Konstruktion und Analyse einer funktionalen Renormierungsgruppengleichung für Gravitation im Einstein-Cartan-Zugang

Während das Standardmodell der Elementarteilchenphysik eine konsistente, renormierbare Quantenfeldtheorie dreier der vier bekannten Wechselwirkungen darstellt, bleibt die Quantisierung der Gravitation ein bislang ungelöstes Problem. In den letzten Jahren haben sich jedoch Hinweise ergeben, nach denen metrische Gravitation asymptotisch sicher ist. Das bedeutet, daß sich auch für diese Wechselwirkung eine Quantenfeldtheorie konstruieren läßt. Diese ist dann in einem verallgemeinerten Sinne renormierbar, der nicht mehr explizit Bezug auf die Störungstheorie nimmt. Zudem sagt dieser Zugang, der auf der Wilsonschen Renormierungsgruppe beruht, die korrekte mikroskopische Wirkung der Theorie voraus. Klassisch ist metrische Gravitation auf dem Niveau der Vakuumfeldgleichungen äquivalent zur Einstein-Cartan-Theorie, die das Vielbein und den Spinzusammenhang als fundamentale Variablen verwendet. Diese Theorie besitzt allerdings mehr Freiheitsgrade, eine größere Eichgruppe, und die zugrundeliegende Wirkung ist von erster Ordnung. Alle diese Eigenschaften erschweren eine zur metrischen Gravitation analoge Behandlung.rnrnIm Rahmen dieser Arbeit wird eine dreidimensionale Trunkierung von der Art einer verallgemeinerten Hilbert-Palatini-Wirkung untersucht, die neben dem Laufen der Newton-Konstante und der kosmologischen Konstante auch die Renormierung des Immirzi-Parameters erfaßt. Trotz der angedeuteten Schwierigkeiten war es möglich, das Spektrum des freien Hilbert-Palatini-Propagators analytisch zu berechnen. Auf dessen Grundlage wird eine Flußgleichung vom Propertime-Typ konstruiert. Zudem werden geeignete Eichbedingungen gewählt und detailliert analysiert. Dabei macht die Struktur der Eichgruppe eine Kovariantisierung der Eichtransformationen erforderlich. Der resultierende Fluß wird für verschiedene Regularisierungsschemata und Eichparameter untersucht. Dies liefert auch im Einstein-Cartan-Zugang berzeugende Hinweise auf asymptotische Sicherheit und damit auf die mögliche Existenz einer mathematisch konsistenten und prädiktiven fundamentalen Quantentheorie der Gravitation. Insbesondere findet man ein Paar nicht-Gaußscher Fixpunkte, das Anti-Screening aufweist. An diesen sind die Newton-Konstante und die kosmologische Konstante jeweils relevante Kopplungen, wohingegen der Immirzi-Parameter an einem Fixpunkt irrelevant und an dem anderen relevant ist. Zudem ist die Beta-Funktion des Immirzi-Parameters von bemerkenswert einfacher Form. Die Resultate sind robust gegenüber Variationen des Regularisierungsschemas. Allerdings sollten zukünftige Untersuchungen die bestehenden Eichabhängigkeiten reduzieren.

Laboruntersuchungen zur Aufnahme atmosphärischer Spurengase auf statischen und wachsenden Eisoberflächen

