Previously Unrecognized Exposure of Desert Bighorn Sheep (Ovis canadensis nelsoni) to Mycoplasma ovipneumoniae in the California Mojave Desert.

A 2013 outbreak of respiratory disease in bighorn sheep from California's Mojave Desert metapopulation caused high mortality in at least one population. Subsequent PCR and strain-typing indicate widespread infection of a single strain of Mycoplasma ovipneumoniae throughout this region. Serosurvey of archived samples showed that some populations have had antibodies to M. ovipneumoniae since at least 1986, although pre-2013 strain-type data are unavailable.

Icelandic ovine Mycoplasma ovipneumoniae are variable bacteria that induce limited immune responses in vitro and in vivo.

PURPOSE: Mycoplasma ovipneumoniae is a pathogen that causes atypical pneumoniae in sheep and goats. While infection of lambs can induce strong immune responses, typically measured as serum antibodies, experimental vaccines appear to induce lower antibody titres. The purpose of this study was to better understand the bacterium and its interaction with the host, in order to improve the vaccination strategy. METHODOLOGY: We designed primers to compare seven M. ovipneumoniae gene sequences, in addition to the 16S sequence typically used, to estimate the variability between isolates. In addition, we labelled bacteria with a two-step process to examine whether bacteria could be intracellular as well as on the host surface in vitro. Finally, we vaccinated sheep four times and examined the induction of humoral and cellular responses. RESULTS: We were able to reliably amplify the seven housekeeping gene sequences to examine variability of the different isolates, and the bacteria could be found intracellularly, as well as on the host cell surface. Four vaccinations of sheep produced only modest humoral and cellular responses in this study, likely due to previous exposure of the animals to mycoplasmas. CONCLUSIONS: The moderate immune responses seen in this study indicate that previous exposure to mycoplasmas is a challenge for vaccination of lambs against M. ovipneumoniae. However, an alternative vaccination strategy, e.g. utilizing a recombinant vaccine, may overcome this vaccination hurdle in endemic regions and we suggest a possible vaccine candidate.

TIPE2 negatively regulates mycoplasma pneumonia-triggered immune response via MAPK signaling pathway.

Excessive immune responses played an important role in pathophysiology of mycoplasma pneumonia (MP) infection. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a negative regulator of immune response. This study investigated the expression change of TIPE2 and its role in immune defense against MP infection, as well as the underlying mechanisms. Expressions of TIPE2 both in patients and in macrophages in vitro after MP infection were measured. We further studied cytokine production and mitogen-activated protein kinase (MAPK) signaling function in macrophages with interfered expression of TIPE2 upon MP infection. A significant decrease of TIPE2 mRNA expression was observed in peripheral blood mononuclear cells (PBMCs) from MP patients, which was correlated with the severity of infection. Accordingly we found down-regulation of TIPE2 expression in macrophages after MP infection. In vitro study further suggested that TIPE2 jeopardized inflammatory cytokine production trigged by MP infection via inhibiting MAPK signaling pathway. These findings provided evidences of the novel function of TIPE2 in anti-MP immunity and its possible clinical utility related clinical significance.

A ROS-dependent and Caspase-3-mediated apoptosis in sheep bronchial epithelial cells in response to Mycoplasma Ovipneumoniae infections.

Mycoplasma Ovipneumoniae (M. ovipneumoniae) is a primary etiological agent of enzootic pneumonia in sheep and goats. It can enter and colonize ovine respiratory epithelial cells to establish an infection, which leads a serious cell death of epithelial cells. However, the nature of the interaction between pathogen of M. ovipneumoniae and host cells in the cell injury is currently not well understood. In this study, we investigated the epithelial cell apoptosis caused by an infection of M. ovipneumoniae in sheep primary air-liquid interface (ALI) epithelial cultures. The results showed that M. ovipneumoniae could specifically bind to ciliated cells at early stage of infection. Flow cytometric analysis demonstrated that an infection of M. ovipneumoniae induced a time-dependent cell apoptotic cell death, accompanied with an increased production of extracellular nitric oxide (NO), intracellular reactive oxygen species (ROS) production and activation of caspase-3 signaling in sheep bronchial epithelial cells. The induced cell apoptosis was further confirmed by a transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL) assay. Interestingly, the M. ovipneumoniae-induced apoptosis and activation of caspase-3 were correlated with the production of ROS but not NO. Mechanistically, M. ovipneumoniae-induced cell apoptosis was mediated by a mechanism by increasing the expression of phosphorylation of p38 and pro-apoptotic proteins, and activating caspase-3, caspase-8 and poly ADP-ribose polymerase (PARP) cleavage. These results suggest a ROS-dependent and caspase-3-mediated cell apoptosis in sheep bronchial epithelial cells in response to M. ovipneumoniae infections.

