessment of the effect of the codon-129 polymorphism on human susceptibility. METHODS: Mice were produced to express human or bovine prion protein (PrP) by direct replacement of the mouse PrP gene. Since the human PrP gene has variation at codon 129, with MM, VV, and MV genotypes, three inbred lines with an identical genetic background were produced to express human PrP with the codon-129 MM, MV, and VV genotypes. Mice were inoculated with BSE or vCJD and assessed for clinical and pathological signs of disease. FINDINGS: BSE was transmitted to the bovine line but did not transmit to the human lines. By contrast, vCJD was transmitted to all three human lines with different pathological characteristics for each genotype and a gradation of transmission efficiency from MM to MV to VV. INTERPRETATION: Transmission of BSE to human beings is probably restricted by the presence of a significant species barrier. However, there seems to be a substantially reduced barrier for human-to-human transmission of vCJD. Moreover, all individuals, irrespective of codon-129 genotype, could be susceptible to secondary transmission of vCJD through routes such as blood transfusion. A lengthy preclinical disease is predicted by these models, which may represent a risk for further disease transmission and thus a significant public-health issue.
Assuntos
Amiloide/genética , Síndrome de Creutzfeldt-Jakob/transmissão , Encefalopatia Espongiforme Bovina/transmissão , Predisposição Genética para Doença , Precursores de Proteínas/genética , Animais , Transfusão de Sangue , Bovinos , Códon , Humanos , Doença Iatrogênica , Camundongos , Camundongos Transgênicos , Polimorfismo Genético , Proteínas Priônicas , Príons , Fatores de Risco , ZoonosesRESUMO
The neural membrane glycoprotein PrP is implicated in the pathogenesis of the transmissible spongiform encephalopathies; however, the normal function of PrP and its precise role in disease are not understood. Recently, gene targeting has been used to produce mice with neo/PrP fusion transcripts, but no detectable PrP protein in the brain (1). Here we report the use of a different targeting strategy, to produce inbred mice with a complete absence of both PrP protein and mRNA sequences. At 7 mo of age, these mice show no overt phenotypic abnormalities despite the normal high levels of expression of PrP during mouse development. The mice are being used in experiments designed to address the role of PrP in the pathogenesis of scrapie and the replication of infectivity.
