Michele Drigo

Bronchial abnormalities found in a consecutive series of 40 brachycephalic dogs

OBJECTIVE To detect abnormalities of the lower respiratory tract (trachea, principal bronchi, and lobar bronchi) in brachycephalic dogs by use of endoscopy, evaluate the correlation between laryngeal collapse and bronchial abnormalities, and determine whether dogs with bronchial abnormalities have a less favorable postsurgical long-term outcome following correction of brachycephalic syndrome. DESIGN Prospective case series study. ANIMALS 40 client-owned brachycephalic dogs with stertorous breathing and clinical signs of respiratory distress. PROCEDURES Brachycephalic dogs anesthetized for pharyngoscopy and laryngoscopy between January 2007 and June 2008 underwent flexible bronchoscopy for systematic evaluation of the principal and lobar bronchi. For dogs that underwent surgical correction of any component of brachycephalic syndrome, owners rated surgical outcome during a follow-up telephone survey. Correlation between laryngeal collapse and bronchial abnormalities and association between bronchial abnormalities and long-term outcome were assessed. RESULTS Pugs (n = 20), English Bulldogs (13), and French Bulldogs (7) were affected. A fixed bronchial collapse was recognized in 35 of 40 dogs with a total of 94 bronchial stenoses. Abnormalities were irregularly distributed between hemithoraces; 15 of 94 bronchial abnormalities were detected in the right bronchial system, and 79 of 94 were detected in the left. The left cranial bronchus was the most commonly affected structure, and Pugs were the most severely affected breed. Laryngeal collapse was significantly correlated with severe bronchial collapse; no significant correlation was found between severity of bronchial abnormalities and postsurgical outcome. CONCLUSIONS AND CLINICAL RELEVANCE Bronchial collapse was a common finding in brachycephalic dogs, and long-term postsurgical outcome was not affected by bronchial stenosis.

Revisiting the taxonomical classification of Porcine Circovirus type 2 (PCV2): still a real challenge

BackgroundPCV2 has emerged as one of the most devastating viral infections of swine farming, causing a relevant economic impact due to direct losses and control strategies expenses. Epidemiological and experimental studies have evidenced that genetic diversity is potentially affecting the virulence of PVC2. The growing number of PCV2 complete genomes and partial sequences available at GenBank questioned the accepted PCV2 classification.MethodsNine hundred seventy five PCV2 complete genomes and 1,270 ORF2 sequences available from GenBank were subjected to recombination, PASC and phylogenetic analyses and results were used for comparison with previous classification scheme.ResultsThe outcome of these analyses favors the recognition of four genotypes on the basis of ORF2 sequences, namely PCV2a, PCV2b, PCV2c and PCV2d-mPCV2b. To deal with the difficulty of founding an unambiguous classification and accounting the impossibility to define a p-distance cut-off, a set of reference sequences that could be used in further phylogenetic studies for PCV2 genotyping was established. Being aware that extensive phylogenetic analyses are time-consuming and often impracticable during routine diagnostic activity, ORF2 nucleotide positions adequately conserved in the reference sequences were identified and reported to allow a quick genotype differentiation.ConclusionsGlobally, the present work provides an updated scenario of PCV2 genotypes distribution and, based on the limits of the previous classification criteria, proposes new rapid and effective schemes for differentiating the four defined PCV2 genotypes.

Genetic characterisation of Porcine circovirus type 2 (PCV2) strains from feral pigs in the Brazilian Pantanal: an opportunity to reconstruct the history of PCV2 evolution.

Since its discovery, Porcine circovirus type 2 has emerged as one of the most relevant swine infectious diseases, causing relevant economic losses for the pig industry. While four genotypes were identified, only three (PCV2a, PCV2b and PCV2d) are currently circulating and display a worldwide distribution. Another genotype, PCV2c, has been described only once in Danish archive samples collected between 1980 and 1990. In addition to commercial pigs, PCV2 has been demonstrated to infect wild boars and other wild species, which can potentially serve as a reservoir for domestic populations. In this study, eight sequences obtained from feral pigs in the Pantanal region (Mato Grosso do Sul State, Brazil) were compared with reference sequences and other Brazilian sequences, and the results revealed remarkable genetic diversity, with all four genotypes currently recognised being detected (PCV2a, PCV2b, PCV2c and PCV2d). This finding represents a remarkable discovery, as it is the first detection of PCV2c since 1990 and the first-ever detection of PCV2c in live animals. The peculiar population history and ecological scenario of feral pigs in the Pantanal coupled with the complex, and still only partially known relationship of feral pigs with other PCV2 susceptible species (i.e., domestic pigs, wild boars and peccaries), open exciting questions concerning PCV2 origin and evolution. Overall, the results of the present study led us to form the following hypothesis: the PCV2 strains found in feral pigs may be the last descent of the strains that circulated among European pigs in the past, or they may have infected these feral pigs more recently through a bridge species.

