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R F Ross

Publications and source records attributed to R F Ross.

At least 37 records · Page 2Linked to original sources
PubMed1990

Evaluation of the ELISA and comparison to the complement fixation test and radial immunodiffusion enzyme assay for detection of antibodies against Mycoplasma hyopneumoniae in swine serum.

An enzyme-linked immunosorbent assay (ELISA) was evaluated for detection of antibodies (Ab) against Mycoplasma hyopneumoniae and M. flocculare in sera from swine experimentally infected with these agents. In addition, the ELISA was compared with the complement fixation test (CFT), and radial immunodiffusion enzyme assay (RIDEA) for the demonstration of Ab against M. hyopneumoniae. Twenty two 6-week-old swine from a respiratory disease-free herd were divided into five groups. Two or three pigs from each of the four groups were inoculated, respectively, with M. hyopneumoniae or with M. flocculare while two pigs in each group were contact exposed to the inoculated penmates. A fifth group, consisting of three pigs, served as inoculated controls. Pigs inoculated with M. hyopneumoniae began coughing 13 days post inoculation (PI). Antibodies were first detected 2 weeks PI with the CFT, 3 weeks PI with the ELISA, and 5 weeks PI with the RIDEA. With the ELISA and RIDEA, Ab were still detectable one year PI at a very low level. With the CFT, Ab were not detectable in sera from any swine beyond 5 months PI. At necropsy 1 year PI, no lesions were detected in lungs of any of the animals nor were mycoplasmas detected. M. flocculare inoculated or contact-exposed pigs never evidenced clinical signs. Antibodies against M. flocculare were first detected 5 to 12 weeks PI with CFT, and 6 to 12 weeks PI with the ELISA. Peak optical density (OD) values obtained in the ELISA with M. flocculare Ab were as high as the values obtained with peak M. hyopneumoniae Ab titers. Levels of Ab against M. flocculare were at relatively higher OD at 1 year PI than Ab against M. hyopneumoniae. Sera with high levels of Ab against M. flocculare cross-reacted slightly with M. hyopneumoniae antigen in immunoblotting and ELISA.

Animals↗
PubMed1990

Effect of growth in cell cultures and strain on virulence of Mycoplasma hyopneumoniae for swine.

In an attempt to develop better methods for consistent induction of pneumonia in naturally born swine, using cultures of Mycoplasma hyopneumoniae, fifty 6-week-old, naturally born pigs from a respiratory disease-free herd were used in 3 trials. Pigs inoculated with Mycoplasma hyopneumoniae strain 232 (passage 21) grown for 1 passage or 5 passages in Eagle minimal essential medium plus 20% porcine serum, with or without human lung fibroblasts, had a mean (+/- SD) value range between 5.4 +/- 3.6 and 9.2 +/- 2.1% of consolidated lung area. In the second trial, pigs inoculated 1, 2, or 3 days in succession with strain 232 grown in Eagle medium or Friis mycoplasmal medium with 20% porcine serum had between 5.1 +/- 7 and 8.7 +/- 4.3% of consolidated lung area. In the third trial, virulence of Mycoplasma hyopneumoniae strains 144L (p27), 11 (p26), J (p60), and 232 (p27) grown in Friis mycoplasmal medium was compared. Pigs inoculated with those strains had 5.1 +/- 4.1, 2.6 +/- 3.1, 0, and 4.3 +/- 4% of consolidated lung area, respectively. Significant differences were not found in consolidated lung area among groups in trials 1 and 2, and among groups of pigs inoculated with M hyopneumoniae strains 144L, 11, and 232 in trial 3. Pneumonia was not detected in pigs inoculated with strain J in trial 3.

Animals↗
PubMed1990

Effects of Mycoplasma hyopneumoniae and Actinobacillus (Haemophilus) pleuropneumoniae infections on alveolar macrophage functions in swine.

Alveolar macrophages were collected at necropsy from pigs inoculated with Mycoplasma hyopneumoniae or Actinobacillus pleuropneumoniae or both and were tested for phagocytic capabilities, using in vitro techniques. Macrophages from noninoculated littermates were used as controls. Alveolar macrophages from pigs inoculated with either M hyopneumoniae or A pleuropneumoniae had significantly (P less than 0.05 to P less than 0.0025) higher phagocytic capacity than that of noninoculated controls. Macrophages from A pleuropneumoniae-inoculated pigs were comparatively more stimulated than were those from M hyopneumoniae-inoculated pigs. Pigs inoculated with M hyopneumoniae and then challenge-exposed with A pleuropneumoniae 2 and 4 weeks later had greatly reduced phagocytosis. Infection with M hyopneumoniae or A pleuropneumoniae caused stimulation of alveolar macrophage functions, and M hyopneumoniae infections may have suppressed phagocytic responses when pigs were challenge-exposed with a secondary pathogen (A pleuropneumoniae). This potential suppression may represent a prediposition of the host by M hyopneumoniae to secondary bacterial infections.

