42 research outputs found
Antigenic behaviour of several Aujeszky's disease viral strains
Desde que la Enfermedad de Aujeszky fue diagnosticada por primera vez en Argentina en 1978, fueron sucedi茅ndose numerosos brotes en diferentes lugares del pa铆s. El objetivo de este trabajo fue comparar diferentes cepas del virus de la Pseudorrabia porcina. Para ello utilizamos 5 cepas argentinas (3 aisladas en nuestro laboratorio) y 4 de referencia internacional. Las mismas fueron caracterizadas mediante pruebas f铆si- co-qu铆micas; sus prote铆nas comparadas por electroforesis en SDS-PAGE; su antigenicidad fue comparada al evaluar los 9 antisueros producidos en ratas mediante un sistema de virus neutralizaci贸n cruzada y ELISA indirecto cruzado. Las pruebas f铆sico-qu铆micas permitieron observar peque帽as diferencias de comportamiento de las cepas virales frente a diferentes variables tales como pH, calor, acci贸n de la tripsina, 茅ter y cloroformo, las que en ning煤n caso aportan datos concluyentes que permitan observar diferencias significativas. El estudio de la movilidad de las prote铆nas estructurales de los virus en geles de poliacrilamida tampoco arroj贸 datos de importancia y result贸 insuficiente para distinguirlos. El uso de la prueba de virus neutralizaci贸n cruzada para estudiar su antigenicidad, en cambio, mostr贸 resultados que permitieron comprobar que las cepas argentinas produjeron t铆tulos neutralizantes m谩s elevados que las extranjeras.Since Aujeszky's Disease was first recognized in Argentina in 1978, many outbreaks occurred in different places in our country. Nine Pseudorabies virus strains, 5 Argentine -3 of them isolated in our laboratory- and 4 reference ones, were characterized by physicochemical, SDS-PAGE, virus neutralization and ELISA methods. Using trypsin, heat, ether, chloroform and pH in physicochemical analysis, only small differences were observed, as well as when the viral structural proteins were compared by SDS-PAGE. Cross virus neutralization test using 9 antisera produced in rats, showed that Argentine Pseudorabies virus strains elicited higher antibodies titres than those obtained with reference ones.Facultad de Ciencias Veterinaria
Evaluation of a blocking ELISA using a urease conjugate for the detection of antibodies to pseudorabies virus
A blocking enzyme-linked immunosorbent assay (ELISA) using a urease conjugate (U-B-ELISA) was evaluated for screening sera for antibodies to pseudorabies virus under field conditions, A total of 764 serum samples were analyzed by U-B-ELISA. Of these, 264 were evaluated by both virus neutralization and U-B-ELISA, and the results were compared. U-B-ELISA showed 98.5% and 98.9% sensitivity and specificity, respectively. This test combines the sensitivity and specificity of the blocking ELISA format while allowing visual assessment of results.Facultad de Ciencias Veterinaria
Evaluation of a blocking ELISA using a urease conjugate for the detection of antibodies to pseudorabies virus
A blocking enzyme-linked immunosorbent assay (ELISA) using a urease conjugate (U-B-ELISA) was evaluated for screening sera for antibodies to pseudorabies virus under field conditions, A total of 764 serum samples were analyzed by U-B-ELISA. Of these, 264 were evaluated by both virus neutralization and U-B-ELISA, and the results were compared. U-B-ELISA showed 98.5% and 98.9% sensitivity and specificity, respectively. This test combines the sensitivity and specificity of the blocking ELISA format while allowing visual assessment of results.Facultad de Ciencias Veterinaria
Ensaladas listas para consumo. An谩lisis de condiciones de higiene y seguridad
Cincuenta ensaladas listas para consumo compradas en mercados de La Plata (Argentina) fueron analizadas microbiol贸gicamente. Se ha encontrado que el 88% ten铆an un promedio de 540 ufc/g de bacterias coliformes fecales, 64% ten铆an Escherichia coli. Ning煤n aislamiento de E.coli O:157H:7 fue logrado. Por otro lado s贸lo se logr贸 un aislamiento de Listeria monocytogenes tipo 4 (2%). Por consiguiente, el 88% de las ensaladas cortadas frescas no se encontr贸 en condiciones de higiene y seguridad requeridas para el consumo humano.Fifty ready to eat salads bought in markets in La Plata (Argentina) have been microbiologically analyzed. It has been found that 88% had an average of 540 cfu/g faecal coliform bacteria, 64% had Escherichia coli. No isolation of E.coli O:157H:7 was achieved. On the other hand there was only one isolation of Listeria monocytogenes type 4 (2%). Therefore 88 % of fresh cut salad did not meet the health and safety conditions required for human consumption.Facultad de Ciencias Veterinaria
Isolation of <i>Clostridium piliformis</i> from mice colonies in Argentina
