Condenações de carcaça suínas devido a doenças respiratórias revisão bibliográfica / Pork carcass condemnation due to respiratory diseases bibliographic review / Condena de canales de cerdo por enfermedades respiratorias revisión bibliográfica

As doenças respiratórias são um problema significativo na produção suína e podem levar à condenação de carcaças no abate. Entre os agentes causadores dessas doenças destacam-se o Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae e a Pasteurella multocida. O Actinobacillus pleuropneumoniae é um patógeno altamente contagioso, que ocasiona hemorragia, pleuropneumonia purulenta e fibrosa. A Pleuropneumonia é amplamente distribuída e gera graves prejuízos para a suinocultura. O Mycoplasma hyopneumoniae ocasionador da pneumonia por micoplasma, doença respiratória crônica. As infecções originadas podem regular negativamente o sistema imunológico do hospedeiro e aumentar a infecção e assim a replicação de outros patógenos. A Pasteurella multocida é o agente causador de uma ampla gama de infecções levando a alto impacto econômico. Patógeno comensal e oportunista da boca, nasofaringe e trato respiratório superior. A identificação precoce e o manejo adequado desses agentes causadores de doenças respiratórias são fundamentais para minimizar a incidência de carcaças suínas. A adoção de medidas preventivas, como a vacinação e práticas de manejo adequadas, pode ajudar a prevenir a propagação dessas doenças e garantir a produção de carne suína segura e de alta qualidade para o consumo humano.(AU)

Respiratory diseases are a significant problem in pork production and can lead to condemnation of carcasses at slaughter. Among the causative agents of these diseases are Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae and Pasteurella multocida. Actinobacillus pleuropneumoniae is a highly contagious pathogen that causes hemorrhage, purulent and fibrous pleuropneumonia. Pleuropneumonia is widely distributed and causes serious damage to pig farming. Mycoplasma hyopneumoniae causes mycoplasma pneumonia, a chronic respiratory disease. Originating infections can down-regulate the host's immune system and increase infection and thus replication of other pathogens. Pasteurella multocida is the causative agent of a wide range of infections leading to high economic impact. Commensal and opportunistic pathogen of the mouth, nasopharynx and upper respiratory tract. Early identification and proper management of these agents that cause respiratory diseases are essential to minimize the incidence of swine carcasses. Adopting preventive measures, such as vaccination and proper management practices, can help prevent the spread of these diseases and ensure the production of safe, high-quality pork for human consumption.(AU)

Las enfermedades respiratorias son un problema importante en la producción porcina y pueden provocar el decomiso de las canales en el matadero. Entre los agentes causantes de estas enfermedades se encuentran Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae y Pasteurella multocida. Actinobacillus pleuropneumoniae es un patógeno altamente contagioso que causa hemorragia, pleuroneumonía purulenta y fibrosa. La pleuroneumonía está ampliamente distribuida y causa graves daños a la cría de cerdos. Mycoplasma hyopneumoniae causa neumonía por micoplasma, una enfermedad respiratoria crónica. Las infecciones que se originan pueden regular a la baja el sistema inmunitario del huésped y aumentar la infección y, por lo tanto, la replicación de otros patógenos. Pasteurella multocida es el agente causal de una amplia gama de infecciones que tienen un alto impacto económico. Patógeno comensal y oportunista de la boca, nasofaringe y tracto respiratorio superior. La identificación temprana y el manejo adecuado de estos agentes causantes de enfermedades respiratorias son fundamentales para minimizar la incidencia de las canales porcinas. La adopción de medidas preventivas, como la vacunación y prácticas de manejo adecuadas, puede ayudar a prevenir la propagación de estas enfermedades y garantizar la producción de carne de cerdo segura y de alta calidad para el consumo humano.(AU)

Pathogenicity of Porcine Circovirus Type 2d (PCV2d) in Pigs Infected with PCV2d or Co-infected with Mycoplasma hyopneumoniae and PCV2d or with Porcine Reproductive and Respiratory Syndrome Virus and PCV2d.

