Bacterial and protozoal causes of pregnancy loss in the bitch and queen

Several bacterial species have been implicated in canine and feline pregnancy loss. Brucella canis is one of the more important bacterial infectious agents that cause pregnancy loss in the bitch. Brucella has been documented in the queen but in general infectious abortion from bacteria and protozoal agents is uncommon in the species. Protozoal causes of pregnancy loss in the bitch and queen are less common than in other species. Etiology, clinical signs, diagnosis and treatment of bacterial and protozoal causes of pregnancy loss in the bitch and queen are reviewed. Veterinary practitioners should be aware that many of these organisms have zoonotic potential.     

Plant-Based Vaccines for Protection Against Infectious and Autoimmune Diseases

Referee: Dr. Yoedono Sovyanhadi, Department of Biological Sciences, Oakwood College, 7000 Adventist Boulevard, NW, Huntsville, AL 35896 Over the last 2 decades, the number of emergent infectious diseases has increased at an alarming rate. Also disheartening is the rise of known infectious pathogens that have acquired extensive drug resistance and reemerged with greater virulence. More recently, the threat of bioweapons has rekindled an urgency for the development of mass immunization programs. In response to this increased infectious disease threat, efforts have been intensified to identify more effective, inexpensive, and more easily deliverable mucosal vaccination methods. One area of research currently under development is the genetic modification of plants for production of immunoprotective proteins. The ability of plants to synthesize complex proteins using the elements of sunlight, soil, air, and water makes them ideal organisms for harvesting large quantities of therapeutic proteins. The introduction of antigen or antibody encoding genes into the genome of a plant through stable transformation enables them to manufacture vaccine proteins that are directly applicable for use in disease treatment, unlike yeast, bacterial, insect or other expression systems that require purification steps before delivery. As an alternative to stable transformation, plants can be used to generate large quantities of vaccines by acting as hosts for genetically altered plant viruses in which antigen proteins can be expressed and later purified from infected plant tissues. In this review, we survey current experimental strategies for using edible plants to achieve passive and active immunization against infectious disease organisms. In addition, methods are described for the construction of transformed plants that can provide protection against autoimmune diseases. Concerns and present obstacles to effective immunization with plant-based vaccines for animals and humans are presented.     

Mast cell-restricted tryptases: structure and function in inflammation and pathogen defense

Mast cells (MCs) are highly specialized immune cells present in mammals and in lower organisms that predate the development of adaptive immunity. The strong evolutionary pressure to retain MCs for >500 million years suggests critical roles for these cells in our survival. In support of this conclusion, no human has been identified to date that lacks MCs, despite the adverse roles of MCs in systemic anaphylaxis and varied inflammatory disorders. MCs express numerous lineage-restricted neutral proteases, and four members of the chromosome 17A3.3 family of tryptases are preferentially expressed in mouse MCs. The anatomical location of MCs at host-environment interfaces has raised the possibility that some of these enzymes are evolutionally conserved because they are needed for combating infectious organisms. Here we review recent insights into the structure and function of MC tryptases in inflammation and host defense against bacteria and other infectious organisms.     

Selective potentiation of host resistance in mice following treatment with Pyrexol

The purpose of this study was to examine the effect of treatment with the biologic response modifier Pyrexol on murine host resistance to various infectious organisms. Adult female CD1 mice were treated with a single subcutaneous 100-micrograms injection of Pyrexol at 14, 7, 5, 2, or 1 day prior to infection with various infectious organisms. These organisms included the Herpes simplex type 2 and influenza viruses, as well as the bacteria Listeria monocytogenes and Streptococcus zooepidemicus. Pyrexol treatment was found to significantly potentiate resistance to Listeria organisms, but had no appreciable effect on resistance to any of the other organisms tested. Previous reports have demonstrated that treatment with Pyrexol augments a number of cell-mediated immune parameters, several of which have been shown to be responsible for the elimination of Listeria organisms. These results suggest that Pyrexol is capable of selectively potentiating host resistance to infection.     

