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1 Parasitology Lab, Section for Microbiology, Immunology, and Parasitology, Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Adamstuen-Campus, Oslo, Norway, 2 Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium, 3 Emerging Pathogens Institute and Department of Animal Sciences, University of Florida, Gainesville, Florida, United States of America, 4 Immunology Section, Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela, 5 Biohelmintiasis Section, Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela, 6 Centro para Estudios Sobre Malaria, Instituto de Altos Estudios “Dr. Arnoldo Gabaldon”, Instituto Nacional de Higiene, MPPS, Caracas, Venezuela, 7 Section of Epidemiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland

Infection biology and invasion strategies of Kretzschmaria deusta were investigated through the analysis of patterns of colonization and population diversity in three case studies, comprising different host species. Molecular analysis and isolation assays performed on stem sections at different heights indicated a prevalent heart rot mode of expansion. Random amplified microsatellites – RAMs and somatic incompatibility assays on isolates allowed detection, in one case, of a genet occupying the entire decay column and, in the other cases, of several different genets in each individual tree. Hypotheses on modes of arrival and entrance of K. deusta in trees are discussed on the basis of the distribution of genets and population genetics analyses. Significant correlation (Spearman ρ = 1.0; p

International audience; The Gram-positive bacterial pathogen Listeria monocytogenes has become one of the best studied models in infection biology. This review will update our knowledge of Listeria virulence factors and highlight their role during the Listeria infection process.

The outcome of an infection is determined by numerous interactions between hosts and pathogens occurring at many different biological levels, ranging from molecule to population. To develop new control strategies for infectious diseases in livestock species, appropriate methodologies are needed allowing more integrated system-level analysis in order to get a coherent picture of host–pathogen interaction networks. The field of systems biology provides such new concepts and methodologies. The chapter describes the first steps in the application of systems biology to study the interaction between two highly interacting biological systems: the invading pathogen and the defending host. Several examples of the application of system biology in this area of infection biology are described. It is concluded that these new approaches may provide a sound innovative basis for improving the prevention and control of infectious diseases in farmed animals.

Trogocytosis, a process in which one cell 'takes a bite' out of another, had previously been seen only in immune cells. But the phenomenon has now been found in Entamoeba histolytica, as a way for this parasite to kill host cells. See Letter p.526 Entamoeba histolytica, the causative agent of fatal diarrhoeal disease in children in the developing world, was so named for its ability to destroy host tissues, although the mechanism underlying this effect was unclear. Here Katherine Ralston et al. describe how these amoeba kill intestinal epithelial cells by biting off and ingesting pieces of cell, in a process reminiscent of the trogocytosis seen between immune cells. Ingestion of the bites is required for killing, and the mechanism operates both in tissue culture and during invasion of intestinal explants. The authors suggest that intercellular exchange via trogocytosis may be more evolutionarily ancient and widespread than was assumed. This work also highlights amoebic trogocytosis as a potential target for new drugs to treat amoebiasis — a major neglected disease.

Loss-of-function genetic screens have facilitated great strides in our understanding of the biology of model organisms but have not been possible in diploid human cells. A recent report by Brummelkamp’s group in Science describes the use of insertional mutagenesis to generate loss-of-function alleles in a largely haploid human cell line and demonstrates the versatility of this method in screens designed to investigate the host/pathogen interaction. This approach has strengths that are complementary to existing strategies and will facilitate progress toward a systems-level understanding of infectious disease and ultimately the development of new therapeutics.

Studying the events that occur when a pathogen comes into contact with its host is the basis of the field of infection biology. Over the years, work in this area has revealed many facets of the infection process, including attachment, invasion and colonization by the pathogen, and of the host responses, such as the triggering of the immune system. Recent advancements in imaging technologies, such as multiphoton microscopy (MPM), mean that the field is in the process of taking another big leap forward. MPM allows for cellular-level visualization of the real-time dynamics of infection within the living host. The use of live animal models means that all the interplaying factors of an infection, such as the influences of the immune, lymphatic and vascular systems, can be accounted for. This review outlines the developing field of MPM in pathogen-host interactions, highlighting a number of new insights that have been ‘brought to light’ using this technique.