Elongation Factor Tu and Heat Shock Protein 70 Are Membrane-Associated Proteins from Mycoplasma ovipneumoniae Capable of Inducing Strong Immune Response in Mice.

Chronic non-progressive pneumonia, a disease that has become a worldwide epidemic has caused considerable loss to sheep industry. Mycoplasma ovipneumoniae (M. ovipneumoniae) is the causative agent of interstitial pneumonia in sheep, goat and bighorn. We here have identified by immunogold and immunoblotting that elongation factor Tu (EF-Tu) and heat shock protein 70 (HSP 70) are membrane-associated proteins on M. ovipneumonaiea. We have evaluated the humoral and cellular immune responses in vivo by immunizing BALB/c mice with both purified recombinant proteins rEF-Tu and rHSP70. The sera of both rEF-Tu and rHSP70 treated BALB/c mice demonstrated increased levels of IgG, IFN-γ, TNF-α, IL-12(p70), IL-4, IL-5 and IL-6. In addition, ELISPOT assay showed significant increase in IFN-γ+ secreting lymphocytes in the rHSP70 group when compared to other groups. Collectively our study reveals that rHSP70 induces a significantly better cellular immune response in mice, and may act as a Th1 cytokine-like adjuvant in immune response induction. Finally, growth inhibition test (GIT) of M. ovipneumoniae strain Y98 showed that sera from rHSP70 or rEF-Tu-immunized mice inhibited in vitro growth of M. ovipneumoniae. Our data strongly suggest that EF-Tu and HSP70 of M. ovipneumoniae are membrane-associated proteins capable of inducing antibody production, and cytokine secretion. Therefore, these two proteins may be potential candidates for vaccine development against M. ovipneumoniae infection in sheep.

Mycoplasma ovipneumoniae induces inflammatory response in sheep airway epithelial cells via a MyD88-dependent TLR signaling pathway.

Mycoplasma ovipneumoniae (M. ovipneumoniae) is a bacterium that specifically infects sheep and goat and causes ovine infectious pleuropneumonia. In an effort to understand the pathogen-host interaction between the M. ovipneumoniae and airway epithelial cells, we investigated the host inflammatory response using a primary air-liquid interface (ALI) epithelial culture model generated from bronchial epithelial cells of Ningxia Tan sheep (Ovis aries). The ALI culture of sheep bronchial epithelial cells showed a fully differentiated epithelium comprising distinct epithelial types, including the basal, ciliated and goblet cells. Exposure of ALI cultures to M. ovipneumoniae led to increased expression of Toll-like receptors (TLRs), and components of the myeloid differentiation factor 88 (MyD88)-dependent TLR signaling pathway, including the MyD88, TNF receptor-associated factor 6 (TRAF6), IL-1 receptor-associated kinases (IRAKs) and nuclear factor-kappa B (NF-κB), as well as subsequent pro-inflammatory cytokines in the epithelial cells. Of interest, infection with M. ovipneumoniae failed to induce the expression of TANK-binding kinase 1 (TBK1), TRAF3 and interferon regulatory factor 3 (IRF3), key components of the MyD88-independent signaling pathway. These results suggest that the MyD88-dependent TLR pathway may play a crucial role in sheep airway epithelial cells in response to M. ovipneumoniae infection, which also indicate that the ALI culture system may be a reliable model for investigating pathogen-host interactions between M. ovipneumoniae and airway epithelial cells.

Safety and Immunogenicity of a Mycoplasma ovipneumoniae bacterin for domestic sheep (Ovis aries).

