Biodegradation of selected aminophosphonates by the bacterial isolate Ochrobactrum sp. BTU1

Aminophosphonates, like glyphosate (GS) or metal chelators such as ethylenediaminetetra(methylenephosphonic acid) (EDTMP), are released on a large scale worldwide. Here, we have characterized a bacterial strain capable of degrading synthetic aminophosphonates. The strain was isolated from LC/MS standard solution. Genome sequencing indicated that the strain belongs to the genus Ochrobactrum. Whole-genome classification using pyANI software to compute a pairwise ANI and other metrics between Brucella assemblies and Ochrobactrum contigs revealed that the bacterial strain is designated as Ochrobactrum sp. BTU1. Degradation batch tests with Ochrobactrum sp. BTU1 and the selected aminophosphonates GS, EDTMP, aminomethylphosphonic acid (AMPA), iminodi(methylene-phosphonic) (IDMP) and ethylaminobis(methylenephosphonic) acid (EABMP) showed that the strain can use all phosphonates as sole phosphorus source during phosphorus starvation. The highest growth rate was achieved with AMPA, while EDTMP and GS were least supportive for growth. Proteome analysis revealed that GS degradation is promoted by C-P lyase via the sarcosine pathway, i.e., initial cleavage at the C-P bond. We also identified C-P lyase to be responsible for degradation of EDTMP, EABMP, IDMP and AMPA. However, the identification of the metabolite ethylenediaminetri(methylenephosphonic acid) via LC/MS analysis in the test medium during EDTMP degradation indicates a different initial cleavage step as compared to GS. For EDTMP, it is evident that the initial cleavage occurs at the C-N bond. The detection of different key enzymes at regulated levels, form the bacterial proteoms during EDTMP exposure, further supports this finding. This study illustrates that widely used and structurally more complex aminophosphonates can be degraded by Ochrobactrum sp. BTU1 via the well-known degradation pathways but with different initial cleavage strategy compared to GS.

Determination of Optimal Phage Load and Administration Time for Antibacterial Treatment

Using phages as antibacterials is becoming a customary practice in Western countries. Nonetheless, successful treatments must consider the growth rate of the bacterial host and the degradation of the virions. Therefore, successful treatments require administering the right amount of phage (viral load, Vφ) at the right moment (administration time, Tφ). The present protocols implement a machine learning approach to determine the best combination of Vφ and Tφ to obtain the elimination of the target bacterium from a system. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: One bacterium, one phage Alternate Protocol 1: One bacterium, one phage (wrapping function) Alternate Protocol 2: One bacterium, one phage (wrapping function, alternative growing model) Basic Protocol 2: Two bacteria, one phage Alternate Protocol 3: Two bacteria, one phage (launch from terminal).

EPI-Net One Health reporting guideline for antimicrobial consumption and resistance surveillance data: a Delphi approach

Strategic and standardised approaches to analysis and reporting of surveillance data are essential to inform antimicrobial resistance (AMR) mitigation measures, including antibiotic policies. Targeted guidance on linking full-scale AMR and antimicrobial consumption (AMC)/antimicrobial residues (AR) surveillance data from the human, animal, and environmental sectors is currently needed. This paper describes the initiative whereby a multidisciplinary panel of experts (56 from 20 countries-52 high income, 4 upper middle or lower income), representing all three sectors, elaborated proposals for structuring and reporting full-scale AMR and AMC/AR surveillance data across the three sectors. An evidence-supported, modified Delphi approach was adopted to reach consensus among the experts for dissemination frequency, language, and overall structure of reporting; core elements and metrics for AMC/AR data; core elements and metrics for AMR data. The recommendations can support multisectoral national and regional plans on antimicrobials policy to reduce resistance rates applying a One Health approach.

Reassessment of Historical Clinical Trials Supports the Effectiveness of Phage Therapy

Phage therapy has become a hot topic in medical research due to the increasing prevalence of antibiotic-resistant bacteria strains. In the treatment of bacterial infections, bacteriophages have several advantages over antibiotics, including strain specificity, lack of serious side effects, and low development costs. However, scientists dismissed the clinical success of early clinical trials in the 1940s, slowing the adoption of this promising antibacterial application in Western countries. The current study used statistical methods commonly used in modern meta-analysis to reevaluate early 20th-century studies and compare them with clinical trials conducted in the last 20 years. Using a random effect model, the development of disease after treatment with or without phages was measured in odds ratios (OR) with 95% confidence intervals (CI). Based on the findings of 17 clinical trials conducted between 1921 and 1940, phage therapy was effective (OR = 0.21, 95% CI = 0.10 to 0.44, P value < 0.0001). The current study includes a topic review on modern clinical trials; four could be analyzed, indicating a noneffective therapy (OR = 2.84, 95% CI = 1.53 to 5.27, P value = 0.0009). The results suggest phage therapy was surprisingly less effective than standard treatments in resolving bacterial infections. However, the results were affected by the small sample set size. This work also contextualizes the development of phage therapy in the early 20th century and highlights the expansion of phage applications in the last few years. In conclusion, the current review shows phage therapy is no longer an underestimated tool in the treatment of bacterial infections.

Impact of cytotoxic agents or apoptosis stimulants on αklotho in MDCK, NRK-52E and HK2 kidney cells

αKlotho is a transmembrane protein acting as a co-receptor for FGF23, a bone hormone regulating renal phosphate and vitamin D metabolism. αKlotho expression is controlled by PPARγ. Soluble αklotho (sKL) regulates cellular signaling impacting stress resistance and death. αKlotho deficiency causes early onset of aging-associated diseases while its overexpression markedly increases lifespan. Cellular stress due to cytotoxic therapeutics or apoptosis induction through caspase activation or serum deficiency may result in cell death. Owing to αklotho's role in cellular stress and aging, this study explored the effect of cytotoxic agents or apoptosis stimulants on cellular αklotho expression. Experiments were performed in renal MDCK, NRK-52E and HK-2 cells. Gene expression was determined by qRT-PCR, sKL by ELISA, apoptosis and necrosis by annexin V binding and a fluorescent DNA dye, and cell viability by MTT assay. Cytostatic drugs cisplatin, paclitaxel, and doxorubicin as well as apoptosis induction with caspase 3 activator PAC-1 and serum deprivation induced αklotho and PPARG gene expression while decreasing viability and proliferation and inducing apoptosis of MDCK and NRK-52E cells to a variable extent. PPARγ antagonism attenuated up-regulation of αklotho in MDCK cells. In HK-2 cells, αklotho gene expression and sKL protein were down-regulated by chemotherapeutics. SKL serum levels in patients following chemotherapy were not significantly changed. In summary, potentially fatal stress results in up-regulation of αKlotho gene expression in MDCK and NRK-52E cells and down-regulation in HK-2 cells. These results indicate that different renal cell lines may exhibit completely different regulation of αklotho.

