History of the urinary concentrating mechanism

Although the processes that generate the osmotic gradients in the inner medulla remain controversial, the countercurrent mechanism for the osmotic concentration and dilution of urine is now generally accepted. It was not always so. The mechanism for urinary dilution posed no conceptual difficulties for renal physiologists. Active transport of sodium chloride by a nephron segment whose epithelium had restricted water permeability in the absence of antidiuretic hormone (ADH), presumably located in the "distal" portion of the uriniferous tubule, was logical and based on proven and analogous processes. It was also obvious that when its water permeability was increased by ADH, water transport would be closely coupled to solute transport and reabsorbate and tubular fluid would be isosmotic. It appeared necessary to postulate the active transport of water as the final step in the production of urine which was hyperosmotic to the body fluids. Despite the fact that there was no proven example of active water transport in the animal kingdom, active water transport by the cells of the collecting ducts was proposed and was generally accepted. The simple biological solution of establishing by solute transport a hypertonic environment in an anatomically restricted portion of the kidney such that all water transport could be postulated as passive was not obvious and was scorned when proposed

Exposure of feral swine (Sus scrofa) in the United States to selected pathogens

Les porcs sauvages (Sus scrofa) sont largement distribués aux États-Unis. En 2011 et 2012, aux États-Unis des échantillons de sérum et d’amygdales furent obtenus de 162 et 37 porcs sauvages, respectivement, afin d’évaluer l’exposition à d’importants agents pathogènes porcins endémiques. Des anticorps contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP) et le circovirus porcin de type 2 (CVP2) furent détectés chez 2,5 % et 25,3 % des sérums testés, respectivement. Des réactions sérologiques positives envers Mycoplasma hyopneumoniae et Actinobacillus pleuropneumoniae ont été détectées chez 19,7 % et 69,7 % des animaux. Plus de 15 % des animaux avaient des anticorps contre ces deux agents pathogènes simultanément. La plupart des animaux étaient également séropositifs pour Lawsonia intracellularis. Les porcs sauvages peuvent également être impliqués dans la transmission d’agents zoonotiques. Près de 50 % des animaux avaient des anticorps contre Salmonella. De plus, 94,4 % des animaux étaient porteurs de Streptococcus suis dans leurs amygdales. En conclusion, les porcs sauvages peuvent être considérés comme des réservoirs potentiels de différentes maladies endémiques des porcs domestiques, aussi bien que d’agents zoonotiques importants.Feral swine (Sus scrofa) are widely distributed in the United States. In 2011 and 2012, serum samples and tonsils were recovered from 162 and 37 feral swine, respectively, in the US to evaluate exposure to important swine endemic pathogens. Antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) were found in 2.5% and 25.3% of tested sera, respectively. Positive serological reactions against Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae have been detected in 19.7% and 69.7% of animals. More than 15% of animals presented antibodies against these 2 pathogens simultaneously. Most animals were also seropositive for Lawsonia intracellularis. Feral swine can also be involved in transmission of zoonotic agents. Almost 50% of animals possessed antibodies against Salmonella. In addition, 94.4% of animals were carriers of Streptococcus suis in their tonsils. In conclusion, feral swine may be considered as a potential reservoir for different endemic diseases in domestic pigs, as well as for important zoonotic agents

Exposure of feral swine (\u3ci\u3eSus scrofa\u3c/i\u3e) in the United States to selected pathogens

