Antigen recognition by serum antibodies in white-tailed deer (Odocoileus virginianus) experimentally infected with Mycobacterium bovis.

White-tailed deer (Odocoileus virginianus) have emerged as reservoirs of bovine tuberculosis in northern America. For tuberculosis surveillance of deer, antibody-based assays are particularly attractive because deer are handled only once and immediate processing of the sample is not required. Sera collected sequentially from 25 Mycobacterium bovis-infected and 7 noninfected deer were evaluated by enzyme-linked immunosorbent assay (ELISA), immunoblotting, and multiantigen print immunoassay (MAPIA) for immunoglobulin specific to M. bovis antigens. Various routes of experimental M. bovis infection, such as intratonsillar inoculation (n = 11), aerosol (n = 6), and exposure to infected deer (in contact, n = 8), were studied. Upon infection, specific bands of reactivity at approximately 24 to 26 kDa, approximately 33 kDa, approximately 42 kDa, and approximately 75 kDa to M. bovis whole-cell sonicate were detected by immunoblot. Lipoarabinomannan-specific immunoglobulin was detected as early as 36 days postchallenge, and responses were detected for 94% of intratonsillarly and "in-contact"-infected deer. In MAPIA, sera were tested with 12 native and recombinant antigens coated on nitrocellulose. All in-contact-infected (8 of 8) and 10 of 11 intratonsillarly infected deer produced antibody reactive with one or more of the recombinant/native antigens. Responses were boosted by injection of tuberculin for intradermal tuberculin skin testing. Additionally, three of six deer receiving a very low dose of M. bovis via aerosol exposure produced antibody specific to one or more recombinant proteins. M. bovis was isolated from one of three nonresponding aerosol-challenged deer. Of the 12 antigens tested, the most immunodominant protein was MPB83; however, a highly sensitive serodiagnostic test will likely require use of multiple antigens.

Use of recombinant ESAT-6:CFP-10 fusion protein for differentiation of infections of cattle by Mycobacterium bovis and by M. avium subsp. avium and M. avium subsp. paratuberculosis.

Immunological diagnosis of Mycobacterium bovis infection of cattle is often confounded by cross-reactive responses resulting from exposure to other mycobacterial species, especially Mycobacterium avium. Early secretory antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10) are dominant gamma interferon (IFN-gamma)-inducing antigens of tuberculous mycobacteria, and they are absent from many environmental nontuberculous mycobacteria. Because M. avium exposure is the primary confounding factor in the diagnosis of M. bovis-infected animals, in vitro responses to a recombinant ESAT-6:CFP-10 (rESAT-6:CFP-10) fusion protein by blood leukocytes from cattle naturally exposed to M. avium or experimentally challenged with Mycobacterium avium subsp. avium or Mycobacterium avium subsp. paratuberculosis were compared to responses by M. bovis-infected cattle. Responses to heterogeneous mycobacterial antigens (i.e., purified protein derivatives [PPDs] and whole-cell sonicates [WCSs]) were also evaluated. Tumor necrosis factor alpha (TNF-alpha), IFN-gamma, and nitric oxide responses by M. bovis-infected cattle to rESAT-6:CFP-10 exceeded (P < 0.05) the corresponding responses by cattle naturally sensitized to M. avium. Experimental infection with M. bovis, M. avium, or M. avium subsp. paratuberculosis induced significant (P < 0.05) IFN-gamma and nitric oxide production to WCS and PPD antigens, regardless of the mycobacterial species used for the preparation of the antigen. Responses to homologous crude antigens generally exceeded responses to heterologous antigens. Nitric oxide and IFN-gamma responses to rESAT-6:CFP-10 by blood leukocytes from M. bovis-infected calves exceeded (P < 0.05) the corresponding responses of noninfected, M. avium-infected, and M. avium subsp. paratuberculosis-infected calves. Despite the reported potential for secretion of immunogenic ESAT-6 and CFP-10 proteins by M. avium and M. avium subsp. paratuberculosis, it appears that use of the rESAT-6:CFP-10 fusion protein will be useful for the detection of tuberculous cattle in herds with pre-existing sensitization to M. avium and/or M. avium subsp. paratuberculosis.