Occurrence of 'Candidatus Mycoplasma haemosuis' in fattening pigs, sows and piglets in Germany using a novel gap-based quantitative real-time PCR assay

Background

The appearance of the novel porcine haemotrophic mycoplasma (HM) species ‘Candidatus Mycoplasma haemosuis’ was reported in apparently healthy but also in clinically sick animals in China, Korea and in a case report from Germany. Outside of Asia, however, nothing further is known about the frequency of ‘Ca. M. haemosuis’ in pigs to date. To investigate the distribution of this novel HM species in Germany, fattening pigs, sows and pre-suckling piglets were examined using a herein developed quantitative real-time PCR assay (qPCR). Because the piglets were sampled before the first colostrum uptake, additional information on a possible vertical transmission from dams to their offspring was obtained.

Results

Our novel qPCR assay successfully detected ‘Ca. M. haemosuis’ in all blood samples from the ‘Ca. M. haemosuis’-infected pigs. No cross-reactivity was detected when DNA from non-target Mycoplasma spp. and other bacterial species representing 10⁵ bacteria/reaction were used as a template. The lower limit of detection of the qPCR was thus 10 gap gene copies per reaction and 2.5 x 10³ genome equivalents (GE) per mL blood.

‘Candidatus M. haemosuis’ was detected by this qPCR in blood samples from a total out of 6.25% sows (13/208), 4.50% pre-suckling piglets (28/622) and 17.50% fattening pigs (35/200). On farm level, 3 out of 21 piglet producing farms (14.28%) and 9 out of 20 fattening farms (45.00%) were positive for ‘Ca. M. haemosuis’. Co-infections with M. suis were evident in all age groups.

Conclusion

‘Candidatus M. haemosuis’ infection is present in German pig farms and the detection of the novel porcine HM species in piglets immediately after birth before colostrum intake indicates vertical transmission. The novel qPCR assay specific for ‘Ca. M. haemosuis’ described herein will be a prerequisite for future studies on the prevalence, epidemiology as well as the clinical and economic impact of ‘Ca. M. haemosuis’ infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03147-1.

Update on shedding and transmission routes of porcine haemotrophic mycoplasmas in naturally and experimentally infected pigs

Horizontal transmission of Mycoplasma suis via parenteral exposure during standard practices or through bites during fightings have been identified as key epidemiological routes. However, as knowledge gaps on other potential shedding and transmission routes exist, the present study combines both laboratory experiments and field surveys to gain new insights into the epidemiology of porcine haemotrophic mycoplasmas. Splenectomised pigs were orally inoculated with a M. suis field strain and investigated for clinical signs related to infectious anaemia of pigs (IAP) and the presence of M. suis in blood, urine and saliva samples by qPCR. All blood samples were negative for M. suis and animals did not show obvious clinical signs of IAP throughout the entire study period. Additionally, urine, nasal and saliva samples from sows of conventional piglet producing farms and semen samples from a boar stud revealed no detection of M. suis and ‘Candidatus Mycoplasma haemosuis’ by qPCR. Thus, the results indicate that blood-independent transmission routes might be of minor relevance under field conditions.

Clinical, haematological and pathomorphological findings in Mycoplasma suis infected pigs

BACKGROUND

Mycoplasma suis (M. suis) belongs to the group of haemotrophic mycoplasmas and is known as the causative agent of infectious anaemia in pigs. In the last few years valuable insights into the mechanism of adhesion and invasion, shedding patterns and cell tropism of M. suis were gained by the use of new molecular techniques. However, details on M. suis induced lesions as well as the distribution of M. suis in different organs are still lacking. Therefore, seven splenectomised pigs were experimentally infected and clinical and laboratory investigations as well as a detailed histopathological examination were performed. Detection and quantification of M. suis DNA in blood and various tissue samples was done using a quantitative real-time PCR.

RESULTS

During the course of experimental infection, periodically occurring signs of infectious anaemia of pigs including severe icteroanaemia, fever, apathy and anorexia were observed. In addition, dermatological manifestations such as haemorrhagic diathesis presenting as petechiae occurred. The most important haematological alterations were normochromic, normocytic anaemia, hypoglycaemia as well as increased bilirubin and urea concentrations. Necropsy revealed predominant evidence of haemolysis with consecutive anaemia, as well as disseminated intravascular coagulation. M. suis was found in all investigated tissues with the highest copy numbers found in the kidneys. In Giemsa stained sections M. suis was only detected red blood cell (RBC)-associated.

CONCLUSION

In the present study, no RBC independent sequestration of M. suis was detected in organs of experimentally infected pigs. Pathological findings are most likely resulting from haemolysis, consecutive anaemia as well as from disseminated intravascular coagulation and subsequent organ impairments.

Study of the antibiotic residues in poultry meat in some of the EU countries and selection of the best compositions of lactic acid bacteria and essential oils against Salmonella enterica

In this study, the presence of antibiotics (ANB) residues was evaluated in poultry meat purchased from German and Lithuanian markets. In addition, the antimicrobial activity of 13 lactic acid bacteria (LAB) strains, 2 essential oils (EO) (Thymus vulgaris and Origanum vulgare L.), and their compositions were tested for the purpose of inhibiting antibiotic-resistant Salmonella spp. ANB residues were found in 3 out of the 20 analyzed poultry meat samples: sample no. 8 contained enrofloxacin (0.46 μg/kg), sample no. 14 contained both enrofloxacin and doxycycline (0.05 and 16.8 μg/kg, respectively), and sample no. 18 contained enrofloxacin (2.06 μg/kg). The maximum residue limits (MRLs) for the sum of enrofloxacin and ciprofloxacin and for doxycycline in the poultry muscle are 100 μg/kg. Finally, none of the tested poultry meat samples exceeded the suggested MRLs; however, the issue of ANB residues still requires monitoring of the poultry industry in Germany, Poland, and Lithuania, despite the currently established low ANB concentrations. These findings can be explained by the increased use of alternatives to ANB in the poultry industry. Our results showed that an effective alternative to ANB, which can help to reduce the occurrence of antibiotic-resistant salmonella, is a composition containing 1.0% of thyme EO and the following LAB strains: Lactobacillus plantrum LUHS122, Enteroccocus pseudoavium LUHS242, Lactobacillus casei LUHS210, Lactobacillus paracasei LUHS244, Lactobacillus plantarum LUHS135, Lactobacillus coryniformins LUHS71, and Lactobacillus uvarum LUHS245, which can be recommended for poultry industry as components of feed or for the treatment of surfaces, to control the contamination with Salmonella strains. However, it should be mentioned that most of the tested LAB strains were inhibited by thyme EO at the concentrations of 0.5 and 1.0%, except for LUHS122, LUHS210, and LUHS245. Finally, it can be noted that the agents responsible for the inhibitory effect on Salmonella are not the viable LAB strains but rather their metabolites, and further studies are needed to identify which metabolites are the most important.

Detection of a novel haemoplasma species in fattening pigs with skin alterations, fever and anaemia

BACKGROUND

In a fattening farm in Southern Germany, skin alterations (urticaria, haemorrhagic diathesis) and high fever were observed in 30% of the pigs 2 weeks after arrival. Feed intake was severely compromised in affected pigs.

METHODS

After detailed clinical observation, blood samples from affected pigs were collected for haematological, PCR and serological investigations. In addition, pathological investigations were performed on one pig.

