RESUMEN
Vellore, a region in southern India, has a high incidence of severe human infections with Beta-hemolytic group C and G streptococci (GCGS). To determine the causative species in these infections, we conducted 16S rRNA gene sequencing: Streptococcus dysgalactiae subsp. equisimilis (81%) and S. anginosus (19%) were the causative organisms in the 2-year study period (2006-2007). We used PCR to detect the virulence-related emm gene; results showed that it was restricted to S. dysgalactieae subsp. equisimilis isolates of 99.2% tested positive. Due to a novel marker, S. anginosus and S. constellatus can be quickly and accurately distinguished from other members of the genus. The notable contribution of the anginosus group to human infections suggests that this group of obligate pathogens deserves more attention in healthcare and research.
Asunto(s)
Infecciones Estreptocócicas/microbiología , Streptococcus anginosus , ADN Bacteriano/genética , Genes Bacterianos/genética , Marcadores Genéticos/genética , Humanos , India/epidemiología , Sistemas de Lectura Abierta/genética , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Infecciones Estreptocócicas/epidemiología , Streptococcus/genética , Streptococcus anginosus/genética , Streptococcus constellatus/genética , Factores de Virulencia/genéticaRESUMEN
A real-time quantitative PCR was developed to assess antiviral activity of molecules against human herpesvirus 8 (HHV-8) and the Epstein-Barr virus (EBV). The antiviral activity of the reference molecules acyclovir, ganciclovir, cidofovir, adefovir and brivudin, as assessed by this methodology, proved very similar to the activity as determined by a DNA-DNA hybridisation method.
Asunto(s)
Antivirales/farmacología , Citosina/análogos & derivados , Herpesvirus Humano 4/efectos de los fármacos , Herpesvirus Humano 8/efectos de los fármacos , Organofosfonatos , Aciclovir/farmacología , Antivirales/sangre , Línea Celular , Cidofovir , Citosina/farmacología , Ganciclovir/farmacología , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/inmunología , Herpesvirus Humano 8/genética , Herpesvirus Humano 8/inmunología , Humanos , Pruebas de Sensibilidad Microbiana , Compuestos Organofosforados/farmacología , Reacción en Cadena de la PolimerasaRESUMEN
Oral streptococci are a heterogeneous group of human commensals, with a potential to cause serious infections. Activation of plasminogen has been shown to increase the virulence of typical human pathogenic streptococci such as S. pneumoniae. One important factor for plasminogen activation is the streptococcal α-enolase. Here we report that plasminogen activation is also common in oral streptococci species involved in clinical infection and that it depends on the action of human plasminogen activators. The ability to activate plasminogen did not require full conservation of the internal plasminogen binding sequence motif FYDKERKVY of α-enolase that was previously described as crucial for increased plasminogen binding, activation and virulence. Instead, experiments with recombinant α-enolase variants indicate that the naturally occurring variations do not impair plasminogen binding. In spite of these variations in the internal plasminogen binding motif oral streptococci showed similar activation of plasminogen. We conclude that the pathomechanism of plasminogen activation is conserved in oral streptococci that cause infections in human. This may contribute to their opportunistic pathogenic character that is unfurled in certain niches.
Asunto(s)
Proteínas Bacterianas/metabolismo , Fosfopiruvato Hidratasa/metabolismo , Plasminógeno/metabolismo , Streptococcus/patogenicidad , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Sitios de Unión/genética , Electroforesis en Gel de Poliacrilamida , Fibrinolisina/metabolismo , Humanos , Immunoblotting , Datos de Secuencia Molecular , Boca/microbiología , Mutación , Fosfopiruvato Hidratasa/genética , Activadores Plasminogénicos/metabolismo , Unión Proteica , Homología de Secuencia de Aminoácido , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Infecciones Estreptocócicas/metabolismo , Infecciones Estreptocócicas/microbiología , Streptococcus/enzimología , Streptococcus/genética , Streptococcus oralis/enzimología , Streptococcus oralis/genética , Streptococcus oralis/patogenicidad , Virulencia/genéticaRESUMEN
The molecular mode of cell killing by the antiviral drug (E)-5-(2-bromovinyl-2'-deoxyuridine (BVDU) was studied in Chinese hamster ovary (CHO) cells stably transfected with the thymidine kinase gene (tk) of varicella zoster virus (CHO-VZVtk). The colony-forming ability of the cells was reduced to <1% at a concentration of approximately 1 microM BVDU, whereas for nontransfected cells or cells transfected with tk gene of herpes simplex virus type 1 (CHO-HSVtk), a 1000-fold higher dose was required to achieve the same response. BVDU inhibited thymidylate synthase in CHO-VZVtk but not in CHO-HSVtk and control cells. On the other hand, the drug was incorporated into DNA of VZVtk- and HSVtk-expressing cells to nearly equal amounts. Because coexposure of CHO-VZVtk cells to exogenous thymidine protected them from BVDU-induced cell killing, the cells obviously die because of thymidine depletion. At highly cytotoxic BVDU doses (50 microM) and longer exposure times (24-48 h), VZVtk cells were blocked to some extent in S and G2/M phase and underwent apoptosis (48-72 h). Not only apoptosis but also necrosis was induced. The findings also show that the drug causes the induction of c-Jun and the activation of activator protein-1 resulting in increased level of Fas ligand (FasL) and caspase-8/-3 activation. Bid and poly(ADP-ribose) polymerase were cleaved by caspases. Expression of Bax increased, whereas Bcl-2/Bcl-x(L) remained unchanged. Transfection of dominant-negative Fas-associated death domain and inhibition of caspase-8 by N-benzyloxycarbonyl-IETD-fluoromethyl ketone strongly abrogated BVDU-induced apoptosis, indicating Fas/FasL to be crucially involved. Thus, BVDU-triggered apoptosis differs significantly from that induced by ganciclovir, which induces in the same cellular background the mitochondrial damage pathway.