Johne's disease caused byMycobacterium aviumsubsp.paratuberculosisinfection in red deer (Cervus elaphus): An histopathological grading system, and comparison of paucibacillary and multibacillary disease

Active surveillance of paratuberculosis in Alpine-dwelling red deer (Cervus elaphus)

Paratuberculosis (Johne's disease) is a globally widespread infectious disease affecting domestic and wild ruminants, caused by Mycobacterium avium subsp. paratuberculosis (MAP). The bacterium is excreted in the feces and is characterized by high environmental resistance. The new Animal Health Law (Regulation EU 2016/429) on transmissible animal diseases, recently in force throughout the European Union, includes paratuberculosis within the diseases requiring surveillance in the EU, listing some domestic and wild Bovidae, Cervidae, and Camelidae as potential reservoirs. Taking advantage of a culling activity conducted in the Stelvio National Park (Italy), this study investigated MAP infection status of red deer (Cervus elaphus) between 2018 and 2022, and evaluated the probability of being MAP-positive with respect to individual and sampling-level variables. A total of 390 subjects were examined macroscopically and tested for MAP, using different diagnostic tools: IS900 qPCR, culture, histopathology, and serology. Twenty-three of them were found positive for MAP by at least one test, with an overall prevalence of 5.9% (95% CI 4.0-8.7), that, respectively, ranged from 12.4% in the first culling season to 2.0 and 2.1% in the 2019-2020 and 2021-2022 culling seasons. Quantitative PCR assay on ileocecal valve and mesenteric lymph nodes detected the highest number of MAP positive animals. The results of the study showed the increased probability of being MAP-positive with increasing age and that red deer with lower body mass values were more likely to be infected with MAP. Overall, the absence of signs of clinical paratuberculosis and gross lesions together with the low level of shedding witness early phases of the disease among the positive red deer and support an improvement of the paratuberculosis status of this population, as shown by the decreased prevalence of the disease over the years.

Vaccination of White-Tailed Deer with Mycobacterium bovis Bacillus Calmette-Guérin (BCG): Effect of Mycobacterium avium ssp. paratuberculosis Infection

In many parts of the world, bovine tuberculosis eradication efforts are hampered by wildlife reservoirs of Mycobacterium bovis, which serve as a constant source of M. bovis for nearby cattle. The human tuberculosis vaccine, M. bovis BCG has been investigated for use in several wildlife species, including deer. In the US, white-tailed deer in Michigan have been the source of infection for over 82 cattle herds since M. bovis was discovered in free-ranging deer in 1995. The efficacy of BCG may be influenced by many factors, including prior exposure or infection with non-tuberculous mycobacteria, that is, species other than members of the M. tuberculosis complex. M. avium subspecies paratuberculosis (Map) infection is not uncommon in ruminants such as deer. Using natural exposure to Map and experimental infection with M. bovis, we demonstrate that Map infection increased BCG vaccine efficacy as measured by lesion severity scores.

Association between the severity of histopathological lesions and Mycobacterium avium subspecies paratuberculosis (MAP) molecular diversity in cattle in southern Chile