Der erste Teil dieser Arbeit befaßt sich mit der Adsorption von H2O2 auf nicht-wachsendem Eis. Die Experimente wurden in einem zylindrischen Strömungsreaktor mit massenspektrometrischer Detektion (Elektronenstoß und chemische Ionisation) ausgeführt. Die Daten einer zuvor bereits am Max Planck-Institut für Chemie (Mainz) von Dr. N. Pouvesle ausgeführten Laborstudie zur Adsorption von H2O2 auf Eis bei 203 bis 233 K wurden im Rahmen der vorliegenden Arbeit durch Coadsorptionsexperimente mit Ameisensäure und Verwendung unterschiedlicher Ionisationsmodi validiert. Zusätzlich wurde eine Korrelation der Langmuir-Konstanten und der Kondensationsenthalpie für H2O2 und andere Moleküle durchgeführt, welche die Ergebnisse der MPI-Studie ebenfalls stützt. Die Ergebnisse belegen, daß die Aufnahme von H2O2 in Eiswolken um bis zu 3 Größenordnungen höher ist als bisher angenommen. Anhand dieser Erkenntnisse wurde die atmosphärische Relevanz der Adsorption von H2O2 auf Eis in der oberen Troposphäre neu bewertet. Der zweite Teil der Arbeit widmet sich der Aufnahme verschiedener organischer Verbindungen (Ethanol, 1-Butanol, Ameisensäure, Trifluoressigsäure) und HCl auf Eis während dieses wächst. Der hierfür erstmals in Betrieb genommene Eiswachstumsreaktor wurde zunächst durch Messung der Adsorptionsisotherme von Ethanol und Butanol und Berechnung der Adsorptionsenthalpien aus experimentellen Daten evaluiert. Im Anschluß wurden die Ergebnisse der Wachstumsexperimente der oben aufgeführten Verbindungen vorgestellt, wobei jedoch nur Trifluoressigsäure und HCl eine erhöhte Aufnahme zeigen. Der Aufnahmekoeffizient g_trapp von HCl wurde bei Temperaturen zwischen 194,3 und 228 K und HCl-Gasphasenkonzentrationen von 6,4x10^9 bis 2,2x10^11 cm^-3 gemessen und war unter den untersuchten Bedingungen proportional zu Eiswachstumsgeschwindigkeit x und antikorreliert zum Bedeckungsgrad theta und der Eistemperatur T. Der vom wachsenden Eis aufgenommene Fluß von HCl-Molekülen war positiv mit x und negativ mit T korreliert, während theta keinen Einfluß hatte. Anhand der erzielten Resultate wurde eine Parametrisierung für g_trapp entwickelt, mit der die Aufnahme künftig in Abhängigkeit von x, T und [HCl]_gas leicht berechnet werden kann, beispielsweise in globalen Modellsimulation der troposphärischen Chemie. Abschließend wurden die Ergebnisse mit einem von Kärcher et al. (2009) entwickelten semiempirischen Modell verglichen und für die offenen Parameter des Modells wurden aus den experimentellen Daten ebenfalls Parametrisierungen entwickelt.

Mesenchymal Stromal Cells (MSCs) and induced Plutipotent Stem Cells (iPSCs) in Domestic Animals: Characterization and Differentiation Potential

Derivation of stem cell lines from domesticated animals has been of great interest as it benefits translational medicine, clinical applications to improve human and animal health and biotechnology. The main types of stem cells studied are Embryonic Stem Cells (ESCs), induced Pluripotent Stem Cells (iPSCs) and Mesenchymal Stem/Stromal Cells (MSCs). This thesis had two main aims: (I) The isolation of bovine MSCs from amniotic fluid (AF) at different trimesters of pregnancy and their characterization to study pluripotency markers expression. Stemness markers were studied also in MSCs isolated from equine AF, Wharton’s jelly (WJ) and umbilical cord blood (UCB) as continuation of the characterization of these cells previously performed by our research group; (II) The establishment and characterization of iPSCs lines in two attractive large animal models for biomedical and biotechnology research such as the bovine and the swine, and the differentiation into the myogenic lineage of porcine iPSCs. It was observed that foetal tissues in domestic animals such as the bovine and the horse represent a source of MSCs able to differentiate into the mesodermal lineage but they do not proliferate indefinitely and they lack the expression of many pluripotency markers, making them an interesting source of cells for regenerative medicine, but not the best candidate to elucidate pluripotency networks. The protocol used to induce pluripotency in bovine fibroblasts did not work, as well as the chemical induction of pluripotency in porcine fibroblasts, while the reprogramming protocol used for porcine iPSCs was successful and the line generated was amenable to being differentiated into the myogenic lineage, demonstrating that they could be addressed into a desired lineage by genetic modification and appropriated culture conditions. Only a few cell types have been differentiated from domestic animal iPSCs to date, so the development of a reliable directed-differentiation protocol represents a very important result.