The objective of this study was to determine the pathogenicity of porcine circovirus type 2d (PCV2d) in pigs inoculated intranasally with PCV2d alone, PCV2d in combination with Mycoplasma hyopneumoniae or PCV2d in combination with porcine reproductive and respiratory syndrome virus (PRRSV). Pigs infected with PCV2d alone were asymptomatic. All pigs inoculated with either M. hyopneumoniae and PCV2d or with PCV2d and PRRSV developed porcine circovirus-associated disease (PCVAD), as characterized by a sudden onset of clinical signs and disseminated granulomatous inflammation. Inflammation was mainly present in lymph nodes and spleen, and occasionally in liver and kidney. Pigs in both of these dually infected groups also had significantly higher (P <0.05) microscopic lymphoid lesion scores and a significantly higher (P <0.05) number of PCV2-positive cells in lymph node tissue than did pigs inoculated with PCV2d alone. The M. hyopneumoniae and PRRSV combination potentiated the PCV2d load in the blood. Co-infection with PRRSV and PCV2d resulted in a significantly higher blood load of PCV2d compared with the M. hyopneumoniae and PCV2d combination. Successful reproduction of PCVAD in pigs appears to require PCV2d with at least one additional infectious agent, such as M. hyopneumoniae or PRRSV, for the full manifestation of disease.

Effect of antibiotic treatment on Mycoplasma hyopneumoniae detection and infectious potential.

Mycoplasma hyopneumoniae (M. hyopneumoniae) causes significant economic losses in the swine industry. Antibiotics with activity against Mycoplasma spp. are employed for disease mitigation and pathogen elimination. However, veterinarians are often challenged with the detection of M. hyopneumoniae by PCR after antibiotic treatment, thus raising the question whether the bacterium is still infectious. The objective of this study was to evaluate the effect of tulathromycin treatment on M. hyopneumoniae detection and infectious potential during the acute and chronic phases of infection. For each infection phase, one age-matched naïve gilt was placed in contact with one M. hyopneumoniae infected gilt that was either treated with tulathromycin, treated and vaccinated, or non-treated, for 14 days. Four replicates per treatment group were performed for each infection phase. A numerical reduction in relative bacterial load was observed in acutely treated gilts compared to non-treated gilts. The rate at which naïve gilts became infected with M. hyopneumoniae was numerically reduced when co-housed with treated, acutely infected gilts compared to those housed with non-treated, infected gilts. During the chronic infection phase, M. hyopneumoniae was detected by PCR in more than 50 % of treated infected gilts and persisted for up to three months post-treatment. Transmission was not detected in all treatment groups however, the possibility that the pathogen was infectious could not be completely ruled out. Further research focused on assessing M. hyopneumoniae detection and viability post-treatment is necessary to guide control and elimination efforts.

Pathogenicity & virulence of Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae: is the etiological agent of porcine enzootic pneumonia (EP), a disease that impacts the swine industry worldwide. Pathogen-induced damage, as well as the elicited host-response, contribute to disease. Here, we provide an overview of EP epidemiology, control and prevention, and a more in-depth review of M. hyopneumoniae pathogenicity determinants, highlighting some molecular mechanisms of pathogen-host interactions relevant for pathogenesis. Based on recent functional, immunological, and comparative "omics" results, we discuss the roles of many known or putative M. hyopneumoniae virulence factors, along with host molecules involved in EP. Moreover, the known molecular bases of pathogenicity mechanisms, including M. hyopneumoniae adhesion to host respiratory epithelium, protein secretion, cell damage, host microbicidal response and its modulation, and maintenance of M. hyopneumoniae homeostasis during infection are described. Recent findings regarding M. hyopneumoniae pathogenicity determinants also contribute to the development of novel diagnostic tests, vaccines, and treatments for EP.

Cytokine expression and Mycoplasma hyopneumoniae burden in the development of lung lesions in experimentally inoculated pigs.