Immune responses of white-tailed deer (Odocoileus virginianus) to Mycobacterium bovis BCG vaccination.

The objective was to evaluate cellular immune response of captive white-tailed deer (Odocoileus virginianus) to live Mycobacterium bovis bacille Calmette Guerin (BCG) vaccination and to determine diagnostic implications of these responses. In vitro proliferative and interferon-gamma (IFN-gamma) responses to M. bovis purified protein derivative (PPD) were detected beginning 9 days postvaccination. Responses to Mycobacterium avium PPD, however, generally exceeded responses to M. bovis PPD. Interferon-gamma responses to M. avium PPD were not detected prior to vaccination nor in nonvaccinated deer, suggesting that vaccination with BCG boosted prior quiescent M. avium-sensitized cells. Both CD4+ and gammadelta T cells from vaccinated deer proliferated in response to M. bovis PPD stimulation. Intradermal administration of M. bovis PPD resulted in increases in skin thickness of vaccinated deer beginning 24 hr postinjection. Such early reactions were characterized by edema and minimal mononuclear cell infiltration, whereas later reactions (i.e., 72 hr postinjection) were more typical of delayed type hypersensitivity. Upon in vitro activation with pokeweed mitogen, CD44 expression increased and CD62L expression decreased on lymphocytes from deer regardless of vaccination status. Likewise, M. bovis PPD stimulation of lymphocytes from vaccinated deer resulted in increases in CD44 expression and decreases in CD62L expression. These findings demonstrate the potential of BCG vaccination to elicit strong cell-mediated immune responses and appropriate alterations in CD44 and CD62L expression with in vitro stimulation of white-tailed deer lymphocytes. In relation to M. bovis diagnosis, vaccination of white-tailed deer with BCG can induce skin test responses that classify the animal as a tuberculosis reactor. In contrast, BCG vaccination will likely not interfere with tuberculosis testing by the IFN-gamma assay.

Mycobacterium bovis infection of vitamin D-deficient NOS2-/- mice.

Vitamin D deficiency is associated with an increased risk for tuberculosis infection. Studies using in vitro systems indicate that 1,25-dihydroxyvitamin D(3) [i.e. 1,25(OH)(2)D(3)], the most active form of the vitamin, enhances mycobacterial killing by increasing nitric oxide (NO) production. To evaluate concurrently the role of 1,25(OH)(2)D(3) and NO on the host response to tuberculosis infection, mice deficient in NO synthase 2 (NOS2(-/-)) and/or vitamin D were aerosol-challenged with Mycobacterium bovis and subsequently evaluated for mycobacterial colonization and lesion formation. Infected NOS2(-/-) mice developed severe necrotizing pyogranulomatous inflammation of the lungs with heavy M. bovis colonization and systemic dissemination of the bacillus. Colonization and lung lesion area of NOS2(-/-) mice exceeded that of NOS2(+/+) mice. Additionally, disease progression was more rapid in NOS2(-/-) mice than in NOS2(+/+) mice. Lung colonization and lesion area of vitamin D deficient mice exceeded that of vitamin D replete mice, regardless of NOS2 phenotype. However, effects of vitamin D on colonization, but not lesion area, were more pronounced in NOS2(+/+) mice than in NOS2(-/-) mice. These findings are consistent with the current hypothesis that 1,25(OH)(2)D(3) enhances mycobacterial killing through a NO-dependent mechanism. As responses of NOS2(-/-) mice were affected by 1,25(OH)(2)D(3) deficiency, albeit to a lesser extent than were those of NOS2(+/+) mice, NO-independent actions of 1,25(OH)(2)D(3) also likely exist.

Mycobacterium bovis bacille Calmette-Guerin vaccination of cattle: activation of bovine CD4+ and gamma delta TCR+ cells and modulation by 1,25-dihydroxyvitamin D3.