Phylodynamic analysis of porcine circovirus type 2 reveals global waves of emerging genotypes and the circulation of recombinant forms

Since the first description of Porcine circovirus type 2 (PCV2), four genotypes (PCV2a, PCV2b, PCV2c and PCV2d) have been recognized and three of them have been shown to exhibit worldwide distribution. Here, the population dynamics of PCV2 has been reconstructed over time and the factors that have shaped its evolution determined. The results obtained confirm that PCV2 originated approximately at the beginning of the 20th century. The most recent common ancestor of genotypes PCV2a, PCV2b, PCV2c and PCV2d circulated in the 1950s, 1980s, 1960s and 1950s, respectively, and the population sizes of the individual genotypes remained low until the mid 90s, coinciding with the identification of PCV2 as a major pathogen of the pig industry. The population dynamics of PCV2 have been characterized by the appearance of periodic waves of distinct genotypes that, after an initial rise, spread following major swine commercial routes and were then superseded by subsequent emerging genotypes. Various recombinant forms displayed comparable population dynamics and spreading routes to those of major genotypes, suggesting that recombinant strains are able to compete with parental ones. The capsid gene is subjected to immune selection and evasion of the host immune response seems to be a major force for the emergence and spread of new genotypes. In contrast, the evolution of other genes appears to be constrained by the particular genomic organization of PCV2. In summary, obtained results suggest that changes in farming strategies, international trade, host population immunity, recombination and the constraints imposed by genome organization have all played a major role in the evolutionary dynamics of PCV2.

Study on Ticks and Tick-Borne Zoonoses in Public Parks in Italy

A survey on tick density and on tick‐borne zoonoses was carried out in four public parks in the outskirts of Imola (northern Italy) from June to October 2006. All stages of Ixodes ricinus and only larvae of Riphicephalus sanguineus were recovered by dragging, performed on 100‐m transects. Almost all ticks (99%) were harvested in one park. I. ricinus density (nymphs/100 m2) ranged from 0 in park L to 6.3 in park F. Nymphs and adults of I. ricinus were subjected to PCR for Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi s. l. and Rickettsia spp. The observed prevalences were 38.3% for Bartonella henselae, 5.2% for Bartonella clarridgeiae, 10.4% for B. burgdorferi s. l., 2.6% for Rickettsia helvetica and 13% for Rickettsia monacensis, respectively. No DNA of A. phagocytophilum was found. Acarological risks (AR) were calculated as probabilities of collecting at least one infected nymph per transect. The AR values calculated for the various zoonotic agents were 11.4% for R. helvetica, 27.7% for B. clarridgeiae, 49.7% for B. burgdorferi s. l., 57.2% for R. monacensis and 90.4% for B. henselae, respectively. In this study, B. clarridgeiae was for the first time identified in I. ricinus ticks.

Evaluation of White Striping prevalence and predisposing factors in broilers at slaughter

White striping ( WS: ) is an alteration of breast and thigh muscles of broiler chickens characterized by the presence of white striations parallel to the direction of muscle fibers. This study was performed to evaluate the prevalence and the predisposing factors to WS in commercial broilers of different weight reared in northern Italy. Fifty seven broiler flocks, including animals of medium- and heavy-weight, were grossly evaluated at slaughter for the presence of WS. For each flock, breeding data (mean BW at slaughter, ADG, sex, color of skin and fat, genetic line, age, antibiotic treatment, and prevalence of deep pectoral myopathy) were collected and statistically analyzed to assess their correlation with WS. Histology of breast fillets affected by different grades of WS was performed to evaluate potential differences between medium- and heavy-weight broilers. The overall prevalence of WS in medium- and heavy-weight broilers (mean BW 2.59 ± 0.13 kg and 3.64 ± 0.34 kg, respectively) was 70.2 ± 7.9% and 82.51 ± 8.5%, respectively, while the percentage of severe WS was 13.3 ± 7.1% and 25.7 ± 12.8%, respectively. A strong correlation was found between presence of WS, BW at slaughter, and ADG (Pearson correlation = 0.69, P < 0.01; Pearson correlation = 0.67, P < 0.01). WS also closely correlated with the prevalence of deep pectoral myopathy (Spearmans Rho slaughterhouse 1 = 0.74, Spearmans Rho slaughterhouse 2 = 0.51, P < 0.01). No correlation was found between genetics or sanitary status of the flock and WS. Histology confirmed that breasts with WS lesions were affected by a polyphasic degenerative and necrotizing myopathy, and that the lesions, as expected, were more severe in heavy-weight broilers. In conclusion, WS is a major concern in commercial meat poultry reared in Italy, affecting more severely heavier broilers, and it is mainly related to the BW and ADG of animals.