The objective was to evaluate the association between the severity of histopathological lesions caused by Mycobacterium avium subspecies paratuberculosis (MAP) infection and the molecular diversity of this pathogen. Blood, ileum, and mesenteric lymph node samples were collected at slaughter, from 1,352 adult cattle [source population 1 (SP1)]. In addition, 42 dairy herds (n = 4,963 cows) were followed for 2 years, and samples from compatible paratuberculosis clinical cases [source population 2 (SP2)] were collected. MAP infection was confirmed using an ELISA test, liquid media culture, and PCR. Isolates were genotyped using five MIRU-VNTR markers. Tissues from confirmed samples were subjected to a histopathological examination. A histopathological severity score (HSS) system was developed and used to grade (0 to 5) the magnitude of lesions caused by MAP. In general, the HSS system assesses the number of foci and degree of macrophage infiltration, together with the presence of multinucleated giant cells (MGCs) and acid-fast bacilli (AFB), in addition to the fusion of the intestinal villi and hyperplasia of the crypts. Despite the large sampling effort, only 79 MAP isolates were successfully genotyped, where 19 different haplotypes were described. A mixed-effect Poisson regression model was used to assess the relationship between haplotypes and HSS values. The model was controlled by animal age, and the farm was used as a random effect. Haplotypes were grouped based on their relative frequency: the most frequent haplotype (group i, 49.4%), the second most frequent haplotype (group ii, 12.7%), and all other haplotypes (group iii, 37.9%). Model outputs indicated that group i had significantly higher HSS values than group iii. In addition, group i was also associated with higher optical density (OD) values of the ELISA test. These results support the existence of differences in pathogenicity between MAP haplotypes. However, results were based on a relatively small sample size; thus, these should be taken with caution. Despite this, study findings suggest that haplotypes would be associated with differences in disease progression, where the dominant haplotype tends to generate more severe lesions, which could be linked to a greater shed of MAP cells than non-dominant haplotypes, increasing their chances of transmission.

Immunohistochemical Characterization of Immune System Cells in Lymphoid Organs from Roe and Fallow Deer

Simple Summary

Diseases emerging from wildlife represent a growing public health issue. Cervids share many pathogens with domestic species and humans, representing useful spontaneous models to evaluate host-pathogen balance. Histology and immunohistochemistry can help in fully understanding the pathogenesis of infection in these species, but few studies have been conducted to characterize immune cell markers. This study highlights that lymphocytes and macrophagic subsets in roe and fallow deer lymphoid tissue can be identified by a panel of commercial antibodies developed against humans. A description of the main immune cell distribution was provided. These results may support future investigations on immune cell response and pathogenesis in roe and fallow deer diseases.

Abstract

Roe and Fallow deer are common wild ruminants widely distributed in Italy. Infectious diseases of these species can potentially pose health risks to domestic animals and humans. However, few studies have been conducted in which immune system cells in these species were phenotyped. The aims of this study were to determine the cross-reactivity of a wide anti-human panel of commercial antibodies on formalin-fixed and paraffin-embedded (FFPE) samples and to describe the distribution of roe and fallow deer main immune cell subsets in the lymph nodes and spleen. Twenty retromandibular lymph nodes (RLNs) and spleen samples were collected from 10 roe deer and 10 fallow deer and were tested by a panel of 12 commercial anti-human antibodies. The CD79a, CD20, CD3, Iba-1, MAC387, and AM-3K antibodies were successfully labeled cells in cervine tissue, while the Foxp3 and the CD68 did not show suitable immunostaining. This study supplies the first immunohistochemical description of immune cell subpopulations in non-pathological spleen and RLNs from roe and fallow deer and provides an easily repeatable manual IHC protocol to immunolocalize cervine B-, T-cells, and macrophages subsets in FFPE tissue samples.

Characteristics of subclinical Mycobacterium avium ssp. paratuberculosis infection in a captive white-tailed deer herd

Paratuberculosis (Johne's disease) is caused by Mycobacterium avium ssp. paratuberculosis (MAP), and affects both domestic and wild ruminants, including cattle, goats, sheep, and deer. In cattle, most infections occur during calfhood followed by a prolonged incubation period of 1-2 y or more before cows shed culturable numbers of MAP bacilli in their feces. As disease progresses, infected animals develop protein-losing enteropathy, intractable diarrhea, and weight loss. In a cohort of 32 clinically normal deer from a herd with a history of periodic clinical paratuberculosis, we found that subclinical infection was characterized by high rates of infection, common involvement of mesenteric lymph nodes, minimal lesion formation, few intralesional acid-fast bacilli, and low-level fecal shedding of MAP. The characteristics of subclinical paratuberculosis in white-tailed deer resemble those of cattle and red deer, although microscopic lesions were less common in subclinical deer than reported for subclinical cattle, and we did not see necrotizing granulomas as described in subclinical red deer and elk.

Chronic regional intestinal inflammatory disease: A trans-species slow infection?

