Long-chain LPS-based enzyme-linked immunosorbent assay to detect swine herds infected by Actinobacillus pleuropneumoniae serotype 17.

Actinobacillus pleuropneumoniae serotype 17, one of the two most recent serotypes described, has been isolated from diseased pigs in North America. Yet, no serological test for surveillance has been developed so far. An enzyme-linked immunosorbent assay (ELISA) using the long-chain lipopolysaccharide antigen (LC-LPS) of this serotype is described. As predicted by previous genetic data on the O-antigen locus, cross reactions were observed between this serotype and serotypes 3, 6, 8, and 15. Although animals infected by serotype 17 would be detected using the current serotype 3 LC-LPS ELISA, better results may be obtained when plates are coated with the antigen purified from the homologous serotype.

Développement d'un test sérologique ELISA en utilisant l'antigène de la chaine O du LPS afin de détecter les troupeaux infectés par Actinobacillus pleuropneumoniae sérotype 17. Le récemment décrit Actinobacillus pleuropneumoniae sérotype 17 a été isolé chez des porcs malades en Amérique du Nord. Pourtant, aucun test sérologique n'a été mis au point à ce jour. Nous avons développé un test ELISA utilisant l'antigène lipopolysaccharidique à longue chaîne (LC-LPS) de ce sérotype. Tel que prévu par l'analyse du locus de l'antigène O du LPS, des réactions croisées ont été observées entre ce sérotype et les sérotypes 3, 6, 8 et 15. Bien que les animaux infectés par le sérotype 17 pourraient être détectés en utilisant le sérotype 3 LC-LPS ELISA, plus de sensibilité pourrait être obtenue en utilisant l'antigène purifié à partir du sérotype homologue.(Traduit par les auteurs).

Field application of a commercial porcine reproductive and respiratory syndrome virus (PRRSV) oral fluid antibody enzyme-linked immunosorbent assay (ELISA).

A commercial porcine reproductive and respiratory syndrome virus (PRRSV) oral fluid antibody enzyme-linked immunosorbent assay (ELISA) was used on 31 commercial swine farms in Ontario using oral fluid samples (~6 per herd) collected from cotton ropes. Using the manufacturer's cutoff [sample-to-positive ratio (S/P) ≥ 0.4], 2 of 135 oral fluid samples from 23 PRRSV presumed negative herds tested positive (1.5% false positive rate). Three approaches to improving test diagnostic specificity were compared: i) use a cutoff of S/P ≥ 0.8 for individual oral fluid samples; ii) use the current cutoff of S/P ≥ 0.4 but use a mean S/P based on several oral fluid samples (6 samples were used in this study); and iii) use serial testing to resolve unexpected positive ELISA results, i.e., retest using a reverse transcription-polymerase chain reaction (RT-PCR) to determine whether low positive S/P ratios are the result of early PRRSV infection in a barn.

Application sur le terrain d'une épreuve immuno-enzymatique (ELISA) commerciale pour détecter des anticorps contre le virus du syndrome reproducteur et respiratoire porcin en utilisant des fluides oraux. Une épreuve immuno-enzymatique (ELISA) commerciale pour détecter des anticorps contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP) en utilisant des fluides oraux fut utilisée sur 31 fermes commerciales en Ontario en utilisant des échantillons de fluides oraux (~6 par troupeau) prélevés en utilisant des cordes en coton. En utilisant le seuil recommandé par le manufacturier [ratio échantillon-à-positif (S/P) ≥ 0,4], 2 des 135 échantillons de fluides oraux provenant de 23 troupeaux présumés négatifs pour le VSRRP ont testé positif (taux de faux positifs de 1,5 %). Trois approches pour améliorer la spécificité du test furent comparées: i) utilisation d'une valeur seuil de S/P ≥ 0,8 pour les échantillons de fluides oraux individuels; ii) utilisant de la valeur seuil actuelle S/P ≥ 0,4 mais utiliser une S/P moyenne basée sur plusieurs échantillons de fluides oraux (6 échantillons furent utilisés dans la présente étude); et iii) utiliser des tests en série pour résoudre les résultats ELISA positifs non-attendus; retester en utilisant la réaction d'amplification en chaine par la polymérase avec la transcriptase reverse (RT-PCR) afin de déterminer si les ratios S/P faiblement positifs sont le résultat d'une infection débutante dans une ferme.(Traduit par Dr Serge Messier).

