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Journal ArticleDOI

Diagnosis of Mycoplasma hyopneumoniae.

01 Dec 2004-Animal Health Research Reviews (Cambridge University Press)-Vol. 5, Iss: 2, pp 317-320

AbstractMycoplasma hyopneumoniae, the cause of enzootic pneumonia, remains an important pathogen in the swine industry. This small, complex organism colonizes the ciliated cells of the respiratory tract, resulting in little exposure to the immune system. Confirming the presence of M. hyopneumoniae, as well as identifying its role in respiratory disease and pneumonia, remains challenging to the veterinary profession. While culture of the organism remains the gold standard for identification, the use of serology, the polymerase chain reaction and various assays to detect the presence of M. hyopneumoniae in tissue is common in diagnostic laboratories. Because of the role M. hyopneumoniae plays in increasing the severity of pneumonia associated with concurrent bacterial and viral infections, understanding the pathogenesis and diagnostic assays available is critical for developing effective intervention strategies to control respiratory disease on a herd basis.

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Journal ArticleDOI
TL;DR: The main effects of vaccination include less clinical symptoms, lung lesions and medication use, and improved performance, however, bacterins provide only partial protection and do not prevent colonization of the organism.
Abstract: Mycoplasma hyopneumoniae, the primary pathogen of enzootic pneumonia, occurs worldwide and causes major economic losses to the pig industry. The organism adheres to and damages the ciliated epithelium of the respiratory tract. Affected pigs show chronic coughing, are more susceptible to other respiratory infections and have a reduced performance. Control of the disease can be accomplished in a number of ways. First, management practices and housing conditions in the herd should be optimized. These include all-in/all-out production, limiting factors that may destabilize herd immunity, maintaining optimal stocking densities, prevention of other respiratory diseases, and optimal housing and climatic conditions. Strategic medication with antimicrobials active against M. hyopneumoniae and, preferably, also against major secondary bacteria may be useful during periods when the pigs are at risk for respiratory disease. Finally, commercial bacterins are widely used to control M. hyopneumoniae infections. The main effects of vaccination include less clinical symptoms, lung lesions and medication use, and improved performance. However, bacterins provide only partial protection and do not prevent colonization of the organism. Different vaccination strategies (timing of vaccination, vaccination of sows, vaccination combined with antimicrobial medication) can be used, depending on the type of herd, the production system and management practices, the infection pattern and the preferences of the pig producer. Research on new vaccines is actively occurring, including aerosol and feed-based vaccines as well as subunit and DNA vaccines. Eradication of the infection at herd level based on age-segregation and medication is possible, but there is a permanent risk for re-infections.

337 citations


Journal ArticleDOI
TL;DR: Lung samples from 148 finishing pigs with cranioventral lobular bronchopneumonia consistent with porcine respiratory disease complex (PRDC) in Denmark revealed a broad range of microscopical lesions and the diversity and number of pathogens were higher in these animals compared with controls.
Abstract: Respiratory infections are among the most important diseases of growing pigs. In order to elucidate the multifactorial aetiology of porcine respiratory disease complex (PRDC) in Denmark, lungs from 148 finishing pigs with cranioventral bronchopneumonia (case group) and 60 pigs without lung lesions (control group) were collected from abattoirs. The pathogens involved in PRDC and their interactions were identified and linked to the histopathological diagnosis. The lung samples were cultured for bacteria and tested by multiplex polymerase chain reaction for presence of swine influenza virus (type A), porcine reproductive and respiratory syndrome virus (both European and US type), porcine circovirus type 2 (PCV2), porcine respiratory coronavirus, porcine cytomegalovirus, Mycoplasma hyopneumoniae and Mycoplasma hyorhinis. All cases had cranioventral lobular bronchopneumonia consistent with PRDC. There was a broad range of microscopical lesions and the cases were characterized as acute (n=10), subacute (n=24) or chronic (n=114) bronchopneumonia. Five bacterial species, five viruses and two Mycoplasma spp. were detected in different combinations. PCV2, M. hyopneumoniae, M. hyorhinis and Pasteurella multocida were detected most frequently among the PRDC affected swine and the diversity and number of pathogens were higher in these animals compared with controls. No clear-cut associations were detected between pathogens and histological lesions or histopathological diagnoses. PRDC occurs more frequently than enzootic pneumonia among Danish finishing pigs and has complex and varied histopathology.