The porcine animal model goes through the 3Rs: development of in vitro and ex vivo system to study vascular biology

Since the publication of the book of Russell and Burch in 1959, scientific research has never stopped improving itself with regard to the important issue of animal experimentation. The European Directive 2010/63/EU “On the protection of animals used for scientific purposes” focuses mainly on the animal welfare, fixing the Russell and Burch’s 3Rs principles as the foundations of the document. In particular, the legislator clearly states the responsibility of the scientific community to improve the number of alternative methods to animal experimentation. The swine is considered a species of relevant interest for translational research and medicine due to its biological similarities with humans. The surgical community has, in fact, recognized the swine as an excellent model replicating the human cardiovascular system. There have been several wild-type and transgenic porcine models which were produced for biomedicine and translational research. Among these, the cardiovascular ones are the most represented. The continuous involvement of the porcine animal model in the biomedical research, as the continuous advances achieved using swine in translational medicine, support the need for alternative methods to animal experimentation involving pigs. The main purpose of the present work was to develop and characterize novel porcine alternative methods for cardiovascular translational biology/medicine. The work was mainly based on two different models: the first consisted in an ex vivo culture of porcine aortic cylinders and the second consisted in an in vitro culture of porcine aortic derived progenitor cells. Both the models were properly characterized and results indicated that they could be useful to the study of vascular biology. Nevertheless, both the models aim to reduce the use of experimental animals and to refine animal based-trials. In conclusion, the present research aims to be a small, but significant, contribution to the important and necessary field of study of alternative methods to animal experimentation.

Caratterizzazione genomica di virus influenzali suini in Italia mediante next generation sequencing

I sottotipi H1N1, H1N2 e H3N2 di influenza A virus sono largamente diffusi nella popolazione suina di tutto il mondo. Nel presente lavoro è stato sviluppato un protocollo di sequenziamento di c.d. nuova generazione, su piattaforma Ion Torrent PGM, idoneo per l’analisi di tutti i virus influenzali suini (SIV). Per valutare l’evoluzione molecolare dei SIV italiani, sono stati sequenziati ed analizzati mediante analisi genomica e filogenetica un totale di sessantadue ceppi di SIV appartenenti ai sottotipi H1N1, H1N2 e H3N2, isolati in Italia dal 1998 al 2014. Sono stati evidenziati in sei campioni due fenomeni di riassortimento: tutti i SIV H1N2 esaminati presentavano una neuraminidasi di derivazione umana, diversa da quella dei SIV H1N2 circolanti in Europa, inoltre l’emoagglutinina (HA) di due isolati H1N2 era originata dal riassortimento con un SIV H1N1 avian-like. L’analisi molecolare dell’HA ha permesso di rivelare un’inserzione di due amminoacidi in quattro SIV H1N1 pandemici e una delezione di due aminoacidi in quattro SIV H1N2, entrambe a livello del sito di legame con il recettore cellulare. E’ stata inoltre evidenziata un’elevata omologia di un SIV H1N1 con ceppi europei isolati negli anni ’80, suggerendo la possibile origine vaccinale di questo virus. E’ stato possibile, in aggiunta, applicare il nuovo protocollo sviluppato per sequenziare un virus influenzale aviare altamente patogeno trasmesso all’uomo, direttamente da campione biologico. La diversità genetica nei SIV esaminati in questo studio conferma l’importanza di un continuo monitoraggio della costellazione genomica dei virus influenzali nella popolazione suina.