Cystic fibrosis infections: treatment strategies and prospects

Pseudomonas aeruginosa and Burkholderia cepacia are the two major Gram-negative rods that colonize/infect the lungs of patients with cystic fibrosis (CF). These organisms may cause progressive respiratory failure, although occasionally more rapid infections result in the ' Cepacia ' syndrome. Many antibiotics have been used against Pseudomonas and Burkholderia , but once chronic colonization has been established, eradication of these organisms is rare. Drug therapy for CF patients is compromised by a number of bacterial factors that render the infectious agents resistant to antibiotics, including efflux pumps that remove antibiotics, lack of penetration of antibiotics into bacterial biofilms, and changes in the cell envelope that reduce the permeability of antibiotics. Any combination of these mechanisms increases the likelihood of bacterial survival. Therefore, combinations of antibiotics or of antibiotic and nonantibiotic compounds are currently being tested against Pseudomonas and Burkholderia . However, progress has been slow, with only occasional combinations showing promise for the eradication of persistent Gram-negative rods in the airways of CF patients. This review will summarize the current knowledge of CF infections and speculate on potential future pathways to treat these chronic infections.     

Nucleic acid techniques and the detection of parasitic diseases

The detection of infectious disease-causing organisms is important for the initiation of effective treatment, in monitoring response to therapy and in epidemiological studies of disease of human or animal hosts. In this article Stuart Wilson primarily considers parasitic diseases, but much can be applied to infectious diseases in general.     

INFECTIOUS ALLERGY

The allergic reactivity which accompanies various infectious diseases is different in certain fundamental principles from the allergic disease associated with hypersensitivity to such agents as pollens, dust, and foods. Allergic sensitivity associated with tuberculosis comes about because of the participation of a fatty fraction of the bacillus with another component of the bacterium which is acutally the sensitizing substance. The fatty fraction, if isolated from the bacillus, can act with various kinds of sensitizing substances that have nothing to do with tuberculosis to bring about the same kind of hypersensitivity that accompanies tuberculosis. Attempts are being made to learn more about the manner of action of this factor, and also to find out whether the organisms of other infectious diseases may have similar chemical constituents that cause allergic disease.     

Infectious allergy

The allergic reactivity which accompanies various infectious diseases is different in certain fundamental principles from the allergic disease associated with hypersensitivity to such agents as pollens, dust, and foods. Allergic sensitivity associated with tuberculosis comes about because of the participation of a fatty fraction of the bacillus with another component of the bacterium which is acutally the sensitizing substance. The fatty fraction, if isolated from the bacillus, can act with various kinds of sensitizing substances that have nothing to do with tuberculosis to bring about the same kind of hypersensitivity that accompanies tuberculosis. Attempts are being made to learn more about the manner of action of this factor, and also to find out whether the organisms of other infectious diseases may have similar chemical constituents that cause allergic disease.     

Cell communication by tunneling nanotubes: Implications in disease and therapeutic applications

Intercellular communication is essential for the development and maintenance of multicellular organisms. Tunneling nanotubes (TNTs) are a recently recognized means of long and short distance communication between a wide variety of cell types. TNTs are transient filamentous membrane protrusions that connect cytoplasm of neighboring or distant cells. Cytoskeleton fiber-mediated transport of various cargoes occurs through these tubules. These cargoes range from small ions to whole organelles. TNTs have been shown to contribute not only to embryonic development and maintenance of homeostasis, but also to the spread of infectious particles and resistance to therapies. These functions in the development and progression of cancer and infectious disease have sparked increasing scrutiny of TNTs, as their contribution to disease progression lends them a promising therapeutic target. Herein, we summarize the current knowledge of TNT structure and formation as well as the role of TNTs in pathology, focusing on viral, prion, and malignant disease. We then discuss the therapeutic possibilities of TNTs in light of their varied functions. Despite recent progress in the growing field of TNT research, more studies are needed to precisely understand the role of TNTs in pathological conditions and to develop novel therapeutic strategies.     

Infectious causes of reproductive loss in camelids

Reproductive losses in camelids are due to infertility, pregnancy loss, udder diseases and neonatal mortality caused by a variety of infectious diseases. Uterine infection and abortion represent the major complaint in camelid veterinary practice. The major infectious organisms in endometritis and metritis are E. coli and Streptococcus equi subspecies zooepidemicus. Abortion rates due to infectious diseases vary from 10% to more than 70% in some areas. Leptospirosis, toxoplasmosis and chlamydiosis have been diagnosed as the major causes of abortion in llamas and alpacas. In camels, brucellosis and trypanosomiasis represent the major causes of infectious abortion in the Middle East and Africa. Mastitis is rare in South American camelids. The prevalence of subclinical udder infection in camels can reach very high proportions in dairy camels. Udder infections are primarily due to Streptococcus agalactiae and Staphylococcus aureus. Neonatal mortality is primarily due to diarrhea following failure of passive transfer and exposure to E. coli, rotavirus, coronavirus, Coccidia and Salmonella. This paper reviews the etio-pathogenesis of these causes of reproductive losses, as well as the major risk factors and strategies to prevent their occurrence.     