151 citations


Journal ArticleDOI
TL;DR: In this review, the characteristics of M. hyopneumoniae related to pathogenesis and control measures will be discussed and special emphasis will be placed on vaccination strategies that have been proposed with the use of reverse vaccinology approaches.
Abstract: Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia (EP), a disease that affects swine production worldwide. Vaccination is the most cost-effective strategy for the control and prevention of the disease. Despite efforts to control M. hyopneumoniae infection, significant economic losses in pig production continue to occur. The results of genome-based research have the potential to help understand the biology and pathogenesis of M. hyopneumoniae, and contribute to the development of more effective vaccines and diagnostic tests. In this review, the characteristics of M. hyopneumoniae related to pathogenesis and control measures will be discussed. Special emphasis will be placed on vaccination strategies that have been proposed with the use of reverse vaccinology approaches.

69 citations


Journal ArticleDOI
TL;DR: A proteomic analysis, based on two-dimensional gel electrophoresis of soluble protein extracts, immunoblot and mass spectrometry, which was carried out aiming the identification of gene products and antigenic proteins from the M. hyopneumoniae pathogenic strain 7448 produced a proteome map that is expected to serve as a reference for comparative analyses for methabolic studies based on cells cultured under modified conditions.
Abstract: Mycoplasma hyopneumoniae is an important pathogen for pigs, being the causative agent of enzootic pneumonia. Recently, the genome sequences of three strains, J, 7448 and 232 have been reported. Here, we describe the results of a proteomic analysis, based on two-dimensional gel electrophoresis of soluble protein extracts, immunoblot and mass spectrometry, which was carried out aiming the identification of gene products and antigenic proteins from the M. hyopneumoniae pathogenic strain 7448. A preliminary M. hyopneumoniae proteome map in two pH ranges (3-10 and 4-7) was produced. A total of 31 different coding DNA sequences (CDSs), including three hypothetical ones, were experimentally verified with the identification of the corresponding protein products by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. According to the Clusters of Orthologous Groups (COG) functional classification, the identified proteins were assigned to the groups of metabolism (13), cellular processes (5) and information and storage processing (4). Nine of the identified proteins were not classifiable by COG, including some related to cytoadherence and possibly involved in pathogenicity. Moreover, at least five highly antigenic proteins of M. hyopneumoniae were identified by immunoblots, including four novel ones (a heat shock protein 70, an elongation factor Tu, a pyruvate dehydrogenase E1-beta subunit and the P76 membrane protein). The now available proteome map is expected to serve as a reference for comparative analyses between M. hyopneumoniae pathogenic and non-pathogenic strains, and for methabolic studies based on cells cultured under modified conditions.

56 citations


Journal ArticleDOI
TL;DR: It is indicated that vaccination does not significantly reduce the transmission of this respiratory pathogen in nursery pigs under field conditions.
Abstract: This study investigated the effect of vaccination against Mycoplasma hyopneumoniae on its transmission in nursery pigs under field conditions. Seventy-two pigs were randomly allocated at weaning into vaccinated (V) and non-vaccinated (NV) groups. Animals in the V group were vaccinated at 3 weeks of age with a commercial M. hyopneumoniae bacterin vaccine. Broncho-alveolar lavage fluid taken at weaning and at the end of the nursery period was assessed for the presence of M. hyopneumoniae by nested PCR, and the reproduction ratio of infection (Rn) was calculated. The percentage of positive pigs in the V and NV groups was 14% and 36% at weaning, and 31% and 64% at the end of the nursery period, respectively. The Rn-values for the V and NV groups were 0.71 and 0.56, respectively (P > 0.05). The study indicates that vaccination does not significantly reduce the transmission of this respiratory pathogen.

54 citations


References
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Abstract: Describes the characteristics of a variety of diseases of swine, and methods for their prevention and treatment.

1,722 citations


Journal ArticleDOI
TL;DR: Results indicate that M. hyopneumoniae infection potentiates PRRSV-induced disease and lesions, which is important with respect to the control of respiratory disease in pigs and has implications in elucidating the potential contribution of mycoplasmas in the pathogenesis of viral infections of other species, including humans.
Abstract: An experimental model that demonstrates a mycoplasma species acting to potentiate a viral pneumonia was developed. Mycoplasma hyopneumoniae, which produces a chronic, lymphohistiocytic bronchopneumonia in pigs, was found to potentiate the severity and the duration of a virus-induced pneumonia in pigs. Pigs were inoculated with M. hyopneumoniae 21 days prior to, simultaneously with, or 10 days after inoculation with porcine reproductive and respiratory syndrome virus (PRRSV), which induces an acute interstitial pneumonia in pigs. PRRSV-induced clinical respiratory disease and macroscopic and microscopic pneumonic lesions were more severe and persistent in M. hyopneumoniae-infected pigs. At 28 or 38 days after PRRSV inoculation, M. hyopneumoniae-infected pigs still exhibited lesions typical of PRRSV-induced pneumonia, whereas the lungs of pigs which had received only PRRSV were essentially normal. On the basis of macroscopic lung lesions, it appears that PRRSV infection did not influence the severity of M. hyopneumoniae infection, although microscopic lesions typical of M. hyopneumoniae were more severe in PRRSV-infected pigs. These results indicate that M. hyopneumoniae infection potentiates PRRSV-induced disease and lesions. Most importantly, M. hyopneumoniae-infected pigs with minimal to nondetectable mycoplasmal pneumonia lesions manifested significantly increased PRRSV-induced pneumonia lesions compared to pigs infected with PRRSV only. This discovery is important with respect to the control of respiratory disease in pigs and has implications in elucidating the potential contribution of mycoplasmas in the pathogenesis of viral infections of other species, including humans.