This study aimed to assess immunopathological factors and M. hyopneumoniae (M. hyo) load in macroscopic lesion formation at four timepoints after experimental infection of swine. To do this, 24 M. hyo-free pigs were divided into two groups: non-inoculated control (n = 8) and inoculated (n = 16). At day 0 post-infection (dpi), animals of infected group were intratracheally inoculated with 5 mL of lung inoculum containing 107 CCU (Color Changing Units) ∕mL of M. hyo strain 232, while control group was mock infected with 5 mL of sterilized Friis medium. At 14, 28, 42 and 56 dpi, four animals from the infected group and two from the control group were euthanized and necropsied. The extent of macroscopic lung lobe lesions was visually assessed, scored and lesion samples (qPCR, histopathology and gene expression) were collected. The macroscopic lesion score and estimated M. hyo load (in copies/µL) at the different timepoints were: 14 dpi: 18.5 %-1.55 × 103 copies∕µL; 28dpi: 15.8 %-8.4 × 103 copies∕µL; 42 dpi: 7.0 %-3.2 × 104 copies∕µL and 56 dpi: 6.3 %-1.11 × 105 copies∕µL; Significant and positive correlations between macroscopic lung lesion and the pathogen load were found (coefficient range: 0.77-0.99). The cytokine's IL-6 (0.73) and INF-γ (-0.69) gene expression were significantly (p < 0.05) correlated to macroscopic lung lesion score while IL-8, TNF- α, IL-1α and IL-1ß were associated to other pathological effects such as losses in average daily weight gain and microscopic lesion score. The results provide a better understanding about the pathogenicity of M. hyo strain 232 and the host-pathogen interactions, which may be helpful for the development of new treatments or control measures.

Differential innate immune responses induced by Mycoplasma hyopneumoniae and Mycoplasma hyorhinis in various types of antigen presenting cells.

Mycoplasma (M.) hyopneumoniae is the etiological agent of enzootic pneumonia in pigs and is closely related to M. hyorhinis, which can be isolated from the healthy mucosal surfaces of the upper respiratory tract. In rare cases it can also cause arthritis and polyserositis. Since the innate immune system is an important first line of defense and promotes adaptive immune responses, we characterized the innate immune response of various antigen presenting cells (APCs) to M. hyopneumoniae and M. hyorhinis, which differ in their pathogenicity in vivo. Porcine peripheral blood mononuclear cells were infected with different multiplicities of infection (MOI) of live and inactivated porcine mycoplasmas. Both Mycoplasma species induced strong tumour necrosis factor (TNF) responses in monocytes, with a stronger activation by M. hyorhinis. This higher stimulatory activity was also confirmed for CD40 upregulation. Conventional and plasmacytoid dendritic cells (cDC and pDC, respectively) did not or poorly respond to mycoplasmas in terms of TNF expression but more efficiently in terms of CD40 upregulation. Again, these responses were generally stronger with M. hyorhinis than with M. hyopneumoniae. Both Mycoplasma species also activated B cells in terms of CD25 upregulation, proliferation, and IgM secretion. Interestingly, while the induction of CD25 and in particular proliferation was higher with M. hyorhinis, the IgM secretion did not differ between the two species with the exception of the highest dose of M. hyopneumoniae,which appeared to suppress IgM responses. Taken together, our results provide a comparative analysis of innate immune response with different porcine APCs and demonstrate Mycoplasma species-dependent differences, which could relate to their different pathogenicity in vivo.

Antimicrobial susceptibility and genetic profile of Mycoplasma hyopneumoniae isolates from Brazil.

Mycoplasma hyopneumoniae is the etiologic agent of porcine enzootic pneumonia, responsible for major production losses worldwide. The bacteria have a limited metabolism and need to obtain molecules from the growth environment, which causes multiple difficulties for in vitro culture. These limitations have a negative influence on the ability to carry out research for the development of the rational use of antimicrobials and vaccines. The objective of this investigation was to evaluate the genetic profile and in vitro susceptibility of field isolates of M. hyopneumoniae to different antimicrobials. All 16 isolates obtained from the samples presented 100% of identity in the partial sequence of 16S rRNA gene when compared to M. hyopneumoniae. A dendrogram was created using the PCR results of the genes related to pathogenicity, and the isolates were distributed into four clusters, suggesting genetic variability among four different isolates circulating on the same farm. The minimum inhibitory concentration of the isolates was higher for the antimicrobials tylosin (< 0.001-16 mg/L) and spiramycin (< 0.001-16 mg/L) than for enrofloxacin (< 0.001-0.125 mg/L) and tiamulin (< 0.001-0.125 mg/L). Our results demonstrate the genetic variability among M. hyopneumoniae isolates from pigs of the same farm, with differences in their susceptibility to antimicrobial agents.