Para el presente estudio se utilizaron 30 ratones BALB/c, provenientes de 6 colonias comerciales positivas para la enfermedad de Tyzzer. Los animales se inmunodeprimieron con cortisona, observ谩ndose s铆ntomas de la enfermedad entre los 3 o 4 d铆as posteriores. Se realiz贸 un homogeinato a partir de los h铆gados e intestinos que presentaban necrosis, el cual se inocul贸 a ratones SPF de los cuales se reaisl贸 el Clostridium piliformis Para su diagn贸stico se us贸 la prueba de IFA y la morfolog铆a de la bacteria se observ贸 con coloraci贸n de Giemsa. Mediante esta infecci贸n experimental se reaisl贸 CIostridium piliformis, confirm谩ndose su presencia como agente infeccioso en colonias de ratones en Argentina.In this study 30 Balb/c mice from 6 commercial colonies, which were positive for Tyzzer disease (Bacillus piliformis) were immunodepressed with cortisone. Clinical symptoms of the disease were observed between days 3 and 4 after inoculation An homogenate was prepared with necrotic livers and intestines of mice and inoculated i.v. to SPF Balb/c strain from which Clostridium piliformis was isolated. The microorganism was identified by using IFA assay and the morphology by Giemsa staining. The infection with Clostridium piliformis in mice colonies in Argentina, was confirmed.Facultad de Ciencias Veterinaria
An outbreak of <i>Bordetella bronchiseptica</i> in a Long Evans rat colony
Bordetella brohisseptica es un germen pat贸geno, el cual debe estar ausente de las colonias de ratas y cobayos de experimentaci贸n, ya que puede interferir en los resultados finales cuando se utilizan estos animales para realizar pruebas de diagn贸stico, investigaci贸n y/o control de calidad. El presente trabajo describe un brote severo de esta enfermedad en una colonia convencional de ratas long Evans. Se estudiaron 18 animales de los cuales 5 presentaban sintomatolog铆a respiratoria. Para realizar el diagn贸stico se tomaron muestras de tr谩quea y pulm贸n y se cultivaron en agar Bordet Gengou, agar sangre agar DHL y caldo PPLO. Se realiz贸 coloraci贸n de Gram, pruebas bioqu铆micas y pruebas serol贸gicas (microaglutinaci贸n y aglutinaci贸n). Los resultados fueron positivos para Bordetella bronchiseptica. Se concluy贸 que dada la magnitud de las p茅rdidas e inconvenientes que produce esta infecci贸n en colonias de ratas y cobayos es aconsejable el establecimiento de medidas sanitarias y de controles microbiol贸gicos estrictos en los bioterios.Bordetella bronchiseptica is a pathogen which must be absent in experimental rats and guinea pigs colonies, since it produces interference in the results. This study describes a severe outbreak of this disease in a Long Evans rat colony. Eighteen animals, five of which showed symptoms were studied. For diagnosis, after necropsy, samples of trachea and lungs were cultured in Bordet Gengou Agar, Blood Agar, DHL agar and PPLO broth. Gram stained, biochemical tests and microagglutination and agglutination tests were performed. The results showed a contamination with Bordetella bronchiseptica. This study demonstrates the importance of establishing sanitary procedures and an appropriate quality control program of experimental animals in conventional facilities.Facultad de Ciencias Veterinaria
Isolation of <i>Clostridium piliformis</i> from mice colonies in Argentina
Para el presente estudio se utilizaron 30 ratones BALB/c, provenientes de 6 colonias comerciales positivas para la enfermedad de Tyzzer. Los animales se inmunodeprimieron con cortisona, observ谩ndose s铆ntomas de la enfermedad entre los 3 o 4 d铆as posteriores. Se realiz贸 un homogeinato a partir de los h铆gados e intestinos que presentaban necrosis, el cual se inocul贸 a ratones SPF de los cuales se reaisl贸 el Clostridium piliformis Para su diagn贸stico se us贸 la prueba de IFA y la morfolog铆a de la bacteria se observ贸 con coloraci贸n de Giemsa. Mediante esta infecci贸n experimental se reaisl贸 CIostridium piliformis, confirm谩ndose su presencia como agente infeccioso en colonias de ratones en Argentina.In this study 30 Balb/c mice from 6 commercial colonies, which were positive for Tyzzer disease (Bacillus piliformis) were immunodepressed with cortisone. Clinical symptoms of the disease were observed between days 3 and 4 after inoculation An homogenate was prepared with necrotic livers and intestines of mice and inoculated i.v. to SPF Balb/c strain from which Clostridium piliformis was isolated. The microorganism was identified by using IFA assay and the morphology by Giemsa staining. The infection with Clostridium piliformis in mice colonies in Argentina, was confirmed.Facultad de Ciencias Veterinaria
An outbreak of <i>Bordetella bronchiseptica</i> in a Long Evans rat colony