Information-Theoretic Measures Predict the Human Judgment of Rhythm Complexity.

To formalize the human judgment of rhythm complexity, we used five measures from information theory and algorithmic complexity to measure the complexity of 48 artificially generated rhythmic sequences. We compared these measurements to human prediction accuracy and easiness judgments obtained from a listening experiment, in which 32 participants guessed the last beat of each sequence. We also investigated the modulating effects of musical expertise and general pattern identification ability. Entropy rate and Kolmogorov complexity were correlated with prediction accuracy, and highly correlated with easiness judgments. A logistic regression showed main effects of musical training, entropy rate, and Kolmogorov complexity, and an interaction between musical training and both entropy rate and Kolmogorov complexity. These results indicate that information-theoretic concepts capture some salient features of the human judgment of rhythm complexity, and they confirm the influence of musical expertise on complexity judgments.

Reduced projection angles for binary tomography with particle aggregation.

This paper extends particle aggregate reconstruction technique (PART), a reconstruction algorithm for binary tomography based on the movement of particles. PART supposes that pixel values are particles, and that particles diffuse through the image, staying together in regions of uniform pixel value known as aggregates. In this work, a variation of this algorithm is proposed and a focus is placed on reducing the number of projections and whether this impacts the reconstruction of images. The algorithm is tested on three phantoms of varying sizes and numbers of forward projections and compared to filtered back projection, a random search algorithm and to SART, a standard algebraic reconstruction method. It is shown that the proposed algorithm outperforms the aforementioned algorithms on small numbers of projections. This potentially makes the algorithm attractive in scenarios where collecting less projection data are inevitable.

Microbiological identification and analysis of swine tonsils collected from carcasses at slaughter.

The primary objective of this 7-month study was to determine the prevalence of porcine pathogens of the tonsil of the soft palate of swine at slaughter. Additional objectives were to determine if sampling the carcasses of normal or abnormal hogs provided different microbiological profiles and if the slaughter plant provides a feasible sampling frame and environment for detecting and monitoring important pathogens in tonsils that have health implications for both swine and humans. A total of 395 samples were collected from 264 farms. Of these, 180 tonsils were collected from normal carcasses and 215 tonsils were collected from carcasses that were diverted to the hold rail. Laboratory testing included bacteriological culture and identification as well as real time-polymerase chain reaction (PCR) testing for porcine reproductive and respiratory syndrome virus (PPRSV) and immunohistochemistry (IHC) for porcine circovirus-2 (PCV-2). The most commonly isolated bacteria included: Streptococcus suis (53.7%), Arcanobacterium pyogenes (29.9%), Pasteurella multocida (27.3%), and Streptococcus porcinus (19.5%). Virus screening revealed evidence of PRRSV and PCV-2 in 22.0% and 11.9% of the samples, respectively. Salmonella Typhimurium and Yersinia enterocolitica were isolated in 0.5% and 1.8% of the samples, respectively. Tonsils collected from the hold rail were more likely to be positive for Staphylococcus hyicus [odds ratio (OR) = 7.51, confidence interval (CI) = 2.89 to 19.54], Streptococcus porcinus (OR = 9.93, CI = 4.27 to 23.10), and Streptococcus suis (OR = 2.16, CI = 1.45 to 3.24). Tonsils collected from abnormal carcasses were less likely to be positive for Staphylococcus aureus (OR = 0.05, CI = 0.005 to 0.482).

Comparison of 2 serologic tests for the diagnosis of porcine proliferative enteropathy.

The purpose of this study was to compare results from 2 serological assays at the individual- and herd-level for porcine proliferative enteropathy diagnosis. Cohen's kappa coefficient (k) was used to measure agreement. The tests tend to show better agreement when used at the herd level.