Crohn's disease and ulcerative colitis in humans and paratuberculosis in domestic and wild ruminants can be defined as chronic regional intestinal inflammatory diseases (CRIID). This review is a literature overview on these diseases in humans, non-human primates, dogs, cats, rabbits, equids and ruminants with a focus on pathological and microbiological features aimed identifying common characteristics that could lead to a unified pathological classification for a better understanding of their mechanisms and causes. The result is a framework of inflammatory forms throughout the different species indicative of common mechanisms of the slow infection type characterized by a time course varying from weeks to months or even years, and where the inflammatory component would be more prominent in the intestinal interphase between host and environment and be morphologically characterized by an infiltrate ranging from lymphoplasmacytic to histiocytic. This should provide new insights for causation demonstration and therapeutic approaches in human IBD.

Case definition terminology for paratuberculosis (Johne's disease)

Paratuberculosis (Johne's disease) is an economically significant condition caused by Mycobacterium avium subsp. paratuberculosis. However, difficulties in diagnosis and classification of individual animals with the condition have hampered research and impeded efforts to halt its progressive spread in the global livestock industry. Descriptive terms applied to individual animals and herds such as exposed, infected, diseased, clinical, sub-clinical, infectious and resistant need to be defined so that they can be incorporated consistently into well-understood and reproducible case definitions. These allow for consistent classification of individuals in a population for the purposes of analysis based on accurate counts. The outputs might include the incidence of cases, frequency distributions of the number of cases by age class or more sophisticated analyses involving statistical comparisons of immune responses in vaccine development studies, or gene frequencies or expression data from cases and controls in genomic investigations. It is necessary to have agreed definitions in order to be able to make valid comparisons and meta-analyses of experiments conducted over time by a given researcher, in different laboratories, by different researchers, and in different countries. In this paper, terms are applied systematically in an hierarchical flow chart to enable classification of individual animals. We propose descriptive terms for different stages in the pathogenesis of paratuberculosis to enable their use in different types of studies and to enable an independent assessment of the extent to which accepted definitions for stages of disease have been applied consistently in any given study. This will assist in the general interpretation of data between studies, and will facilitate future meta-analyses.

Detection of Mycobacterium avium subsp. paratuberculosis in kidney samples of red deer (Cervus elaphus) in Portugal: Evaluation of different methods

Paratuberculosis or Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (Map), is a chronic granulomatous enteritis affecting both domestic and wild ruminants. The present work is part of a wider set of studies designed to assess the prevalence of paratuberculosis in free ranging red deer (Cervus elaphus). With that purpose, 877 free-ranging red deer legally hunted in the Centre-eastern Portugal were submitted to necropsy and sampled for molecular methods, microbiology and histopathology. Thirty-seven (4.2%) kidneys revealed acid-fast bacilli when screened with the Ziehl-Neelsen technique. Map was detected by IS900 polymerase chain reaction (PCR) in thirty (81.1%) of the Ziehl-Neelsen positive kidneys. Subsequent PCR and/or culture from the different organs of the 37 examined animals allowed us to detect 86.4% (32 animals) infected red deer. Our results suggest that renal involvement in Map infected deer may be underdiagnosed and thus the routine examination of this organ and its inclusion in PCR techniques designed for Map detection could substantially improve the diagnostic of paratuberculosis in red deer.

Farmed deer: A veterinary model for chronic mycobacterial diseases that is accessible, appropriate and cost-effective

Although most studies in immunology have used inbred mice as the experimental model to study fundamental immune mechanisms they have been proven to be limited in their ability to chart complex functional immune pathways, such as are seen in outbred populations of humans or animals. Translation of the findings from inbred mouse studies into practical solutions in therapeutics or the clinic has been remarkably unproductive compared with many other areas of clinical practice in human and veterinary medicine. Access to an unlimited array of mouse strains and an increasing number of genetically modified strains continues to sustain their paramount position in immunology research. Since the mouse studies have provided little more than the dictionary and glossary of immunology, another approach will be required to write the classic exposition of functional immunity. Domestic animals such as ruminants and swine present worthwhile alternatives as models for immunological research into infectious diseases, which may be more informative and cost effective. The original constraint on large animal research through a lack of reagents has been superseded by new molecular technologies and robotics that allow research to progress from gene discovery to systems biology, seamlessly. The current review attempts to highlight how exotic animals such as deer can leverage off the knowledge of ruminant genomics to provide cost-effective models for research into complex, chronic infections. The unique opportunity they provide relates to their diversity and polymorphic genotypes and the integrity of their phenotype for a range of infectious diseases.