Actinobacillus Infections↗
PubMed1990

Adherence of Mycoplasma hyopneumoniae to cell monolayers.

This work was an attempt to develop an in vitro adherence model for Mycoplasma hyopneumoniae, using monolayers of human and porcine lung fibroblasts and porcine kidney cells. Mycoplasma hyopneumoniae grown in Friis mycoplasma broth was radiolabeled with 35[S]-methionine, washed, concentrated, and inoculated on the monolayers. After 15 minutes of centrifugation to facilitate adherence, monolayers were washed 3 times, dissolved with 0.1N NaOH, and suspended in scintillation liquid, and the radioactivity was determined in a liquid scintillation counter. Adherence, measured as a percentage of counts added, varied according to the mycoplasma strain and the cell line used. Comparison of strains J, 144L, and 232 of M hyopneumoniae revealed 7.5 +/- 5.9, 31.9 +/- 13, and 9.6 +/- 5% adherence to porcine kidney cells, respectively. Slightly different, but proportionally the same relationships were obtained with swine or human fibroblasts. Adherence was decreased slightly by repeated washings of the mycoplasma-treated cell monolayers; however, a plateau was reached, indicating irreversibility of the adherence process. Pretreatment of cell monolayers with nonlabeled organisms substantially blocked adherence by labeled organisms. Dilution of labeled organisms resulted in an increased proportion adhering. Therefore, it appears that the adherence was a receptor-dependent event. Treatment of the mycoplasmas with trypsin prior to the inoculation of monolayers resulted in a marked reduction in adherence. Treatment of the mycoplasmas with hyperimmune swine serum against M hyopneumoniae or normal swine serum resulted in 80 to 90% reduction of adherence; however, no inhibition occurred when mycoplasmas were treated with purified IgG from the hyperimmune serum.

Animals↗
PubMed1990

Humoral and cellular immune responses of pigs inoculated with Mycoplasma hyopneumoniae.

Cellular and humoral immune responses of pigs inoculated with Mycoplasma hyopneumoniae were investigated at postinoculation weeks (PIW) 2, 4, and 6. The response of blood lymphocytes (BL) and bronchial lymph node lymphocytes (LNL) to stimulation by M hyopneumoniae antigens was evaluated by a lymphocyte-stimulation test. Specific antibodies in serum and lung washing samples were assayed by ELISA. Immunoglobulin-positive cells in lungs and bronchial lymph nodes were identified by indirect fluorescent antibody test, using isotype-specific monoclonal antibodies. At PIW 0 to 6, BL from control and M hyopneumoniae-inoculated pigs were stimulated by M hyopneumoniae cells; however, BL from inoculated pigs generally had higher stimulation indices, especially at PIW 6. The response of LNL was influenced by previous exposure to M hyopneumoniae, as indicated by higher stimulation indices (P less than 0.01) of LNL from inoculated pigs killed at PIW 2 and 6. Specific ELISA antibodies to M hyopneumoniae in lung washings from inoculated pigs consisted mainly of IgG and IgA isotypes. Examination of lung sections by indirect immunofluorescence revealed that cells producing IgM and IgA were in controls as well as M hyopneumoniae-inoculated pigs, but IgG-positive cells were only in lungs of inoculated pigs. Resolution of pneumonia appeared to correlate with development of increased sensitization of BL, as well as development of marked increases in immunoglobulins, particularly IgG in lung washings at PIW 6.

Animals↗
PubMed1989

Hemagglutination and hemagglutination inhibition of turkey red blood cells with Mycoplasma hyopneumoniae.

The ability of Mycoplasma hyopneumoniae to agglutinate RBC was evaluated to develop an in vitro cytadsorption assay. Using swine RBC in a microtitration hemagglutination test, no agglutination or partial agglutination was detected. Comparison of RBC from various other species indicated that improved hemagglutination was obtained with RBC from turkeys. This hemagglutination was detected only when mycoplasma cells used in the assay had been frozen and thawed, heated at 50 C for 30 minutes, or treated with trypsin. Treatment of RBC with trypsin or neuraminidase enhanced hemagglutination. Possible surface lectin activity in M hyopneumoniae was evaluated by use of carbohydrates in a blocking assay; hemagglutination was not inhibited by any of 13 carbohydrates evaluated. Mycoplasma hyopneumoniae convalescent porcine serum and monoclonal antibodies against 2 M hyopneumoniae immunogens of molecular weights of 64,000 and 41,000 inhibited hemagglutination.

