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At least 1,621 records · Page 90Linked to original sources
PubMed1965

FRACTIONATION ON CROSS-LINKED DEXTRAN, SEPHADEX G-25, OF SERA FROM SHEEP INFECTED WITH JOHNE'S BACILLI. PRELIMINARY REPORT.

Ten sera collected during the winter months from six sheep infected with Johne's bacilli were fractionated on Sephadex G-25 columns, and all fractions tested for complement-fixing antibody, anticomplementary properties and for supplementing and inhibitory activities when added to complement-fixation tests of a heterologous antigen-antibody system: bovine or ovine antiserum with Brucella abortus antigen. Serum from a normal sheep was similarly fractionated and examined. The complement-fixing activity with a carbohydrate fraction of Johne's bacilli was confined principally to supernatant fractions of the earlier eluates containing the greater part of the serum proteins. Some of the unheated earlier and later fractions displayed a limited degree of supplementing effect. Inhibitory activity was demonstrated by certain of the earlier and later eluates after they had been heated, particularly those of antisera with initially low complement-fixing antibody titer.

Animals↗
PubMed1965

STUDIES OF JOHNE'S DISEASE IN CANADA. XII. ELECTROPHORETIC ANALYSIS OF CHANGES IN SERUM PROTEINS IN INFECTED CATTLE AND SHEEP.

Electrophoretic examinations were made on sera collected monthly for a period of eleven months from ten cattle naturally or experimentally infected with Johne's bacilli and from ten contact sheep. With one exception, the percentage estimates for the four major classes of serum proteins, albumin, alpha(1)-, alpha(2)-, beta- and gamma-globulins did not differ significantly in sera from infected and non-infected, presumably healthy cattle. One cow with a persistently high complement-fixing titre with Johne's bacillus antigen, showed an exceptionally high proportion of gamma-globulin in its serum. The percentage of gamma-globulin tended to be higher in sera of contact sheep than in that of normal sheep sera but the monthly variation in the relative proportion of these and other globulins showed no evident relationship to the fluctuations observed in the specific complement-fixing and anti-complementary properties of these sera.

Alpha-Globulins↗
PubMed2006

Characterization of Minnesota dairy herds participating in a Johne's disease control program and evaluation of the program risk assessment tool.

The objectives of this study were to: (1) characterize Minnesota dairy herds participating in a Johne's disease control program (JDCP) based on herd size, milk production, and clinical Johne's disease (JD) history, (2) evaluate if change in farm management practices, expressed in risk assessment (RA) total score, is associated with the change between the first and most recent ELISA test herd seroprevalence or change in clinical JD culling rate, and (3) identify farm factors associated with ELISA seroprevalence. A total of 1234 RA, performed between January 2000 and February 2004, were available for analysis from 714 dairy herds. ELISA test results from herd sampling between 2000 and 2004 were obtained from the Minnesota board of animal health (MBAH) database, and were available for 474 herds. Both the first and the most recent ELISA test results for herds with more than one RA were available for 262 herds. Mean herd size and mean annual milk production per cow was higher in JDCP dairy herds (161 milking cows) than either all Minnesota dairy herds or Minnesota dairy herd improvement association (DHIA) herds. For herds with more than one RA available, the most recent RA total score was significantly lower (mean 11% less) than the first. The change in RA total score (and any RA subtotal scores) between the first and most recent RA was not associated with the change between the first and the most recent ELISA within-herd seroprevalence or the change in JD culling rate between the first and most recent RA. The most recent ELISA test results were positively associated with postweaned heifer score and JD culling rate. The RA score was not found to be an effective tool for the prediction of ELISA seroprevalence.

Animal Husbandry↗
PubMed2005

A model of the relationship between the epidemiology of Johne's disease and the environment in suckler-beef herds.

A non-predictive, dynamic and stochastic herd-level simulation model of an outbreak of Johne's in a suckler-beef herd is reported. Importantly, the model incorporates, with a simple method, the environment as the primary source of infection, reflecting the consensual understanding of the disease. The model also takes into account the density of the infectious agent in the environment. A sensitivity analysis suggests that the model is highly and equally sensitive to certain parameters (probability of infection in the presence of one unit of bacterial density, infectious area and bacterial shedding rate). Mathematical reasons for this similarity in sensitivity are presented. Compared to many other diseases, data for Johne's are scarce. Therefore models of Johne's outbreaks including this one cannot be predictive or easily validated. The qualitative results: (a) demonstrate the modelled effect of inclusion of infection via the environment; (b) suggest management factors that could be tested by experimentation or observation. Estimates for the rate of transmission, arising from the model output, are similar to published empirical estimates. The results of future empirical research should aid scientific understanding of the disease, help validate this model and might bring economic benefits through improved management.

Age Factors↗