Biosafety: future priorities for research in health care

Currently the public interest in biosafety issues has focussed on the discussions surrounding the use of genetically modified organisms, very specifically on the use of transgenic plants in agriculture. Although many of the questions raised in connection with genetically modified organisms are of legitimate scientific interest, attention should be drawn back to a number of other more classical biosafety research areas, namely the problem of control of new and reemerging infectious diseases, the need for new vaccines, control of transport and routes of dissemination, biosafety information exchange and networking, where research results are dearly needed. In the area of modern biotechnology new applications such as gene therapy and transgenic animals will be on the list of future priorities for biosafety related activities and research.     

Validity of the indicator organism paradigm for pathogen reduction in reclaimed water and public health protection

The validity of using indicator organisms (total and fecal coliforms, enterococci, Clostridium perfringens, and F-specific coliphages) to predict the presence or absence of pathogens (infectious enteric viruses, Cryptosporidium, and Giardia) was tested at six wastewater reclamation facilities. Multiple samplings conducted at each facility over a 1-year period. Larger sample volumes for indicators (0.2 to 0.4 liters) and pathogens (30 to 100 liters) resulted in more sensitive detection limits than are typical of routine monitoring. Microorganisms were detected in disinfected effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%; C. perfringens, 61%; F-specific coliphages, approximately 40%; and enteric viruses, 31%. Cryptosporidium oocysts and Giardia cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable Cryptosporidium, based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation was found for any indicator-pathogen combination. When data for all indicators were tested using discriminant analysis, the presence/absence patterns for Giardia cysts, Cryptosporidium oocysts, infectious Cryptosporidium, and infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed. Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health is suggested by this study.     

Validity of the Indicator Organism Paradigm for Pathogen Reduction in Reclaimed Water and Public Health Protection

The validity of using indicator organisms (total and fecal coliforms, enterococci, Clostridium perfringens, and F-specific coliphages) to predict the presence or absence of pathogens (infectious enteric viruses, Cryptosporidium, and Giardia) was tested at six wastewater reclamation facilities. Multiple samplings conducted at each facility over a 1-year period. Larger sample volumes for indicators (0.2 to 0.4 liters) and pathogens (30 to 100 liters) resulted in more sensitive detection limits than are typical of routine monitoring. Microorganisms were detected in disinfected effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%; C. perfringens, 61%; F-specific coliphages, ~40%; and enteric viruses, 31%. Cryptosporidium oocysts and Giardia cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable Cryptosporidium, based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation was found for any indicator-pathogen combination. When data for all indicators were tested using discriminant analysis, the presence/absence patterns for Giardia cysts, Cryptosporidium oocysts, infectious Cryptosporidium, and infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed. Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health is suggested by this study.     

Digest: Propagule pressure might not matter in the establishment of invasive prokaryotes*

Lavigne et al. developed models to investigate the adaptive colonization of sink environments by asexual organisms. Their results have clear relevance to the spread of infectious disease, but they may also provide insights into prokaryotic invasions into natural communities. Their results show that propagule pressure might not be a good predictor of invasion success in prokaryotes, suggesting that more work is needed to understand how microbial invasions differ from those of plants and animals.     

Pollution and parasitism in the aquatic environment

The studies of aquatic parasitology and of aquatic pollution effects both have experienced increasing interest during the recent fifteen years. Although considerable effort has been spent on studying the role of pollution as a cause or a trigger of anomalies, tumors and infectious diseases in aquatic organisms, the interactions between pollution and parasitism have been largely neglected by scientists.Pollution and other man-made alterations of the aquatic environment may affect a parasite community directly by acting on free-living parasite stages or on ectoparasites, or indirectly by acting on the intermediate or the definitive host population. Certain pollution conditions favour the propagation of parasites by excluding their natural predators, by reducing the resistance of their hosts or by providing improved living conditions for their intermediate hosts. In a number of experimental studies parasitized organisms have been shown to suffer from greater mortalities when exposed to high temperature, to low oxygen stress or to high levels of dissolved heavy metal salts, when compared to nonparasitized control animals. Unfortunately, field studies on synergistic effects of pollution and parasites on host populations are still scarce and seldom offer more than qualitative observations and theoretical evaluations.The complexity of the pollution-parasite-host system complicates the use of parasites as indicators of pollution effects. However, experience from aquaculture practice teaches that a number of (mostly ecto-) parasites are more susceptible to certain chemicals (used as parasiticides) and to artificial alterations of salinity, temperature or oxygen content of the water than their hosts. Accordingly, it is postulated that during future studies the composition of ectoparasitic faunas of aquatic organisms might turn out to become a useful and quickly reacting indicator for effects of certain pollution conditions, such as anthropogene oxygen deficiency, salt introduction from salines into freshwater ecosystems, and introduction of certain heavy metal salts.     