Feral swine (Sus scrofa) are widely distributed in the United States. In 2011 and 2012, serum samples and tonsils were recovered from 162 and 37 feral swine, respectively, in the US to evaluate exposure to important swine endemic pathogens. Antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) were found in 2.5% and 25.3% of tested sera, respectively. Positive serological reactions against Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae have been detected in 19.7% and 69.7% of animals. More than 15% of animals presented antibodies against these 2 pathogens simultaneously. Most animals were also seropositive for Lawsonia intracellularis. Feral swine can also be involved in transmission of zoonotic agents. Almost 50% of animals possessed antibodies against Salmonella. In addition, 94.4% of animals were carriers of Streptococcus suis in their tonsils. In conclusion, feral swine may be considered as a potential reservoir for different endemic diseases in domestic pigs, as well as for important zoonotic agents. Les porcs sauvages (Sus scrofa) sont largement distribués aux États-Unis. En 2011 et 2012, aux États-Unis des échantillons de sérum et d’amygdales furent obtenus de 162 et 37 porcs sauvages, respectivement, afin d’évaluer l’exposition à d’importants agents pathogènes porcins endémiques. Des anticorps contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP) et le circovirus porcin de type 2 (CVP2) furent détectés chez 2,5 % et 25,3 % des sérums testés, respectivement. Des réactions sérologiques positives envers Mycoplasma hyopneumoniae et Actinobacillus pleuropneumoniae ont été détectées chez 19,7 % et 69,7 % des animaux. Plus de 15 % des animaux avaient des anticorps contre ces deux agents pathogènes simultanément. La plupart des animaux étaient également séropositifs pour Lawsonia intracellularis. Les porcs sauvages peuvent également être impliqués dans la transmission d’agents zoonotiques. Près de 50 % des animaux avaient des anticorps contre Salmonella. De plus, 94,4 % des animaux étaient porteurs de Streptococcus suis dans leurs amygdales. En conclusion, les porcs sauvages peuvent être considérés comme des réservoirs potentiels de différentes maladies endémiques des porcs domestiques, aussi bien que d’agents zoonotiques importants

Transcriptional analysis of PRRSV-infected porcine dendritic cell response to Streptococcus suis infection reveals up-regulation of inflammatory-related genes expression

The porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important swine pathogens and often serves as an entry door for other viral or bacterial pathogens, of which Streptococcus suis is one of the most common. Pre-infection with PRRSV leads to exacerbated disease caused by S. suis infection. Very few studies have assessed the immunological mechanisms underlying this higher susceptibility. Since antigen presenting cells play a major role in the initiation of the immune response, the in vitro transcriptional response of bone marrow-derived dendritic cells (BMDCs) and monocytes in the context of PRRSV and S. suis co-infection was investigated. BMDCs were found to be more permissive than monocytes to PRRSV infection; S. suis phagocytosis by PRRSV-infected BMDCs was found to be impaired, whereas no effect was found on bacterial intracellular survival. Transcription profile analysis, with a major focus on inflammatory genes, following S. suis infection, with and without pre-infection with PRRSV, was then performed. While PRRSV pre-infection had little effect on monocytes response to S. suis infection, a significant expression of several pro-inflammatory molecules was observed in BMDCs pre-infected with PRRSV after a subsequent infection with S. suis. While an additive effect could be observed for CCL4, CCL14, CCL20, and IL-15, a distinct synergistic up-regulatory effect was observed for IL-6, CCL5 and TNF-α after co-infection. This increased pro-inflammatory response by DCs could participate in the exacerbation of the disease observed during PRRSV and S. suis co-infection

Genetic diversity of Mycoplasma hyopneumoniae isolates of abattoir pigs

Mycoplasma hyopneumoniae, the causative agent of porcine enzootic pneumonia, is present in swine herds worldwide. However, there is little information on strains infecting herds in Canada. A total of 160 swine lungs with lesions suggestive of enzootic pneumonia originating from 48 different farms were recovered from two slaughterhouses and submitted for gross pathology. The pneumonic lesion scores ranged from 2% to 84%. Eighty nine percent of the lungs (143/160) were positive for M. hyopneumoniae by real-time PCR whereas 10% (16/160) and 8.8% (14/160) were positive by PCR for M. hyorhinis and M. flocculare, respectively. By culture, only 6% of the samples were positive for M. hyopneumoniae (10/160). Among the selected M. hyopneumoniae-positive lungs (n = 25), 9 lungs were co-infected with M. hyorhinis, 9 lungs with PCV2, 2 lungs with PRRSV, 12 lungs with S. suis and 10 lungs with P. multocida. MLVA and PCR-RFLP clustering of M. hyopneumoniae revealed that analyzed strains were distributed among three and five clusters respectively, regardless of severity of lesions, indicating that no cluster is associated with virulence. However, strains missing a specific MLVA locus showed significantly less severe lesions and lower numbers of bacteria. MLVA and PCR-RFLP analyses also showed a high diversity among field isolates of M. hyopneumoniae with a greater homogeneity within the same herd. Almost half of the field isolates presented less than 55% homology with selected vaccine and reference strains

