Inflammatory toxin from Mycoplasma bovis: isolation and characterization

Geraniol-a potential alternative to antibiotics for bovine mastitis treatment without disturbing the host microbial community or causing drug residues and resistance

Mastitis is one of the most prevalent diseases of dairy cows. Currently, mastitis treatment in dairy cows is mainly based on antibiotics. However, the use of antibiotics causes adverse effects, including drug resistance, drug residues, host-microbiome destruction, and environmental pollution. The present study sought to investigate the potentiality of geraniol as an alternative to antibiotics for bovine mastitis treatment in dairy cows. Additionally, the effectiveness of treatment, improvement in inflammatory factors, the influence on microbiome, presence of drug residues, and drug resistance induction were compared and analyzed comprehensively.Geraniol showed an equivalent therapeutic rate as antibiotics in the mouse infection model and cows with mastitis. Moreover, geraniol significantly inhibited the pathogenic bacteria and restored the microbial community while increasing the abundance of probiotics in milk. Notably, geraniol did not destroy the gut microbial communities in cows and mice, whereas antibiotics significantly reduced the diversity and destroyed the gut microbial community structure. Additionally, no geraniol residue was detected in milk four days after treatment discontinuation, but, antibiotic residues were detected in milk at the 7th day after drug withdrawal. In vitro experiments revealed that geraniol did not induce drug resistance in the Escherichia coli strain ATCC25922 and Staphylococcus aureus strain ATCC25923 after 150 generations of culturing, while antibiotics induced resistance after 10 generations. These results suggest that geraniol has antibacterial and anti-inflammatory effects similar to antibiotics without affecting the host-microbial community structure or causing drug residues and resistance. Therefore, geraniol can be a potential substitute for antibiotics to treat mastitis or other infectious diseases and be widely used in the dairy industry.

Aorto-enteric fistula development secondary to mycotic abdominal aortic aneurysm following intravesical bacillus Calmette-Guerin (BCG) treatment for transitional cell carcinoma of the bladder

INTRODUCTION

Intravesical BCG-instillation for bladder cancer is considered safe but is not without risk. While most side-effects are localised and self-limiting, the development of secondary vascular pathology is a rare but significant complication.

PRESENTATION OF CASE

A 77-year-old male presented with a mycotic abdominal aortic aneurysm and associated aorto-enteric fistula 18 months after receiving intravesical BCG-instillations for early stage transitional cell carcinoma.

DISCUSSION

Response rates to intravesical BCG for early stage transitional cell carcinoma are high. The procedure produces a localised inflammatory response in the bladder but the exact mechanism of action is unclear. The treatment is generally well tolerated but BCG-sepsis and secondary vascular complications have been documented. Mycotic abdominal aortic aneurysm with associated aorto-enteric fistula secondary to BCG is very rare. Few examples have been documented internationally and the extent of corresponding research and associated management proposals is limited. Surgical options include in situ repair with prosthetic graft, debridement with extra-anatomical bypass and, occasionally, endovascular stent grafting. Recommended medical therapy for systemic BCG infection is Isoniazid, Rifampicin and Ethambutol.

CONCLUSION

Current screening methods must be updated with clarification regarding duration of anti-tuberculous therapy and impact of concomitant anti-tuberculous medication on the therapeutic action of intravesical BCG. Long-term outcomes for patients post graft repair for mycotic aneurysm are unknown and more research is required regarding the susceptibility of vascular grafts to mycobacterial infection. Recognition of the risks associated with BCG-instillations, even in immunocompetent subjects, is paramount and must be considered even several months or years after receiving the therapy.

