Parasitic diseases of cultured marine finfishes and their surveillance in China

More than 40 species of marine fishes are cultured in China and a wide variety of parasites are reported as lethal pathogens of these fishes in culture conditions. In the case of net cages, the culture facilities provides a good substrate for monogenean eggs to become entangled and the intensive aggregation of fishes facilitates the transmission of parasites between hosts. Relatively thorough studies on parasitic pathogens of marine fishes in China predominately concern the ciliate Cryptocaryon irritans and capsalid monogeneans (mainly Benedenia sp. and Neobenedenia sp.). Although nearly all such reports are related to treatment procedures, no single method has proved to be adequate for the effective control of these parasitic pathogens in marine cultured fishes. The National Fisheries Technology Extension Center (NFTEC) has established surveillance systems to monitor the diseases of aquaculture, including the parasitic diseases of maricultured fishes. The national monitoring stations for diseases of cultured marine fishes are distributed in the coastal counties or cities and provide remote in situ diagnoses of diseased fishes. International cooperation and effort are required for the control of parasitic diseases of marine finfish because of both the increasing international trade of eggs (seed) and larvae and commercial products in terms of live marine finfishes, which can readily result in the transmission of pathogens.     

The effects of environmental stress on outbreaks of infectious diseases of fishes*

Infectious diseases of fishes occur when susceptible fishes are exposed to virulent pathogens under certain environmental stress conditions. Very little research has been carried out to show the effect of pollution on outbreaks of infectious diseases of fishes. Therefore, examples taken from the literature were selected and reviewed to show the coincidence of infectious diseases with stress caused by temperature, eutrophication, sewage, metabolic products of fishes, industrial pollution, and pesticides.     

宏基因组测序在中枢神经系统感染性疾病诊断中的应用及研究进展

中枢神经系统(central nervous system,CNS)感染是指由病毒、细菌或真菌等侵染中枢神经系统引起的急性或慢性炎症性(或非炎症性)疾病,致死率高,易引发严重后遗症。由于检测通量及灵敏度的限制,一半以上的中枢神经系统感染患者无法通过常规检测方法确定病原体。宏基因组测序是一种新兴的病原检测技术,能够极大地提升病原检出率。当前部分临床医生及相关从业人员对宏基因组测序的认识存在不足,限制了其在临床诊疗中的快速推广和应用。本文系统介绍了宏基因组测序整体流程,综述了该技术在中枢神经系统感染性疾病诊疗中的发展历程和最新研究进展,希望为中枢神经系统感染性疾病的诊断和治疗提供参考。     

Plant‐based oral vaccines against zoonotic and non‐zoonotic diseases

The shared diseases between animals and humans are known as zoonotic diseases and spread infectious diseases among humans. Zoonotic diseases are not only a major burden to livestock industry but also threaten humans accounting for >60% cases of human illness. About 75% of emerging infectious diseases in humans have been reported to originate from zoonotic pathogens. Because antibiotics are frequently used to protect livestock from bacterial diseases, the development of antibiotic‐resistant strains of epidemic and zoonotic pathogens is now a major concern. Live attenuated and killed vaccines are the only option to control these infectious diseases and this approach has been used since 1890. However, major problems with this approach include high cost and injectable vaccines is impractical for >20 billion poultry animals or fish in aquaculture. Plants offer an attractive and affordable platform for vaccines against animal diseases because of their low cost, and they are free of attenuated pathogens and cold chain requirement. Therefore, several plant‐based vaccines against human and animals diseases have been developed recently that undergo clinical and regulatory approval. Plant‐based vaccines serve as ideal booster vaccines that could eliminate multiple boosters of attenuated bacteria or viruses, but requirement of injectable priming with adjuvant is a current limitation. So, new approaches like oral vaccines are needed to overcome this challenge. In this review, we discuss the progress made in plant‐based vaccines against zoonotic or other animal diseases and future challenges in advancing this field.     

Autophagy and pathogens: «Bon appétit Messieurs!»

Autophagy is a highly conserved, self-degradative pathway for clearance and recycling of cytoplasmic contents. This ubiquitous cell intrinsic process can be used as a defence mechanism against intracellular pathogens. Indeed autophagy is increased upon pathogen detection, and experimental extinction in vitro and in vivo of this cellular process has been demonstrated as a crucial role to control intracellular pathogens. Co-evolution between host-cells and pathogens has selected numerous micoorganisms able to avoid or usurp autophagy to their own benefit. Understanding mechanisms underlying the anti-microbial properties of autophagy as well as those used by certain pathogens to escape this cellular process might be crucial to manipulate this cellular function in order to prevent or treat infectious diseases.     