The 100th anniversary of the Nobel Prize for Medicine to Paul Ehrlich and Elie Metchnikoff gives us a good opportunity to reflect on their research about infectious diseases. Elie Metchnikoff was not only the first to describe phagocytosis of invading pathogens by specialized blood cells - macrophages and neutrophils - he also was interested in the impact of normal flora on well-being and in pre- and probiotic diet and their influence on the normal flora. Paul Ehrlich not only developed the concept of the side-chain theory of antibody formation but also discovered the first chemotherapeutic agent against microbial pathogens through a combination of chemical modification of a lead substance and experimental animal screening on a broad-scale. Hence, they are not only the founders of immunology but also were the first to envisage infection biology as the result of an interplay between host and pathogen.

Factor H defect Sandra Habbig, Michael J. Mihatsch, Stefan Heinen, Bodo Beck, Mathias Emmel, Christine Skerka, Michael Kirschfink, Bernd Hoppe, Peter F. Zipfel and Christoph Licht Division of Pediatric Nephrology, Children’s Hospital of the University of Cologne, Cologne, Germany; Institute of Pathology, Basel, Switzerland; Leibniz Institute for Natural Products Research and Infection Biology, Jena, Germany; Department of Pediatric Cardiology, Children’s Hospital of the University of Cologne, Cologne, Germany; Institute of Immunology, University of Heidelberg, Heidelberg, Germany; Friedrich Schiller University, Jena, Germany; Division of Pediatric Nephrology, The Hospital for Sick Children; University of Toronto, Toronto, Ontario, Canada

International audience; This review rather than covering the whole field intends to highlight recent findings on the Listeria monocytogenes infectious process or some Listeria specific traits, place them within the framework of well-established data, and demonstrate how this Gram-positive bacterium has, in two decades, emerged as a multifaceted paradigm. Indeed, the cell biology of the infectious process has been deciphered in great detail and provided insights in both the way bacterial pathogen manipulate the host and unsuspected functions of well-known cellular proteins. The intra- and intercellular motility has in particular been instrumental in understanding actin-based motility in general. The analysis of the two main Listeria invasion proteins and that of their host specificities have illustrated how in vitro studies can help generating or choosing relevant animal models for in vivo studies. Listeria post-genomics studies have highlighted the power of comparative genomics in virulence studies. Together, Listeria, after being recognized as a powerful tool in immunology, now appears as one of the most insightful models in infection biology.

outlook of the “Anthrax-Euronet” – a research network formed to harmonize best practices in the anthrax field and to strengthen networking activities or the research community with public and private health sectors regarding preparedness to counter the threat of bioterrorism. Strategies for addressing the dual-use dilemma of research on dangerous pathogens (i.e., potential misuse of life sciences to cause harm) and the need to engage infection biology researchers in the task of improving risk assessment and risk communication approaches related to communicable diseases will be discussed.

Over the past several decades, knowledge of the biology and epidemiology of human papillomavirus (HPV) infection has increased tremendously. However, there are still many unanswered questions concerning the interaction of the virus with its host. The virus has been identified as a necessary causal agent for cervical squamous neoplasia and has been linked to the development of neoplasia in several other mucosal sites. The viral oncogenes E6 and E7 are the major players in the virus9 scheme to evade the immune system and use the host cell replication machinery to survive. Many risk factors for infection with HPV have been identified; however, the focus now centers on identifying risk factors for persistence of the infection as it is likely that transient infections play a very small role in the overall development of clinical disease. Prevention measures to date have centered around screening programs, mostly for cervical cancer, including the perfection of screening techniques and inclusion of molecular testing for HPV into screening regimens. The development of prophylactic and therapeutic vaccines has also increased as primary prevention measures appear to have the best hope for long-term effects on cancer incidence.