RESULTS AND CONCLUSION

Analysis of blood parameters revealed a normocytic, normochromic anaemia. A novel porcine haemoplasma species was detected in blood samples of affected pigs and spleen sample of the necropsied pig by PCR. Phylogenetic analyses based on the 16S rDNA showed 99% identity to a novel porcine haemoplasma ('Candidatus (Ca.) M. haemosuis') species which has recently been described in China. Interestingly, this is the first report of 'Ca. M. haemosuis' in pigs with clinical signs resembling those of Mycoplasma (M) suis and the first description of this novel haemoplasma species outside Asia. On-farm affected pigs were treated with oxytetracycline and non-steroidal anti-inflammatory drugs. Clinical signs improved after implementation of treatment and optimisation of management procedures. This case might indicate that other porcine haemoplasma species than M suis can induce fever and skin alterations and may have an economic impact on affected farms.

Symposium report: emerging threats for human health - impact of socioeconomic and climate change on zooanthroponosis in the Republic of Sakha (Yakutia), Russia

Population growth, socio-cultural and economic changes as well as technological progress have an immediate impact on the environment and human health in particular. Our steadily rising needs of resources increase the pressure on the environment and narrow down untainted habitats for plants and wild animals. Balance and resilience of ecosystems are further threatened by climate change, as temperature and seasonal shifts increase the pressure for all species to find successful survival strategies. Arctic and subarctic regions are especially vulnerable to climate change, as thawing of permafrost significantly transforms soil structures, vegetation and habitats. With rising temperature, the risk of zoonotic diseases in the Republic of Sakha (Yakutia) has also increased. As vegetation periods prolong and habitats broaden, zoonotic pathogens and their vectors find more favourable living conditions. Moreover, permafrost degradation may expose historic burial grounds and allow for reviving the vectors of deadly infections from the past. To assess the current state of knowledge and emerging risks in the light of the “One Health” concept, a German-Russian Symposium took place on 13 August 2018 in Yakutsk, Russian Federation. This symposium report presents the main findings generated from presentations and discussions.

Detection of Mycoplasma suis in pre-suckling piglets indicates a vertical transmission

Background

Transmission of Mycoplasma (M.) suis mainly occurs via iatrogenic or zootechnical manipulations or due to ranking fights. Other transmission routes including ingestion of secretes/excretes; blood-sucking arthropods and intra-uterine transmission have thought to play an epidemiological role without being experimentally proven. To investigate a vertical transmission of M. suis under field conditions blood samples from pre-suckling piglets and their corresponding dam were examined for M. suis by quantitative polymerase chain reaction (qPCR) in 21 farms in Southern Germany.

Results

A total of 14.35% of the 474 blood samples from pre-suckling piglets reacted qPCR positive. Additionally, M. suis was detected in 65 (31.25%) of the 208 sows at farrowing. On farm level, 16 (76.2%) of the 21 farms had at least one M. suis positive animal. M. suis positive farms had an average of 0.41 more stillborn piglets per litter than M. suis negative farms (p = 0.007).

Conclusion

The present study provides further insights into M. suis infection dynamics as it is the first detection of M. suis in piglets immediately after birth prior to colostrum intake and the first large scale investigation of M. suis in sows at farrowing.

Dietary changes in nutritional studies shape the structural and functional composition of the pigs' fecal microbiome-from days to weeks

BACKGROUND

The possible impact of changes in diet composition on the intestinal microbiome is mostly studied after some days of adaptation to the diet of interest. The question arises if a few days are enough to reflect the microbial response to the diet by changing the community composition and function. The present study investigated the fecal microbiome of pigs during a time span of 4 weeks after a dietary change to obtain insights regarding the time required for adaptation. Four different diets were used differing in either protein source (field peas meal vs. soybean meal) or the concentration of calcium and phosphorus (CaP).

RESULTS

Twelve pigs were sampled at seven time points within 4 weeks after the dietary change. Fecal samples were used to sequence the 16S rRNA gene amplicons to analyse microbial proteins via LC-MS/MS and to determine the SCFA production. The analysis of OTU abundances and quantification values of proteins showed a significant separation of three periods of time (p = 0.001). Samples from the first day are used to define the 'zero period'; samples of weeks 1 and 2 are combined as 'metabolic period' and an 'equilibrium period was defined based on samples from weeks 3 and 4. Only in this last period, a separation according to the supplementation of CaP was significantly detectable (p = 0.001). No changes were found based on the corn-soybean meal or corn-field peas administration. The analysis of possible factors causing this significant separation showed only an overall change of bacterial members and functional properties. The metaproteomic approach yielded a total of about 9700 proteins, which were used to deduce possible metabolic functions of the bacterial community.

CONCLUSIONS

A gradual taxonomic and functional rearrangement of the bacterial community has been depicted after a change of diet composition. The adaptation lasts several weeks despite the usually assumed time span of several days. The obtained knowledge is of a great importance for the design of future nutritional studies. Moreover, considering the high similarities between the porcine and human gastrointestinal tract anatomy and physiology, the findings of the current study might imply in the design of human-related nutritional studies.

The Priority position paper: Protecting Europe's food chain from prions

Bovine spongiform encephalopathy (BSE) created a global European crisis in the 1980s and 90s, with very serious health and economic implications. Classical BSE now appears to be under control, to a great extent as a result of a global research effort that identified the sources of prions in meat and bone meal (MBM) and developed new animal-testing tools that guided policy. Priority ( www.prionpriority.eu ) was a European Union (EU) Framework Program 7 (FP7)-funded project through which 21 European research institutions and small and medium enterprises (SMEs) joined efforts between 2009 and 2014, to conduct coordinated basic and applied research on prions and prion diseases. At the end of the project, the Priority consortium drafted a position paper ( www.prionpriority.eu/Priority position paper) with its main conclusions. In the present opinion paper, we summarize these conclusions. With respect to the issue of re-introducing ruminant protein into the feed-chain, our opinion is that sustaining an absolute ban on feeding ruminant protein to ruminants is essential. In particular, the spread and impact of non-classical forms of scrapie and BSE in ruminants is not fully understood and the risks cannot be estimated. Atypical prion agents will probably continue to represent the dominant form of prion diseases in the near future in Europe. Atypical L-type BSE has clear zoonotic potential, as demonstrated in experimental models. Similarly, there are now data indicating that the atypical scrapie agent can cross various species barriers. More epidemiological data from large cohorts are necessary to reach any conclusion on the impact of its transmissibility on public health. Re-evaluations of safety precautions may become necessary depending on the outcome of these studies. Intensified searching for molecular determinants of the species barrier is recommended, since this barrier is key for important policy areas and risk assessment. Understanding the structural basis for strains and the basis for adaptation of a strain to a new host will require continued fundamental research, also needed to understand mechanisms of prion transmission, replication and how they cause nervous system dysfunction and death. Early detection of prion infection, ideally at a preclinical stage, also remains crucial for development of effective treatment strategies.