Isolierung von Essigsäure-, Propionsäure- und Buttersäure-bildenden Bakterien aus Biogasanlagen

In der vorliegenden Arbeit wurden Essigsäure-, Propionsäure und Buttersäure-bildende Bakterien aus einer thermophilen und drei mesophilen Biogasanlagen sowie aus zwei Hochdruck-Biogas-Laborfermentern isoliert. Die Fermenter waren mit dem nachwachsenden Rohstoff Maissilage, teilweise mit Rinder- oder Schweinegülle und weiteren festen Inputstoffen gefüttert. Für die Isolierung von Säure-bildenden Bakterien wurde ein Mineralsalzmedium verwendet, welchem als Kohlenstoffquelle Na-DL-Laktat, Succinat, Ethanol, Glycerin, Glucose oder eine Aminosäuremischung (Alanin, Serin, Threonin, Glutaminsäure, Methionin und Cystein) hinzugefügt wurde. Hierbei handelt es sich um Substrate, welche beim anaeroben Abbau während der Hydrolyse oder der primären Gärung entstehen können. Die erhaltenen Isolate waren in der Lage, aus diesen Substraten Essigsäure, Propionsäure oder Buttersäure zu bilden. Insgesamt wurden aus den beprobten Anlagen 49 Isolate gewonnen, welche zu den Phyla Firmicutes, Tenericutes oder Thermotogae gehörten. Mit Hilfe von 16S rDNA-Sequenzen konnten die meisten Isolate als Clostridium sporosphaeroides, Defluviitoga tunisiensis und Dendrosporobacter sp. identifiziert werden. Die Bildung von Essigsäure, Propionsäure oder Buttersäure wurde in Kulturen von Isolaten festgestellt, welche als folgende Arten identifiziert wurden: Bacillus thermoamylovorans, Clostridium aminovalericum, Clostridium cochlearium/Clostridium tetani, Clostridium sporosphaeroides, Dendrosporobacter sp., Proteiniborus sp., Selenomonas bovis und Tepidanaerobacter sp. Zwei Isolate, verwandt mit Thermoanaerobacterium thermosaccharolyticum, konnten Buttersäure und Milchsäure bilden. In Kulturen von Defluviitoga tunisiensis wurde Essigsäurebildung festgestellt. Ein Vergleich der 16S rDNA-Sequenzen mit Datenbanken und die Ergebnisse der PCR-Amplifikationen mit Isolat-spezifischen Primerpaaren ergaben zusätzlich Hinweise, dass es sich bei einigen Isolaten um neue Arten handeln könnte (z. B. Stamm Tepidanaerobacter sp. AS34, Stamm Proteiniborus sp. ASG1.4, Stamm Dendrosporobacter sp. LG2.4, Stamm Desulfotomaculum sp. EG2.4, Stamm Gallicola sp. SG1.4B und Stamm Acholeplasma sp. ASSH51). Durch die Entwicklung Isolat-spezifischer Primerpaare, abgeleitet von 16S rDNA-Sequenzen der Isolate oder Referenzstämmen, konnten die Isolate in Biogasanlagen detektiert und mittels qPCR quantifiziert werden (hauptsächlich im Bereich zwischen 1000 bis 100000000 Kopien der 16S rDNA/g BGA-Probe). Weiterhin konnten die Isolate mit Hilfe physiologischer Versuche charakterisiert und deren Rolle in der anaeroben Abbaukette diskutiert werden. Die Art Defluviitoga tunisiensis scheint eine große Bedeutung in Biogasanlagen zu spielen. Defluviitoga tunisiensis wurde am häufigsten in Untersuchungen im Rahmen der vorliegenden Arbeit isoliert und konnte auch mit Hilfe des entwickelten Primerpaares in hohen Abundanzen in den beprobten Biogasanlagen detektiert werden (10000 - 100000000 Kopien der 16S rDNA/g BGA-Probe). Die manuelle Annotation des Gesamtgenoms sowie die Substratverwertungsversuche haben gezeigt, dass Defluviitoga tunisiensis ein sehr breites Substratspektrum in der Verwertung von Kohlenhydraten besitzt und dadurch möglicherweise eine wichtige Rolle bei der Verwertung von Biomasse in Biogasanlagen einnimmt. Mit Hilfe der Ergebnisse der vorliegenden Arbeit konnten somit neue Einblicke in die zweite Stufe des anaeroben Abbaus, die Acidogenese, in Biogasanlagen gegeben werden. rn