BACKGROUND: Mortality from epizootic pneumonia is hindering re-establishment of bighorn sheep populations in western North America. Mycoplasma ovipneumoniae, a primary agent of this disease, is frequently carried asymptomatically by the domestic sheep and goats that constitute the reservoir of this agent for transmission to bighorn sheep. Our long-term objective is to reduce the risk of M. ovipneumoniae infection of bighorn sheep; one approach to this objective is to control the pathogen in its reservoir hosts. METHODS: The safety and immunogenicity of M. ovipneumoniae for domestic sheep was evaluated in three experimental immunization protocols: 1) live M. ovipneumoniae (50 ug protein); 2) killed M. ovipneumoniae (50 ug whole cell protein) in oil adjuvant; and 3) killed M. ovipneumoniae (250 ug whole cell protein) in oil adjuvant. Immunogenicity was assessed by two serum antibody measures: competitive enzyme-linked immunosorbent assay (cELISA) (experiments 1-3) and serum growth inhibition (Experiment 3). Passive immunogenicity was also assessed in the third experiment using the same assays applied to blood samples obtained from the lambs of immunized ewes. RESULTS AND CONCLUSIONS: Adverse reactions to immunization were generally minor, but local reactions were regularly observed at immunization sites with bacterins in oil adjuvants. No evidence of M. ovipneumoniae specific antibody responses were observed in the first or second experiments and no resistance to colonization was observed in the first experiment. However, the ewes in the third experiment developed strong cELISA serum antibody responses and significant serum M. ovipneumoniae inhibition activity, and these responses were passively transferred to their lambs. The results of these trials indicate that immunization with relatively large antigenic mass combined with an adjuvant is capable of inducing strong active antibody responses in ewes and passively immunizing lambs.

Molecular cloning of HSP70 in Mycoplasma ovipneumoniae and comparison with that of other mycoplasmas.

Mycoplasma ovipneumoniae, a bacterial species that specifically affects ovine and goat, is the cause of ovine infectious pleuropneumonia. We cloned, sequenced and analyzed heat shock protein 70 (HSP70) (dnaK) gene of M. ovipneumoniae. The full length open reading frame of the M. ovipneumoniae HSP70 gene consists of 1812 nucleotides, with a G+C content of 34.16%, encoding 604 amino acids. Comparative analysis with the HSP70 sequences of 15 Mycoplasma species revealed 59 to 87% DNA sequence identity, with an amino acid sequence identity range of 58 to 94%. M. ovipneumoniae and M. hyopneumoniae shared the highest DNA and amino acid sequence identity (87 and 94%, respectively). Based on phylogenetic analysis, both the DNA and amino acid identities of M. ovipneumoniae with other mycoplasmal HSP70 were correlated with the degree of relationship between the species. The C-terminus of the HSP70 was cloned into a bacterial expression vector and expressed in Escherichia coli cells. The recombinant C-terminal portion of HSP70 protein strongly reacted with convalescent sera from M. ovipneumoniae-infected sheep, based on an immunoblotting assay. This indicates that HSP70 is immunogenic in a natural M. ovipneumoniae infection and may be a relevant antigen for vaccine development.

[Molecular typing and immunoblotting of 17 Mycoplasma ovipneumoniae isolates from China].

OBJECTIVE: To study the heterogeneity and immunogenic variability among Mycoplasma ovipneumoniae (M. ovipneumoniae) isolates from different regions of China. METHODS: The heterogeneity of 17 strains of M. ovipneumoniae isolated from 8 regions of China was studied by the amplified fragment length polymorphism (AFLP) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The software NTsys-2. 10e was used to analyze the profiles obtained from the AFLP and SDS-PAGE. The proteins reacted with the antiserum against M. ovipneumoniae type strain Y98 were then detected by Western-blot. RESULTS: Seventeen strains of M. ovipneumoniae were divided into 8 AFLP groups based on the source regions when the coefficient was 0.78. They were also divided into 8 SDS-PAGE groups based on the source regions when the coefficient was 0.85. A total of 6 immunogenic proteins were detected within 8 strains of M. ovipneumoniae, and their molecular weights were 105 kDa, 83 kDa, 65 kDa, 42 kDa, 40 kDa or 26 kDa, respectively. Interestingly, the 83 kDa and 40 kDa proteins were conserved in all the 8 isolates. CONCLUSION: M. ovipneumoniae isolates from some regions of China were genetically different, but the 83 kDa and 40 kDa antigenic proteins were conserved among the tested isolates. This study can provide some insights for the diagnosis and vaccine development of the disease caused by M. ovipneumoniae.

Mycoplasma ovipneumoniae can predispose bighorn sheep to fatal Mannheimia haemolytica pneumonia.

