Publicaciones científicas 2001

A role for ActA in epithelial cell invasion by Listeria monocytogenes

Cellular Microbiology 3(12):853-64.

     We assessed the role of the actin-polymerizing protein, ActA, in host cell invasion by Listeria monocytogenes. An in frame DeltaactA mutant was constructed in a hyperinvasive strain of prfA* genotype, in which all genes of the PrfA-dependent virulence regulon, including actA, are highly expressed in vitro. Loss of ActA production in prfA* bacteria reduced entry into Caco-2, HeLa, MDCK and Vero epithelial cells to basal levels. Reintroduction of actA into the DeltaactA prfA* mutant fully restored invasiveness, demonstrating that ActA is involved in epithelial cell invasion. ActA did not contribute to internalization by COS-1 fibroblasts and Hepa 1-6 hepatocytes. Expression of actA in Listeria innocua was sufficient to promote entry of this n… Leer más

Suarez M., Gonzalez-Zorn B., Vega Y., Chico I. y Vazquez-Boland JA.

Antimicrobial susceptibility of corynebacteria isolated from ewe`s mastitis

International Journal Of Antimicrobial Agents 18(6):571-4.

     The antimicrobial susceptibility of 50 coryneform isolates from subclinical mastitis in sheep was evaluated. Arcanobacterium pyogenes (five isolates) had a susceptibility pattern distinct from the Corynebacterium species tested. The Corynebacterium isolates could be divided in two groups according to the MIC values for ciprofloxacin. Their antimicrobial susceptibility was usually unpredictable and consequently antimicrobial susceptibility tests are necessary for clinical and epidemiological purposes… Leer más

Fernandez EP., Vela AI., Las Heras A., Dominguez L., Fernandez-Garayzabal JF. y Moreno MA.

Molecular typing by pulsed-field gel electrophoresis of Spanish animal and human Listeria monocytogenes isolates

Applied And Environmental Microbiology 67(12):5840-3.

     A total of 153 strains of Listeria monocytogenes isolated from different sources (72 from sheep, 12 from cattle, 18 from feedstuffs, and 51 from humans) in Spain from 1989 to 2000 were characterized by pulsed-field gel electrophoresis. The strains of L. monocytogenes displayed 55 pulsotypes. The 84 animal, 51 human, and 18 feedstuff strains displayed 31, 29, and 7 different pulsotypes, respectively, indicating a great genetic diversity among the Spanish L. monocytogenes isolates studied. L. monocytogenes isolates from clinical samples and feedstuffs consumed by the diseased animals were analyzed in 21 flocks. In most cases, clinical strains from different animals of the same flock had identical pulsotypes, confirming the existence of a list… Leer más

Vela AI., Fernandez-Garayzabal JF., Vazquez-Boland JA., Latre MV., Blanco MM., Moreno MA., de la Fuente I., Marco J., Franco CM., Cepeda A., Rodriguez AA., Suarez G. y Dominguez L..

Cellular distribution of bovine leukemia virus proteins gp51SU, Pr72(env), and Pr66(gag-pro) in persistently infected cells

Virus Research 79(1-2):47-57.

     Monoclonal antibodies (mAbs) against bovine leukemia virus (BLV) mature proteins and precursors were used to map the localization of these proteins in persistently infected non-lymphocytic cell lines using immunofluorescence assay (IFA) and immuno-electron microscopy. IFA staining was observed in the basolateral surface of live FLK-BLV cells. When using a mAb against Pr66(gag-pro), mottled pinpoint fluorescence was seen in the cell surface of polarized cells, but no reaction was observed in cells undergoing mitosis. However, a mAb against Pr72(env) stained only mitotic cells and cellular fragments. Additionally, in these dividing cells, this envelope (Env) precursor polyprotein was not evenly distributed but concentrated predominantly in on… Leer más

Llames L., Goyache J., Domenech A., Montana AV., Suarez G. y Gomez-Lucia E.

Lactococcus lactis subsp. lactis infection in waterfowl: first confirmation in animals

Emerging Infectious Diseases 7(5):884-6.

     We report the first description, confirmed by bacteriologic and molecular (polymerase chain reaction and pulsed-field gel electrophoresis) analysis, of an infection in animals caused by Lactococcus lactis subsp. lactis, affecting waterfowl.

Until recently, members of the genus Lactococcus were considered opportunistic pathogens (1,2). They are often misidentified as enterococci or streptococci (3,4), and the difficulties in correctly identifying them have probably hindered elucidation of their clinical significance. However, the number of clinical cases associated with infections by these microorganisms has increased in the last decade in both humans and animals (5-7). Lactococcus lactis subsp. lactis, L. piscium, and L. garv… Leer más

Goyache J., Vela AI., Gibello A., Blanco MM., Briones V., Gonzalez S., Tellez S., Ballesteros C., Dominguez L. y Fernandez-Garayzabal JF..

Identification and mutagenesis by allelic exchange of choE, encoding a cholesterol oxidase from the intracellular pathogen Rhodococcus equi

Journal Of Bacteriology 183(16):4796-805.