Influenza A(H1N1) infection and severe cardiac dysfunction in adults: A case series

BACKGROUND: While viral myocarditis and heart failure are recognized and feared complications of seasonal influenza A infection, only limited information is available for 2009 influenza A(H1N1)-induced heart failure. METHODS AND MAIN FINDINGS: This case series summarizes the disease course of four patients with 2009 influenza A(H1N1) infection who were treated at our institution from November 2009 until September 2010. All patients presented with severe cardiac dysfunction (acute heart failure, cardiogenic shock or cardiac arrest due to ventricular fibrillation) as the leading symptom of influenza A(H1N1) infection. Two patients most likely had pre-existent cardiac pathologies, and three required catecholamine therapy to maintain hemodynamic function. Except for one patient who died before influenza A(H1N1) infection had been diagnosed, all patients received antiviral therapy with oseltamivir and supportive critical care. Acute respiratory distress syndrome due to influenza A(H1N1) infection developed in one patient. Heart function normalized in two of the three surviving patients but remained impaired in the other one at hospital discharge. CONCLUSIONS: Influenza A(H1N1) infection may be associated with severe cardiac dysfunction which can even be the leading clinical symptom at presentation. During an influenza pandemic, a thorough history may reveal flu-like symptoms and should indicate testing for H1N1 infection also in critically ill patients with acute heart failure.

Combining spatial-temporal and phylogenetic analysis approaches for improved understanding on global H5N1 transmission

Background Since late 2003, the highly pathogenic influenza A H5N1 had initiated several outbreak waves that swept across the Eurasia and Africa continents. Getting prepared for reassortment or mutation of H5N1 viruses has become a global priority. Although the spreading mechanism of H5N1 has been studied from different perspectives, its main transmission agents and spread route problems remain unsolved. Methodology/Principal Findings Based on a compilation of the time and location of global H5N1 outbreaks from November 2003 to December 2006, we report an interdisciplinary effort that combines the geospatial informatics approach with a bioinformatics approach to form an improved understanding on the transmission mechanisms of H5N1 virus. Through a spherical coordinate based analysis, which is not conventionally done in geographical analyses, we reveal obvious spatial and temporal clusters of global H5N1 cases on different scales, which we consider to be associated with two different transmission modes of H5N1 viruses. Then through an interdisciplinary study of both geographic and phylogenetic analysis, we obtain a H5N1 spreading route map. Our results provide insight on competing hypotheses as to which avian hosts are responsible for the spread of H5N1. Conclusions/Significance We found that although South China and Southeast Asia may be the virus pool of avian flu, East Siberia may be the source of the H5N1 epidemic. The concentration of migratory birds from different places increases the possibility of gene mutation. Special attention should be paid to East Siberia, Middle Siberia and South China for improved surveillance of H5N1 viruses and monitoring of migratory birds.

A navigation system for percutaneous needle interventions based on PET/CT images: design, workflow and error analysis of soft tissue and bone punctures

Percutaneous needle intervention based on PET/CT images is effective, but exposes the patient to unnecessary radiation due to the increased number of CT scans required. Computer assisted intervention can reduce the number of scans, but requires handling, matching and visualization of two different datasets. While one dataset is used for target definition according to metabolism, the other is used for instrument guidance according to anatomical structures. No navigation systems capable of handling such data and performing PET/CT image-based procedures while following clinically approved protocols for oncologic percutaneous interventions are available. The need for such systems is emphasized in scenarios where the target can be located in different types of tissue such as bone and soft tissue. These two tissues require different clinical protocols for puncturing and may therefore give rise to different problems during the navigated intervention. Studies comparing the performance of navigated needle interventions targeting lesions located in these two types of tissue are not often found in the literature. Hence, this paper presents an optical navigation system for percutaneous needle interventions based on PET/CT images. The system provides viewers for guiding the physician to the target with real-time visualization of PET/CT datasets, and is able to handle targets located in both bone and soft tissue. The navigation system and the required clinical workflow were designed taking into consideration clinical protocols and requirements, and the system is thus operable by a single person, even during transition to the sterile phase. Both the system and the workflow were evaluated in an initial set of experiments simulating 41 lesions (23 located in bone tissue and 18 in soft tissue) in swine cadavers. We also measured and decomposed the overall system error into distinct error sources, which allowed for the identification of particularities involved in the process as well as highlighting the differences between bone and soft tissue punctures. An overall average error of 4.23 mm and 3.07 mm for bone and soft tissue punctures, respectively, demonstrated the feasibility of using this system for such interventions. The proposed system workflow was shown to be effective in separating the preparation from the sterile phase, as well as in keeping the system manageable by a single operator. Among the distinct sources of error, the user error based on the system accuracy (defined as the distance from the planned target to the actual needle tip) appeared to be the most significant. Bone punctures showed higher user error, whereas soft tissue punctures showed higher tissue deformation error.