Genetic variation of Mycoplasma hyopneumoniae from Brazilian field samples.

BACKGROUND: Porcine enzootic pneumonia is a worldwide problem in swine production. The infected host demonstrates a respiratory disease whose etiologic agent is Mycoplasma hyopneumoniae (Mhp). A total of 266 lung samples with Mycoplasma-like lesions were collected from two slaughterhouses. We analyzed the genetic profile of Mhp field samples using 16 genes that encode proteins involved in the mechanisms of bacterial pathogenesis and/or the immune responses of the host. Bioinformatic analyses were performed to classify the Mhp field samples based on their similarity according to the presence of the studied genes. RESULTS: Our results showed variations in the frequency of the 16 studied genes among different Mhp field samples. It was also noted that samples from the same farm were genetically different from each other and samples from different regions could be genetically similar, which is evidence of the presence of different genetic profiles among the Mhp field strains that circulate in Brazilian swine herds. CONCLUSION: This work demonstrated the genetic diversity of several Mhp field strains based on 16 selected genes related to virulence and/or immune response in Brazil. Our findings demonstrate the difference between Mhp field strains could influence the virulence, and we hypothesize that the most frequent genes in Mhp field strains could possibly be used as vaccine candidates. Based on our results, we suspect that Mhp genetic variability may be associated with the frequency of genes among the field strains and we have demonstrated that some Mhp field samples could not have many important genes described in the literature.

Intracellular changes of a swine tracheal cell line infected with a Mycoplasma hyopneumoniae pathogenic strain.

Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia (EP), a widespread disease that causes major economic losses to the pig industry. The swine host response plays an important role in the outcome of M. hyopneumoniae infections. The whole proteome of newborn pig trachea (NPTr) epithelial cells infected with the M. hyopneumoniae pathogenic strain 7448 was analyzed using an LC-MS/MS approach to shed light on intracellular processes triggered in response to the pathogen. Overall, 853 swine protein species were identified, 156 of which were differentially represented in response to M. hyopneumoniae 7448 infection in comparison with non-infected control cells. These differentially represented proteins were categorized by function. Fifty-seven of them were assigned to the immune system and/or response to stimulus functional subcategories. Comparative expression analysis of these immune-related proteins in NPTr cells infected with attenuated or non-pathogenic mycoplasmas (M. hyopneumoniae J strain and M. flocculare, respectively) revealed proteins whose abundance was altered only in response to the pathogenic M. hyopneumoniae 7448 strain. Among these proteins, calcium homeostasis and endoplasmic reticulum stress-related biomarkers were detected, providing evidence of molecular mechanisms that might lead to swine cell apoptosis.

Identification and Genomic Analysis of a Pathogenic Strain of Mycoplasma hyopneumoniae (TB1) Isolated from Tibetan Pigs.

The present study aims to identify the species and strains of Mycoplasma hyopneumoniae isolated from Tibetan pigs (Mh TB1) at the genetic level for understanding the basis of its pathogenicity. Mh TB1 was isolated from the consolidated lungs of Tibetan pigs by liquid culture and agar plate colony method. Polymerase chain reaction (PCR) amplification of the 16S recombinant DNA (rDNA) conservative sequence and a species-specific gene (P36) of Mh provided species confirmation. PCR products were imaged on gels and shotgun sequencing was performed. DNA sequences were compared for assessing genetic similarity between Mh TB1 and Mh reference strains in the GenBank database. The isolated strains were >98% similar to the Mh reference strains. Genomic analysis revealed significant sequence conservation between Mh TB1 and the reference strains; however, differential genes were more prevalent in Mh TB1 than in other reported strains. Therefore, we concluded that Mh is a major pathogen of Tibetan pigs that cause enzootic pneumonia. The Mh TB1 strain harbors more genes and specific virulence factors, consistent with its plateau-related adaptability to hypoxia and virulence. Differential gene analysis revealed gene variations in the inclement plateau environment, enriched gene pool, and plateau adaptability of the Mh TB1 strain, which will be important for vaccine development.