Concept,Definition, Prevalence,and Host-Interactions of Xenosomes (Cytoplasmic and Nuclear Endosymbionts)1,2

ABSTRACT. In this paper the concept of “xenosome” is greatly expanded from its current usage, which has been based on its application during the past 10 years by Soldo and co-workers solely to certain bacterial invaders of the cytoplasm in species of a single genus of marine scuticociliales. The author proposes that the term now be considered to embrace all DNA-containing, membrane-bounded bodies or organelles—prokaryotic or eukaryotic in original nature—found within the cytoplasm or nucleus of eukaryotic cells of any or all kinds, whether the occupation (“colonization”) is temporary and transient or permanent and stable. Thus, virulent or pathogenically infectious organisms can be included as well as the commonly recognized cell endosymbionts sensu stricto, which are often mutualistic in nature. Of significance, such “normal” cell organelles as plastids, mitochondria, and even nuclei may also be embraced by this expanded definition of xenosome, based on the conjecture that these inclusions might have been “alien” or “foreign” extracellular, independent, free-living organisms in their own past evolutionary histories. The author's enlarged concept and unifying principle allows more meaningful comparative consideration of the numerous and diverse kinds of xenosome-host interrelationships, many of which involve species of protozoa and algae from a large number of the taxonomic groups comprising the kingdom Protista.     

气候变化对传染病爆发流行的影响研究进展

全球气候变化已影响到传染病发生、传播与变化的各个环节,从病原体及其携带者、传播途径和人体自身抵抗力等方面直接或间接影响传染病的发病趋势,从而对人类健康造成了巨大的威胁。所以加强对气候变化与传染病间关系、预测预报研究,对进一步认识、预防和控制传染病的爆发流行具有重要意义。本文首先阐述了全球气候变化对生物物种的地理分布和人类健康的影响,气候变化改变了生物物种的地理分布范围,增加了某些物种的潜在分布区域,并造成生物物侯期的改变;同时,极端气候事件成为导致种群数量波动的一个重要驱动力。气候变化对人类健康有直接和间接影响,它使得传染病发病率增加、传染病分布范围扩大、人群对疾病易感性增强。文章重点评述了气候变化对疟疾、登革热、霍乱、流行性乙型脑炎、流感、SARS、肠道传染病、鼠疫、血吸虫病等常见传染病流行机制和传播过程的影响研究进展。评述了传染病和气象因子关系分析中常用的定性和定量分析方法,传统的研究多以定性分析为主,方法较单一;目前,利用流行病学资料与同期的气象因子进行单因素相关分析、多元回归分析是常用的研究方法;主成分回归分析、逐步判别分析、灰色关联分析法、RS和GIS等方法近年来逐渐得到应用;数学建模、实验室生物学仿真实验方法是今后需强化的方向。提出了该研究领域国内外研究普遍存在和亟待解决的问题,针对目前的研究现状和存在的问题,提出了未来的研究重点和发展方向。     

Signalling and oxidant adaptation in Candida albicans and Aspergillus fumigatus

Candida species and Aspergillus fumigatus were once thought to be relatively benign organisms. However, it is now known that this is not the case - Candida species rank among the top four causes of nosocomial infectious diseases in humans and A. fumigatus is the most deadly mould, often having a 90% mortality rate in immunocompromised transplant recipients. Adaptation to stress, including oxidative stress, is a necessary requisite for survival of these organisms during infection. Here, we describe the latest information on the signalling pathways and target proteins that contribute to oxidant adaptation in C. albicans and A. fumigatus, which has been obtained primarily through the analysis of mutants or inference from genome annotation.     

Application of stains in clinical microbiology

Stains have been used for diagnosing infectious diseases since the late 1800s. The Gram stain remains the most commonly used stain because it detects and differentiates a wide range of pathogens. The next most commonly used diagnostic technique is acid-fast staining that is used primarily to detect Mycobacterium tuberculosis and other severe infections. Many infectious agents grow slowly on culture media or may not grow at all; stains may be the only method to detect these organisms in clinical specimens. In the hands of experienced clinical microscopists, stains provide rapid and cost-effective information for preliminary diagnosis of infectious diseases. A review of the most common staining methods used in the clinical microbiology laboratory is presented here.