Invasion of bovine peripheral blood mononuclear cells and erythrocytes by Mycoplasma bovis

Mycoplasma bovis is a small, cell wall-less bacterium that contributes to a number of chronic inflammatory diseases in both dairy and feedlot cattle, including mastitis and bronchopneumonia. Numerous reports have implicated M. bovis in the activation of the immune system, while at the same time inhibiting immune cell proliferation. However, it is unknown whether the specific immune-cell population M. bovis is capable of attaching to and potentially invading. Here, we demonstrate that incubation of M. bovis Mb1 with bovine peripheral blood mononuclear cells (PBMC) resulted in a significant reduction in their proliferative responses while still remaining viable and capable of gamma interferon secretion. Furthermore, we show that M. bovis Mb1 can be found intracellularly (suggesting a role for either phagocytosis or attachment/invasion) in a number of select bovine PBMC populations (T cells, B cells, monocytes, γδ T cells, dendritic cells, NK cells, cytotoxic T cells, and T-helper cells), as well as red blood cells, albeit it at a significantly lower proportion. M. bovis Mb1 appeared to display three main patterns of intracellular staining: diffuse staining, an association with the intracellular side of the cell membrane, and punctate/vacuole-like staining. The invasion of circulating immune cells and erythrocytes could play an important role in disease pathogenesis by aiding the transport of M. bovis from the lungs to other sites.

Expression of Mycoplasma bovis variable surface membrane proteins in the respiratory tract of calves after experimental infection with a clonal variant of Mycoplasma bovis type strain PG45

The pathomorphological findings and the expression and distribution of variable surface protein antigens (Vsp) of Mycoplasma (M.) bovis were characterised immunohistochemically in lungs of eight calves following inoculation with a Vsp A-expressing clonal variant of M. bovis type strain PG45. Within 48 h post inoculation (p.i.) an innate immune response dominated by macrophages and neutrophils develops. The monoclonal antibodies (mAbs) 1A1 and 1E5 detected M. bovis Vsp antigens in paraffin tissue sections of seven calves. Vsp antigens were widely distributed and were already present at day two p.i. within macrophages and other lung compartments. Taken together, the results demonstrate that the bovine is unable to eliminate M. bovis during the time period examined. Based on the different immunohistochemical labelling patterns obtained with the mAbs, the results also support the speculation that the in vivo variability of Vsps together with immunological factors may contribute to the chronicity of pulmonary disease.

Mycoplasma bovis pneumonia in cattle

Mycoplasma bovis is an important and emerging cause of respiratory disease and arthritis in feedlot cattle and young dairy and veal calves, and has a variety of other disease manifestations in cattle. M. bovis is certainly capable of causing acute respiratory disease in cattle, yet the attributable fraction has been difficult to estimate. In contrast, M. bovis is more accepted as a cause of chronic bronchopneumonia with caseous and perhaps coagulative necrosis, characterized by persistent infection that seems poorly responsive to many antibiotics. An understanding of the disease has been recently advanced by comparisons of natural and experimentally induced disease, development of molecular diagnostic tools, and understanding some aspects of virulence, yet uncertainties regarding protective immunity, the importance of genotypic diversity, mechanisms of virulence, and the role of co-pathogens have restricted our understanding of pathogenesis and our ability to effectively control the disease. This review critically considers the relationship between M. bovis infection and the various manifestations of the bovine respiratory disease complex, and addresses the pathogenesis, clinical and pathologic sequelae, laboratory diagnosis and control of disease resulting from M. bovis infection in the bovine respiratory tract.

Detection of antibodies against the Mycoplasma bovis glyceraldehyde-3-phosphate dehydrogenase protein in beef cattle

Diseases caused by Mycoplasma bovis are an important source of financial losses for beef and dairy cattle producers. Antigenic variation in M. bovis hinders the production of effective vaccines and although there are few vaccines available, they are prepared from bacteria obtained from few isolates potentially limiting their effectiveness. Thus, to develop a vaccine that protects against all M. bovis isolates, it is necessary to use a common antigen that shows less or no antigenic variation. We have isolated the gap gene of M. bovis encoding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and showed that cattle colonized with M. bovis were able to mount an immune response to GAPDH. Using restriction-fragment length polymorphism (RFLP) of several M. bovis gap genes amplified by PCR, we were able to detect small intragenic variations that allowed us to classify the genes into two groups without changing the antigenic makeup of the proteins. The immune responses detected in cattle combined with the antigenic conservation of the proteins suggest that the M. bovis GAPDH protein could be a potential target for development of a more effective vaccine against all M. bovis isolates.

