Friis Nf

Bio: Friis Nf is an academic researcher. The author has contributed to research in topics: Mycoplasma & Mycoplasma hyopneumoniae. The author has an hindex of 1, co-authored 1 publications receiving 290 citations.

Some recommendations concerning primary isolation of Mycoplasma suipneumoniae and Mycoplasma flocculare a survey.

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.

Ciliostasis and loss of cilia induced by Mycoplasma hyopneumoniae in porcine tracheal organ cultures.

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.

Evaluation of local and systemic immune responses induced by intramuscular injection of a Mycoplasma hyopneumoniae bacterin to pigs.

Abstract: Objective—To evaluate immune responses induced by administration of Mycoplasma hyopneumoniae bacterin to pigs. Animals—60 healthy 7- to 10-day-old cross-bred boars. Procedure—Pigs were assigned to 1 of 4 pig groups (15 pigs/group): vaccinated, challenged; vaccinated, nonchallenged; nonvaccinated, challenged; nonvaccinated, nonchallenged. Vaccinated pigs received IM injections of a mycoplasma bacterin on days 0 and 14, whereas nonvaccinated pigs received saline (0.9% NaCl) solution. Pigs in the challenged groups were inoculated intratracheally with M hyopneumoniae on day 42. Pigs were euthanatized and necropsied 41, 44, 48, and 70 days after the first vaccination, and proportion of lung surface with pneumonic lesions was determined. Percentage of lymphocyte subpopulations and number of interferon-γ (IFN-γ) secreting lymphocytes in blood and tissues, cytokine and antibody concentrations in bronchoalveolar lavage (BAL) fluid, and serum antibody concentrations were determined. Results—Vaccination against and ...

Application of a nested polymerase chain reaction assay to detect Mycoplasma hyopneumoniae from nasal swabs.

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.

Identification and characterization of a Mycoplasma hyopneumoniae adhesin.

Abstract: An adhesin of Mycoplasma hyopneumoniae was identified and characterized in this study. A monoclonal antibody (MAb), F2G5, and its F(ab')2 fragments inhibited the adherence of M. hyopneumoniae to porcine tracheal cilia, the natural targets to which the mycoplasma binds during infection. MAb F2G5 detected multiple bands, but predominantly recognized a 97-kDa (P97) protein of M. hyopneumoniae on immunoblots. Affinity chromatography, conducted with immobilized MAb F2G5, mainly purified P97. The purified proteins were able to bind to cilia and blocked the adherence of intact M. hyopneumoniae cells to cilia. Immunolabeling of mycoplasmas with MAb F2G5 under electron microscopy demonstrated that the proteins recognized by MAb F2G5 were located at the surface of the mycoplasma, predominantly on a surface fuzzy layer. These results indicate that P97 functions as an adhesin of M. hyopneumoniae. The N-terminal amino acid sequence of P97 did not have significant homology with any known bacterial or mycoplasmal adhesins, suggesting that P97 is a novel protein. The predominant proteins detected by MAb F2G5 in different strains varied in size, indicating that the antigen bearing the epitope for MAb F2G5 undergo intraspecies size variation. Antigenic variation of adhesins may be a pathogenic mechanism utilized by M. hyopneumoniae to evade the porcine immune system.