A Olvera

Publications (13)30.43 Total impact

• Article: Pyogranulomatous pleuropneumonia and mediastinitis in ferrets (Mustela putorius furo) associated with Pseudomonas luteola Infection.

  J Martínez, J Martorell, M L Abarca, A Olvera, A Ramis, L Woods, N Cheville, C Juan-Sallés, A Moya, A Riera, S Soto
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  ABSTRACT: Between 2008 and 2009, three pet ferrets from different sources presented with acute episode of dyspnoea. Cytological examination of pleural exudates revealed severe purulent inflammation with abundant clusters of rod-shaped microorganisms with a clear surrounding halo. Treatment was ineffective and the ferrets died 2-5 days later. Two ferrets were subjected to necropsy examination, which revealed pyothorax, mediastinal lymphadenopathy and multiple white nodules (1-2mm) in the lungs. Microscopical examination showed multifocal necrotizing-pyogranulomatous pleuropneumonia and lymphadenitis with aggregates of encapsulated microorganisms, some of which were positively stained by periodic acid-Schiff and alcian blue. In-situ hybridization for Pneumocystis spp., Ziehl-Neelsen staining and immunohistochemistry for distemper, coronavirus and influenza antigen were negative in all cases. Electron microscopically, the bacteria were 2-3 μm long with a thick electron-lucent capsule. Microbiology from one ferret yielded a pure culture of gram-negative bacteria identified phenotypically as Pseudomonas luteola. This speciation was later confirmed by 16S RNA gene amplification.
  Journal of comparative pathology 05/2011; 146(1):4-10. · 1.73 Impact Factor
• Article: Systemic herpesvirus and morbillivirus co-infection in a striped dolphin (Stenella coeruleoalba).

  S Soto, B González, K Willoughby, M Maley, A Olvera, S Kennedy, A Marco, M Domingo
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  ABSTRACT: During 2007 a dolphin morbillivirus epizootic affected the western Mediterranean and several striped dolphins (Stenella coeruleoalba) stranded on the Catalonian coasts. One of those animals had severe lymphoid depletion, necrosis and syncytial formation in lymph nodes and spleen, with large basophilic nuclear inclusions compatible with herpesvirus detected by immunohistochemical and ultrastructural examination. Non-suppurative encephalitis with associated morbillivirus antigen and morbillivirus antigen within alveolar macrophages were also observed. A pan-herpesvirus nested polymerase chain reaction amplified a sequence virtually identical to two cetacean herpesvirus sequences previously identified in systemic infections in an Atlantic Cuvier's beaked whale (Ziphius cavirostris) and in a Mediterranean striped dolphin. The herpesviral infection was probably secondary to the immunosuppression caused by the morbillivirus. To our knowledge, this is the first report of a cetacean co-infected by dolphin morbillivirus and herpesvirus with evidence of lesions attributable to both viruses.
  Journal of comparative pathology 05/2011; 146(2-3):269-73. · 1.73 Impact Factor
• Article: Sow vaccination modulates the colonization of piglets by Haemophilus parasuis.

  M Cerdà-Cuéllar, J F Naranjo, A Verge, M Nofrarías, M Cortey, A Olvera, J Segalés, V Aragon
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  ABSTRACT: Haemophilus parasuis is the etiologic agent of Glässer's disease in pigs and a colonizer of the upper respiratory tract of healthy pigs. A good balance between colonization and immunity is important to avoid a disease outbreak. This work studied the colonization of H. parasuis in healthy piglets coming from vaccinated and non-vaccinated sows. Piglets from vaccinated sows had higher IgG levels at early time points and subsequently were colonized later and to a lower degree than piglets from non-vaccinated ones. The variability of H. parasuis isolates was investigated by 2 genotyping methods: enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus sequence typing (MLST). A high turnover of strains was found in both groups of piglets, with few strains found on more than one sampling occasion. We found a higher number of H. parasuis strains (16 strains) within a given farm than previously thought. Overall, more H. parasuis diversity was found in piglets from non-vaccinated sows than in those from vaccinated sows. These results indicate that vaccination of sows in a farm delays the colonization of piglets and reduces the carriage and heterogeneity of H. parasuis strains.
  Veterinary Microbiology 04/2010; 145(3-4):315-20. · 3.33 Impact Factor
• Article: PCV-2 genotype definition and nomenclature.