Experimental Evaluation of Immediate Recanalization Effect and Recanalization Efficacy of a New Thrombus Retriever for Acute Stroke Treatment In Vivo

BACKGROUND AND PURPOSE: Currently, several new stent retriever devices for acute stroke treatment are under development and early clinical evaluation. Preclinical testing under standardized conditions is an important first step to evaluate the technical performance and potential of these devices. The aim of this study was to evaluate the immediate recanalization effect, recanalization efficacy, thrombus-device interaction, and safety of a new stent retriever intended for thrombectomy in patients with acute stroke. MATERIAL AND METHODS: The pREset thrombectomy device (4 × 20 mm) was evaluated in 16 vessel occlusions in an established swine model. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. Flow-restoration effect immediately after deployment and after 5-minute embedding time before retrieval, recanalization rate after retrieval, thromboembolic events, and complications were assessed. High-resolution FPCT was performed to illustrate thrombus-device interaction during the embedding time. RESULTS: Immediate flow restoration was achieved in 75% of occlusions. An increase or stable percentage of recanalizations during embedding time before retrieval was seen in 56.3%; a decrease, in 12.5%; reocclusion of a previously recanalized vessel, in 18.8%; and no recanalization effect at all, in 12.5%. Complete recanalization (TICI 3) after retrieval was achieved in 93.8%; partial recanalization (TICI 2b), in 6.2%. No distal thromboembolic events were observed. High-resolution FPCT illustrated entrapment of the thrombus between the stent struts and compression against the contralateral vessel wall, leading to partial flow restoration. During retrieval, the thrombus was retained in a straight position within the stent struts. CONCLUSIONS: In this experimental study, the pREset thrombus retriever showed a high recanalization rate in vivo. High-resolution FPCT allows detailed illustration of the thrombus-device interaction during embedding time and is advocated as an add-on tool to the animal model used in this study.

Genotyping of Mycoplasma hyopneumoniae in wild boar lung samples

Mycoplasma hyopneumoniae is the etiologic agent of enzootic pneumonia (EP), an important cause of disease-associated losses in swine production and a role of wild boar in recurrent infections can be supposed. Genotypes of M. hyopneumoniae from wild boar are unknown but could indicate its role as a potential reservoir. Therefore, 34 lung samples being PCR-positive for M. hyopneumoniae from wild boar from the Geneva region in Switzerland were assayed by genotyping using the p146 and multi-locus sequence typing (MLST) approaches and compared to data from outbreak cases from domestic swine in Switzerland. Successful genotyping was dependent on a sufficiently high concentration of M. hyopneumoniae DNA in the samples as assessed by different real-time PCR assays. The p146 genotyping was more successful with 24 samples (70.5%) being typeable whereas only 6 samples (17.6%) could be genotyped using the MLST approach. Variability of genotypes was high but identical types were found in geographically related animals. Genotypes from wild boar showed phylogenetic relatedness to those from domestic pigs but no matching types could be identified. Results show that direct genotyping from wild boar lung samples is possible and provides a promising approach to investigate future EP outbreak related samples from wild boar. (C) 2011 Elsevier B.V. All rights reserved.