Updating the proteome of the uncultivable hemotrophic Mycoplasma suis in experimentally infected pigs

Mycoplasma suis belongs to the hemotrophic mycoplasmas that are associated with acute and chronic anemia in a wide range of livestock and wild animals. The inability to culture M. suis in vitro has hindered its characterization at the molecular level. Since the publication of M. suis genome sequences in 2011 only one proteome study has been published. Aim of the presented study was to significantly extend the proteome coverage of M. suis strain KI_3806 during acute infection by applying three different protein extraction methods followed by 1D SDS-PAGE and LC-MS/MS. A total of 404 of 795 M. suis KI_3806 proteins (50.8%) were identified. Data analysis revealed the expression of 83.7% of the predicted ORFs with assigned functions but also highlights the expression of 179 of 523 (34.2%) hypothetical proteins with unknown functions. Computational analyses identified expressed membrane-associated hypothetical proteins that might be involved in adhesion or host-pathogen interaction. Furthermore, analyses of the expressed proteins indicated the existence of a hexose-6-phosphate-transporter and an ECF transporter. In conclusion, our proteome study provides a further step toward the elucidation of the unique life cycle of M. suis and the establishment of an in vitro culture. All MS data have been deposited in the ProteomeXchange with identifier PXD002294 (http://proteomecentral.proteomexchange.org/dataset/PXD002294).

Spatial Variation of the Gut Microbiota in Broiler Chickens as Affected by Dietary Available Phosphorus and Assessed by T-RFLP Analysis and 454 Pyrosequencing

Molecular fingerprinting and sequencing based techniques have been widely used to characterize microbial communities. Terminal restriction fragment length polymorphism (T-RFLP) and 454-pyrosequencing were used to determine the microorganisms present in the different sections of the chicken gastrointestinal tract (GIT) (crop, jejunum, ileum and caeca). Broilers fed with diets differing in phosphorous (P) and calcium (Ca) as well as in phytase levels were used to study the microbiota of the upper and lower part of the GIT. A database with terminal restriction fragments (T-RF) of the most important organism present in the different gastrointestinal sections was constructed. The analysis revealed a distinct microbial assemblage on each section. Regardless of the diet, crop, jejunum and ileum were mainly colonized by Lactobacillaceae, and caeca were the most diverse site. The correlation between Lactobacillus crispatus and L. reuteri was positive in the crop, but negative in the jejunum. In crop samples, higher P and Ca levels led to a shift in the abundance of L. reuteri and L. crispatus to L. salivarius and L. taiwanensis whereas in the ileum supplementation of phytase favored L. salivarius and L. taiwanensis but resulted in decreased abundance of L. crispatus. Both methods were correlating significantly, being T-RFLP a reliable fingerprinting method to rapidly analyze large numbers of samples in a cost-effective and rapid manner. Results are easy to interpret with no need of deep bioinformatics knowledge and can be integrated with taxonomic information.

Pathobiology of Mycoplasma suis

Mycoplasma suis is an uncultivable bacterium lacking a cell wall that attaches to and may invade the red blood cells of pigs. M. suis infections occur worldwide and cause the pig industry serious economic losses due to the disease known as infectious anaemia of pigs or, historically, porcine eperythrozoonosis. Infectious anaemia of pigs is characterised predominantly by acute haemolytic or chronic anaemia, along with non-specific manifestations, such as growth retardation in feeder pigs and poor reproductive performance in sows. The fastidious nature of M. suis, as well as the lack of an in vitro cultivation system, has hampered the understanding of the biology and pathogenicity of this organism. Pathogenetic mechanisms of M. suis include direct destruction of red blood cells by adhesion, invasion, nutrient scavenging, immune-mediated lysis and eryptosis, as well as endothelial targeting. Recently published genome sequences, in combination with proteome analyses, have generated new insights into the pathogenicity of M. suis. The present review combines these data with the knowledge provided by experimental M. suis infections.

Quantitative PCR analysis of Mycoplasma suis shedding patterns during experimental infection

The uncultivable hemotrophic bacterium Mycoplasma suis causes infectious anemia in pigs worldwide. The mechanisms by which M. suis is transmitted from pig to pig are largely unknown. Thus, the present study aimed at investigating urine, feces, saliva, nasal and vaginal secrets as well as environmental samples for the presence of M. suis DNA to get insights into potential transmission routes. Seven pigs were experimentally infected with M. suis KI3806. Samples were taken for 8 days post infection (p.i.). A quantitative LightCycler msg1 PCR was used to detect and quantify M. suis. Shedding was found in saliva as well as nasal and vaginal secrets from day 6 p.i. on with a quantity of 3.4 × 10(2) to 2.7 × 10(5)M. suis/swab. In urine M. suis DNA could be detected in 100.0% of the samples from day 6 p.i. on with a quantity of 4.7 × 10(2) to 6.3 × 10(5)M. suis per mL. When shedding patterns were correlated to the median bacterial blood loads shedding was observed at loads of 2.0 × 10(9)-7.0 × 10(10)M. suis per mL blood. No M. suis DNA could be amplified from feces. Dust and water samples of the pig drinking troughs were positive for M. suis on days 2 and 6 post infection, air samples were M. suis-negative throughout the experiment. Our results indicate that blood independent direct transmission as well as indirect transmission via environmental contamination could play a role in the epidemiology of M. suis infections.

Clinical and haematological characterisation of Mycoplasma suis infections in splenectomised and non-splenectomised pigs

Mycoplasma suis causes infectious anaemia in pigs (IAP), which can manifest in various degrees of severity depending on the virulence and the host's susceptibility. As M. suis cannot be cultured in vitro experimental infections of splenectomised animals play an essential role for pathogenesis research. The aim of the present study was to characterise the course of experimental infection using the highly virulent and red blood cell (RBC-) invasive M. suis strain KI3806, to compare the experimental course in splenectomised and non-splenectomised pigs and to correlate clinical and haematological parameters with M. suis blood loads. All infected splenectomised pigs (n=7) were PCR-positive 2 days post infection (DPI) with maximum mean bacterial loads of 1.61 × 10(10)M. suis/mL on 8 DPI. They developed severe anaemia and massive hypoglycaemia by 8 DPI and had to be euthanised preterm (until 8 DPI) without seroconversion. The non-splenectomised pigs (n=7) became PCR-positive within 23 DPI and reached a maximum mean M. suis load of 1.64 × 10(5)M. suis/mL on 8 DPI. They developed mild anaemia, massive skin alterations with petechiae and haemorrhagic diathesis and seroconverted within 35 DPI. The study demonstrated that experimental infection of splenectomised pigs with the highly virulent M. suis strain KI3806 induces a fulminant course of infection. In contrast, M. suis strain KI3806 induces a mild course of disease in non-splenectomised pigs, which resembles the situation in naturally infected pigs. Therefore, these infection models are valuable for future pathogenesis studies on acute and chronic M. suis infections.

[Investigation of potential causes for the development of porcine ear necrosis: different study designs--comparable results?]