Intestinal Adenocarcinoma in a Herd of Farmed Sika Deer (Cervus nippon)

Intestinal adenocarcinomas were identified in 76 adult deer from a closed herd of 193 breeding animals grazing pasture heavily infested with bracken fern ( Pteridium aquilinum). Tumors were observed postmortem in 32 animals with rapid weight loss, and similar neoplasms were detected in a further 44 clinically normal deer at “cull.” Tumors were located in distal ileum, cecum, and proximal colon and presented as single (26%) or multiple (74%), variably sized, pale-gray, firm, poorly circumscribed neoplasms with associated intestinal strictures. Histopathologically tumors were well-differentiated, locally infiltrative, low-grade adenocarcinomas of tubular (51%), mucinous (33.5%), or mixed (15.5%) types. Extraintestinal metastases were not observed. The high incidence of intestinal adenocarcinoma within this herd suggests a specific and novel syndrome, and genetic and/or environmental factors may be involved in the pathogenesis.

Composite testing for ante-mortem diagnosis of Johne's disease in farmed New Zealand deer: correlations between bacteriological culture, histopathology, serological reactivity and faecal shedding as determined by quantitative PCR

Background

In the absence of overt clinical signs of Johne’s Disease (JD), laboratory based tests have largely been limited to organism detection via faecal culture or PCR and serological tests for antibody reactivity. In this study we describe the application of quantitative faecal PCR for the detection of Mycobacterium avium subsp. paratuberculosis (MAP) in New Zealand farmed deer to quantify the bacterial load in cervine faecal samples as an adjunct to an existing serodiagnostic test (Paralisa™) tailored for JD diagnosis in deer. As ELISA has potential as a cheap, high throughput screening test for JD, an attempt was made to assess the sensitivity, specificity and positive/negative predictive (PPV/NPV) values of Paralisa™ for estimating levels of faecal shedding of MAP as a basis for JD management in deer.

Results

Correlations were made between diagnostic tests (ELISA, qPCR, culture and histopathology) to establish the precision and predictive values of individual tests. The findings from this study suggest there is strong correlation between bacterial shedding, as determined by faecal qPCR, with both culture (r = 0.9325) and histopathological lesion severity scoring (r = 0.7345). Correlation between faecal shedding and ELISA reactivity in deer was weaker with values of r = 0.4325 and r = 0.4006 for Johnin and Protoplasmic antigens, respectively. At an ELISA Unit (EU) cutoff of >50 (Johnin antigen) the PPV of Paralisa™ for significant faecal shedding in deer (>10⁴ organisms/g) was moderate (0.55) while the NPV was higher (0.89). At an EU cutoff of ≥150, the PPV for shedding >10⁵ organisms/g rose to 0.88, with a corresponding NPV of 0.85.

Conclusions

The evidence available from this study suggests that Paralisa™ used at a cutoff of 50EU could be used to screen deer herds for MAP infection with sequential qPCR testing used to cull all Paralisa™ positive animals that exhibit significant MAP faecal shedding.