Animals↗
PubMed1988

Evaluation of tiamulin for treatment of mycoplasmal pneumonia in swine.

During 3 trials, using affected pigs of various ages, tiamulin was evaluated for treatment of experimentally induced mycoplasmal pneumonia. Pneumonia was induced in respiratory tract disease-free swine by intratracheal inoculation of a lung homogenate containing Mycoplasma hyopneumoniae. Eleven days after inoculation, when more than 20% of pigs were coughing, pigs were allotted to 3 or 4 groups (n = 8 pigs each) and were given regimens of no medication or 60 mg, 120 mg, or 180 mg of tiamulin/L of drinking water for 10 days. Twenty-one days after cessation of medication, pigs were euthanatized and then were necropsied. Results obtained from the 3 trials did not indicate significant difference among treatment groups in severity of macroscopic or microscopic lesions induced by M hyopneumoniae or in detection of M hyopneumoniae by use of immunofluorescent technique. Clinical evaluations, daily gain, and feed efficiency did not differ significantly among treatment groups. In this study, tiamulin administration did not have beneficial effects in swine with mycoplasmal pneumonia.

Animals↗
PubMed1988

Isolation of Mycoplasma salivarium from swine.

Mycoplasma salivarium, a common human oropharyngeal mycoplasma, was isolated from nasal and pharyngeal secretions of 14 of 284 swine in a barrier-maintained, disease-free herd. M. salivarium was recovered from one boar 6 times over a 26-month period and one time only from 13 other swine. Human isolates of M. salivarium were compared with the swine isolates by DNA-DNA hybridization and SDS-PAGE of the cell proteins and the strains were shown to be closely related. One of eight of the swine from which M. salivarium was isolated had complement-fixing antibodies and another culture-positive animal had metabolic-inhibiting antibodies to M. salivarium. Overt disease was not associated with the organism. These results support previous findings that mycoplasmas closely related to M. salivarium may be isolated from the nasopharynges of swine and they further indicate that the organism can establish persistently in swine without evidence of overt disease.

Animals↗
PubMed1987

Assessment of antibody response of swine infected with Mycoplasma hyopneumoniae by immunoblotting.

An immunoblot procedure was used to evaluate porcine antibody response to inoculation with Mycoplasma hyopneumoniae. Mycoplasmas solubilized with sodium dodecyl sulfate were used as antigens. Antibodies to 5 antigens, estimated to be of molecular weight (mol wt) 110,000, 64,000, 50,000, 41,000, and 36,000, were detected in sera collected during the course of induced mycoplasmal pneumonia. Mycoplasma hyopneumoniae antigens, mol wt 110,000, 50,000, 41,000, and 36,000, cross-reacted with M flocculare when antigen prepared from M flocculare or hyperimmune serum against it were used in the immunoblot procedure. The 36,000-dalton (D) antigen reacted with M hyopneumoniae and M hyorhinis convalescent sera. The 64,000-D M hyopneumoniae antigen was the only antigen that did not cross-react with M flocculare or M hyorhinis. Exposure of immunoblot strips with antigens to trypsin before reacting them with the convalescent sera abolished binding ability of the 110,000-D and 36,000-D antigens, but had no effect on binding by 64,000-D, 50,000-D, or 41,000-D antigens. None of the 5 antigens bound to 11 lectins.

Animals↗
PubMed1987

Relationship between Mycoplasma hyosynoviae infection and front limb weakness in Duroc swine.

A relationship between degree of Mycoplasma hyosynoviae infection and front limb soundness was examined in 254 Duroc swine. These pigs represented 3 lines of pigs (structurally sound, control, and unsound) from a population divergently selected for 4 generations for front limb soundness. Analysis of sera collected every 4 weeks between 6 and 26 weeks of age yielded complement-fixing antibody titers that were believed to be indicative of the degree of natural infection with M hyosynoviae. Analysis of several variables defined by using titer values failed to reveal significant differences among the 3 selected lines, but trends indicated higher mean and peak titer values for pigs from the unsound line. Correlations between titer variables and front limb soundness variables within genetic groups were low and not significantly different from zero. Correlations between all titer variables were calculated; the correlation between mean titer and peak titer was 0.81 (P less than 0.01), and between mean titer and age at detection of first titer, was -0.56 (P less than 0.01). Pooled heritability estimates were 0.51 +/- 0.28 for mean titer and 0.28 +/- 0.25 for peak titer.