Endothelial cells from bovine pulmonary microvasculature respond to Mycoplasma bovis preferentially with signals for mononuclear cell transmigration

Mycoplasma bovis can cause arthritis or mastitis following pneumonia and mycoplasmemia in cattle. Interactions with pulmonary vascular endothelium have been recorded as localized vasculitis, perivascular mononuclear cell infiltrations, and accumulation of inflammatory cells in lesions. We compared adhesion mediators and cytokine gene expression as well as cytotoxicity of cultured primary bovine aortic and bovine pulmonary microvascular endothelial cells (BPMEC) challenged with M. bovis. We also tested if abscess-forming ability of strains of M. bovis is associated with changes on endothelial cells. Increased VCAM-1 surface expression was found in both cell types, while only infected BPMEC increased MCP-1 transcription, both mediators specific for mononuclear cell transmigration. Given no induction of ICAM-1 mRNA in either cell type, induction of IL-8 mRNA by BPMEC suggested that neutrophil transmigration was signaled in microvascular areas. Infected BPMEC showed early induction of IL-1beta and IL-6 mRNA. Excepting VCAM-1, differential strain effects were limited to BPMEC and not correlated with their abscess-forming capability. In addition, only strain DSA16 had minor cytotoxic effect on both cell types. We thus show that BPMEC are more susceptible than aortic cells to M. bovis-induced activation. Activation preferentially yielded signals for mononuclear cell transmigration, correlating well with in vivo observations of infiltrating cells at pulmonary sites.

Immunohistopathological findings in the lungs of calves naturally infected with Mycoplasma bovis

Histology and immunohistochemistry were used to analyse the lesions and distribution of Mycoplasma bovis antigen in the lungs of 18 naturally infected calves. Microscopic examination of pneumonic lungs revealed two distinct patterns of necrosis and inflammation. The first pattern was observed in six of 18 (33.3%) calves in which microscopic lesions were characterized by large irregular areas of coagulative necrosis surrounded by a dense zone of degenerated neutrophils. Moderate amounts of mycoplasmal antigen were in the centre and periphery of these necrotic foci and, to a lesser extent, in mononuclear cells of the peribronchial lymphoid tissue. The second pattern was observed in 18 of 18 (100%) calves and consisted of rounded foci of caseous necrosis composed by granular eosinophilic material surrounded by a rim of granulation tissue. Large amounts of M. bovis antigen were detected in the centre and periphery of these necrotic foci and, to a lesser extent, in the peribronchial lymphoid tissue, and alveolar and interstitial macrophages. It was concluded that both caseous and coagulative necrosis of the lung parenchyma was primarily caused by M. bovis. Infection with M. bovis should be suspected in bovine necrotic bronchopneumonia, particularly in cases in which the pulmonary necrosis is part of a pyogranulomatous inflammation centred around airways. The pattern of caseous necrosis with pyogranulomatous inflammation is characteristic of M. bovis infection while the pattern of coagulative necrosis is similar to and must be differentiated from Mannheimia haemolytica and Haemophilus somnus infection.

Identification and serological specificity of a polysaccharide component from Mycoplasma bovis

Whole-cell lysate and proteinase K digest preparations of the Mycoplasma bovis type strain (American Type Culture Collection 25523) were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Coomassie blue staining for protein revealed approximately 50 bands for the lysate but only a single band for the digest. Silver staining for polysaccharide revealed at least 19 bands for the digest. Fourteen monoclonal antibodies (MAbs) were produced using a screening procedure with an M. bovis digest. On immunoblots of digests of four M. bovis strains, an almost identical profile was seen with each strain for all 14 MAbs but differences were evident between strains. One MAb, M1557, was used to analyse 17 M. bovis strains on immunoblots. Ten to 20 bands were observed with 16 of the 17 strains, and differences were apparent among all 16 strains. In an enzyme-linked immunosorbent assay, M1557 reacted with 16 of the 17 M. bovis strains, but did not react with any of 41 non-M. bovis organisms tested. Strong reactions were observed with the MAbs and M. bovis colonies in immunofluorescence. The M. boris polysaccharide and MAbs to this component may be useful for the development of diagnostic assays for this organism.

Lameness in feedlot cattle

This article examines the various causes of lameness in feedlot cattle, with an emphasis on clinical signs, treatment, and prevention. Specific conditions are discussed, including interdigital necrobacillosis, laminitis, feedlot injuries, and feedlot lameness associated with Mycoplasma bovis. Immune management of the foot is also reviewed.