Pathological findings in young and adult sheep following experimental infection with 2 different doses of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subsp paratuberculosis (Map) is assumed to infect young ruminants; however, little is known concerning the possibility of adult animals becoming infected. An experimental infection was conducted to establish the effect of age and doses of Map on susceptibility to paratuberculosis in sheep. Sixteen of twenty-four 1.5-month-old Churra lambs and 23 of 30 adult ewes (from 2-11 years old) were orally challenged with an ovine field strain of Map. Thirteen ewes and 8 lambs were infected with a high dose (HD) and 10 adult sheep and 8 lambs with a low dose (LD) of Map. The remaining animals were unchallenged controls. Animals were euthanized at 110 to 120 and 210 to 220 days postinfection. Histological, bacteriological, and nested polymerase chain reaction (PCR) studies were conducted in samples of intestine and related lymphoid tissue (Peyer patches, lymph nodes). Animals were classified according to their lesions. The number of granulomas was counted in 3 tissue sections from each sample. Only the HD groups showed lesions associated with paratuberculosis (92.3% of ewes and 100% of lambs). Adults had lesions characterized by few small demarcated focal granulomas restricted to the lymphoid tissue, whereas granulomas were more numerous and larger, appearing in the lamina propria unrelated to lymphoid tissue, in the lambs. Only HD-infected lambs were positive to culture, whereas nested PCR also detected positive HD ewes and some LD animals. These results suggest that adult sheep can become infected by Map, as seen by the development of lesions, but they are focal and restricted to the lymphoid tissue.

Paratuberculose em ruminantes no Brasil

A paratuberculose ou doença de Johne é uma enterite granulomatosa causada por Mycobacterium avium subsp. paratuberculosis (Map) e comumente afeta ruminantes domésticos, no entanto, pode infectar várias espécies de mamíferos. Está presente nos cinco continentes e é considerada endêmica em algumas regiões pela Organização Internacional de Epizootias (OIE). Pertence à lista de enfermidades notificáveis, que compreende as doenças transmissíveis de importância sócio-econômica e/ou em saúde-pública, cujo controle é necessário para o comércio internacional de animais e alimentos de origem animal. A importância da doença de Johne não se restringe somente aos prejuízos econômicos causados à indústria animal, mas também na possível participação do Map na íleocolite granulomatosa que afeta seres humanos, conhecida como doença de Crohn. No Brasil, a paratuberculose já foi descrita em diversas espécies de ruminantes e em vários estados. Embora os relatos naturais da enfermidade sejam pontuais, acredita-se na possibilidade da transmissão interespecífica e na disseminação do agente através da compra e venda de animais infectados. O objetivo deste artigo foi reunir as informações disponíveis referentes aos aspectos epidemiológicos, clínico-patológicos e laboratoriais da paratuberculose em bovinos, bubalinos, caprinos e ovinos no Brasil, e salientar a necessidade de implementação de medidas de controle sanitário da enfermidade no país, o que possibilitaria a melhoria da qualidade e valorização dos produtos de origem animal no mercado internacional.

Host responses to persistent Mycobacterium avium subspecies paratuberculosis infection in surgically isolated bovine ileal segments

A lack of appropriate disease models has limited our understanding of the pathogenesis of persistent enteric infections with Mycobacterium avium subsp. paratuberculosis. A model was developed for the controlled delivery of a defined dose of M. avium subsp. paratuberculosis to surgically isolated ileal segments in newborn calves. The stable intestinal segments enabled the characterization of host responses to persistent M. avium subsp. paratuberculosis infections after a 9-month period, including an analysis of local mucosal immune responses relative to an adjacent uninfected intestinal compartment. M. avium subsp. paratuberculosis remained localized at the initial site of intestinal infection and was not detected by PCR in the mesenteric lymph node. M. avium subsp. paratuberculosis-specific T cell proliferative responses included both CD4 and γδ T cell receptor (γδTcR) T cell responses in the draining mesenteric lymph node. The levels of CD8(+) and γδTcR(+) T cells increased significantly (P < 0.05) in the lamina propria, and M. avium subsp. paratuberculosis-specific tumor necrosis factor alpha (TNF-α) and gamma interferon secretion by lamina propria leukocytes was also significantly (P < 0.05) increased. There was a significant (P < 0.05) accumulation of macrophages and dendritic cells (DCs) in the lamina propria, but the expression of mucosal toll-like receptors 1 through 10 was not significantly changed by M. avium subsp. paratuberculosis infection. In conclusion, surgically isolated ileal segments provided a model system for the establishment of a persistent and localized enteric M. avium subsp. paratuberculosis infection in cattle and facilitated the analysis of M. avium subsp. paratuberculosis-specific changes in mucosal leukocyte phenotype and function. The accumulation of DC subpopulations in the lamina propria suggests that further investigation of mucosal DCs may provide insight into host responses to M. avium subsp. paratuberculosis infection and improve vaccine strategies to prevent M. avium subsp. paratuberculosis infection.