During the last years two studies for the investigation of the etiology of porcine ear necrosis were carried out at the Clinic for Swine of the University of Veterinary Medicine Vienna. In study 1, parameters, which are discussed in this context, were collected by veterinary practitioners by completing specially designed questionnaires in farms with symptoms of the porcine ear necrosis syndrome. In study 2, samples of piglets and feed were collected for laboratory analysis of the most important infectious agents as well as mycotoxins. In the present manuscript, the results of both projects were compared. Even if the selection criteria of both studies differed, the affected age class was comparable (5.5 to ten weeks of life in study 1 and six to ten weeks of life in study 2). The herd-specific prevalence of the porcine ear necrosis syndrome varied considerably with percentages between 2 and 10, respectively, to 100%. The evaluation of questionnaires in study 1 showed that 51% of the farms had problems with cannibalism. Particles of plant material, which were frequently seen on the histologic slides of study 2, could have got into the tissue by chewing the ears of the pen mates or cannibalism. Whereas in study 1 the negative effect of parameters as high pig density, suboptimal climate, missing enrichment material and bad quality of feed and water were considered, in study 2 all these factors were checked at sample collection and ruled out as precursor for cannibalism. In both studies bacterial agents proved to be a crucial co-factor for the expansion of the necroses to deeper tissue layers, whereas viral pathogens were classified less important. In both projects it was not possible to estimate the direct impact of infectious agents and mycotoxins as direct trigger of the necroses as well as their participation as co-factors or precursor in the sense of an immunosuppression or previous damage of blood vessels or tissue.

Mycoplasma suis infection results endothelial cell damage and activation: new insight into the cell tropism and pathogenicity of hemotrophic mycoplasma

Hemotrophic mycoplasmas (HM) are highly specialized red blood cell parasites that cause infectious anemia in a variety of mammals, including humans. To date, no in vitro cultivation systems for HM have been available, resulting in relatively little information about the pathogenesis of HM infection. In pigs, Mycoplasma suis-induced infectious anemia is associated with hemorrhagic diathesis, and coagulation dysfunction. However, intravasal coagulation and subsequent consumption coagulopathy can only partly explain the sequence of events leading to hemorrhagic diathesis manifesting as cyanosis, petechial bleeding, and ecchymosis, and to disseminated coagulation. The involvement of endothelial activation and damage in M. suis-associated pathogenesis was investigated using light and electron microscopy, immunohistochemistry, and cell sorting. M. suis interacted directly with endothelial cells in vitro and in vivo. Endothelial activation, widespread endothelial damage, and adherence of red blood cells to the endothelium were evident in M. suis-infected pigs. These alterations of the endothelium were accompanied by hemorrhage, intravascular coagulation, vascular occlusion, and massive morphological changes within the parenchyma. M. suis biofilm-like microcolonies formed on the surface of endothelial cells, and may represent a putative persistence mechanism of M. suis. In vitro analysis demonstrated that M. suis interacted with the endothelial cytoskeletal protein actin, and induced actin condensation and activation of endothelial cells, as determined by the up-regulation of ICAM, PECAM, E-selectin, and P-selectin. These findings demonstrate an additional cell tropism of HM for endothelial cells and suggest that M. suis interferes with the protective function of the endothelium, resulting in hemorrhagic diathesis.

[Subclinical alveolar echinococcosis in a dog initially showing clinical features of leptospirosis]

A 3.5-year-old male Labrador retriever dog showed a short history of illness characterized by vomiting, apathy, and fever. Ultrasonographically, large nodular liver masses of high echogenicity were noted in both left and right liver lobes. Cytological and bacteriological examinations revealed a neutrophilic hepatitis without detectable agents. During treatment with doxycycline a four-fold decrease of serum titers to Leptospira (L.) icterohaemorrhagiae and L. sejroe was detected in paired serum samples by use of the complement-fixation test. The dog remained without clinical signs and no significant biochemical changes were recorded. However, ultrasonsographic examinations showed a progression of the hepatic lesions, presenting now as nodular parts with high echogenicity and cavernous parts with lower echogenicity. Diagnostic laparotomy was performed and the dog was euthanized due to severity of hepatic lesions. Histopathologically, a severe chronic granulomatous hepatitis with numerous parasitic structures was diagnosed. Morphology of the parasitic structures was comparable to the metacestode stage of Echinococcus multilocularis.

Porcine ear necrosis syndrome: a preliminary investigation of putative infectious agents in piglets and mycotoxins in feed

The aim of this study was to identify the causative factors of porcine ear necrosis syndrome (PENS) in 72 pigs, 5.5-10 weeks in age housed on nine farms. Biopsy samples of ear pinnae were collected from all piglets for bacteriology, histopathology and in situ hybridization for porcine circovirus type 2 (PCV2). At the same time, serum samples were taken for serological analysis and viral PCR, and feed was sampled for mycotoxin analysis. The initial lesion of PENS seemed to be a focal epidermal necrosis. Streptococci were isolated from 44 and staphylococci from 36 pinnae. PCV2 could not be detected by in situ hybridization or qPCR. Seven piglets were positive for porcine reproductive and respiratory syndrome virus, and one for Mycoplasma suis. One piglet had antibodies against Sarcoptes scabiei var. suis. No infectious agents were found in 15 samples. Positive virology and parasitology were often found alongside positive bacteriology. Deoxynivalenol, zearalenone and ergot alkaloids were detected in feed. The findings suggest that PENS is multifactorial in origin and that although infectious agents can be involved in the development of the syndrome they are not the exclusive triggering factor.

Hemotrophic mycoplasmas induce programmed cell death in red blood cells

Hemotrophic mycoplasmas (HM) are uncultivable bacteria found on and in the red blood cells (RBCs). The main clinical sign of HM infections is the hemolytic anemia. However, anemia-inducing pathogenesis has not been totally clarified. In this work we used the splenectomized pig as animal model and Mycoplasma suis as a representative for hemotrophic mycoplasmas to study anemia pathogenesis. Eryptosis, i.e. programmed cell death of RBCs, is characterized by cell shrinkage, microvesiculation and phosphatidylserine (PS) exposure on the outer membrane. The eryptosis occurrence and its influence on anemia pathogenesis was observed over the time-course of M. suis infections in pigs using 3 M. suis isolates of differing virulence. All 3 isolates induced eryptosis, but with different characteristics. The occurrence of eryptosis could as well be confirmed in vitro: serum and plasma of an acutely ill pig induced PS exposure on erythrocytes drawn from healthy pigs. Since M. suis is able to induce eryptotic processes it is concluded that eryptosis is one anemia-inducing factor during M. suis infections and, therefore, plays a significant role in the pathogenesis of infectious anemia due to HM infection.

Detection of Candidatus Mycoplasma haemobos in cattle with anaemia

Haemotrophic mycoplasmas are unculturable eperythrocytic pathogens that are found in a wide range of domestic and wild animals. In this study an outbreak of haemotrophic mycoplasmosis in cattle herds in Northern Germany is reported. Affected animals exhibited anaemia and depression and infection was confirmed following microscopic examination of blood smears and on PCR. Sequence analysis indicated that in addition to infection with Mycoplasma wenyonii, animals were infected with a novel bovine haemotrophic mycoplasma Candidatus Mycoplasma haemobos.