Potential use of a recombinant replication-defective adenovirus vector carrying the C-terminal portion of the P97 adhesin protein as a vaccine against Mycoplasma hyopneumoniae in swine

Mycoplasma hyopneumoniae causes severe economic losses to the swine industry worldwide and the prevention of its related disease, enzootic porcine pneumonia, remains a challenge. The P97 adhesin protein of M. hyopneumoniae should be a good candidate for the development of a subunit vaccine because antibodies produced against P97 could prevent the adhesion of the pathogen to the respiratory epithelial cells in vitro. In the present study, a P97 recombinant replication-defective adenovirus (rAdP97c) subunit vaccine efficiency was evaluated in pigs. The rAdP97c vaccine was found to induce both strong P97 specific humoral and cellular immune responses. The rAdP97c vaccinated pigs developed a lower amount of macroscopic lung lesions (18.5 ± 9.6%) compared to the unvaccinated and challenged animals (45.8 ± 11.5%). rAdP97c vaccine reduced significantly the severity of inflammatory response and the amount of M. hyopneumoniae in the respiratory tract. Furthermore, the average daily weight gain was slightly improved in the rAdP97c vaccinated pigs (0.672 ± 0.068 kg/day) compared to the unvaccinated and challenged animals (0.568 ± 0.104 kg/day). A bacterin-based commercial vaccine (Suvaxyn® MH-one) was more efficient to induce a protective immune response than rAdP97c even if it did not evoke a P97 specific immune response. These results suggest that immunodominant antigens other than P97 adhesin are also important in the induction of a protective immune response and should be taken into account in the future development of M. hyopneumoniae subunit vaccines

Transcriptional approach to study porcine tracheal epithelial cells individually or dually infected with swine influenza virus and Streptococcus suis

Background: Swine influenza is a highly contagious viral infection in pigs affecting the respiratory tract that can have significant economic impacts. Streptococcus suis serotype 2 is one of the most important post-weaning bacterial pathogens in swine causing different infections, including pneumonia. Both pathogens are important contributors to the porcine respiratory disease complex. Outbreaks of swine influenza virus with a significant level of co-infections due to S. suis have lately been reported. In order to analyze, for the first time, the transcriptional host response of swine tracheal epithelial (NPTr) cells to H1N1 swine influenza virus (swH1N1) infection, S. suis serotype 2 infection and a dual infection, we carried out a comprehensive gene expression profiling using a microarray approach. Results: Gene clustering showed that the swH1N1 and swH1N1/S. suis infections modified the expression of genes in a similar manner. Additionally, infection of NPTr cells by S. suis alone resulted in fewer differentially expressed genes compared to mock-infected cells. However, some important genes coding for inflammatory mediators such as chemokines, interleukins, cell adhesion molecules, and eicosanoids were significantly upregulated in the presence of both pathogens compared to infection with each pathogen individually. This synergy may be the consequence, at least in part, of an increased bacterial adhesion/invasion of epithelial cells previously infected by swH1N1, as recently reported. Conclusion: Influenza virus would replicate in the respiratory epithelium and induce an inflammatory infiltrate comprised of mononuclear cells and neutrophils. In a co-infection situation, although these cells would be unable to phagocyte and kill S. suis, they are highly activated by this pathogen. S. suis is not considered a primary pulmonary pathogen, but an exacerbated production of proinflammatory mediators during a co-infection with influenza virus may be important in the pathogenesis and clinical outcome of S. suis-induced respiratory diseases