The pathogenicity and pathogenesis of Mycoplasma capricolum subsp. capripneumoniae (F38) in the caprine mammary gland

The right mammary gland of 12 lactating goats was inoculated intracisternally with 1 ml of Mycoplasma capricolum subsp. capripneumoniae (Mcc) containing 10(6) colony-forming units (CFU), while their left mammary halves received 1 ml of sterile PPLO broth only. Two goats served as uninfected controls. The clinical mastitis that developed in the infected mammary halves within 24 h was initially acute but became increasingly chronic by the end of the experiment at 24 days post inoculation (DPI). The disease was characterized by atrophy of the infected mammary halves, leading to marked agalactia and an increase in somatic cell counts, with a preponderance of neutrophils initially and lymphocytes later. The Mycoplasma was re-isolated from infected mammary secretions up to 16 DPI but not from blood. Histopathology revealed that the mastitis was acute and purulent initially, followed by infiltration of lymphonuclear cells and fibroplasia in the lymphomononuclear cells and fibroplasia in the interacinar tissue, and later by massive fibrosis. Immunohistology demonstrated the presence of Mycoplasma-like bodies localized mainly on the surface of acinar/duct epithelial cells. The studies showed that Mcc was highly pathogenic in the caprine mammary gland.

Development of a specific DNA probe and PCR for the detection of Mycoplasma bovis

Mycoplasma bovis is responsible for several production diseases in cattle, including mastitis, arthritis, pneumonia, abortion and infertility. Current methodologies for detecting and identifying M. bovis are time consuming and difficult. Tests which rely on antigen or antibody detection have poor sensitivity and specificity. In this paper associated protocols for the development of a hybridization probe and PCR are described. A genomic library (SauIIIA digested) was prepared from M. bovis DNA (Colindale Reference Strain: NC10131:02) and cloned into pUC19. Colony hybridization, using a probe preparation made from purified M. bovis DNA, was used to identify colonies of interest. M. bovis DNA fragments were retrieved from recombinant plasmids by digestion with EcoRI and HindIII. This DNA was used to prepare randomly primed probes for dot blot hybridization analysis with immobilized DNA from M. bovis (two strains), M. dispar, M. agalactiae, M. bovigenitalium (two strains), M. ovipneumoniae, a Group 7 strain, M. arginini and bacteria belonging to different genera. Four probes were found to hybridize only with M. bovis and M. ovipneumoniae DNA, whereas one probe reacted with genomic DNA from only one of the two M. bovis strains. The level of sensitivity of the dot blot hybridization assay was 200 CFU (colony forming units)/mL. To enhance the sensitivity further, an M. bovis-specific PCR assay was developed. The primers were designed using sequences obtained from the probe DNA which discriminated M. bovis from all other Mycoplasma DNA tested. The minimum amount of target DNA that could be detected by the PCR assay was that isolated from 10-20 CFU/mL. The PCR assay was therefore 10 times more sensitive than dot blot hybridization.

Contagious mastitis

Contagious mastitis is defined. The major mastitis pathogens are Streptococcus agalactiae, Staphylococcus aureus, Corynebacterium bovis, Mycoplasma sp, and Streptococcus dysgalactiae. These pathogens are discussed relative to prevalence, virulence factors, pathology, and control. These control measures include milking time hygiene, segregation, culling, vaccination, and treatment.

The nature and detection of mycoplasmal immunogens

Mycoplasmal infections are important causes of disease in cattle, swine, sheep, goats and poultry. Vaccination has been shown experimentally to induce protection against challenge with several mycoplasmas, and vaccines have been used to control naturally occurring mycoplasmal disease in swine, sheep, goats and poultry. Immune responses to mycoplasmal immunogens have been determined using ELISA and immunoblotting as well as other serologic techniques. However, the importance of specific immunogens as virulence factors or putative protective immunogens has generally not been determined. Investigations are underway to determine the pathogenic mechanisms and identify important virulence factors involved in mycoplasmal disease. Examples are discussed of investigations with Mycoplasma hyopneumoniae from our own laboratory. We have utilized ATP luminometry in attempts to develop better methods for quantitation of growth of M. hypopneumoniae and competitive ELISA as a potential method for in vitro quantitation of specific important immunogens.