Featured Species-Specific Loops Are Found in the Crystal Structure of Mhp Eno, a Cell Surface Adhesin From Mycoplasma hyopneumoniae.

Enolase is an evolutionarily conserved enzyme involved in the processes of glycolysis and gluconeogenesis. Mycoplasma hyopneumoniae belongs to Mycoplasma, whose species are wall-less and among the smallest self-replicating bacteria, and is an important colonizing respiratory pathogen in the pig industry worldwide. Mycoplasma hyopneumoniae enolase (Mhp Eno) expression is significantly increased after infection and was previously found to be a virulence factor candidate. Our studies show that Mhp Eno is a cell surface-localized protein that can adhere to swine tracheal epithelial cells (STECs). Adhesion to STECs can be specifically inhibited by an Mhp Eno antibody. Mhp Eno can recognize and interact with plasminogen with high affinity. Here, the first crystal structure of the mycoplasmal enolase from Mycoplasma hyopneumoniae was determined. The structure showed unique features of Mhp Eno in the S3/H1, H6/S6, H7/H8, and H13 regions. All of these regions were longer than those of other enolases and were exposed on the Mhp Eno surface, making them accessible to host molecules. These results show that Mhp Eno has specific structural characteristics and acts as a multifunctional adhesin on the Mycoplasma hyopneumoniae cell surface.

Tn-sequencing of Mycoplasma hyopneumoniae and Mycoplasma hyorhinis mutant libraries reveals non-essential genes of porcine mycoplasmas differing in pathogenicity.

Mycoplasma hyopneumoniae and Mycoplasma hyorhinis are two phylogenetically related species colonizing the respiratory tract of pigs but differing in pathogenicity, the basis of which is not well resolved. We hypothesize that genes belonging to the species-specific portion of the genome and being non-essential during ideal laboratory growth conditions encode possible virulent determinants and are the driver of interspecies differences. To investigate this, transposon mutant libraries were generated for both species and a transposon sequencing (Tn-seq) method for mycoplasmas was established to identify non-essential genes. Tn-seq datasets combined with bidirectional Blastp analysis revealed that 101 out of a total 678 coding sequences (CDS) are species-specific and non-essential CDS of M. hyopneumoniae strain F7.2C, while 96 out of a total 751 CDS are species-specific and non-essential CDS in the M. hyorhinis strain JF5820. Among these species-specific and non-essential CDS were genes involved in metabolic pathways. In particular, the myo-inositol and the sialic acid pathways were found to be non-essential and therefore could be considered important to the specific pathogenicity of M. hyopneumoniae and M. hyorhinis, respectively. Such pathways could enable the use of an alternative energy source providing an advantage in their specific niche and might be interesting targets to knock out in order to generate attenuated live vaccines.

Quantitative Proteomic Analyses of a Pathogenic Strain and Its Highly Passaged Attenuated Strain of Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia, a chronic respiratory disease in swine resulting in enormous economic losses. To identify the components that contribute to virulence and unveil those biological processes potentially related to attenuation, we used isobaric tags for relative and absolute quantification technology (iTRAQ) to compare the protein profiles of the virulent M. hyopneumoniae strain 168 and its attenuated highly passaged strain 168L. We identified 489 proteins in total, 70 of which showing significant differences in level of expression between the two strains. Remarkably, proteins participating in inositol phosphate metabolism were significantly downregulated in the virulent strain, while some proteins involved in nucleoside metabolism were upregulated. We also mined a series of novel promising virulence-associated factors in our study compared with those in previous reports, such as some moonlighting adhesins, transporters, lipoate-protein ligase, and ribonuclease and several hypothetical proteins with conserved functional domains, deserving further research. Our survey constitutes an iTRAQ-based comparative proteomic analysis of a virulent M. hyopneumoniae strain and its attenuated strain originating from a single parent with a well-characterized genetic background and lays the groundwork for future work to mine for potential virulence factors and identify candidate vaccine proteins.