[Porcine eperythrozoonosis: from Eperythrozoon suis to Mycoplasma suis]

Mycoplasma suis (formerly known as Eperythrozoon suis ) is the most prevalent agent causing haemolytic anaemia in swine. The disease is also known as porcine eperythrozoonosis. M.suis is a small, pleomorphic bacteria parasitizing porcine erythrocytes. To date, no in vitro cultivation system for M.suis has been established and, therefore, our knowledge about the characteristics of M.suis and the pathogenesis of porcine eperythrozoonosis is rather limited. M.suis can cause acute disease, but the major significance of M.suis infections lies in the fact that M.suis can establish chronic and persistent infections leading to a higher susceptibility to other infections, especially of the respiratory and digestive tracts. The present article summarizes the current knowledge of the pathogen, the clinical signs and pathogenesis, diagnostic as well as therapy and prophylaxis.

Inorganic pyrophosphatase in uncultivable hemotrophic mycoplasmas: identification and properties of the enzyme from Mycoplasma suis

Background

Mycoplasma suis belongs to a group of highly specialized hemotrophic bacteria that attach to the surface of host erythrocytes. Hemotrophic mycoplasmas are uncultivable and the genomes are not sequenced so far. Therefore, there is a need for the clarification of essential metabolic pathways which could be crucial barriers for the establishment of an in vitro cultivation system for these veterinary significant bacteria.

Inorganic pyrophosphatases (PPase) are important enzymes that catalyze the hydrolysis of inorganic pyrophosphate PP_i to inorganic phosphate P_i. PPases are essential and ubiquitous metal-dependent enzymes providing a thermodynamic pull for many biosynthetic reactions. Here, we describe the identification, recombinant production and characterization of the soluble (s)PPase of Mycoplasma suis.

Results

Screening of genomic M. suis libraries was used to identify a gene encoding the M. suis inorganic pyrophosphatase (sPPase). The M. suis sPPase consists of 164 amino acids with a molecular mass of 20 kDa. The highest identity of 63.7% was found to the M. penetrans sPPase. The typical 13 active site residues as well as the cation binding signature could be also identified in the M. suis sPPase. The activity of the M. suis enzyme was strongly dependent on Mg²⁺ and significantly lower in the presence of Mn²⁺ and Zn²⁺. Addition of Ca²⁺ and EDTA inhibited the M. suis sPPase activity. These characteristics confirmed the affiliation of the M. suis PPase to family I soluble PPases. The highest activity was determined at pH 9.0. In M. suis the sPPase builds tetramers of 80 kDa which were detected by convalescent sera from experimentally M. suis infected pigs.

Conclusion

The identification and characterization of the sPPase of M. suis is an additional step towards the clarification of the metabolism of hemotrophic mycoplasmas and, thus, important for the establishment of an in vitro cultivation system. As an antigenic and conserved protein the M. suis sPPase could in future be further analyzed as a diagnostic antigen.

Antibodies to actin in autoimmune haemolytic anaemia

Background

In autoimmune haemolytic anaemia (AIHA), autoreactive antibodies directed against red blood cells are up-regulated, leading to erythrocyte death. Mycoplasma suis infections in pigs induce AIHA of both the warm and cold types. The aim of this study was to identify the target autoantigens of warm autoreactive IgG antibodies. Sera from experimentally M. suis-infected pigs were screened for autoreactivity.

Results

Actin-reactive antibodies were found in the sera of 95% of all animals tested. The reactivity was species-specific, i.e. reactivity with porcine actin was significantly higher than with rabbit actin. Sera of animals previously immunised with the M. suis adhesion protein MSG1 showed reactivity with actin prior to infection with M. suis indicating that molecular mimicry is involved in the specific autoreactive mechanism. A potentially cross-reactive epitope was detected.

Conclusions

This is the first report of autoreactive anti-actin antibodies involved in the pathogenesis of autoimmune haemolytic anaemia.

Detection of Candidatus Mycoplasma haemobos in cattle with anaemia

Haemotrophic mycoplasmas are unculturable eperythrocytic pathogens that are found in a wide range of domestic and wild animals. In this study an outbreak of haemotrophic mycoplasmosis in cattle herds in Northern Germany is reported. Affected animals exhibited anaemia and depression and infection was confirmed following microscopic examination of blood smears and on PCR. Sequence analysis indicated that in addition to infection with Mycoplasma wenyonii, animals were infected with a novel bovine haemotrophic mycoplasma Candidatus Mycoplasma haemobos.

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P<0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.

Vaccination with the Mycoplasma suis recombinant adhesion protein MSG1 elicits a strong immune response but fails to induce protection in pigs

Mycoplasma suis is the unculturable pathogen of porcine infectious anemia. The study was aimed to determine the immunogenicity and protective efficacy of MSG1, an immunodominant adhesin of M. suis as the first vaccine candidate against M. suis. The results demonstrated that recombinant MSG1 and Escherichia coli transformants expressing MSG1 (E. coli_MSG1) induced a strong humoral and cellular immunity against M. suis. The induced antibodies were found to be functionally active as confirmed by an in vitro adhesion inhibition assay. Both, IgG1 and IgG2 antibodies were induced, but E. coli_MSG1 immune response was characterized by a significantly higher IgG1 antibody production. Both vaccine candidates failed to protect against M. suis challenge. However, E. coli_MSG1 vaccination has a considerable effect on the severity of the disease as shown by higher post-challenge hemoglobin and hematocrit values in comparison to control groups. This indicated that a high IgG1 antibody titer is negatively connected with severity of M. suis-induced anemia. Furthermore, the induction of monospecific anti-MSG1 antibodies by both vaccine candidates clearly allows for the differentiation between infected and vaccinated animals (DIVA principle). Overall, the importance of MSG1 as potential vaccine candidate remains to be established. Future studies will evaluate the conditions (i.e. adjuvant, vaccination scheme, and application route) to optimize the effects of E. coli_MSG1 vaccines.

A DNA microarray facilitates the diagnosis of Bacillus anthracis in environmental samples

AIMS

In order to improve the diagnosis of Bacillus anthracis in environmental samples, we established a DNA microarray based on the ArrayTube technology of Clondiag.

METHODS AND RESULTS

Total DNA of a bacterial colony is randomly biotinylated and hybridized to the array. The probes on the array target the virulence genes, the genomic marker gene rpoB, as well as the selective 16S rDNA sequence regions of B. anthracis, of the Bacillus cereus group and of Bacillus subtilis. Eight B. anthracis reference strains were tested and correctly identified. Among the analysed environmental Bacillus isolates, no virulent B. anthracis strain was detected.

CONCLUSIONS

This array clearly differentiates B. anthracis from members of the B. cereus group and other Bacillus species in environmental samples by chromosomal (rpoB) and plasmid markers. Additionally, recognition of B. cereus strains harbouring the toxin genes or atypical B. anthracis strains that have lost the virulence plasmids is feasible.

SIGNIFICANCE AND IMPACT OF THE STUDY

The array is applicable to the complex diagnostics for B. anthracis detection in environmental samples. Because of low costs, high security and easy handling, the microarray is applicable to routine diagnostics.