SETTING: 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D(3)) is a potent modulator of immune responses and may be beneficial in the treatment of tuberculosis. Recent evidence suggest that 1,25(OH)(2)D(3) may affect T-dependent responses in cattle; however, mechanisms by which this vitamin modulates activation of bovine T cells are unclear. OBJECTIVE: Determine the effects of 1,25(OH)(2)D(3) on the expression of CD25, CD44, and CD62L by bovine T cell subsets proliferating in response to antigen stimulation. DESIGN: Antigen-specific recall responses of Mycobacterium bovis bacille Calmette-Guerin (BCG) vaccinated cattle were used as a model system to evaluate effects of 1,25(OH)(2)D(3) on the proliferation and activation of bovine T cell subsets. RESULTS: CD4(+) and gamma delta TCR(+) cells were the predominant T cell subsets responding to soluble crude M. bovis-derived antigens (i.e., purified protein derivative and a BCG whole cell sonicate) by proliferation and activation-induced alterations in phenotype. These subsets exhibited increased CD25 and CD44 mean fluorescence intensity (mfi) and decreased CD62L mfi upon antigen stimulation. Addition of 1,25(OH)(2)D(3) inhibited proliferation of CD4(+) cells and decreased the expression of CD44 on responding (i.e., proliferating) CD4(+) and gamma delta TCR(+) cells. CONCLUSION: These findings suggest that the production of 1,25(OH)(2)D(3) by macrophages within tuberculous lesions would inhibit proliferation and CD44 expression by co-localized CD4(+) and gamma delta TCR(+) cells.

Diagnostic implications of antigen-induced gamma interferon, nitric oxide, and tumor necrosis factor alpha production by peripheral blood mononuclear cells from Mycobacterium bovis-infected cattle.

Bovine tuberculosis in the United States has proven costly to cattle producers as well as to government regulatory agencies. While in vivo responsiveness to mycobacterial antigens is the current standard for the diagnosis of tuberculosis, in vitro assays are gaining acceptance, especially as ancillary or complementary tests. To evaluate in vitro indices of cellular sensitization, antigen-induced gamma interferon (IFN-gamma), nitric oxide (NO), and tumor necrosis factor alpha (TNF-alpha) responses by blood mononuclear cells from Mycobacterium bovis-infected cattle were quantified and compared. Using an aerosol model of infection, two doses of each of two strains of M. bovis (95-1315 and HC-2045T) were used to induce a range of IFN-gamma, NO, and TNF-alpha responses. Infection-specific increases in NO, but not in IFN-gamma or TNF-alpha, were detected in nonstimulated cultures at 48 h, a finding that is indicative of nonspecific activation and spontaneous release of NO. The infective dose of M. bovis organisms also influenced responses. At 34 days postinfection, IFN-gamma, NO, and TNF-alpha responses in antigen-stimulated cells from cattle receiving 10(5) CFU of M. bovis organisms were greater than responses of cells from cattle infected with 10(3) CFU of M. bovis organisms. The NO response, but not the IFN-gamma and TNF-alpha responses, was influenced by infective strains of M. bovis. The TNF-alpha, NO, and IFN-gamma responses followed similar kinetics, with strong positive associations among the three readouts. Overall, these findings indicate that NO and TNF-alpha, like IFN-gamma, may prove useful as indices for the diagnosis of bovine tuberculosis.

Immune responses of elk to Mycobacterium bovis bacillus Calmette Guerin vaccination.