Atypical findings in delayed presentation of unilateral acute idiopathic maculopathy

Unilateral acute idiopathic maculopathy is a rare disease affecting young healthy patients resulting in moderate to severe unilateral visual loss preceded by prodromal flu-like illness. We present a case of delayed presentation of unilateral acute idiopathic maculopathy associated with hand, foot and mouth disease.

Immunogenicity and safety of seasonal and 2009 pandemic A/H1N1 influenza vaccines for patients with autoimmune diseases: a prospective, monocentre trial on 199 patients

The 2009 pandemic A/H1N1 influenza outbreak represented a theoretical risk for patients with autoimmune diseases (AID), especially those immunosuppressed. This study was undertaken to evaluate immunogenicity and tolerance of seasonal (SFV) and A/H1N1 flu vaccines (HFV) in AID patients.

"Self" and "nonself" manipulation of interferon defense during persistent infection: bovine viral diarrhea virus resists alpha/beta interferon without blocking antiviral activity against unrelated viruses replicating in its host cells

Bovine viral diarrhea virus (BVDV), together with Classical swine fever virus (CSFV) and Border disease virus (BDV) of sheep, belongs to the genus Pestivirus of the Flaviviridae. BVDV is either cytopathic (cp) or noncytopathic (ncp), as defined by its effect on cultured cells. Infection of pregnant animals with the ncp biotype may lead to the birth of persistently infected calves that are immunotolerant to the infecting viral strain. In addition to evading the adaptive immune system, BVDV evades key mechanisms of innate immunity. Previously, we showed that ncp BVDV inhibits the induction of apoptosis and alpha/beta interferon (IFN-alpha/beta) synthesis by double-stranded RNA (dsRNA). Here, we report that (i) both ncp and cp BVDV block the induction by dsRNA of the Mx protein (which can also be induced in the absence of IFN signaling); (ii) neither biotype blocks the activity of IFN; and (iii) once infection is established, BVDV is largely resistant to the activity of IFN-alpha/beta but (iv) does not interfere with the establishment of an antiviral state induced by IFN-alpha/beta against unrelated viruses. The results of our study suggest that, in persistent infection, BVDV is able to evade a central element of innate immunity directed against itself without generally compromising its activity against unrelated viruses ("nonself") that may replicate in cells infected with ncp BVDV. This highly selective "self" and "nonself" model of evasion of the interferon defense system may be a key element in the success of persistent infection in addition to immunotolerance initiated by the early time point of fetal infection.

Distribution of RTX toxin genes in strains of [Actinobacillus] rossii and [Pasteurella] mairii

Strains of [Actinobacillus] rossii, [Pasteurella] mairii and [Pasteurella] aerogenes can be isolated from abortion in swine. The RTX toxin Pax has previously been found only in those [P.] aerogenes strains isolated from abortion. Nothing is known about RTX toxins in field isolates of the other two species. To gain insight into the distribution of selected RTX toxin genes and their association with abortion, PCR screening for the pax, apxII and apxIII operons on 21 [A.] rossii and seven [P.] mairii isolates was done. Since species can be phenotypically misidentified, the study was backed up by a phylogenetic analysis of all strains based on 16S rRNA, rpoB and infB genes. The pax gene was detected in all [P.] mairii but not in [A.] rossii strains. No apx genes were found in [P.] mairii but different gene combinations for apx were detected in [A.] rossii strains. Most of these strains were positive for apxIII, either alone or in combination with apxII. Whereas pax was found to be associated to strains from abortion no such indication could be found with apx in [A.] rossii strains. Phylogenetically [A.] rossii strains formed a heterogeneous cluster separated from Actinobacillus sensu stricto. [P.] mairii strains clustered with [P.] aerogenes but forming a separate branch. The fact that [P.] aerogenes, [P.] mairii and [A.] rossii can phylogenetically clearly be identified and might contain distinct RTX toxin genes allows their proper diagnosis and will further help to investigate their role as pathogens.