International trades, local spread and viral evolution: The case of porcine circovirus type 2 (PCV2) strains heterogeneity in Italy

Porcine circovirus type 2 is one of the most widespread and economically relevant infections of swine. Four genotypes have been recognized, but currently, only three (PCV2a, PCV2b and PCV2d) are effectively circulating. The widespread livestock trade and rapid viral evolution have contributed to determining the high heterogeneity of PCV2 and the dispersal of potentially more virulent strains. Italian swine farming and the related processing industry are relevant in the national economy. Despite the noteworthy losses associated with direct and control measure costs, no data are currently available on the molecular epidemiology of PCV2 in Italy. Our study, which was intended to fill this gap, considered 75 completed genome PCV2 sequences, which were obtained from samples collected from the highly densely populated area of Northern Italy between 2007 and 2014. Phylogenetic analysis and comparison with reference sequences demonstrated the co-circulation, with different prevalences, of PCV2a, PCV2b and PCV2d within the national borders, with PCV2b being the most prevalent. Recombination between different genotypes was also proven to be frequent. Phylogeographic analysis demonstrated that the marked variability of Italian PCV2 strains can be attributable to multiple introduction events. The comparison of the phylogenetic analysis results, the location of different haplotypes and the international commercial routs of live pigs allow the speculation of several links as well as the role of Italy as both an importer and exporter of PCV2 haplotypes, mainly from and to European and Asian countries. A similarly intricate contact network was demonstrated within national borders, with different haplotypes being detected in the same province and different provinces harbouring the same haplotype. Overall, this paper represents the first description of PCV2 in Italy and demonstrates that the high variability of circulating Italian strains is due to multiple introduction events, wide circulation within national boundaries and rapid viral evolution.

Distributed rate control algorithm for VANETs (DRCV)

This paper presents Distributed Rate Control for VANETs (DRCV), a distributed light-weight congestion control algorithm tailored for safety messages. DRCV monitors and estimates channel load and controls the packet rate of outgoing periodic packets. A new approach called Fast Drop is adopted to promptly drop the rate of periodic packets when event-driven safety packets are detected. Simulations show the effectiveness of DRCV in increasing packet reception probabilities and achieving efficient channel usage.

Porcine circovirus type 2 (PCV2) evolution before and after the vaccination introduction: A large scale epidemiological study

Since their commercialization, vaccines against Porcine circovirus type 2 (PCV2) have been the cornerstone control strategy. Nevertheless, the periodic emergence of new genotype waves and the recent reports of vaccine failure outbreaks have raised the question if widespread vaccination strategies could have driven viral evolution and affected different genotype fitness. To investigate this issue an in-deep analysis, based on a bioinformatics and biostatistics approach, has been implemented. ORF2 sequences from vaccinated and non-vaccinated populations (i.e. domestic pigs before and after vaccine introduction and wild boars) were considered. The action of selective forces on PCV2 strains has been analyzed and compared among groups. Remarkable differences were found in the selective forces acting on viral populations circulating in different “immune environments”. Particularly for PCV2a, a directional selection promoting a change in the viral capsid away from the vaccine specific antigenic determinants has been detected after vaccine introduction. Involved amino acids were previously reported to be part of viral epitopes whose variability is responsible of immune escape. Our findings support a change in PCV2 evolutionary pattern after widespread vaccination introduction and stress once more the compulsoriness of a continuous monitoring of PCV2 epidemiology to promptly act in response to the emergence of possible vaccine-escaping mutants.

Minimal residual disease detection by flow cytometry and PARR in lymph node, peripheral blood and bone marrow, following treatment of dogs with diffuse large B-cell lymphoma

The most promising techniques for detecting minimal residual disease (MRD) in canine lymphoma are flow cytometry (FC) and polymerase chain reaction amplification of antigen receptor genes (PARR). However, the agreement between these methods has not been established. MRD was monitored by FC and PARR following treatment of dogs affected with diffuse large B-cell lymphoma (DLBCL), comparing results in lymph node (LN), peripheral blood (PB) and bone marrow (BM) samples. The prognostic impact of MRD on time to relapse (TTR) and lymphoma-specific survival (LSS) was also assessed. Fourteen dogs with previously untreated DLBCL were enrolled into the study; 10 dogs eventually relapsed, while four dogs with undetectable MRD were still in remission at the end of the study. At diagnosis, the concordance rate between FC and PARR was 100%, 78.6%, and 64.3% for LN, PB and BM, respectively. At the end of treatment, the agreement rates were 35.7%, 50%, and 57.1% for LN, PB and BM, respectively. At least one of the follow-up samples from dogs experiencing relapse was PARR(+); conversely, FC was not able to detect MRD in seven of the dogs that relapsed. PARR was more sensitive than FC in predicting TTR, whereas the combination of PARR and FC was more sensitive than either technique alone in predicting LSS using PB samples. The results suggest that immunological and molecular techniques should be used in combination when monitoring for MRD in canine DLBCL.