Longitudinal Pathogenesis Study of Young Red Deer (Cervus elaphus) after Experimental Challenge with Mycobacterium avium subsp. paratuberculosis (MAP)

Paratuberculosis progresses more quickly in young red deer than in sheep or cattle. This study describes the clinical, immunological and pathological changes over a 50-week period in fourteen 4-month-old red deer that received heavy oral challenge with Mycobacterium avium subsp. paratuberculosis (MAP). At 4 and 12 weeks post challenge they were anaesthetized and a section of jejunal lymph node was surgically removed for culture, histopathology, and genetic studies. All 14 deer became infected, none were clinically affected, and they had varying degrees of subclinical disease when killed at week 50. Week 4 biopsies showed no paratuberculosis lesions, but MAP was cultured from all animals. At weeks 12 and 50 histopathological lesions ranged from mild to severe with corresponding low-to-high antibody titres, which peaked at 12–24 weeks. IFN-γ responses peaked at 8–15 weeks and were higher in mildly affected animals than in those with severe lesions.

Crohn's disease and the mycobacterioses: a quarter century later. Causation or simple association?

It has been more than 25 years since Mycobacterium paratuberculosis was first proposed as an etiologic agent in Crohn's disease based on the isolation of this organism from several patients. Since that time, a great deal of information has been accumulated that clearly establishes an association between M. paratuberculosis and Crohn's disease. However, data are conflicting and difficult to interpret and the field has become divided into committed advocates and confirmed skeptics. This review is an attempt to provide a thorough and objective summary of current knowledge from both basic and clinical research from the views and interpretations of both the antagonists and proponents. The reader is left to draw his or her own conclusions related to the validity of the issues and claims made by the opposing views and data interpretations. Whether M. paratuberculosis is a causative agent in some cases or simply represents an incidental association remains a controversial topic, but current evidence suggests that the notion should not be so readily dismissed. Remaining questions that need to be addressed in defining the role of M. paratuberculosis in Crohn's disease and future implications are discussed.

Diverse cytokine profile from mesenteric lymph node cells of cull cows severely affected with Johne's disease

Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne's disease, is able to dampen or distort immune responses at the mucosal sites and coexist with a massive infiltration of immune cells in the gastrointestinal tract. Knowledge of the mechanism by which M. avium subsp. paratuberculosis subverts the immune response at the mucosal level in cattle is important for the development of improved disease control strategies, including new vaccines and diagnostic tests. In this study, 38 cull cows from herds infected with M. avium subsp. paratuberculosis were divided into four groups, based on M. avium subsp. paratuberculosis culture from gut tissues and histopathological lesion scores. Cytokine gene expression and secretion from M. avium subsp. paratuberculosis sonicate-stimulated peripheral blood mononuclear cell (PBMC) and mesenteric lymph node (MLN) cultures of the animals were compared. Antigen stimulation of MLN cells from the severely lesioned group resulted in significant upregulation of the mRNA expression of five cytokines, gamma interferon (IFN-γ), interleukin-10 (IL-10), IL-13, IL-17A, and tumor necrosis factor alpha (TNF-α), which have a diverse range of functions, while there was no significant upregulation of these cytokines by the other groups. There were major differences between the responses of the PBMC and MLN cultures, with higher levels of secreted IFN-γ released from the MLN cultures and, conversely, higher levels of IL-10 released from the PBMC cultures. The upregulation of all five cytokines from cells at the site of infection in the severely lesioned animals suggested a dysregulated immune response, contributing to a failure to clear infection in this group of animals.

