In vivo administration of a monoclonal antibody against the type I IL-1 receptor inhibits the ability of mice to eliminate Mycobacterium paratuberculosis.

The purpose of this study was to determine the influence of endogenous interleukin-1 (IL-1) on resistance to paratuberculosis infection in experimentally infected gnotobiotic mice. Following a 6-month treatment with prednisolone to facilitate bacillary multiplication, control mice substantially reduced the numbers of M. paratuberculosis in the liver and ileum. In contrast, mice injected with a monoclonal antibody against the type I IL-1 receptor failed to reduce the numbers of M. paratuberculosis in the liver and ileum and exhibited more liver granulomas, which contained numerous acid-fast bacilli. These results indicate a significant role for endogenous IL-1 in host defense against experimental M. paratuberculosis infection in mice.

Induction of interleukin-1 release by high- and low-passage isolates of Borrelia burgdorferi.

Low-passage isolates of Borrelia burgdorferi induced arthritis when injected into the hind paws of irradiated hamsters, while high-passage isolates did not. To examine a possible mechanism for induction of arthritis, peritoneal exudate cells were coincubated with high- and low-passage isolates of B. burgdorferi, and the resultant conditioned medium was assayed for interleukin-1 (IL-1) activity. Comparable amounts of IL-1 activity were detected in culture supernatants generated by high- and low-passage spirochetes and were dependent on the number of spirochetes added. Live B. burgdorferi stimulated greater release of IL-1 activity than did heat-killed organisms. No evidence of release of IL-1 due to shedding of soluble components from spirochetes was obtained. A recombinant human IL-1 receptor antagonist blocked the proliferative activity of conditioned medium in a murine thymocyte assay for IL-1 activity. The greater ability of low-passage spirochetes to survive in vivo may be more important than the ability to induce IL-1 production in the pathogenesis of Lyme arthritis.

Borrelia burgdorferi stimulates release of interleukin-1 activity from bovine peripheral blood monocytes.

Infection with Borrelia burgdorferi is suspected to be a cause of lameness and arthritis in cattle. Interleukin-1 (IL-1) activity has been detected in joint fluids from human patients affected by various arthritides, including Lyme arthritis. In addition, human monocytes and murine macrophages have been reported to release IL-1 activity when incubated with B. burgdorferi in vitro. To address a possible mechanism by which B. burgdorferi might cause a bovine arthritic syndrome, we determined whether bovine peripheral blood monocytes released IL-1 activity when coincubated with B. burgdorferi in vitro. High-passage and low-passage isolates of B. burgdorferi stimulated release of IL-1 activity from bovine monocytes. The amount of IL-1 activity released was dependent on the number of borreliae added to the monocyte cultures. In addition, live and heat-killed B. burgdorferi cells stimulated release of similar amounts of IL-1. We also obtained no evidence that soluble components released from in vitro-cultured B. burgdorferi stimulated IL-1 release from bovine monocytes. A recombinant IL-1 receptor antagonist blocked the proliferative activity of monocyte-conditioned medium in a thymocyte costimulation assay, thus demonstrating that the costimulatory activity detected was due to IL-1.

Enhanced radiometric detection of Mycobacterium paratuberculosis by using filter-concentrated bovine fecal specimens.

A commercial radiometric medium, BACTEC 12B, was modified by addition of mycobactin, egg yolk suspension, and antibiotics (vancomycin, amphotericin B, and nalidixic acid). Decontaminated bovine fecal specimens were filter concentrated by using 3-microns-pore-size, 13-mm-diameter polycarbonate filters, and the entire filter was placed into the radiometric broth. Comparison of the radiometric technique with conventional methods on 603 cattle from 9 Mycobacterium paratuberculosis-infected herds found that of 75 positive specimens, the radiometric technique detected 92% while conventional methods detected 60% (P less than 0.0005). Only 3.9% of radiometric cultures were contaminated. To measure the effect of filter concentration of specimens on the detection rate, 5 cattle with minimal and 5 with moderate ileum histopathology were sampled weekly for 3 weeks. M. paratuberculosis was detected in 33.3% of nonfiltered specimens and 76.7% of filtered specimens (P less than 0.005). Detection rates were directly correlated with the severity of disease, and the advantage of specimen concentration was greatest on fecal specimens from cattle with low-grade infections. Detection times were also correlated with infection severity: 13.4 +/- 5.9 days with smear-positive specimens, 27.9 +/- 8.7 days with feces from cows with typical subclinical infections, and 38.7 +/- 3.8 days with fecal specimens from cows with low-grade infections. Use of a cocktail of vancomycin, amphotericin B, and nalidixic acid for selective suppression of nonmycobacterial contaminants was better than the commercial product PANTA (Becton Dickinson Microbiologic Systems, Towson, Md.) only when specimens contained very low numbers of M. paratuberculosis. Radiometric culture of filter-concentrated specimens generally doubled the number of positive fecal specimens detected over conventional methods, making it a useful tool for diagnosis and control of bovine paratuberculosis.

Isolation of group eugonic fermenter-4 bacteria from a cat with multifocal suppurative pneumonia.

A pure growth of Group Eugonic Fermenter-4 bacteria (gram-negative) was isolated from the lungs of an 11-year-old male domestic cat that had been ill for 2 days before death. Clinical signs included anorexia, severe dyspnea, and salivation. The lungs contained several firm, slightly raised, yellowish-gray, spherical nodules of various sizes. Purulent exudate was found in the pericardial sac and left pleural cavity. Histologic evaluation revealed multifocal suppurative pneumonia.