New enzyme-linked immunoassay for the detection of specific antibodies against multiple Leptospira serogroups in bovine sera.

Leptospirosis is a zoonotic disease with worldwide endemicity in Argentina, it is a significant public health problem in low-income populations. Bovine leptospirosis is a serious economic problem for cattle production, causing abortions, reduced milk yield, mortality in calves and decreased daily weight gain. We developed an enzyme-linked immunosorbent assay (ELISA) with sonicated Leptospira interrogans serogroup Icterohaemorrhagiae serovar Copenhageni M 20. We evaluated its performance for the detection of specific antibodies against multiple Leptospira serogroups in bovine. The microscopic agglutination test (MAT) was used as the gold standard. The performance of this ELISA was evaluated with a panel of sera (118 MAT confirmed positive and 97 MAT negative). The overall sensitivity was close to 85.6 % and the specificity was 83.5 %, according to the MAT reference method. Analytical specificity of the IgG-ELISA was evaluated using 50 bovine serum samples from animals showing serum antibodies against other pathogens that cause abortion in bovine, such as Brucella sp., Neospora sp. and Bovine Viral Diarrhea (BVD), and no cross-reaction was observed. This IgG-ELISA can be an alternative to the MAT for diagnosis of leptospiral infection in bovine.

Post-mortem findings in southern right whales Eubalaena australis at Península Valdés, Argentina, 2003-2012.

Between 2003 and 2012, 605 southern right whales (SRW; Eubalaena australis) were found dead along the shores of Península Valdés (PV), Argentina. These deaths included alarmingly high annual losses between 2007 and 2012, a peak number of deaths (116) in 2012, and a significant number of deaths across years in calves-of-the-year (544 of 605 [89.9%]; average = 60.4 yr(-1)). Post-mortem examination and pathogen testing were performed on 212 whales; 208 (98.1%) were calves-of-the-year and 48.0% of these were newborns or neonates. A known or probable cause of death was established in only a small number (6.6%) of cases. These included ship strike in a juvenile and blunt trauma or lacerations (n = 5), pneumonia (n = 4), myocarditis (n = 2), meningitis (n = 1), or myocarditis and meningitis (n = 1) in calves. Ante-mortem gull parasitism was the most common gross finding. It was associated with systemic disease in a single 1-2 mo old calf. Immunohistochemical labeling for canine distemper virus, Toxoplasma gondii and Brucella spp., and PCR for cetacean morbillivirus (CeMV), influenza A, and apicomplexan protozoa were negative on formalin-fixed, paraffin-embedded lung and brain samples from a subset of whales; PCR for Brucella spp. was positive in a newborn/neonate with pneumonia. Skin samples from whales with gull parasitism were PCR negative for CeMV, poxvirus, and papillomavirus. This is the first long-term study to investigate and summarize notable post-mortem findings in the PV SRW population. Consistent, significant findings within or between years to explain the majority of deaths and those in high-mortality years remain to be identified.

Detección de un complejo clonal con el genotipo de Brucella abortus biovariedad 2 como fundador en aislamientos de B. abortus de Argentina / Detection of a clonal complex with Brucella abortus biovar 2 genotype as founder in B. abortus isolates from Argentina

Brucella abortus es el agente causal de la brucelosis bovina, enfermedad zoonótica que se encuentra ampliamente distribuida en el mundo. Actualmente existen ocho biovariedades de B. abortus. En Argentina se encuentra con mayor frecuencia la biovariedad 1, pero también se suele aislar la biovariedad 2, que es más patogénica que la anterior. Resulta necesario contar con métodos de tipificación que tengan la resolución suficiente para permitir el seguimiento epidemiológico de los brotes de brucelosis y de los programas de control de la enfermedad. Debido a la gran homogeneidad genética que existe entre las distintas especies del género Brucella, ha sido dificultoso el desarrollo de herramientas moleculares para realizar el análisis epidemiológico de los aislamientos. La publicación del genoma de varias especies de Brucella facilitó el diseño de estas herramientas. El objetivo del presente trabajo fue emplear un esquema de análisis multilocus de VNTR en aislamientos de Argentina obtenidos en nuestro laboratorio. De los 56 aislamientos analizados se obtuvieron 47 perfiles genotípicos diferentes. El empleo de este esquema permitió asignarles a dichos aislamientos la biovariedad correspondiente. A través del análisis goeBURST se pudo relacionar a todos los genotipos entre sí, y además, proponer al genotipo de la biovariedad 2 como fundador.