Recent advances in detection and control of infectious hematopoietic necrosis virus in aquaculture

Infectious hematopoietic necrosis (IHN) is one of the most important viral diseases of salmon and trout reared in culture. The disease remains untreatable with avoidance being the only control measure. Much has been learned about the chemical, physical, and serological characteristics of the rhabdovirus causing IHN, but critical gaps exist in our understanding of the biology of the virus in nature. The tools of molecular biology have provided improved methods for detection of pathogens and new strategies for control of viral diseases. This paper reviews several recent improvements in methods for detecting infectious hematopoietic necrosis virus including the application of enzyme-linked immunosorbent assays, development of monoclonal antibodies and DNA probes, and use of the polymerase chain reaction. New strategies for control of IHN through the use of better water treatment, more resistant fish, antiviral drugs or chemicals, and new generation vaccines are discussed.     

General and specialized media routinely employed for primary isolation of bacterial pathogens of fishes

There are a number of significant diseases among cultured and free-ranging freshwater fishes that have a bacterial etiology; these represent a variety of gram-negative and gram-positive genera. Confirmatory diagnosis of these diseases involves primary isolation of the causative bacterium on bacteriologic media. Frequently used "general" bacteriologic media simply provide the essential nutrients for growth. For most of the major pathogens, however, there are differential and/or selective media that facilitate primary recovery. Some specialized media are available as "ready-to-use" from suppliers, while others must be prepared. Differential media employ various types of indicator systems, such as pH indicators, that allow diagnosticians to observe assimilation of selected substrates. An advantage to the use of differential media for primary isolation is that they hasten bacterial characterization by yielding the appropriate positive or negative result for a particular substrate, often leading to a presumptive identification. Selective media also incorporate agent(s) that inhibit the growth of contaminants typically encountered with samples from aquatic environments. Media that incorporate differential and/or selective components are ideally based on characters that are unique to the targeted bacterium, and their use can reduce the time associated with diagnosis and facilitate early intervention in affected fish populations. In this review, the concepts of general and differential/selective bacteriologic media and their use and development for fish pathogens are discussed. The media routinely employed for primary isolation of the significant bacterial pathogens of fishes are presented.     

Applications of monoclonal antibodies in aquaculture

Monoclonal antibodies (MAbs) currently are being applied to the study of fish immunology and fish infectious diseases. MAbs to fish immunoglobulins (Igs) have helped isolate fish Igs, identify heavy and light chain variants in fish Ig, study the ontogeny of B lymphocytes, and improve techniques for the measurement of fish Ig and specific antibodies (Abs). MAbs have been obtained against several leucocyte surface antigens and are being used as markers for different subsets of fish leukocytes: neutrophils, non-specific cytotoxic cells and cells responsible for the mixed leucocyte reaction. The sensitivity and specificity of many immunoassays for identifying fish pathogens have been improved by the use of MAbs. Further improvement of these tests is currently being attempted by the use of MAbs together with the polymerase chain reaction (PCR). Epizootiological studies of fish diseases are beginning to emerge from the use of these reagents and techniques. In the near future these new methods should detect low levels of pathogens in adult carriers and perhaps in eggs, thus helping to prevent the dissemination of fish diseases. MAbs to fish pathogens are also being used for passive immunization studies as well as for conformational probes in the development of genetically engineered vaccines.     

线粒体自噬在感染性疾病中的作用机制研究进展

线粒体自噬作为一种选择性自噬方式是近年研究的热点。细胞通过自噬机制选择性清除受损伤或不必需的线粒体,从而维持其功能稳态。近年来,越来越多的研究聚焦于病原体通过胁迫线粒体自噬在机体感染过程中调节先天免疫信号通路,从而影响感染性疾病的进程。本文分别从线粒体自噬在病毒、细菌和真菌感染性疾病中的作用机制研究进展进行综述,以期为感染性疾病的防治提供新的指导策略。     

A falsification of the thermal specialization paradigm: compensation for elevated temperatures in Antarctic fishes

Specialization to a particular environment is one of the main factors used to explain species distributions. Antarctic fishes are often cited as a classic example to illustrate the specialization process and are regarded as the archetypal stenotherms. Here we show that the Antarctic fish Pagothenia borchgrevinki has retained the capacity to compensate for chronic temperature change. By displaying astounding plasticity in cardiovascular response and metabolic control, the fishes maintained locomotory performance at elevated temperatures. Our falsification of the specialization paradigm indicates that the effect of climate change on species distribution and extinction may be overestimated by current models of global warming.     