Animals↗
PubMed1986

Sweet itch.

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Animals↗
PubMed1986

Outer membrane protein profiles of Haemophilus pleuropneumoniae.

Outer membrane protein profiles of Haemophilus pleuropneumoniae were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cells were disrupted by sonication, and outer membrane-enriched fractions were prepared by differential centrifugation and selective solubilization of the inner membrane with sodium N-lauroyl sarcosinate. Colony type, growth medium, time of harvest, and in vitro or in vivo passage had no appreciable effect on the protein profiles of the strains examined. Seven patterns were distinguished among the reference strains of the nine capsular serotypes. These patterns were based on the mobility of the major outer membrane proteins migrating in the 39,000- to 44,000-molecular-weight region of the gel, a 16K to 16.5K protein, and a heat-modifiable 29K protein. Strains of serotypes 1 and 9 had identical outer membrane protein profiles, as did strains of serotypes 2 and 6. The reference strains of the remaining five serotypes each had a distinct pattern. The outer membrane protein profiles of 95 field isolates belonging to serotypes 1, 5, 7, and 9 from swine in the midwestern United States were determined and compared with the reference patterns. The results indicate that the population of H. pleuropneumoniae is clonal, with three predominant clones distinguished by both serotype and outer membrane protein profile responsible for the majority of H. pleuropneumoniae disease occurring in swine in the United States.

Animals↗
PubMed1986

Antibody response of swine to outer membrane components of Haemophilus pleuropneumoniae during infection.

Sera from pigs infected with Haemophilus (Actinobacillus) pleuropneumoniae were tested for antibodies to outer membrane proteins (OMPs) of the organism by immunoblotting. Convalescent sera were produced in naturally born, colostrum-fed pigs and in cesarean-derived, colostrum-deprived pigs given H. pleuropneumoniae serotype 5 intranasally twice at 5-week intervals. Sera, collected at weekly intervals, were reacted with Sarkosyl-insoluble, OMP-enriched preparations of H. pleuropneumoniae which had been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to nitrocellulose. Antibodies were detected to OMPs with an apparent molecular weight of 16,500 (16.5K OMP); to 29K, 38.5K, 43.5K, 45K, 49.5K, and 66.5K OMPs; and to several high-molecular-weight (greater than or equal to 94,000) OMPs, but not to the major 42K OMP. Antibodies to the heat-modifiable OMP (29K/43.5K) and the 38.5K OMP were detected in sera from noninfected pigs. Antibodies were also detected to two broad 54,000- and 95,000-molecular-weight bands which did not stain with Coomassie blue, stained with silver nitrate, resisted proteinase K digestion, and were eliminated by oxidation with sodium metaperiodate. This indicates that the 54,000- and 95,000-molecular-weight bands represent polysaccharide, possibly capsular or lipopolysaccharide immunogens. Adsorption of sera with cells from the homologous serotype 5 strain removed antibodies to the 45K, 49.5K, 66.5K, and greater than or equal to 94K OMPs and to the two polysaccharide bands, indicating that these antibodies were directed primarily to surface-exposed epitopes. When tested with OMP preparations from other serotype 5 strains, heterogeneity was apparent, both in the reactions with OMPs and with the polysaccharide bands. Silver staining of proteinase K-treated, whole-cell lysates from serotype 5 strains also indicated variable expression of the polysaccharide bands. Sera also reacted with OMPs from H. pleuropneumoniae serotypes 1 and 7; however, several OMPs and the lipopolysaccharide or polysaccharide determinants of these serotypes appeared to be type specific.

Animals↗
PubMed1985

Characterization of Haemophilus spp. isolated from healthy swine and evaluation of cross-reactivity of complement-fixing antibodies to Haemophilus pleuropneumoniae and Haemophilus taxon "minor group".

Of 30 sows from a herd believed to be free of Haemophilus pleuropneumoniae infection, 2 had complement-fixing antibodies to H. pleuropneumoniae serotype 5. Necropsy and microbiological examination of the two sows revealed no evidence of H. pleuropneumoniae infection; however, Haemophilus taxon "minor group" and a urease-negative, indole-positive Haemophilus sp. were isolated from numerous respiratory tract sites in both sows. Isolation of these Haemophilus spp. was facilitated by serially diluting specimens in two broth media. Pigs from a closed, respiratory disease-free herd were inoculated with four strains of Haemophilus taxon "minor group" to determine whether the organism induces antibodies which cross-react with H. pleuropneumoniae in the complement fixation test. Antigenic heterogeneity among the taxon "minor group" strains was apparent; however, antibodies cross-reacting between these strains and H. pleuropneumoniae serotypes 1 through 5 and 7 were not detected.