Brucella abortus is the causative agent of bovine brucellosis, a worldwide zoonosis. Up to date, eight biovars of B. abortus have been described. In Argentina, biovar 1 is the most frequently isolated. However, biovar 2, which is more pathogenic than biovar 1, is also found. Molecular methods for subtyping isolates are necessary for allowing epidemiological surveillance and control of eradication programs. Due to the genetic homogeneity of the genus Brucella, the development of molecular typing tools has been difficult. The publication of microorganism genomes facilitates the design of this approach. The aim of this work was to employ a Multiple Locus VNTR Analysis (MLVA) scheme for strains from Argentina isolated in our laboratory. From the 56 isolates analyzed, 47 different genotypic profiles were obtained. All the strains typed as biovar 2 showed the same profile. This scheme allowed assigning each isolate to the biovar it belongs to. All the genotypes were related using the goeBURST analysis and biovar 2 was proposed as founder.

Detección de un complejo clonal con el genotipo de Brucella abortus biovariedad 2 como fundador en aislamientos de B. abortus de Argentina / Detection of a clonal complex with Brucella abortus biovar 2 genotype as founder in B. abortus isolates from Argentina

Brucella abortus es el agente causal de la brucelosis bovina, enfermedad zoonótica que se encuentra ampliamente distribuida en el mundo. Actualmente existen ocho biovariedades de B. abortus. En Argentina se encuentra con mayor frecuencia la biovariedad 1, pero también se suele aislar la biovariedad 2, que es más patogénica que la anterior. Resulta necesario contar con métodos de tipificación que tengan la resolución suficiente para permitir el seguimiento epidemiológico de los brotes de brucelosis y de los programas de control de la enfermedad. Debido a la gran homogeneidad genética que existe entre las distintas especies del género Brucella, ha sido dificultoso el desarrollo de herramientas moleculares para realizar el análisis epidemiológico de los aislamientos. La publicación del genoma de varias especies de Brucella facilitó el diseño de estas herramientas. El objetivo del presente trabajo fue emplear un esquema de análisis multilocus de VNTR en aislamientos de Argentina obtenidos en nuestro laboratorio. De los 56 aislamientos analizados se obtuvieron 47 perfiles genotípicos diferentes. El empleo de este esquema permitió asignarles a dichos aislamientos la biovariedad correspondiente. A través del análisis goeBURST se pudo relacionar a todos los genotipos entre sí, y además, proponer al genotipo de la biovariedad 2 como fundador.(AU)

Brucella abortus is the causative agent of bovine brucellosis, a worldwide zoonosis. Up to date, eight biovars of B. abortus have been described. In Argentina, biovar 1 is the most frequently isolated. However, biovar 2, which is more pathogenic than biovar 1, is also found. Molecular methods for subtyping isolates are necessary for allowing epidemiological surveillance and control of eradication programs. Due to the genetic homogeneity of the genus Brucella, the development of molecular typing tools has been difficult. The publication of microorganism genomes facilitates the design of this approach. The aim of this work was to employ a Multiple Locus VNTR Analysis (MLVA) scheme for strains from Argentina isolated in our laboratory. From the 56 isolates analyzed, 47 different genotypic profiles were obtained. All the strains typed as biovar 2 showed the same profile. This scheme allowed assigning each isolate to the biovar it belongs to. All the genotypes were related using the goeBURST analysis and biovar 2 was proposed as founder.(AU)

[Detection of a clonal complex with Brucella abortus biovar 2 genotype as founder in B. abortus isolates from Argentina]. / Detección de un complejo clonal con el genotipo de Brucella abortus biovariedad 2 como fundador en aislamientos de B. abortus de Argentina.

Brucella abortus is the causative agent of bovine brucellosis, a worldwide zoonosis. Up to date, eight biovars of B. abortus have been described. In Argentina, biovar 1 is the most frequently isolated. However, biovar 2, which is more pathogenic than biovar 1, is also found. Molecular methods for subtyping isolates are necessary for allowing epidemiological surveillance and control of eradication programs. Due to the genetic homogeneity of the genus Brucella, the development of molecular typing tools has been difficult. The publication of microorganism genomes facilitates the design of this approach. The aim of this work was to employ a Multiple Locus VNTR Analysis (MLVA) scheme for strains from Argentina isolated in our laboratory. From the 56 isolates analyzed, 47 different genotypic profiles were obtained. All the strains typed as biovar 2 showed the same profile. This scheme allowed assigning each isolate to the biovar it belongs to. All the genotypes were related using the goeBURST analysis and biovar 2 was proposed as founder.