Although rare, detection of Mycobacterium bovis infection of captive or free-ranging elk (Cervus elaphus) elicits serious concern due to regulatory and zoonotic implications. Few studies, however, have evaluated the immune response of elk to M. bovis or other pathogens. To model natural infection, elk were vaccinated with live M. bovis bacillus Calmette Guerin (BCG, Pasteur strain) for evaluation of immune responsiveness to this attenuated live vaccine. Peripheral blood mononuclear cells (PBMC) of vaccinated elk proliferated in response to stimulation with a soluble mycobacterial antigen preparation (i.e. M. bovis purified protein derivative, PPDb). Greater numbers of sIgM(+) cells (i.e. B cells) proliferated in this response than did either CD4(+), gammadeltaTCR(+) or CD8(+) cells. The in vivo response (i.e. delayed type hypersensitivity, DTH) to PPDb by vaccinated elk exceeded both the response by non-vaccinated elk and BCG-vaccinated cattle at 24, 48, and 72h post-administration of PPD. In vivo responses to PPDb by vaccinated elk diminished after 72h as compared to responses at 24 and 48h. Serum was also collected periodically and evaluated by ELISA for immunoglobulin (i.e. IgG heavy and light chains) reactivity to crude mycobacterial antigens. Two weeks post-vaccination and throughout the duration of the study, serum immunoglobulin reactivity to PPDb and to a proteinase K-digested whole cell sonicate of BCG exceeded that of serum from non-vaccinated elk. Intradermal administration of PPD for measurement of hypersensitive responses boosted the serum antibody response. These findings demonstrate that BCG vaccination of elk induces a serum antibody response to crude M. bovis antigens, a B cell in vitro proliferative response, and in vivo trafficking of mononuclear cells to sites of mycobacterial antigen administration (i.e. delayed type hypersensitivity). A predominant B cell in vitro proliferative response by elk PBMC to crude mycobacterial test antigens will likely impact the development of improved diagnostic tests of tuberculosis infection for this species.

Expression of L-Selectin (CD62L), CD44, and CD25 on activated bovine T cells.

Mycobacterium bovis infection of cattle represents a natural host-pathogen interaction and, in addition to its economic and zoonotic impact, represents a model for human tuberculosis. Extravasation and trafficking of activated lymphocytes to inflammatory sites is modulated by differential expression of multiple surface adhesion molecules. However, effects of M. bovis infection on adhesion molecule expression have not been characterized. To determine these changes, peripheral blood mononuclear cells from M. bovis-infected cattle were stimulated with M. bovis purified protein derivative (PPD) or pokeweed mitogen (PWM) and evaluated concurrently for proliferation and activation marker expression. Stimulation with PPD or PWM increased CD25 and CD44 mean fluorescence intensity (MFI) and decreased CD62L MFI on CD4(+) cells from infected animals. CD62L MFI on PPD- and PWM-stimulated gammadelta T-cell receptor-positive (TCR(+)) and CD8(+) cells was also reduced compared to that of nonstimulated gammadelta TCR(+) and CD8(+) cells. Using a flow cytometry-based proliferation assay, it was determined that proliferating cells, regardless of lymphocyte subset, exhibited increased expression of CD25 and CD44 and decreased expression of CD62L compared to cells that had not proliferated. In contrast to proliferation, activation-induced apoptosis of CD4(+) cells resulted in a significant down regulation of CD44 expression. Lymphocytes obtained from lungs of M. bovis-infected cattle also had reduced expression of CD44 compared to lymphocytes from lungs of noninfected cattle. These alterations in surface molecule expression upon activation likely impact trafficking to sites of inflammation and the functional capacity of these cells within tuberculous granulomas.

Milk containing Mycobacterium bovis as a source of infection for white-tailed deer fawns (Odocoileus virginianus).

SETTING: White-tailed deer represent the first wildlife reservoir of Mycobacterium bovis in the United States. The behavior of does with nursing fawns provides several potential mechanisms for disease transmission. Little information exists concerning transmission between doe and fawn, specifically transmammary transmission. OBJECTIVE: Determine if fawns can become infected by ingestion of milk replacer containing M. bovis, thus simulating transmission from doe to fawn through contaminated milk. DESIGN: Seventeen, 21-day-old white-tailed deer fawns were inoculated orally with 2 x 10(8) CFU (high dose, n=5), 2.5 x 10(5) to 2.5 x 10(6) CFU (medium dose, n=5), and 1 x 10(4) CFU (low dose, n=5) of M. bovis in milk replacer. Dosages were divided equally and fed daily over a 5-day period. Positive control fawns (n=2) received 1 x 10(5) CFU of M. bovis instilled in the tonsillar crypts. Fawns were euthanized and examined 35-115 days after inoculation and various tissues collected for bacteriologic and microscopic analysis. RESULTS: All fawns in the tonsillar, high oral and medium oral dose groups developed generalized tuberculosis involving numerous organs and tissues by 35-84 days after inoculation. Three of five fawns in the low-dose oral group had tuberculous lesions in the mandibular lymph node, and one of five had lesions in the medial retropharyngeal lymph node when examined 115 days after inoculation. CONCLUSION: White-tailed deer fawns can become infected through oral exposure to M. bovis. Therefore, the potential exists for fawns to acquire M. bovis while nursing tuberculous does.