  J Segalés, A Olvera, L Grau-Roma, C Charreyre, H Nauwynck, L Larsen, K Dupont, K McCullough, J Ellis, S Krakowka, A Mankertz, M Fredholm, C Fossum, S Timmusk, N Stockhofe-Zurwieden, V Beattie, D Armstrong, B Grassland, P Baekbo, G Allan
  The Veterinary record 07/2008; 162(26):867-8. · 1.25 Impact Factor
• Source

  Available from: Elisa Crisci

  Article: A proposal on porcine circovirus type 2 (PCV2) genotype definition and their relation with postweaning multisystemic wasting syndrome (PMWS) occurrence.

  L Grau-Roma, E Crisci, M Sibila, S López-Soria, M Nofrarias, M Cortey, L Fraile, A Olvera, J Segalés
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  ABSTRACT: Porcine circovirus type 2 (PCV2) is the essential infectious agent of postweaning multisystemic wasting syndrome (PMWS). Despite first sequencing studies did not find any association between PCV2 sequences and PMWS occurrence, recent works have suggested the opposite. In the present study, 87 open reading frame 2 (ORF2) sequences obtained from pigs with different clinical conditions and coming from farms with different PMWS status were analyzed. Results further confirmed the existence of two genogroups and the definition of two PCV2 genotypes (1 and 2) is proposed. All sequences included in genotype 1 came from pigs from PMWS affected farms, while all sequences obtained from non-PMWS affected farms corresponded to genotype 2. Moreover, infection of single pigs from PMWS affected farms harbouring both genotypes is described. Present results suggest that PCV2 genotype 1 may potentially be more pathogenic than PCV2 genotype 2.
  Veterinary Microbiology 05/2008; 128(1-2):23-35. · 3.33 Impact Factor
• Source

  Available from: Gregorio Mentaberre

  Article: First isolation of Haemophilus parasuis and other NAD-dependent Pasteurellaceae of swine from European wild boars.

  A Olvera, M Cerdà-Cuéllar, G Mentaberre, E Casas-Diaz, S Lavin, I Marco, V Aragon
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  ABSTRACT: Haemophilus parasuis is a colonizer of the upper respiratory tract of pigs and the etiological agent of Glässer's disease, which is characterized by a fibrinous polyserositis, meningitis and arthritis. Glässer's disease has never been reported in wild boar (Sus scrofa), although antibodies against H. parasuis have been detected. The goal of this study was to confirm the presence of this bacterium in wild boar by bacterial isolation and to compare the strains to H. parasuis from domesticated pigs. Therefore, nasal swabs from 42 hunted wild boars were processed for bacterial isolation and subsequent H. parasuis identification by specific PCR, biochemical tests and 16S rRNA gene sequencing. Two different strains of H. parasuis from two wild boars were isolated. These strains belonged to serotype 2 and were included by 16S rRNA gene sequencing and MLST analysis in a cluster with other H. parasuis strains of nasal origin from domestic pigs. During this study, Actinobacillus minor and Actinobacillus indolicus, which are NAD-dependent Pasteurellaceae closely related to H. parasuis, were also isolated. Our results indicate similarities in the respiratory microbiota of wild boars and domestic pigs, and although H. parasuis was isolated from wild boars, more studies are needed to determine if this could be a source of H. parasuis infection for domestic pigs.
  Veterinary Microbiology 12/2007; 125(1-2):182-6. · 3.33 Impact Factor
• Article: First description of postweaning multisystemic wasting syndrome (PMWS) in wild boar (Sus scrofa) in Croatia and phylogenetic analysis of partial PCV2 sequences.