Bordetella brohisseptica es un germen pat贸geno, el cual debe estar ausente de las colonias de ratas y cobayos de experimentaci贸n, ya que puede interferir en los resultados finales cuando se utilizan estos animales para realizar pruebas de diagn贸stico, investigaci贸n y/o control de calidad. El presente trabajo describe un brote severo de esta enfermedad en una colonia convencional de ratas long Evans. Se estudiaron 18 animales de los cuales 5 presentaban sintomatolog铆a respiratoria. Para realizar el diagn贸stico se tomaron muestras de tr谩quea y pulm贸n y se cultivaron en agar Bordet Gengou, agar sangre agar DHL y caldo PPLO. Se realiz贸 coloraci贸n de Gram, pruebas bioqu铆micas y pruebas serol贸gicas (microaglutinaci贸n y aglutinaci贸n). Los resultados fueron positivos para Bordetella bronchiseptica. Se concluy贸 que dada la magnitud de las p茅rdidas e inconvenientes que produce esta infecci贸n en colonias de ratas y cobayos es aconsejable el establecimiento de medidas sanitarias y de controles microbiol贸gicos estrictos en los bioterios.Bordetella bronchiseptica is a pathogen which must be absent in experimental rats and guinea pigs colonies, since it produces interference in the results. This study describes a severe outbreak of this disease in a Long Evans rat colony. Eighteen animals, five of which showed symptoms were studied. For diagnosis, after necropsy, samples of trachea and lungs were cultured in Bordet Gengou Agar, Blood Agar, DHL agar and PPLO broth. Gram stained, biochemical tests and microagglutination and agglutination tests were performed. The results showed a contamination with Bordetella bronchiseptica. This study demonstrates the importance of establishing sanitary procedures and an appropriate quality control program of experimental animals in conventional facilities.Facultad de Ciencias Veterinaria
Extended phylogeny of the equine arteritis virus sequences including South American sequences
Objective: To perform genetic analysis of the ORF5 of equine arteritis virus (EAV) may provide new insights into the genetic evolution and origin of the Argentinean EAV sequences. Methods: A total of 76 sequences were analyzed by neighbor joining (NJ), maximum parsimony and maximum likelihood algorithms. The analysis of the selective pressures was performed using the Tajima's test. Results: The trees showed similar topologies. Two clades were identified: the first clade was formed by strains isolated mainly from a donkey, whereas the second clade presented four large groups from different geographic regions exclusively from Equus caballus. In this clade, we identified a group formed by South African and another one by South American and European sequences. In the latter, the monophyletic group was formed by seven Argentinean sequences. In the NJ tree, we identified a group formed by six Argentinean sequences. The Tajima's test showed a D value of 1.73663, indicating that the sequences analyzed follow a neutral evolution model. Conclusion: We concluded that the Argentinean sequences have a paraphyletic origin and that the fixation of point mutation might follow the neutral model evolution; however, we identified purifying pressures that may be involved in the differentiation of the EAV sequences.Facultad de Ciencias Veterinaria
Extended phylogeny of the equine arteritis virus sequences including South American sequences
Objective: To perform genetic analysis of the ORF5 of equine arteritis virus (EAV) may provide new insights into the genetic evolution and origin of the Argentinean EAV sequences. Methods: A total of 76 sequences were analyzed by neighbor joining (NJ), maximum parsimony and maximum likelihood algorithms. The analysis of the selective pressures was performed using the Tajima's test. Results: The trees showed similar topologies. Two clades were identified: the first clade was formed by strains isolated mainly from a donkey, whereas the second clade presented four large groups from different geographic regions exclusively from Equus caballus. In this clade, we identified a group formed by South African and another one by South American and European sequences. In the latter, the monophyletic group was formed by seven Argentinean sequences. In the NJ tree, we identified a group formed by six Argentinean sequences. The Tajima's test showed a D value of 1.73663, indicating that the sequences analyzed follow a neutral evolution model. Conclusion: We concluded that the Argentinean sequences have a paraphyletic origin and that the fixation of point mutation might follow the neutral model evolution; however, we identified purifying pressures that may be involved in the differentiation of the EAV sequences.Facultad de Ciencias Veterinaria