College of Pharmacy, Wonkwang University, Iksan, Jeonbuk 570-749, Korea Department of Infection Biology, School of Medicine, Wonkwang University, Iksan, Jeonbuk 570-749, Korea *E-mail: hyunpk@wku.ac.kr College of Pharmacy, Institute of Pharmaceutical research and development, Wonkwang University, Iksan, Jeonbuk 570-749, Korea. *E-mail: hankidad@wku.ac.kr Received February 22, 2011, Accepted March 28, 2011

Understanding the creation, induction and function of natural products that are important for microbial communication are central aims for scientists at the Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoll Institute.

Hazelnut eastern filbert blight caused by Anisogramma anomala in Oregon, USA, is discussed. The subjects included are the infection biology, ascospores, disease management, host resistance and the prospects in the Oregon industry.

Infection biology of Crinipellis perniciosa on vegetative flushes of cacao (Theobroma cacao) was studied by fluorescent microscopy. Basidiospores germinated only if they landed on wet tissue or were suspended in water and sprayed onto the plant parts; those landed on dry surfaces were no longer viable. Interruption of the period of wetness during the prepenetration phase resulted in irreversible termination of the infection process. Growth of germ tubes on the surface of young flushes was strongly oriented toward natural infection sites (stomata) and wounds. On hardened flushes, growth of germ tubes was random (...)

The paper surveys the methods used for studying the root rot in Norway spruce (Picea abies) and summarizes the major results on Heterobasidion infection, the importance of the rhizosphere, preformed and induced resistance factors, search for trees with high resistance, and on virulence factors of the fungus. New approaches are discussed regarding where to look for resistance, how to study host-parasite interaction, the importance of stress factors, and the need for short-term experiments and standardized inoculum.

Anatomical studies on the infection biology of Scleroderris lagerberii (Brunchorstia pinea). Infection of Pinus nigra shoots by B. pinea was studied by means of both ordinary light and fluorescent microscopy. Following spore germination, the mycelium lives under and between the leaf scales, subsequently invading the leaf scales directly. The hyphae can grow through periderms, later invading the xylem via the rays.

The soils of thirty-five Sitka spruce (Picea sitchensis) plantations in southern Britain were surveyed for the presence of the root- and butt-rotting fungus P. Schweinitzii. As a soil inhabitant, the fungus was found to be present in plantations with both broadleaved woodland histories and non-woodland histories, but it was normally isolated at a higher frequency from those ex-broadleaved woodland sites which contained diseased Sitka spruce. The implications of the presence of the fungus in the soils of the formerly non-woodland sites, where no disease has been observed, is discussed in relation to its infection biology, as currently understood.

Isolates from wood, fruit body tissue and single basidiospores of Stereum gausapatum from several locations in South-West England showed several types of reaction when paired on 2% malt agar. ‘Compatible’ reactions resulted in the formation of a distinct secondary mycelium between monospore isolates. ‘Lytic’ reactions resulted in the development, between monospore isolates, of a crescent-shaped zone of appressed mycelium bounded by regions of liquid droplet exudation. In pairings between sibs, the distribution of these two reaction types showed a reciprocal relationship depending on which fruit body had been used for isolation. In non-sib pairings the compatible reaction predominated although, as in a few sib pairings, in many instances it appeared to follow an initial lytic reaction. A narrow pigmented zone of ‘mutual antagonism’ was usually formed between different wood or fruit body tissue isolates, or laboratory-produced secondary mycelia, and also between certain non-compatible/non-lytic combinations of monospore sibs. Some interactions between monospore sibs were ‘weak’, with little or no pigment production or other obvious effect. These observations suggest that S. gausapatum is heterothallic and that there is a link between the mechanisms underlying the lytic and compatible reactions. The implications in the infection biology of S. gausapatum and in relation to findings for other Stereum spp. are discussed.

The study of how microbes cause disease has initiated unique research avenues in both infection biology and cell biology. As our knowledge of the infected cell improves and innovative technologies become available, new domains of investigation hold promise for better understanding pathogenesis and fundamental cellular processes.