Inhibition of Mycoplasma bovis cytadherence by a monoclonal antibody and various carbohydrate substances

The attachment of Mycoplasma bovis to permanent embryonic bovine lung (EBL) cells was studied in order to identify factors participating in the adhesion process. A monoclonal antibody directed against a 26 kDa protein of M. bovis was shown to reduce cytadherence of strains 120 and 454 by 46% and 70%, respectively. In uninhibited assays, strain 120 which exhibits an intense 26 kDa band in electrophoretic protein patterns adhered more strongly to EBL cell monolayers than strain 454 whose corresponding band is considerably weaker. The findings indicate involvement of the 26 kDa protein in M. bovis adherence. In further inhibition experiments, the ability of N-acetyl-neuraminlactose, glycophorin and dextran sulfate to significantly reduce adherence could be demonstrated. This suggests participation of sialic acid residues and probably also sulfatide groups as binding receptors. The data point to a complex adhesion mechanism with similarities to M. pneumoniae.

Mycoplasma bovis suppression of bovine lymphocyte response to phytohemagglutinin

The effect of viable Mycoplasma bovis on the in vitro bovine peripheral blood lymphocyte response to phytohemagglutinin (PHA) was studied. Results showed that M. bovis did not act as a mitogen for bovine lymphocytes. Viable M. bovis produced a dose and time dependent suppression of the PHA stimulated lymphocyte response. Suppression was not a result of differences in the viability of infected or control lymphocyte cultures. The suppressive effect of M. bovis was found to be independent of the concentration of PHA used in the test and the lymphocyte response could not be restored by supplementation of the culture medium with arginine. Delay for 48 h after PHA stimulation before adding M. bovis to the lymphocyte cultures diminished, but did not prevent, the suppression of the lymphocyte response. These results show that suppression of the lymphocyte response does not require the presence of M. bovis during the period of PHA stimulation, and that M. bovis was capable of interrupting [3H]-thymidine incorporation in lymphocytes which were actively synthesizing DNA.

Growth of Mycoplasma bovis in organ cultures of bovine foetal trachea and comparison with Mycoplasma dispar

Inoculation of tracheal organ cultures from bovine foetuses with Mycoplasma bovis resulted in a loss of cellular structure of the lamina propria, followed 20-22 days later by lifting and detachment of overlying epithelium. The effect was associated with large numbers of M. bovis, identified by immunoperoxidase labelling and electromicroscopy, infiltrating between the epithelial cells and amassing in the lamina propria, especially in the region of the basement membrane of the epithelium. Ciliary activity was undiminished for up to 18 days following inoculation and little or no cytopathic effect on the ciliated epithelium was seen in spite of the close proximity of large numbers of organisms. In contrast, M. dispar was restricted to the margin of the ciliated epithelium where, as previously reported, it caused pyknosis, sloughing and flattening of the epithelium with consequent loss of ciliary activity. The cytopathology observed for each mycoplasma bore a close similarity to the behaviour of the two mycoplasmas in vivo and it is suggested that the organ culture system may be a useful and relevant system to elucidate the pathogenic mechanisms for each mycoplasma.

Mycoplasma bovis infection in gnotobiotic calves and combined infection with respiratory syncytial virus

Mycoplasma bovis was inoculated alone or in combination with respiratory syncytial virus into the respiratory tracts of 12 gnotobiotic calves. Clinical signs ranged from transient pyrexia to protracted fever accompanied by severe lower respiratory signs and in one case, arthritis. Pulmonary lesions included foci of coagulative necrosis surrounded by mononuclear cells and suppurative bronchiolitis with varying degrees of lympho-reticular hyperplasia. No enhancement of lesions occurred in the combined infections of M. bovis and respiratory syncytial virus. M. bovis was identified by immunoperoxidase labelling in lesions of necrosis, especially at interfaces between the lesion and mononuclear cells and in bronchiolar exudates. Organisms were also located in necrotic lesions of joint capsules, in tonsillar crypts, and in liver.