Immunological and pathological responses of red deer resistant or susceptible genotypes, to experimental challenge with Mycobacterium avium subsp. paratuberculosis

This study aimed to monitor the clinical, immunological and pathological changes in red deer for 49 weeks after experimental oral challenge with Mycobacterium avium subsp. paratuberculosis (MAP) and to assess the heritability of resistance in the offspring of two red stags. Eighteen young deer, which were bred from unselected hinds and sired by two stags resistant (R) or susceptible (S) to paratuberculosis, were challenged with MAP and monitored for 49 weeks. Biopsy samples of the jejunal lymph node were collected at Weeks 4 and 13 and at necropsy after euthanasia of clinically affected animals or when electively killed at Week 49. Three animals (two S and one R) developed clinical disease and were euthanised. The nine S offspring had significantly more severe lesions than the nine R offspring (Mantel-Haenszel Chi-square P=0.017). The average Lesion Severity Score (LSS) of R offspring was 5.9 (mild), and 7/9 had no or very mild lesions. In contrast, the LSS of S offspring averaged 11.7 (severe), and 7/9 had severe lesions. Most of the resistant, but not the susceptible, animals showed evidence of resolving lesions and a reduction in the number of MAP between 13 and 49 weeks after challenge. One R offspring appeared to completely cure itself, and progressed from mild culture-positive paratuberculosis lesions at Week 13 to having no signs of disease or infection 36 weeks later. This study showed significant heritable resistance/susceptibility to paratuberculosis and key differences in immunological responses in the first 3 months after challenge, indicating different paths to relative success or failure to control MAP. In general, R deer had higher IFN-γ levels, low antibody titres and fewer MAP, while S deer had lower IFN-γ levels, higher antibody and more MAP.

Immunoregulatory cytokines are associated with protection from immunopathology following Mycobacterium avium subspecies paratuberculosis infection in red deer

Although the causative agent of Johne's disease, Mycobacterium avium subsp. paratuberculosis, is well known, the etiology of disease and the immune responses generated in response to infection are still poorly understood. Knowledge of definitive markers of protective immunity, infection, and the establishment of chronic granulomatous Johne's disease is necessary to advance vaccine and diagnostic development. We sought to profile the immune responses occurring within jejunal lymph nodes of experimentally challenged red deer (Cervus elaphus). Quantitative PCR was utilized to measure a range of cytokines, signaling molecules, and transcription factors involved in Th1, Th2, Treg, and Th17 immune responses. Significant differences in gene expression were observed between control, minimally diseased, and severely diseased animals, with severely diseased animals showing elevated proinflammatory transcripts and reduced anti-inflammatory transcripts. We identified a proinflammatory cytokine milieu of gamma interferon, interleukin-1α (IL-1α), and IL-17, which may contribute to the immunopathology observed during clinical Johne's disease and suggest that Th2 and Treg immune responses may play an important role in controlling the development of immunopathology in infected animals.

Histopathology of Grossly Normal Mesenteric Lymph Nodes of New Zealand Farmed Red Deer (Cervus elaphus) Including Identification of Lipopigment

This article describes the histopathology of grossly normal mesenteric lymph nodes (MLNs) of New Zealand farmed red deer ( Cervus elaphus). Eighty MLNs were sourced from 10 deer from 5 North Island herds and 5 South Island herds classified as low risk and high risk of Mycobacterium avium subspecies paratuberculosis (MAP) infection, respectively. Fixed sections were stained with hematoxylin and eosin; Ziehl-Neelsen; and, selectively, periodic acid–Schiff, Perl’s, and Sudan black. Positive Ziehl-Neelsen stain, follicular hyperplasia, capsular eosinophil infiltration, focal granulomas, foci of macrophages containing lipopigment, parasitic granulomas, and calcified foci are described and severity graded where appropriate. Animal age, sex, and herd of origin are variably associated with the presence of one or more features. Trabecular fibrosis and dilated edema-filled sinusoids are described. These observations allow differentiation between likely nonpathologic histologic features in deer MLNs and features possibly attributable to infection with a pathogen such as MAP.