Mycobacterial isolations in captive elephants in the United States.

Interest in tuberculosis in elephants has been increasing over the past several years in the United States. Several techniques have been used to diagnose mammalian tuberculosis. Currently, the test considered most reliable for diagnosis of TB in elephants is based on the culture of respiratory secretions obtained by trunk washes.

Bovine tuberculosis in Michigan wildlife.

White-tailed deer in Michigan are now recognized as a reservoir host of bovine tuberculosis (TB). It has been determined that the most likely cause of bovine TB infection in the deer is from congregating in artificially high numbers at feed sites. The presence of a wildlife reservoir of TB in Michigan poses a serious threat to the control and eradication programs that are now in their final stages in the United States.

Apoptosis in lymph node granulomas from white-tailed deer (Odocoileus virginianus) experimentally infected with Mycobacterium bovis.

Apoptosis is a morphologically and biochemically distinct mechanism of cell death seen in many physiological conditions as well as in various infectious diseases. To examine apoptosis in tuberculous white-tailed deer, 32 deer were each given an intra-tonsillar injection of 300 colony-forming units of Mycobacterium bovis. Medial retropharyngeal lymph nodes were collected at 15, 28, 42, 56, 89, 180, 262 and 328 days after inoculation. Microscopical sections of lymph nodes were labelled for apoptotic cells by the terminal deoxynucleotidyl transferase nick end labelling (TUNEL) method. TUNEL, and other morphological changes within developing granulomas, were analysed and quantified by computerized image analysis. TUNEL within granulomas was greatest 28 days after inoculation and had declined to negligible levels by 328 days. Granuloma enlargement was due primarily to an increase in size of the caseo-necrotic core of the granuloma and not to increased inflammatory cellular infiltrate. These findings suggested that cell death within M. bovis -induced granulomas in white-tailed deer was due mainly to mechanisms other than apoptosis.

Nitric oxide production as an indication of Mycobacterium bovis infection in white-tailed deer (Odocoileus virginianus).

White-tailed deer (Odocoileus virginianus) are reservoirs for Mycobacterium bovis in northeast Michigan, USA. Production of nitric oxide (NO) by activated macrophages is a potent mechanism of mycobacterial killing. The capacity of macrophages to produce NO, however, varies among mammalian species. The objective of this study was to determine if mononuclear cells from white-tailed deer produce nitrite as an indication of NO production and, if so, is NO produced in response to stimulation with M. bovis antigens. Supernatants were harvested from adherent peripheral blood mononuclear cell (PBMC) cultures that had been stimulated with either Mannheimia haemolytica lipopolysaccharide (LPS) or media alone (i.e., no stimulation). Nitrite levels within M. haemolytica LPS-stimulated culture supernatants exceeded (P < 0.05) those detected within supernatants from non-stimulated cultures as well as those detected within supernatants from cultures receiving an inhibitor of NO synthase in addition to M. haemolytica LPS. In response to stimulation with M. bovis antigens, nitrite production by PBMC from M. bovis-infected deer exceeded (P < 0.05) the production by PBMC from non-infected deer. The response of PBMC from infected deer to M. bovis antigens exceeded (P < 0.05) the response of parallel cultures from the same deer receiving no stimulation. The response of PBMC from M. bovis-infected deer to M. avium antigens did not differ from that of PBMC from M. bovis-infected deer to no stimulation or from that of PBMC from non-infected deer to M. avium antigens. These findings indicate that adherent PBMC from white-tailed deer are capable of NO production and that mononuclear cells isolated from M. bovis-infected white-tailed deer produce NO in an antigen-specific recall response.