Fishes as models in studies of sexual selection and parental care

Fishes are by far the most diverse group of vertebrates. This fact is in no way, however, reflected in their use as model organisms for understanding sexual selection or parental care. Why is this so? Is it because fishes are actually poor models? The usefulness of fishes as models for sexual selection and parental care is discussed by emphasizing some problems inherent in fish studies, along with a number of reasons why fishes are indeed excellently suited. The pros and cons of fishes as models are discussed mainly by comparison with birds, the most popular model organisms in animal behaviour. Difficulties include a lack of background knowledge for many species, and the problems of marking and observing fishes in their natural environment. Positive attributes include the diversity of lifestyles among fishes, and the ease with which they can be studied experimentally in the laboratory. How useful fish models can be is briefly illustrated by the impressive and broadly relevant advances derived from studies of guppies Poecilia reticulata and three‐spined sticklebacks Gasterosteus aculeatus . A selection of topics is highlighted where fish studies have either advanced or could greatly enhance, the understanding of processes fundamental to animal reproductive dynamics. Such topics include sex role dynamics, the evolution of female ornamentation and mate choice copying. Finally, a number of potential pitfalls in the future use of fish as models for sexual selection and parental care are discussed. Researchers interested in these issues are recommended to make much more extensive use of fish models, but also to adopt a wider range of models among fishes.     

Perspectives in the control of infectious diseases by transgenic mosquitoes in the post-genomic era--a review

Arthropod-borne diseases caused by a variety of microorganisms such as dengue virus and malaria parasites afflict billions of people worldwide imposing major economic and social burdens. Despite many efforts, vaccines against diseases transmitted by mosquitoes, with the exception of yellow fever, are not available. Control of such infectious pathogens is mainly performed by vector management and treatment of affected individuals with drugs. However, the numbers of insecticide-resistant insects and drug-resistant parasites are increasing. Therefore, inspired in recent years by a lot of new data produced by genomics and post-genomics research, several scientific groups have been working on different strategies to control infectious arthropod-borne diseases. This review focuses on recent advances and perspectives towards construction of transgenic mosquitoes refractory to malaria parasites and dengue virus transmission.     

The challenges of implementing pathogen control strategies for fishes used in biomedical research

Over the past several decades, a number of fish species, including the zebrafish, medaka, and platyfish/swordtail, have become important models for human health and disease. Despite the increasing prevalence of these and other fish species in research, methods for health maintenance and the management of diseases in laboratory populations of these animals are underdeveloped. There is a growing realization that this trend must change, especially as the use of these species expands beyond developmental biology and more towards experimental applications where the presence of underlying disease may affect the physiology animals used in experiments and potentially compromise research results. Therefore, there is a critical need to develop, improve, and implement strategies for managing health and disease in aquatic research facilities. The purpose of this review is to report the proceedings of a workshop entitled "Animal Health and Disease Management in Research Animals" that was recently held at the 5th Aquatic Animal Models for Human Disease in September 2010 at Corvallis, Oregon to discuss the challenges involved with moving the field forward on this front.     

Epidemiological study of zoonoses derived from humans in captive chimpanzees

Emerging infectious diseases (EIDs) in wildlife are major threats both to human health and to biodiversity conservation. An estimated 71.8 % of zoonotic EID events are caused by pathogens in wildlife and the incidence of such diseases is increasing significantly in humans. In addition, human diseases are starting to infect wildlife, especially non-human primates. The chimpanzee is an endangered species that is threatened by human activity such as deforestation, poaching, and human disease transmission. Recently, several respiratory disease outbreaks that are suspected of having been transmitted by humans have been reported in wild chimpanzees. Therefore, we need to study zoonotic pathogens that can threaten captive chimpanzees in primate research institutes. Serological surveillance is one of several methods used to reveal infection history. We examined serum from 14 captive chimpanzees in Japanese primate research institutes for antibodies against 62 human pathogens and 1 chimpanzee-borne infectious disease. Antibodies tested positive against 29 pathogens at high or low prevalence in the chimpanzees. These results suggest that the proportions of human-borne infections may reflect the chimpanzee’s history, management system in the institute, or regional epidemics. Furthermore, captive chimpanzees are highly susceptible to human pathogens, and their induced antibodies reveal not only their history of infection, but also the possibility of protection against human pathogens.     

Hydropower-related pulsed-flow impacts on stream fishes: a brief review,conceptual model,knowledge gaps,and research needs

The societal benefits of hydropower systems (e.g., relatively clean electrical power, water supply, flood control, and recreation) come with a cost to native stream fishes. We reviewed and synthesized the literature on hydropower-related pulsed flows to guide resource managers in addressing significant impacts while avoiding unnecessary curtailment of hydropower operations. Dams may release pulsed flows in response to needs for peaking power, recreational flows, reservoir storage adjustment for flood control, or to mimic natural peaks in the hydrograph. Depending on timing, frequency, duration, and magnitude, pulsed flows can have adverse or beneficial short and long-term effects on resident or migratory stream fishes. Adverse effects include direct impacts to fish populations due to (1) stranding of fishes along the changing channel margins, (2) downstream displacement of fishes, and (3) reduced spawning and rearing success due to redd/nest dewatering and untimely or obstructed migration. Beneficial effects include: (1) maintenance of habitat for spawning and rearing, and (2) biological cues to trigger spawning, hatching, and migration. We developed a basic conceptual model to predict the effects of different types of pulsed flow, identified gaps in knowledge, and identified research activities to address these gaps. There is a clear need for a quantitative framework incorporating mathematical representations of field and laboratory results on flow, temperature, habitat structure, fish life stages by season, fish population dynamics, and multiple fish species, which can be used to predict outcomes and design mitigation strategies in other regulated streams experiencing pulsed flows.     