328 citations


Journal Article
TL;DR: A description is given of a new medium with which primary isolation of mycoplasma species of the porcine respiratory tract is usually successful, and various additives often recommended for myCoplasma cultivation have been examined for growth promoting effect.
Abstract: Two mycoplasma species of the porcine respiratory tract: Mycoplasma suipneumoniae and Mycoplasma flocculare, have been notoriously difficult to cultivate. In the present paper a description is given of a new medium with which primary isolation of these organisms is usually successful. The basal medium is made from commercial dehydrated products. Pig serum is added and phenol red used as pH indicator. Contrary to what is customary in the preparation of mycoplasma media, various inorganic salts (Hank's balanced salt solution) are included and penicillin-G replaced as a bacteriostatic by bacitracin and meticillin. The volume of water is adjusted so as to give isotonia. Various additives often recommended for mycoplasma cultivation have been examined for growth promoting effect; apparently, however, they were all without effect. Working procedures for primary isolation trials are briefly described.

290 citations


Journal ArticleDOI
TL;DR: In vivo- and in vitro-grown Mycoplasma hyopneumoniae organisms were inoculated onto newborn piglet tracheal organ cultures to provide a model for interaction of this organism with ciliated respiratory epithelium.
Abstract: In vivo- and in vitro-grown Mycoplasma hyopneumoniae organisms were inoculated onto newborn piglet tracheal organ cultures to provide a model for interaction of this organism with ciliated respiratory epithelium. Ciliostasis and loss of cilia in tracheal rings were induced by M. hyopneumoniae grown in vivo and with low-passage cultures when grown in vitro. Levels of calmodulin or dehydrogenase enzymes in tracheal ring epithelium were not altered even though ciliostasis and loss of cilia induced by M. hyopneumoniae were extensive. The capacity for inducing epithelial damage diminished with in vitro passage of the organism. Attempts to induce higher-passage cultures to attach to cilia, cause ciliostasis, or cause ciliary damage by supplementation of mycoplasmal medium with porcine lung extract failed. Epithelial damage induced by M. hyopneumoniae in tracheal rings was averted by using porcine immune serum or by separating the organisms from ciliated epithelium with a 0.1-microns-pore-size membrane. Attachment, or at least close association, of M. hyopneumoniae to ciliated epithelium appeared to be necessary to induce ciliostasis and loss of cilia in this model.

163 citations


Journal ArticleDOI
TL;DR: A nested PCR using 2 species-specific sets of primers from the 16S ribosomal DNA gave positive results with as little as 80 microorganisms and did not cross-react with other mycoplasma species or with other microorganisms commonly found in the respiratory tract of pigs.
Abstract: The porcine respiratory disease complex (PRDC) is an increasingly important cause of decreased swine productivity and is characterized by slow growth, decreased feed efficiency, anorexia, cough, and dyspnea. Mycoplasma hyopneumoniae is among the most prevalent and important infectious agents associated with PRDC. Understanding of mycoplasmal pneumonia has been hindered by inadequate diagnostic methods. Many of the currently available tests are relatively insensitive or nonspecific when used in a diagnostic laboratory setting or are too costly or difficult for routine diagnostic use. Several polymerase chain reaction (PCR) assays have been described, but they are not sensitive enough to detect the microorganisms in live pigs, from either nasal or tracheal swabs. A nested PCR using 2 species-specific sets of primers from the 16S ribosomal DNA gave positive results with as little as 80 microorganisms and did not cross-react with other mycoplasma species or with other microorganisms commonly found in the respiratory tract of pigs. This assay was better suited for detection of M. hyopneumoniae from nasal swabs than was conventional PCR. Nasal swab samples were taken at different time periods following experimental challenge of 10 susceptible pigs. Only 2 of the 55 swabs examined gave a positive result with conventional PCR, whereas 30 of the 55 swabs gave a positive result using the nested PCR. Twenty of 40 (50%) nasal swabs from pigs experiencing a respiratory disease outbreak where M. hyopneumoniae had been diagnosed also gave a positive result with the nested PCR. To confirm that the amplified product was specific, 4 nested PCR products were purified, sequences were determined and aligned, and they were confirmed to be from M. hyopneumoniae.

147 citations