In vivo transmission studies of 'Candidatus Mycoplasma turicensis' in the domestic cat

The natural transmission routes of the three feline haemotropic mycoplasmas – Mycoplasma haemofelis, ‘Candidatus Mycoplasma haemominutum’, and ‘Candidatus Mycoplasma turicensis’ (CMt) – are largely unknown. Since CMt has been detected in the saliva of infected cats using PCR, we hypothesised that direct transmission via social or aggressive contact may occur. The aim of this study was to evaluate this transmission route. CMt-positive saliva and blood samples were obtained from three prednisolone-treated specific pathogen-free (SPF) cats that were infected intraperitoneally with CMt. Five SPF cats were inoculated with CMt-positive saliva or blood subcutaneously to mimic cat bites, and five cats were inoculated orally with blood or oronasally with saliva to mimic social contact. Blood samples were monitored for CMt infection using quantitative real-time PCR and for seroconversion using a novel western blot assay. Neither oronasal nor subcutaneous inoculation with CMt-positive saliva led to CMt infection in the recipient cats, as determined by PCR, independent of prior prednisolone treatment. However, when blood containing the same CMt dose was given subcutaneously, 4 of the 5 cats became PCR-positive, while none of the 5 cats inoculated orally with up to 500 μL of CMt-positive blood became PCR-positive. Subsequently, the latter cats were successfully subcutaneously infected with blood. All 13 CMt-exposed cats seroconverted. In conclusion, CMt transmission by social contact seems less likely than transmission by aggressive interaction. The latter transmission may occur if the recipient cat is exposed to blood from an infected cat.

Haemotrophic mycoplasmas: recent advances in Mycoplasma suis

Haemotrophic mycoplasmas (haemoplasmas) are uncultivable, small epicellular, cell wall less, tetracycline-sensitive bacteria that attach to the surface of host erythrocytes. Today, haemotrophic mycoplasmas are found in a large number of animals, with Mycoplasma suis being the porcine pathogen. Haemoplasmas can cause infections which are clinically marked, either by an overt life-threatening haemolytic anaemia or a mild chronic anaemia, by illthrift, infertility, and immune suppression. The life cycle of haemoplasmas on the surface of nucleus-less red blood cells is unique for mycoplasma and therefore, it is evident that these haemotrophic pathogens must have features that allow them to colonise and replicate on red blood cells. However, the mechanisms of adhesion and replication of M. suis on erythrocytes, for instance, as well as the significance of metabolic interchanges between the agent and the target cells, are completely unknown to date. Far from having gained clear insight into the clinical significance of the haemoplasmas, our knowledge about the physiology, genetics, and host-pathogen interaction of this novel group of bacteria within the Mollicutes order is rather limited. This can be explained primarily by the unculturability of these bacteria. The enormous advances in molecular biology witnessed in recent years have had a major impact on several areas of biological sciences, i.e. the fields of modern medical bacteriology and infectious diseases. This review describes progress made in research of the pathobiology of M. suis these past few years.

First identification and functional characterization of an immunogenic protein in unculturable haemotrophic Mycoplasmas (Mycoplasma suis HspA1)

The antigenic structures of the haemotrophic Mycoplasma suis, an epicellular parasite of porcine erythrocytes, are largely unknown due to its unculturability. In this study, serological proteome and mass spectrometry analyses allowed the characterization of M. suis proteins targeted by the porcine antibody response: two proteins with characteristics of heat shock proteins, two proteins with characteristics of glycolytic enzymes, a RNA helicase- and an actin-like protein. The DnaK-like protein of M. suis (HspA1) was further analysed genetically and functionally. Its encoding gene (M. suis a1 gene) is 1.830 bp in size and corresponds to a 67 kDa protein. Immunoelectron microscopy verified the surface accessibility of HspA1 in M. suis. Recombinant HspA1 expressed in Escherichia coli demonstrated ATPase activity and antigenicity in experimentally infected pigs. In conclusion, this first identification and recombinant expression of an antigenic protein of M. suis provides the basis for the development of vaccines and new in vitro diagnostic assays.

First LightCycler real-time PCR assay for the quantitative detection of Mycoplasma suis in clinical samples

Mycoplasma suis cannot be cultivated in vitro. Therefore, PCR-based methods are irreplaceable for the diagnosis of M. suis infections especially when clinical symptoms are not evident. Currently, no easy and reliable method allowing the quantitative detection of M. suis is available. This report describes the development of a quantitative LightCycler PCR assay based on the msg1 gene of M. suis (LC MSG1 PCR). No PCR signals were obtained with closely related haemotrophic and non-haemotrophic mycoplasmas, with other bacteria, and with M. suis-free blood and tissue arguing for a high analytical specificity. Test sensitivity was found to be 100%, and test specificity 96.7%. To test the diagnostic suitability of the LC MSG1 PCR, 25 pigs with clinical porcine eperythrozoonosis and 25 healthy pigs were investigated. All ill pigs revealed a positive real-time PCR result whereas only one healthy pig was detected to be M. suis-infected. M. suis was quantitatively detected in 19 blood specimens of 100 sows from Switzerland and in 17 of 160 post-weaning piglets from Germany. In conclusion, this new LC MSG1 PCR assay represents a powerful tool for the improvement of the current M. suis diagnosis and for prevalence and pathogenesis studies.

MSG1, a surface-localised protein of Mycoplasma suis is involved in the adhesion to erythrocytes

Mycoplasma suis is a member of the group of uncultivable haemoplasmas which colonise erythrocytes of a wide range of vertebrates. Adhesion to erythrocytes is the crucial step in the unique haemoplasma life cycle. Due to the lack of a cultivation system, no adhesion structures have been identified so far. In order to determine potential adhesion molecules of M. suis, we screened genomic M. suis libraries. The protein MSG1 with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) similarity was identified. The encoding gene msg1 is 1011bp in size. The overall homology of the deduced amino acid sequence to GAPDHs of other pathogenic mycoplasmas ranged from 52.6% to 54.5%. Recombinant MSG1 expressed in Escherichia coli exhibited GAPDH activity. Immunoblot and immunoelectron microscopy analyses using antibodies against rMSG1 verified the membrane and surface localisation of native MSG1 in M. suis. Furthermore, we showed that rMSG1 binds to erythrocyte lysate in a dose-dependent manner. E. coli transformants which express MSG1 on their surface acquire the ability to adhere to porcine erythrocytes. This adhesion could be specifically and significantly inhibited by rMSG1 and antibodies to MSG1. In conclusion, our studies indicate that the membrane-associated MSG1 represents the first putative adhesion protein identified in the group of haemoplasmas.