Mycoplasma hyopneumoniae variability: Current trends and proposed terminology for genomic classification.

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the aetiologic agent of enzootic pneumonia in swine, a prevalent chronic respiratory disease worldwide. Mycoplasma hyopneumoniae is a small, self-replicating microorganism that possesses several characteristics allowing for limited biosynthetic abilities, resulting in the fastidious, host-specific growth and unique pathogenic properties of this microorganism. Variation across several isolates of M. hyopneumoniae has been described at antigenic, proteomic, transcriptomic, pathogenic and genomic levels. The microorganism possesses a minimal number of genes that regulate the transcription process. Post-translational modifications (PTM) occur frequently in a wide range of functional proteins. The PTM by which M. hyopneumoniae regulates its surface topography could play key roles in cell adhesion, evasion and/or modulation of the host immune system. The clinical outcome of M. hyopneumoniae infections is determined by different factors, such as housing conditions, management practices, co-infections and also by virulence differences among M. hyopneumoniae isolates. Factors contributing to adherence and colonization as well as the capacity to modulate inflammatory and immune responses might be crucial. Different components of the cell membrane (i.e. proteins, glycoproteins and lipoproteins) may serve as adhesins and/or be toxic for the respiratory tract cells. Mechanisms leading to virulence are complex and more research is needed to identify markers for virulence. The utilization of typing methods and complete or partial-gene sequencing for M. hyopneumoniae characterization has increased in diagnostic laboratories as control and elimination strategies for this microorganism are attempted worldwide. A commonly employed molecular typing method for M. hyopneumoniae is Multiple-Locus Variable number tandem repeat Analysis (MLVA). The agreement of a shared terminology and classification for the various techniques, specifically MLVA, has not been described, which makes inferences across the literature unsuitable. Therefore, molecular trends for M. hyopneumoniae have been outlined and a common terminology and classification based on Variable Number Tandem Repeats (VNTR) types has been proposed.

Differential responses to stress of two Mycoplasma hyopneumoniae strains.

Mycoplasma hyopneumoniae is a respiratory pathogen, causing porcine enzootic pneumonia. To survive in the porcine respiratory tract, M. hyopneumoniae must cope with both oxidative and heat stress imposed by the host. To get insights into M. hyopneumoniae stress responses and pathogenicity mechanisms, the protein profiles of two M. hyopneumoniae strains, pathogenic 7448 strain and non-pathogenic strain J, were surveyed under oxidative (OS) or heat (HS) stress. M. hyopneumoniae strains were submitted to OS (0.5% hydrogen peroxide) or HS (temperature shifts to 42 °C) conditions and protein profiling was carried out by LC-MS/MS and label-free quantitative analyses. Data are available via ProteomeXchange with identifier PXD012742. Qualitative and quantitative differences involving 40-60 M. hyopneumoniae proteins were observed for both strains when comparing bacteria exposed to OS or HS to non-treated controls. However, no differences in abundance were found in proteins classically related to stress responses, as peroxidases and chaperones, suggesting that these proteins would be constitutively present in both strains in the tested conditions. Interestingly, under stress conditions, more virulence-related proteins were detected in M. hyopneumoniae 7448 differentially represented proteins than in M. hyopneumoniae J, suggesting that stress may trigger a differential response of the corresponding genes, shared by both strains.

Surface proteins mhp390 (P68) contributes to cilium adherence and mediates inflammation and apoptosis in Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia (EP) and responsible for major economic losses in global swine industry. After colonization of the respiratory epithelium, M. hyopneumoniae elicits a general mucociliary clearance loss, prolonged inflammatory response, host immunosuppression and secondary infections. Until now, the pathogenesis of M. hyopneumoniae is not completely elucidated. This present study explores the pathogenicity of mhp390 (P68, a membrane-associated lipoprotein) by elucidating its multiple functions. Microtitrer plate adherence assay demonstrated that mhp390 is a new cilia adhesin that plays an important role in binding to swine tracheal cilia. Notably, mhp390 could induce significant apoptosis of lymphocytes and monocytes from peripheral blood mononuclear cells (PBMCs), as well as primary alveolar macrophages (PAMs), which might weaken the host immune response. In addition, mhp390 contributes to the production of proinflammatory cytokines, at least partially, via the release of IL-1ß and TNF-α. To the best of our knowledge, this is the first report of the multiple functions of M. hyopneumoniae mhp390, which may supplement known virulence genes and further develop our understanding of the pathogenicity of M. hyopneumoniae.