Lesion development in white-tailed deer (Odocoileus virginianus) experimentally infected with Mycobacterium bovis.

The recent discovery of tuberculosis in free-living white-tailed deer in northeastern Michigan underscores the need for increased understanding of the pathogenesis of tuberculosis in wildlife species. To investigate lesion development in white-tailed deer, 32 deer were experimentally infected by intratonsilar instillation of 300 colony-forming units of Mycobacterium bovis. Three deer each were euthanatized and examined at days 15, 28, 42, and 56 after inoculation, and five deer each were euthanatized and examined at days 89, 180, 262, and 328 after inoculation. Microscopic lesions first were seen in the medial retropharyngeal lymph node and lung 28 and 42 days after inoculation, respectively. Lung lesions were present in 12 (38%) of 32 deer, involving 23 lung lobes. Left caudal and right middle and caudal lobes were involved in 17 (74%) of the 23 affected lung lobes. Lesions in the medial retropharyngeal lymph node first appeared as granulomas composed of aggregates of macrophages and Langhans-type giant cells. Some early granulomas contained centrally located neutrophils. As granulomas developed, neutrophils were replaced with a central zone of caseous necrosis that first showed signs of mineralization 42 days after inoculation. Granulomas increased in size as the zone of caseous necrosis expanded. Peripheral fibrosis, first seen at 56 days after inoculation, progressed to only a thin fibrous capsule by 328 days after inoculation. By the termination of the study, the central necrotic core of the granuloma contained abundant liquefied necrotic material and grossly resembled an abscess. Although tuberculous lesions in white-tailed deer follow a developmental pattern similar to that in cattle, fibrosis is less pronounced and the advanced lesions may liquefy, a change seldom reported in cattle. An understanding of lesion development will aid in the identification of the spectrum of disease that may be seen in this important wildlife reservoir of tuberculosis.

Aerosol delivery of virulent Mycobacterium bovis to cattle.

SETTING: Although animal models of aerosol inoculation of Mycobacterium tuberculosis and M. bovis have been reported using laboratory animals, a model of aerosol delivery of M. bovis to cattle has not been reported previously. OBJECTIVE: Develop and characterize a model of aerosol delivery of M. bovis to cattle, and compare the distribution of lesions in cattle infected with either of two different strains of M. bovis, one isolated from cattle (HC2005T), and the other isolated from white-tailed deer (1315). DESIGN: Cattle (n=20, female and castrated males) aged 4 months, were infected with 1 x 10(3) (n=5) or 1 x 10(5) (n=5) colony-forming units (CFU) of M. bovis 1315 or 1 x 10(3) (n=5) or 1x10(5) (n=5) CFU of M. bovis HC2005T. Calves were infected using a commercially available aerosol delivery system. One hundred fifty-five days after infection, calves were euthanized, examined and tissues collected for microscopic analysis and bacteriologic culture. RESULTS: Nineteen of 20 calves developed tuberculosis. Typical tuberculous lesions were most pronounced in the lungs and tracheobronchial and mediastinal lymph nodes. CONCLUSION: The system described provides a reliable method of aerosol delivery of M. bovis to cattle. Lesion distribution suggests that the aerosolized inoculum was delivered deep into pulmonary alveoli and thus represents true aerosol exposure. Disease was more severe in groups receiving the highest dose of either inoculum strain; however, differences between strains were not seen. Published by Elsevier Science Ltd.

Tuberculin skin testing in white-tailed deer (Odocoileus virginianus).

The comparative cervical skin test for antemortem diagnosis of tuberculosis was done 169 times on 116 different white-tailed deer of known Mycobacterium bovis infection status. The sensitivity and specificity were 97 and 81%, respectively. The magnitude of change in skin thickness at test sites was not significantly influenced by dosage of inoculum, dissemination of the disease process, or repeated skin testing. However, the magnitude of change in skin thickness was significantly greater in deer infected for less than 109 days than in deer infected for more than 109 days. As used in the present study, the comparative cervical skin test is a sensitive method of antemortem diagnosis of M. bovis infection in white-tailed deer.