     The virulence mechanisms of the facultative intracellular parasite Rhodococcus equi remain largely unknown. Among the candidate virulence factors of this pathogenic actinomycete is a secreted cholesterol oxidase, a putative membrane-damaging toxin. We identified and characterized the gene encoding this enzyme, the choE monocistron. Its protein product, ChoE, is homologous to other secreted cholesterol oxidases identified in Brevibacterium sterolicum and Streptomyces spp. ChoE also exhibits significant similarities to putative cholesterol oxidases encoded by Mycobacterium tuberculosis and Mycobacterium leprae. Genetic tools for use with R. equi are poorly developed. Here we describe the first targeted mutagenesis system available for this ba… Leer más

Navas J., Gonzalez-Zorn B., Ladron N., Garrido P. y Vazquez-Boland JA.

Evaluation of virus excretion by cells persistently infected with the bovine leukaemia virus (BLV) using monoclonal antibodies

Journal Of Clinical Virology 22(1):31-9.

     Bovine leukaemia virus (BLV) is the causative agent of enzootic bovine leukaemia. Studies in vitro usually require the use of infected cell lines, mostly to produce antigen. Two of the most widely used cell lines are FLK-BLV and BLV-bat2. OBJECTIVE: the dynamics of the excretion of BLV proteins and whole virus by the persistently BLV-infected cell lines mentioned above was studied using an indirect ELISA in combination with eight monoclonal antibodies (mAbs) and cow and rabbit serum. STUDY DESIGN: tissue culture flasks were seeded with different concentrations of cells (13000-67000 cells per cm2, corresponding to 1-5 million cells per 75 cm2 flask) and were studied for 20 days. Samples (1.5 ml) were removed every 24 h and the presence of BL… Leer más

Llames L., Goyache J., Domenech A., Arjona A., Suarez G. y Gomez-Lucia E.

Listeria pathogenesis and molecular virulence determinants

Clinical Microbiology Reviews 14(3):584-640.

     The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis d… Leer más

Vazquez-Boland JA., Kuhn M., Berche P., Chakraborty T., Dominguez-Bernal G., Goebel W., Gonzalez-Zorn B., Wehland J. y Kreft J.

Pathogenicity islands and virulence evolution in Listeria

Microbes And Infection 3(7):571-84.

     As in other bacterial pathogens, the virulence determinants of Listeria species are clustered in genomic islands scattered along the chromosome. This review summarizes current knowledge about the structure, distribution and role in pathogenesis of Listeria virulence loci. Hypotheses about the mode of acquisition and evolution of these loci in this group of Gram-positive bacteria are presented and discussed… Leer más

Vazquez-Boland JA., Dominguez-Bernal G., Gonzalez-Zorn B., Goebel W. y Kreft J.

Antimicrobial susceptibility of Listeria monocytogenes isolated from meningoencephalitis in sheep

International Journal Of Antimicrobial Agents 17(3):215-20.

     The antimicrobial susceptibility to different antimicrobial agents of 41 Listeria monocytogenes strains isolated from sheep with meningoencephalitis and from feedstuff was tested by both microdilution and disk diffusion methods. Both sets of isolates of L. monocytogenes were susceptible to penicillin G, amoxicillin, cephalothin, erythromycin, vancomycin, rifampicin, gentamicin, kanamycin, trimethoprim, sulfisoxazole, chloramphenicol and ciprofloxacin, but resistant to tetracycline and doxycycline (7.3 and 4.9%, respectively). Tetracycline was the most frequent resistance trait in L. monocytogenes strains of animal origin. Four strains (9.8%) also exhibited reduced susceptibility (MIC 4 mg/l) to doxycycline suggesting the need of surveillanc… Leer más

Vela AI., Fernandez-Garayzabal JF., Latre MV., Rodriguez AA., Dominguez L. y Moreno MA.

Avian pox infection in Spanish Imperial eagles (Aquila adalberti)

Avian Pathology: Journal Of The W.V.P.A 30(1):91-97.

     A cutaneous lesion, previously known as "warts", affecting the featherless parts of face and legs has long been recognized in juvenile Spanish Imperial eagles (Aquila adalberti). This paper describes the presentation, microbiological, histopathological, and electron microscopic findings of lesions and diagnosis of poxvirus infection in nine juveniles. Lesions consisted of single or multiple nodules with a crust and surrounded by skin swelling. Seventy-eight percent of the swabs taken from lesions yielded bacterial growth, with Escherichia coli being the most common bacterium isolated. Histopathology revealed typical pox lesions in all cases. Histopathological changes found consisted of proliferative epithelium, with ballooning degeneration … Leer más

Hernandez M., Sanchez C., Galka M., Dominguez L., Goyache J., Oria J. y Pizarro M.

Immunodiagnosis of bovine tuberculosis. Summary of a satellite workshop of the Mycobacterium bovis 2000 conference, Cambridge, UK, 17 August 2000

Tuberculosis (Edinburgh, Scotland) 81(1-2):177-80.

Vordermeier M., Aranaz A. y Pollock JM.