  Z Lipej, J Segalés, Lorena Jemersić, A Olvera, Besi Roić, D Novosel, Z Mihaljević, L Manojlović
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  ABSTRACT: This report describes the first case of postweaning multisystemic wasting syndrome (PMWS) in wild boar in Croatia. During the winter season of 2004, eight wild young piglets (of approximately 2 to 5 months of age) were found dead in a fenced hunting area. Polymerase chain reaction (PCR) was carried out on mesenteric lymph nodes and all animals yielded positive results. In one of these animals diagnosis of PMWS was established based on the three key diagnostic criteria including the clinical manifestation, moderate lymphoid lesions consisting of lymphocyte depletion and granulomatous inflammation, and detection of the presence of PCV2 genome within the lymphoid lesions by in situ hybridisation (ISH). Three additional wild piglets had also mild PMWS-like lesions and a low amount of PCV2 was also found. No PMWS-like lesions or PCV2 genome were detected in the rest of the wild piglets studied. Three PCR-positive isolates were partially sequenced, which confirmed the diagnosis of PCV2 and demonstrated that the three sequences were genetically identical. The phylogenetic analysis of a representative PCV2 isolate indicated that its sequence (DQ875444) is grouped in a separate branch with Hungarian isolate (AY256460) and differs from any of the annotated sequences.
  Acta Veterinaria Hungarica 10/2007; 55(3):389-404. · 0.67 Impact Factor
• Source

  Available from: Joaquim Segalés

  Article: Dynamics of Haemophilus parasuis genotypes in a farm recovered from an outbreak of Glässer's disease.

  A Olvera, M Cerdà-Cuéllar, M Nofrarías, E Revilla, J Segalés, V Aragon
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  ABSTRACT: Haemophilus parasuis is a colonizer of the upper respiratory tract of pigs, although it is better known as the etiological agent of Glässer's disease. Interestingly, several strains can be isolated from a single farm, as determined by both genotyping and serotyping. However, it is not known how an outbreak and the subsequent treatment affect the population of H. parasuis strains. In this study, a farm was studied during an outbreak of Glässer's disease and 1 year after antimicrobial treatment and elimination of clinical signs. Bacterial isolation was attempted from nasal swabs and lesions. After isolation, antimicrobial susceptibility, serotype and genotype were determined. Two different genotyping techniques, enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus sequence typing (MLST) were used. The H. parasuis strain that was isolated from lesions during the disease outbreak clustered with other virulent strains by both MLST and serotyping analysis. Nasal isolates were included in the corresponding nasal cluster by MLST, but they presented high variability by serotyping. These nasal isolates included serotypes previously classified as virulent and non-virulent. Finally, we found that during the antimicrobial treatment the diversity of strains isolated in the farm was affected and just one strain, which was resistant to the treatment, was detected. One year after the treatment strain diversity was back to normal (three strains).
  Veterinary Microbiology 08/2007; 123(1-3):230-7. · 3.33 Impact Factor
• Article: Molecular evolution of porcine circovirus type 2 genomes: phylogeny and clonality.

  A Olvera, M Cortey, J Segalés
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  ABSTRACT: Porcine circoviruses (PCVs) type 1 (PCV1) and type 2 (PCV2) show high levels of nucleotide similarity, but PCV1 is considered non-pathogenic and PCV2 has been associated with several disease outcomes in pigs, mainly postweaning multisystemic wasting syndrome (PMWS). After exploring different topologies of the origin of PCVs, it was concluded that PCV1 and PCV2 seem to have a common origin. On the other hand, PCV2 could be divided into two groups (1 and 2) and eight clusters (1A to 1C and 2A to 2E), but none of those was apparently associated with disease status or geographic area. When phylogenetic trees constructed with the whole PCV2 genome, the cap or the rep genes were compared, some incongruence was identified. The possible existence of recombination was evaluated and cluster 1B was found to have a possible recombinant origin. Selective pressure was detected in all parts of the PCV2 genome, especially in the rep gene. Finally, the cap gene was the more suitable phylogenetic and epidemiological marker for PCV2, despite the fact that the virus can undergo recombination mainly within the first part of the rep region.
  Virology 02/2007; 357(2):175-85. · 3.35 Impact Factor
• Article: Genotypic diversity of Haemophilus parasuis field strains.