Modulation of Mycobacterium bovis-specific responses of bovine peripheral blood mononuclear cells by 1,25-dihydroxyvitamin D(3).

Historically, administration of vitamin D has been considered beneficial in the treatment of tuberculosis. The interaction of this vitamin [i.e., 1,25-dihdroxyvitamin D(3) [1,25(OH)(2)D(3)]] with the antitubercular immune response, however, is not clear. In the present study, in vitro recall responses of peripheral blood mononuclear cells (PBMC) from cattle infected with Mycobacterium bovis were used to study the immune-modulatory effects of 1,25(OH)(2)D(3) on M. bovis-specific responses in vitro. Addition of 1 or 10 nM 1,25(OH)(2)D(3) inhibited M. bovis-specific proliferative responses of PBMC from M. bovis-infected cattle, affecting predominantly the CD4(+) cell subset. In addition, 1,25(OH)(2)D(3) inhibited M. bovis-specific gamma interferon (IFN-gamma) production yet enhanced M. bovis-specific nitric oxide (NO) production. Lymphocyte apoptosis, measured by flow cytometry using annexin-V staining, was diminished by addition of 1,25(OH)(2)D(3) to PBMC cultures. These findings support the current hypothesis that 1,25(OH)(2)D(3) enhances mycobacterial killing by increasing NO production, a potent antimicrobial mechanism of activated macrophages, and suggest that 1,25(OH)(2)D(3) limits host damage by decreasing M. bovis-induced IFN-gamma production.

Abomasal ulcers in captive white-tailed deer (Odocoileus virginianus).

Abomasal ulceration was noted in 32 of 200 white-tailed deer. Ulceration was most common in the abomasal pylorus and at the abomasal-duodenal junction. Abomasal ulceration was characterized by focal to multifocal, sharply demarcated areas of coagulation necrosis and haemorrhage extending through the mucosa, with fibrin thrombi in mucosal blood vessels of small diameter. Ulcerated areas were often covered by a mixture of mucus, debris and neutrophils. Visible bacteria were not associated with ulcerative lesions. All deer with abomasal ulceration had intercurrent disease, including bacterial pneumonia, enterocolitis, intussusception, chronic diarrhoea, capture myopathy, or experimentally induced tuberculosis. The anatomical distribution of abomasal ulcers in this population of captive white-tailed deer resembled that seen in veal calves.

Experimental deer-to-deer transmission of Mycobacterium bovis.

OBJECTIVE: To determine whether Mycobacterium bovis can be transmitted from experimentally infected deer to uninfected in-contact deer. ANIMALS: Twenty-three 6-month-old white-tailed deer. PROCEDURE: On day 0, M bovis (2 X 10(8) colony-forming units) was administered by intratonsillar instillation to 8 deer; 3 control deer received saline (0.9% NaCl) solution. Eight in-contact deer were comingled with inoculated deer from day 21. On day 120, inoculated deer were euthanatized and necropsied. On day 180, 4 in-contact deer were euthanatized, and 4 new in-contact deer were introduced. On day 360, all in-contact deer were euthanatized. Rectal, oral, and nasal swab specimens and samples of hay, pelleted feed, water, and feces were collected for bacteriologic culture. Tissue specimens were also collected at necropsy for bacteriologic culture and histologic analysis. RESULTS: On day 90, inoculated and in-contact deer developed delayed-type hypersensitivity (DTH) reactions to purified protein derivative of M bovis. Similarly, new in-contact deer developed DTH reactions by 100 days of contact with original in-contact deer. Tuberculous lesions in in-contact deer were most commonly detected in lungs and tracheobronchial and medial retropharyngeal lymph nodes. Mycobacterium bovis was isolated from nasal secretions and saliva from inoculated and in-contact deer, urine and feces from in-contact deer, and hay and pelleted feed. CONCLUSIONS AND CLINICAL RELEVANCE: Mycobacterium bovis is efficiently transmitted from experimentally infected deer to uninfected in-contact deer through nasal secretions, saliva, or contaminated feed. Wildlife management practices that result in unnatural gatherings of deer may enhance both direct and indirect transmission of M bovis.