Prevalence of chlamydiae in semen and genital tracts of bulls, rams and bucks

Chlamydiae infect male genital organs of ruminants. However, little is known about their prevalence. Hence, we investigated fresh and cryopreserved semen (bulls: n=304; rams: n=78; bucks: n=44) by polymerase chain reaction (PCR), as well as genital organs (bulls: n=13; rams: n=10; bucks: n=6) by immunohistochemistry (IHC) and PCR. Sera from bulls (n=104) and small ruminants (n=61) were tested by LPS and rMOMP (recombinant major outer membrane protein) ELISA and competitive ELISA (cELISA), respectively. Three PCR assays were compared in this study for detection of chlamydial DNA in semen: 16S rRNA, IGS-S (intergenic spacer 16S/23S-short), and IGS-L (intergenic spacer 16S/23S-long) PCRs. PCR sensitivity and inhibitory effects were determined by spiking semen with Chlamydophila (Cp.) abortus DNA. In bull semen, detection limits of the 16S, IGS-S and IGS-L PCRs were 10, 10, 100 templates, respectively. However, PCR sensitivity was reduced in ram and buck semen suggesting the presence of potential PCR inhibitors. Of 304 bull semen samples, the 16S PCR revealed DNA of chlamydiae in 20 samples (6.6%), including Cp. abortus (n=2), Cp. psittaci (n=1), Chlamydia suis (n=2), and Chlamydia-like organisms (n=15). In rams, one semen sample was positive for Chlamydia-like organism. All investigated male genital organs were negative for Chlamydia. Serology revealed 47.1% (49/104) positive bulls by LPS ELISA. Of these, 30 samples were positive by rMOMP ELISA, predominantly for Cp. pecorum. In small ruminants, cELISA displayed 34.8% (16/46) and 60% (9/15) positivity for Cp. abortus in rams and bucks, respectively. There was no correlation between serology and PCR of semen. The presence of chlamydiae in semen suggests the possibility of venereal transmission, although risk may be low in Switzerland.

[Significance of haemotrophic mycoplasmas in veterinary medicine with particular regard to the Mycoplasma suis infection in swine]

Phylogenetic investigations led to the definition of a new group of bacteria called haemotrophic mycoplasmas (haemoplasmas). The life cycle of said globally spread bacteria is dependent on their intimate contact with their host erythrocytes. Illnesses showing symptoms of a haemolytic anaemia are usually found in cats and swine. Haemoplasmas are small pleomorphic bacteria (0.3-3 microm) with a very small genome (745-1245 kbp). To date there is very limited knowledge on their biology and the host-bacteria-interactions (immune response, pathogenesis) since these bacteria are yet not culturable. Applying modern molecular biological techniques we succeeded during the last few years in gaining new facts on the antigen structure of M.suis as well as on the immunology and pathogenesis of the porcine eperythrozoonosis. Thus we detected three main antigens two of which we expressed recombinant in our laboratory. These surface-exposed antigens serve as a basis for establishing serologic assays, and are vaccine candidates, too. Preliminary studies allowed us to find the function of an adhesin of M. suis for one of the two proteins.

Mycoplasma suis antigens recognized during humoral immune response in experimentally infected pigs

Today, serodiagnostic tests for Mycoplasma suis infections in pigs have low accuracies. The development of novel serodiagnostic strategies requires a detailed analysis of the humoral immune response elicited by M. suis and, in particular, the identification of antigenic proteins of the agent. For this study, indirect enzyme-linked immunosorbent assay (ELISA) and immunoblot analyses were performed using pre- and sequential postinoculation sera from M. suis-infected and mock-infected control pigs. M. suis purified from porcine blood served as the antigen. Eight M. suis-specific antigens (p33, p40, p45, p57, p61, p70, p73, and p83) were identified as targets of the immunoglobulin G (IgG) antibody response during experimental infection, with p40, p45, and p70 being the preferentially recognized M. suis antigens. Besides the M. suis-specific antigens, porcine immunoglobulins were identified in blood-derived M. suis preparations. By immunoglobulin depletion, the specificity of the M. suis antigen for use in indirect ELISA was significantly improved. M. suis-specific Western blot and ELISA reactions were observed in all infected pigs by 14 days postinfection at the latest and until week 14, the end of the experiments. During acute clinical attacks of eperythrozoonosis, a derailment of the antibody response, determined by decreases in both the M. suis net ELISA values and the numbers of M. suis-specific immunoblot bands, was accompanied by peaking levels of autoreactive IgG antibodies. In conclusion, the M. suis-specific antigens found to stimulate specific IgG antibodies are potentially useful for the development of novel serodiagnostic tests.

Development and evaluation of a Mycobacterium avium subspecies paratuberculosis (MAP) specific multiplex PCR assay

There are specificity questions inherent in most of the current PCR systems that amplify the MAP IS900 sequence as an indicator for Mycobacterium avium subspecies paratuberculosis (MAP) presence due to false positives associated with IS900-like sequences that exists in other Mycobacterium species besides MAP. We developed a multiplex PCR system designed to enhance specificity for MAP detection in a single PCR reaction. This PCR assay co-amplifies the mycobacterium species 16S rRNA gene, MAP IS900 and f57 sequences. The assay incorporates an internal PCR amplification control (IC) template system enabling PCR amplification conditions to be assessed in each reaction. The assay's specificity was confirmed by testing 10 isolates of MAP and 59 isolates of other bacterial species. In parallel we also applied on the same samples, one of the established nested PCR systems that targets only the IS900 sequence. The multiplex PCR assay was highly specific for MAP, the nested PCR system was also positive with several other mycobacterium species. In this context, we report for the first time false positive IS900 PCR signals in Mycobacterium chelonae, Mycobacterium terrae and Mycobacterium xenopi strains associated with one of the established PCR systems widely used for MAP detection. Finally, the potential application of this multiplex PCR system in milk analysis is demonstrated through analysis of raw milk samples artificially contaminated with MAP.

Detection of Mycobacterium avium subspecies paratuberculosis in Swiss dairy cattle by culture and serology

Faecal samples from 186 dairy cows representing ten commercial dairy herds with sporadic clinical paratuberculosis (group A), and from 100 dairy cows from herds without a history of paratuberculosis (group B) were cultured for Mycobacterium avium subspecies paratuberculosis (MAP). Two different decontamination methods, a NaOH/oxalic acid method and treatment with 0.75% hexadecylpyridinium chloride (HPC) were performed prior to inoculation of Loewenstein-Jensen agar slants with and without mycobactin. Cultures were incubated for 16 weeks. Acid-fast staining bacteria were identified as MAP on the basis of mycobactin dependency and by PCR-RFLP analysis of the IS 1311-insertion element of M. avium. MAP was grown from 15 out of 186 group A animals (8.1%) whereas faecal culture for MAP was consistently negative in group B. The growth rate of MAP was significantly higher (8.1% vs. 1.6%) and the contamination rate of cultures was significantly lower (17.6% vs. 21.5%) in faecal samples decontaminated with NaOH/oxalic acid than with HPC-treated faecal samples (p<0.01, McNemar's test). Atypical mycobacteria which were grown from 46.8% of NaOH/oxalic acid treated specimens were not obtained from any of the HPC-treated samples. A commercial ELISA with MAP-lipoarabinomannan as the antigen was used to detect MAP-antibodies in unabsorbed sera from all animals. The percentage of ELISA-positive cows was 16.8%. Overall agreement between antibody detection and MAP-positive faecal culture was 15.4%.