  A Olvera, M Calsamiglia, V Aragon
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  ABSTRACT: Haemophilus parasuis is the cause of Glässer's disease and other clinical disorders in pigs. It can also be isolated from the upper respiratory tracts of healthy pigs, and isolates can have significant differences in virulence. In this work, a partial sequence from the 60-kDa heat shock protein (Hsp60) gene was assessed as an epidemiological marker. We analyzed partial sequences of hsp60 and 16S rRNA genes from 103 strains of H. parasuis and other related species to obtain a better classification of the strains and examine the correlation with virulence. The results were compared with those obtained by enterobacterial repetitive intergenic consensus PCR. Our results showed that hsp60 is a reliable marker for epidemiological studies of H. parasuis and that the analysis of its sequence is a better approach than fingerprinting methods. Furthermore, the analysis of the hsp60 and 16S rRNA gene sequences revealed the presence of a separate lineage of virulent strains and indicated the occurrence of lateral gene transfer among H. parasuis and Actinobacillus strains.
  Applied and Environmental Microbiology 07/2006; 72(6):3984-92. · 3.83 Impact Factor
• Article: Quantification of porcine circovirus type 2 (PCV2) DNA in serum and tonsillar, nasal, tracheo-bronchial, urinary and faecal swabs of pigs with and without postweaning multisystemic wasting syndrome (PMWS).

  J Segalés, M Calsamiglia, A Olvera, M Sibila, L Badiella, M Domingo
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  ABSTRACT: The present study focused on PCV2 quantification by TaqMan PCR in nasal (n=99), tonsillar (n=108), tracheo-bronchial (n=72), urinary (n=91) and faecal (n=42) swabs, as well as in serum (n=57), from a total of 146 pigs received at the Pathological Diagnostic Service at the Veterinary School of Barcelona (Spain). Animals were classified into three categories based on histopathological and in situ hybridisation (ISH) results: PMWS affected pigs (Group A, n=42), PCV2 subclinically infected pigs (Group B, n=29), and non-PMWS with PCV2 ISH negative pigs (Group C, n=75). Overall, tracheo-bronchial swabs had the higher PCV2 load followed by serum, tonsillar, nasal, faecal and, finally, urinary swabs. PCV2 genome was also detected in different proportions in all three categories of pigs; in all tested sites, viral load means were significantly higher (P<or=0.02) in animals with PMWS (Group A pigs) than in animals without PMWS (Group B and C pigs). Therefore, the more severe the lesions, the higher amounts of viral genome by ISH, and the higher PCV2 load in serum and swab specimens. Except for the tracheo-bronchial swab, no significant differences (p>0.05) were observed among tested specimens when age-groups (pigs younger than 1.5 months, and equal or older than 1.5 months of age) were compared. In summary, PCV2 is presumably excreted through respiratory (nasal and tracheo-bronchial) and oral (tonsillar) secretions, urine and faeces of both PMWS and non-PMWS affected pigs, with higher viral loads being associated with the presence of PMWS lesions.
  Veterinary Microbiology 12/2005; 111(3-4):223-9. · 3.33 Impact Factor
• Article: Postweaning multisystemic wasting syndrome in pigs in Venezuela.

  J P Cano, C Rodríguez-Cariño, E Sogbe, V Utrera, C T Díaz, J Segalés, A Olvera, M Calsamiglia
  The Veterinary record 06/2005; 156(19):620. · 1.25 Impact Factor
• Article: PCV-2 genotype definition and nomenclature

  J. Segales, A Olvera, L Grau-Roma, C Charreyre, H Nauwynck, L Larsen, K Dupont, K McCullough, J Ellis, S Krakowka, A Mankertz, M. Fredholm, C Fossum, S Timmusk, N. Stockhofe-Zurwieden, V. Beattie, D. Armstrong, B. Grassland, P Baekbo, G Allan
  Veterinary Record 162 (2008) 26.