Immunochemical characterization of a heat-stable surface antigen of Mycoplasma pulmonis expressing both species-specific and strain-specific determinants

We sought to characterize the strain-specific antigens of four strains of Mycoplasma pulmonis (47, 63, Negroni, and 19612) by crossed immunoelectrophoresis. Although the strains possessed a number of common antigens, type-specific antigens of 0.32 mobility (bovine albumin was assigned a value of 1) were detected in strains 47 and 63. Strains 19612 and Negroni cross-reacted and represented a third group. Each strain possessed a major heat-stable antigen complex of 0.32 mobility characterized by a faster-moving component of 0.55 mobility. Monospecific antiserum to heat-stable antigen 0.32 of strain 63 demonstrated that this antigen complex consisted of at least three antigen-antibody precipitating systems characterized by type-specific and group-specific determinants. Adsorption of antiserum with whole cells revealed that the 0.32 antigen complex was surface exposed. The antigen complex is pronase sensitive and only partially sensitive to periodate. Purification of antigen 0.32 from detergent-extracted cells by affinity chromatography using monospecific antiserum revealed two major polypeptides of 86,500 and 83,500 dalton which reacted strongly with monospecific antiserum by immunoblotting. These reactive polypeptides were present in all strains examined. Additional polypeptides of different molecular weights in strains 19612 and Negroni produced strong reactions with monospecific antiserum, although sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of the two strains were strikingly similar. Common heat-stable antigens were observed also. This study demonstrates that M. pulmonis strains possess an antigenically variable heat-stable surface antigen which is unique in that it contains not only strain-specific determinants but also species-specific determinants.

Toxic properties of the Mycoplasma arthritidis ISR-1 membrane

Isolated membranes of Mycoplasma arthritidis ISR-1 possess toxic properties for rats, mice and chicken embryos. Reactions are dose-dependent. By intravenous injection of 20 mg of membrane protein, a lethal toxicity syndrome resembling shock is induced in Sprague-Dawley rats of 100 g body weight. Mice of approximately 20-g body weight show the same syndrome by intravenous injection of 15 mg of membrane protein. The lethal toxicity for chicken embryos increases from 10 to 80% after injection of 0.3 to 1.5 mg of membrane protein. The LD50 in chicken embryos was found to be 0.5 mg membrane protein. After administration of 10-15 mg of membrane protein, rats showed an increase in temperature from 38 to 41 degrees C within 5 h. Because of the difficulty in measuring the temperature in mice, loss of body weight was taken as the criterion for toxicity. Body weight was reduced up to 16% within 1 day after intravenous injection of 500 micrograms of membrane protein per g of body weight. For sheep red blood cells, M. arthritidis ISR-1 membranes were haemolytic in concentrations of 4 mg of membrane protein and higher. Intradermal injection of 1 mg of membrane protein into guinea-pigs resulted in red swelling reactions measuring approximately 10 mm in diameter 10 h after injection. For foetal rat skin fibroblasts, M. arthritidis ISR-1 membranes were toxic in concentrations from 1 micrograms (3H-uridine incorporation), 10 micrograms (14C-leucine incorporation) and 100 micrograms (3H-thymidine incorporation) of membrane protein.

Morphologic changes following intraarticular inoculation of Mycoplasma bovis in calves

Intraarticular inoculation of Mycoplasma bovis into the joints of six-week-old calves caused severe arthritis in five inoculates and mild arthritis in a sixth. Intraarticular inoculation of killed M. bovis did not cause arthritis. Arthritic calves had fever, joint swelling, lameness, neutrophilia, and intercurrent pneumonia from which M. bovis could not be recovered. Gross lesions were massive fibrinosuppurative synovitis and tenosynovitis, erosion of cartilage, and its replacement by polypoid granulation tissue. Histologic lesions were extensive ulceration of synovial membranes, leukocytic infiltration of the subsynovium, congestion, hyperemia, and thrombosis of the subsynovial vessels. Cartilage erosion was accompanied by chronic osteomyelitis and formation of pannus tissue. The presence of thrombi and platelet aggregates suggests that the inflammatory process in the synovium may arise from the interaction of M. bovis with the vasculature and the coagulation process of the host.