Animals↗
PubMed1985

Cell-mediated and humoral immune response to Mycoplasma hyopneumoniae in pigs enhanced by dextran sulfate.

The effect of dextran sulfate (DS), known to be cytotoxic to macrophages, on the cell-mediated and humoral immune response to nonviable Mycoplasma hyopneumoniae in pigs was investigated. The cell-mediated immune response was determined by means of lymphocyte transformation a test, using uptake of [3H]thymidine in a microculture system and the humoral immune response by means of a microplate complement-fixation test. Peripheral blood lymphocytes from pigs vaccinated with nonviable M hyopneumoniae and DS incorporated substantially more [3H]thymidine than did those from pigs given Mycoplasma or DS alone. The transformation of lymphocytes from M hyopneumoniae-DS vaccinated pigs was enhanced when M hyopneumoniae cells used in the assay system were heated at 60 C for 30 minutes. Similarly prepared M flocculare and M hyorhinis cells also stimulated lymphocytes from M hyopneumoniae-DS vaccinated pigs, but not nearly as great as when M hyopneumoniae cells were used. The humoral antibody response and the cell-mediated immune response to nonviable M hyopneumoniae was markedly enhanced by DS. Pigs were vaccinated with nonviable M hyopneumoniae and/or DS 4 times and challenge exposed intratracheally with viable M hyopneumoniae. Pigs vaccinated with M hyopneumoniae and DS had less severe pneumonia than did nonvaccinated pigs.

Animals↗
PubMed1985

Serotyping of Haemophilus pleuropneumoniae by rapid slide agglutination and indirect fluorescent antibody tests in swine.

One hundred and forty-one isolates of Haemophilus pleuropneumoniae from Iowa and Illinois swine were characterized morphologically and biochemically and serotyped by rapid slide agglutination (RSA) and indirect fluorescent antibody (IFA) tests. Hyperimmune antisera were produced in rabbits using inactivated whole-cell suspensions of the reference strains for H pleuropneumoniae serotypes 1 to 7 and strain 202, representing the taxon "minor group." Cross testing of the reference strains and reference antisera indicated the antisera to be essentially serotype-specific, although reactivity of some antisera with heterologous strains was observed. Cultures of the 141 isolates formed adherent or smooth colonies or mixtures of these colony forms. Adherent and smooth colony types were found in all serotypes identified. Microscopic and biochemical characteristics of all isolates were typical of those previously described for H pleuropneumoniae. The overall incidence of H pleuropneumoniae serotypes was serotype 5, 55.3%; serotype 1, 34.0%; serotype 7, 7.8%; and nontypeable, 2.8%. Comparing the 2 test procedures, 87.2% of the isolates could be typed by RSA, and 66.0% could be typed by IFA. Cross-reactions between serotype 4 antisera and serotype 5 and 7 isolates were common with the IFA test. The reactions with serotype 7, but not serotype 5, were eliminated by cross adsorption of serotype 4 antisera. There was good correlation between the 2 test procedures, but RSA was judged to be more specific and sensitive than IFA.

Agglutination Tests↗
PubMed1985

Suppressive effect of nonviable Mycoplasma hyopneumoniae on phytohemagglutinin-induced transformation of swine lymphocytes.

The effect of nonviable Mycoplasma hyopneumoniae on transformation of swine peripheral blood lymphocytes by mitogen was investigated. Lymphocyte transformation was evaluated as incorporation of [3H]-thymidine, using a microculture system. Mycoplasma hyopneumoniae was grown in Friis medium, inactivated with sodium azide, and washed with phosphate-buffered saline solution. Four strains of M hyopneumoniae, strain J, strain 11, and 2 low-passage isolates (1361A, 1375C), were found to suppress phytohemagglutinin-induced lymphocyte transformation. Mycoplasma hyopneumoniae strains J, 11, and 1361A reduced lymphocyte transformation by about 50%, whereas strain 1375C reduced lymphocyte transformation by 98.7%. The suppressive effect was abrogated by heating M hyopneumoniae at 60 C or at higher temperatures for 30 minutes. Sonication of the heated M hyopneumoniae cells partially restored the suppressive effect.

Animals↗