Occurrence of Mycoplasma hyopneumoniae in slaughter pigs from Southern Brazil / Ocorrência de Mycoplasma hyopneumoniae em amostras de pulmão de suínos obtidas de frigorífico do sul do Brasil

Mycoplasma hyopneumoniae is the causative agent of enzootic pneumonia (EP), a disease that is highly prevalent and globally distributed, causing significant economic losses to the swine industry. Disease progression is characterized by reduced feed conversion and the development of lung lesions. Considering the limited information about the epidemiology of EP in Southern Brazil, the main objective of this study was to determine the occurrence of M. hyopneumoniae in swine lung samples and to evaluate the scores of lung lesions caused by local strains. A total of 120 samples was randomly collected and processed. DNA was extracted from lung tissue to perform nested-PCR and lungs were inspected to evaluate the presence of the pneumonia-like gross lesions of M. hyopneumoniae. The results showed 95.8% positive samples, while the lung lesion score analysis showed suggestive lesions in 60% of samples. The detection of positive samples in nested-PCR was associated with the presence of pneumonia-like gross lesions (P < 0.01). The results demonstrate a high occurrence of EP in slaughter pigs from southern Brazil.(AU)

O Mycoplasma hyopneumoniae é o agente causador da Pneumonia Enzoótica Suína (PES), doença altamente prevalente e mundialmente distribuída, causando grandes perdas econômicas para a indústria suinícola. A progressão da doença é caracterizada pela redução das taxas de conversão alimentar e o desenvolvimento de lesões pulmonares. Visto que há informação limitada sobre a epidemiologia da PES no sul do Brasil, o objetivo do presente trabalho foi determinar a prevalência de M. hyopneumoniae em amostras de pulmão suíno e avaliar o score de lesões pulmonares causadas pelas cepas locais. Um total de 120 amostras foram coletadas aleatoriamente, processadas e analisadas. O DNA foi extraído do tecido pulmonar para realização de Nested-PCR e os pulmões foram inspecionados para presença de lesões macroscópicas sugestivas de M. hyopneumoniae. Os resultados demonstraram 95,8% das amostras positivas para o patógeno. A análise do score pulmonar mostrou lesões sugestivas da PES em 60% das amostras. A detecção de amostras positivas no Nested-PCR foi associada com a presença de lesões sugestivas (P < 0.01). Os dados obtidos neste trabalho demonstram a alta prevalência da PES em granjas do RS.(AU)

Mycoplasma hyopneumoniae resides intracellularly within porcine epithelial cells.

Enzootic pneumonia incurs major economic losses to pork production globally. The primary pathogen and causative agent, Mycoplasma hyopneumoniae, colonises ciliated epithelium and disrupts mucociliary function predisposing the upper respiratory tract to secondary pathogens. Alleviation of disease is reliant on antibiotics, vaccination, and sound animal husbandry, but none are effective at eliminating M. hyopneumoniae from large production systems. Sustainable pork production systems strive to lower reliance on antibiotics but lack of a detailed understanding of the pathobiology of M. hyopneumoniae has curtailed efforts to develop effective mitigation strategies. M. hyopneumoniae is considered an extracellular pathogen. Here we show that M. hyopneumoniae associates with integrin ß1 on the surface of epithelial cells via interactions with surface-bound fibronectin and initiates signalling events that stimulate pathogen uptake into clathrin-coated vesicles (CCVs) and caveosomes. These early events allow M. hyopneumoniae to exploit an intracellular lifestyle by commandeering the endosomal pathway. Specifically, we show: (i) using a modified gentamicin protection assay that approximately 8% of M. hyopneumoniae cells reside intracellularly; (ii) integrin ß1 expression specifically co-localises with the deposition of fibronectin precisely where M. hyopneumoniae cells assemble extracellularly; (iii) anti-integrin ß1 antibodies block entry of M. hyopneumoniae into porcine cells; and (iv) M. hyopneumoniae survives phagolysosomal fusion, and resides within recycling endosomes that are trafficked to the cell membrane. Our data creates a paradigm shift by challenging the long-held view that M. hyopneumoniae is a strict extracellular pathogen and calls for in vivo studies to determine if M. hyopneumoniae can traffic to extrapulmonary sites in commercially-reared pigs.

