Thus, D. siboney seems to be most closely related to D. farinae.

The aim of this study was to standardize a diagnosis procedure to detect Mycobacterium avium subsp. paratuberculosis (Map) DNA in raw cow milk samples under field conditions. A procedure that combines both immunomagnetic separation and IS900-PCR detection (IMS-IS1 PCR) was employed on milk samples from 265 lactating Holstein cows from Map infected and uninfected herds in Argentina. IMS-IS1 PCR results were analyzed and compared with those obtained from milk and fecal culture and serum ELISA. The extent of agreement between both tests was determined by the Kappa test. IMS-IS1 PCR showed a detection limit of 101 CFU of Map/mL of milk, when 50:50 mix of monoclonal and polyclonal antibodies were used to coat magnetic beads. All of the 118 samples from the Map uninfected herds were negative for the set of the tests. In Map infected herds, 80 out of 147 cows tested positive by milk IMS-IS1 PCR (55%), of which 2 (1.4%) were also positive by milk culture, 15 (10%) by fecal culture, and 20 (14%) by serum ELISA. Kappa statistics (95% CI) showed a slight agreement between the different tests (<0.20), and the proportions of agreement were ≤0.55. The IMS-IS1 PCR method detected Map in milk of the cows that were not positive in other techniques. This is the first report dealing with the application of IMS-IS1 PCR in the detection of Map in raw milk samples under field conditions in Argentina.

Lipoarabinomannan (LAM) is a major glycolipidic antigen on the mycobacterial envelope. The aim of this study was to characterize the humoral immune response induced by immunization with a LAM extract in bovines and to evaluate the role of the generated antibodies in the in vitro infection of macrophages with Mycobacterium avium subsp. paratuberculosis (MAP). Sera from fourteen calves immunized with LAM extract or PBS emulsified in Freund's Incomplete Adjuvant and from five paratuberculosis-infected bovines were studied. LAM-immunized calves developed specific antibodies with IgG1 as the predominant isotype. Serum immunoglobulins were isolated and their effect was examined in MAP ingestion and viability assays using a bovine macrophage cell line. Our results show that the antibodies generated by LAM immunization significantly increase MAP ingestion and reduce its intracellular viability, suggesting an active role in this model.

According to the influence of patient selection criteria on the estimation of the potency of mite extracts, the determination of the biologic activity of allergenic extracts in subjects without a clear-cut clinical history should be replaced by new methods when available.

No abstract

Johne's Disease or Paratuberculosis is a chronic granulomatous enteritis disease affecting ruminants. Detection of subclinically infected animals is difficult, hampering the control of this disease. The aim of this work was to evaluate the performance of detection of IgG isotypes in a PPA-ELISA to improve the recognition of cattle naturally infected with Map in different stages. A total of 108 animals from Tuberculosis-free herds were grouped as follows: exposed (n = 30), subclinically infected (n = 26), clinically infected (n = 14), and healthy controls (n = 38). Receiver-operating characteristic (ROC) curves of isotypes/PPA-ELISAs were constructed and areas under the curves were compared to evaluate the performance of each test. Our study demonstrated that the conventional PPA-ELISA (detecting IgG) is the best to identify clinically infected animals with high sensitivity (92.9%) and specificity (100%). Meanwhile, IgG2/PPA-ELISA improved the number of subclinically infected cattle detected as compared with conventional IgG/PPA-ELISA (53.8 versus 23.1%). In addition, it had the maximum sensitivity (65.0%, taking into account all Map-infected cattle). In conclusion, the combination of IgG and IgG2/PPA-ELISAs may improve the identification of Map-infected cattle in different stages of disease. The usefulness of IgG2 detection in serological tests for Johne's Disease diagnosis should be further evaluated.

No abstract

The aim of the present study was to determine whether lipoarabinomannan (LAM), in combination with Freund's incomplete adjuvant (FIA), was able to improve cell-mediated and antibody-mediated immune responses against ovalbumin (OVA) in cattle. Twenty-three calves were assigned to four treatment groups, which were subcutaneously immunized with either OVA plus FIA, OVA plus FIA and LAM from Mycobacterium avium subsp avium, FIA plus LAM, or FIA alone. Lymphoproliferation, IFN-γ production and cell subpopulations on peripheral blood mononuclear cells before and 15 days after treatment were evaluated. Delayed hypersensitivity was evaluated on day 57. Specific humoral immune response was measured by ELISA. Inoculation with LAM induced higher levels of lymphoproliferation and IFN-γ production in response to ConA and OVA (P < 0.05). Specific antibody titers were similar in both OVA-immunized groups. Interestingly, our results showed that the use of LAM in vaccine preparations improved specific cell immune response evaluated by lymphoproliferation and IFN-γ production by at least 50 and 25%, respectively, in cattle without interfering with tuberculosis and paratuberculosis diagnosis.