Detección de un complejo clonal con el genotipo de Brucella abortus biovariedad 2 como fundador en aislamientos de B. abortus de Argentina. / [Detection of a clonal complex with Brucella abortus biovar 2 genotype as founder in B. abortus isolates from Argentina].

Brucella abortus is the causative agent of bovine brucellosis, a worldwide zoonosis. Up to date, eight biovars of B. abortus have been described. In Argentina, biovar 1 is the most frequently isolated. However, biovar 2, which is more pathogenic than biovar 1, is also found. Molecular methods for subtyping isolates are necessary for allowing epidemiological surveillance and control of eradication programs. Due to the genetic homogeneity of the genus Brucella, the development of molecular typing tools has been difficult. The publication of microorganism genomes facilitates the design of this approach. The aim of this work was to employ a Multiple Locus VNTR Analysis (MLVA) scheme for strains from Argentina isolated in our laboratory. From the 56 isolates analyzed, 47 different genotypic profiles were obtained. All the strains typed as biovar 2 showed the same profile. This scheme allowed assigning each isolate to the biovar it belongs to. All the genotypes were related using the goeBURST analysis and biovar 2 was proposed as founder.

Brucella alters endocytic pathway in J774 macrophages.

Brucella is a facultative intracellular bacterium which causes chronic infections in mammals by surviving and replicating within host cells. The putative role of the endoplasmic reticulum (ER) in the formation of the phagosome in non-professional phagocytes is supported by several research groups, but still leaves open the question of the fate of Brucella inside professional phagocytes and its resistance mechanisms therein. Macrophages are particularly important for the survival and spreading of Brucella during infection. The intracellular transport of Brucella in these cells has not been thoroughly characterized. To study the maturation process of Brucella-containing phagosomes in phagocytes, we comparatively monitored the intracellular transport of a virulent strain (2308) with two vaccine strains (S19 and RB51) in J 774 macrophages. Then, we compared the behavior of all three strains studied through transmission electron microscopy. The results indicate that the virulent strain not only occupies two different kinds of compartments but also alters the endocytic pathway of the cell it parasitizes, unlike what has been reported for non-professional phagocytes, like HeLa cell. Besides, differences are observed in the behavior of both Brucella abortus vaccine strains.

Buenos Aires, a new Leptospira serovar of serogroup Djasiman, isolated from an aborted dog fetus in Argentina.

This study describes the isolation of a new leptospiral serovar from the Djasiman group from an Argentinean aborted fetus of a dog. The strain was isolated from a culture of mixed liver and kidney tissue from one aborted dog fetus. Bitch's serum showed a titre of 1:800 against the new serovar and 1:400 or less against other serovars tested. Microscopic Agglutination test (MAT) with a panel of 38 rabbit anti-Leptospira sera representative for all pathogenic serogroups was performed to establish the putative serogroup of the isolated strain. Serovar identification was done by Cross-Agglutination Absorption Test (CAAT). Species determination was carried out on basis of sequence identity of primer pair G1/G2 generated PCR products from the isolate with those from reference strains belonging to the various pathogenic Leptospira species. Results showed that the new strain named, Baires, belongs to species L. interrogans sensu stricto and the serogroup Djasiman. However, the isolate could not be identified as any of the known serovars within this serogroup. These results allow us to conclude that the strain Baires represents a new serovar (Buenos Aires) of Djasiman serogroup.

Brucellosis in Argentina.

Brucellosis has been recognized in Argentina since the 19th century. Several studies demonstrated the presence of the disease in most of the domestic species. Actually, the estimate of prevalence is that between 10 and 13% of the farm animals are infected with bovine brucellosis with an individual rate of 4-5%. The annual economical losses have been estimated at 60,000,000 US dollars. The control of bovine brucellosis began in 1932 and successive resolutions have been issued since then. The current resolution indicates that B. abortus S19 is mandatory in female calves between 3 and 8 months of age. The vaccine strain B. abortus RB51 was provisionally approved but only for cattle older than 10 months of age. The brucellosis control program consists principally of test and slaughter. This methodology has been successful mainly in the dairy farms that have the incentive due to increased pricing because of obtaining a low prevalence of the disease. Brucellosis has been found in porcine, caprine, ovine and canine species. All Brucella species have been found in the country. Human brucellosis is an important disease and a national coordinated diagnostic net has been formed to better control the disease in man.