Lesões pulmonares em suínos abatidos no matadouro Público Municipal de Esperança, Paraíba / Pulmonary lesions of slaughtered pigs at the municipal public slaughterhouse of Esperança, Paraíba

O objetivo do presente estudo foi avaliar as lesões macroscópicas e histológicas em pulmões de suínos abatidos no abatedouro público de Esperança, Paraíba. Foram inspecionados pulmões de 180 suínos entre julho e dezembro de 2013. Destes, 34 (18,8%) apresentaram lesões. Na análise anatomopatológica dos fragmentos coletados, 82,3% (28/34) exibiram lesões sugestivas de Pneumonia Enzoótica Suína (PES). Seis (17,7%) amostras apresentaram alterações causadas pela distribuição irregular de sangue. Casos sugestivos de PES crônica foram observados em 57,1% (16/28) dos fragmentos coletados. Em 42,9% (12/28) das amostras foram definidos como sugestivos de PES subaguda. Nenhum pulmão apresentou lesões sugestivas de PES aguda. A pesquisa demonstrou que lesões pulmonares em suínos são frequentemente detectadas no abatedouro de Esperança, Paraíba, sendo a maioria destas lesões sugestivas de PES.

The objective of the present study was to evaluate the macroscopic and histological lesions in the lungs of slaughtered pigs at the public slaughterhouse of Esperança, Paraíba. Lungs from 180 pigs were inspected between July and December 2013. Lesions were observed in 34 (18.8%) lungs. In the anatomopathological analysis of the collected fragments, 82.3% (28/34) presented suggestive lesions of Swine Enzootic Pneumonia (SEP). Six (17.7%) samples presented alterations caused by irregular blood distribution. Suggestive cases of chronic SEP were observed in 57.1% (16/28) of the collected fragments. In 42.9% (12/28) of the samples were defined as suggestive of subacute SEP. No lungs presented lesions suggestive of acute PES. The research showed that lung lesions in pigs are frequently detected in the Esperança, Paraíba slaughterhouse, with the majority of these lesions suggestive for SEP.

Fructose-1,6-bisphosphate aldolase encoded by a core gene of Mycoplasma hyopneumoniae contributes to host cell adhesion.

Mycoplasma hyopneumoniae is an important respiratory pathogen that causes great economic losses to the pig industry worldwide. Although some putative virulence factors have been reported, pathogenesis remains poorly understood. Herein, we evaluated the relative abundance of proteins in virulent 168 (F107) and attenuated 168L (F380) M. hyopneumoniae strains to identify virulence-associated factors by two-dimensional electrophoresis (2-DE). Seven proteins were found to be ≥ 1.5-fold more abundant in 168, and protein-protein interaction network analysis revealed that all seven interact with putative virulence factors. Unexpectedly, six of these virulence-associated proteins are encoded by core rather than accessory genomic elements. The most differentially abundant of the seven, fructose-1,6-bisphosphate aldolase (FBA), was successfully cloned, expressed and purified. Flow cytometry demonstrated the surface localisation of FBA, recombinant FBA (rFBA) mediated adhesion to swine tracheal epithelial cells (STEC), and anti-rFBA sera decreased adherence to STEC. Surface plasmon resonance showed that rFBA bound to fibronectin with a moderately strong KD of 469 nM. The results demonstrate that core gene expression contributes to adhesion and virulence in M. hyopneumoniae, and FBA moonlights as an important adhesin, mediating binding to host cells via fibronectin.