Mycoplasma ovipneumoniae has been isolated from the lungs of pneumonic bighorn sheep (BHS). However experimental reproduction of fatal pneumonia in BHS with M. ovipneumoniae was not successful. Therefore the specific role, if any, of M. ovipneumoniae in BHS pneumonia is unclear. The objective of this study was to determine whether M. ovipneumoniae alone causes fatal pneumonia in BHS, or predisposes them to infection by Mannheimia haemolytica. We chose M. haemolytica for this study because of its isolation from pneumonic BHS, and its consistent ability to cause fatal pneumonia under experimental conditions. Since in vitro culture could attenuate virulence of M. ovipneumoniae, we used ceftiofur-treated lung homogenates from pneumonic BHS lambs or nasopharyngeal washings from M. ovipneumoniae-positive domestic sheep (DS) as the source of M. ovipneumoniae. Two adult BHS were inoculated intranasally with lung homogenates while two others received nasopharyngeal washings from DS. All BHS developed clinical signs of respiratory infection, but only one BHS died. The dead BHS had carried leukotoxin-positive M. haemolytica in the nasopharynx before the onset of this study. It is likely that M. ovipneumoniae colonization predisposed this BHS to fatal infection with the M. haemolytica already present in this animal. The remaining three BHS developed pneumonia and died 1-5 days following intranasal inoculation with M. haemolytica. On necropsy, lungs of all four BHS showed lesions characteristic of bronchopneumonia. M. haemolytica and M. ovipneumoniae were isolated from the lungs. These results suggest that M. ovipneumoniae alone may not cause fatal pneumonia in BHS, but can predispose them to fatal pneumonia due to M. haemolytica infection.

Global suppression of mitogen-activated ovine peripheral blood mononuclear cells by surface protein activity from Mycoplasma ovipneumoniae.

Mycoplasma ovipneumoniae is associated with chronic non-progressive pneumonia of sheep and goats. As with many other mycoplasmas involved in animal diseases, protective immune responses have not been achieved with vaccines, even though antibody responses can be obtained. This study focuses on characterizing the interaction of M. ovipneumoniae with ovine PBMC using carboxy-fluorescein-succinimidyl-ester (CFSE) loading and flow cytometry to measure lymphoid cell division. M. ovipneumoniae induced a strong in vitro polyclonal suppression of CD4(+), CD8(+), and B blood lymphocyte subsets. The suppressive activity could be destroyed by heating to 60 degrees C, and partially impaired by formalin and binary ethyleneimine treatment that abolished its viability. The activity resided on the surface-exposed membrane protein fraction of the mycoplasma, since mild trypsin treatment not affecting viability was shown to reduce suppressive activity. Trypsin-treated mycoplasma regained suppressive activity once the mycoplasma was allowed to re-synthesize its surface proteins. Implications for the design of vaccines against M. ovipneumoniae are discussed.

Isolation and immunological detection of Mycoplasma ovipneumoniae in sheep with atypical pneumonia, and lack of a role for Mycoplasma arginini.

Mycoplasma ovipneumoniae NCTC 10151(T) and four new isolates from UK sheep flocks were compared. Only glucose and pyruvate were used as energy sources by the five strains: glucose was the best energy source for the type strain, pyruvate supported better growth of the new strains. Whole cell protein patterns and antigenic profiles showed high similarity between all five strains. The new isolates fell into two groups in ELISA tests. Serum samples from 30 pneumonic sheep were assessed for M. ovipneumoniae infection and Mycoplasma arginini co-infection. Fourteen (out of 30) serum samples were positive for M. ovipneumoniae both by ELISA and immunoblotting. Twelve antigenic proteins of M. ovipneumoniae were detected in infected serum samples: the antigen patterns were unique, with between one and at least seven occurring in any one sample. All serum samples were designated as negative for M. arginini antibodies by both ELISA and immunoblotting.

New transtracheal bronchoalveolar lavage technique for the diagnosis of respiratory disease in sheep.

A new transtracheal bronchoalveolar lavage technique for the diagnosis of respiratory disease in sheep under field conditions was tested in 76 sheep. The sheep were divided into three groups, normal sheep, sheep with clinical signs of respiratory disease and housed sheep, on the basis of their respiratory disease history and husbandry conditions. The detection of Mannheimia haemolytica and Mycoplasma ovipneumoniae or parainfluenza virus type 3 and bovine respiratory syncytial virus antigen in the lavage samples was closely correlated with clinical disease. The sheep with clinical respiratory disease had a higher mean percentage of neutrophils in the lavage fluid than the sheep in the other two groups.