Small and lethal: searching for new antibacterial compounds with novel modes of action.

The discovery of drugs used to combat infectious diseases is in the process of constant change to address the ever-worsening problem of antibiotic resistance in pathogens and a lack of recent success in discovering new antibacterial drugs. In the past 2 decades, research in both academia and industry has made use of molecular biology, genetics, and comparative genomics, which has led to the development of key technologies for the discovery of novel antibacterial agents. Genome-scale efforts have led to the identification of numerous molecular targets. Chemical diversity from synthetic combinatorial libraries and natural products is being used to screen for new molecules. A wide variety of approaches are being used in the search for novel antibiotics, and these can be categorized as being either biochemically focused or cell based. The over-riding goal of all methods in use today is to discover new chemical matter with novel mechanisms of action against drug-resistant pathogens.     

Genomic approaches with natural fish populations

Natural populations v. inbred stocks provide a much richer resource for identifying the effects of nucleotide substitutions because natural populations have greater polymorphism. Additionally, natural populations offer an advantage over most common research organisms because they are subject to natural selection, and analyses of these adaptations can be used to identify biologically important changes. Among fishes, these analyses are enhanced by having a wide diversity of species (>28 000 species, more than any other group of vertebrates) living in a huge range of environments (from below freezing to > 46° C, in fresh water to salinities >40 ppt.). Moreover, fishes exhibit many different life‐history and reproductive strategies and have many different phenotypes and social structures. Although fishes provide numerous advantages over other vertebrate models, there is still a dearth of available genomic tools for fishes. Fishes make up approximately half of all known vertebrate species, yet <0·2% of fish species have significant genomic resources. Nonetheless, genomic approaches with fishes have provided some of the first measures of individual variation in gene expression and insights into environmental and ecological adaptations. Thus, genomic approaches with natural fish populations have the potential to revolutionize fundamental studies of diverse fish species that offer myriad ecological and evolutionary questions.     

感染组学 (infectomics) ———对感染性疾病的总体性和综合性研究

在感染性疾病的范畴内,目前急需一个能有效地、精确地和综合性地研究微生物感染的结构性和功能性基因组学和蛋白质组学 ( 感染组学 ) 的全面方法. 新的方法 ( 如 DNA 和蛋白质微阵列 ) 和传统方法 ( 如分子克隆、 PCR 、基因敲除,加进 (knockin) 和反义术等 ) 的结合将有助于克服今天的困难. 在感染时,微生物及其宿主的全部表型改变 ( 感染组 ) 均由微生物病原体及其宿主的基因组所编码,并在特异的微生物 - 宿主相互作用时的某些环境条件下表达. 微生物及其宿主的全部药物反应 ( 药理组 ) 可用基因组或蛋白质组的方法检出. 分析基因型和表型或表达形式的全基因组方法将最终导致对微生物的发病机理、感染性疾病的快速诊断和控制感染的新策略的全面研究. 感染性疾病中最基本的问题是,如何全面地和综合性地应用感染组学,来了解微生物病原体及其宿主的相互作用.     

Insect immune responses to nematode parasites

Host innate immunity plays a central role in detecting and eliminating microbial pathogenic infections in both vertebrate and invertebrate animals. Entomopathogenic or insect pathogenic nematodes are of particular importance for the control of insect pests and vectors of pathogens, while insect-borne nematodes cause serious diseases in humans. Recent work has begun to use the power of insect models to investigate host-nematode interactions and uncover host antiparasitic immune reactions. This review describes recent findings on innate immune evasion strategies of parasitic nematodes and host cellular and humoral responses to the infection. Such information can be used to model diseases caused by human parasitic nematodes and provide clues indicating directions for research into the interplay between vector insects and their invading tropical parasites.     

Control Strategies in Multigroup Models: The Case of the Star Network Topology

In this paper, we propose control strategies for multigroup epidemic models. We use compartmental \({\textit{SIRS}}\) models to study the dynamics of n host groups sharing the same source of infection in addition to the transmission among members of the same group. In particular, we consider a model for infectious diseases with free-living pathogens in the environment and a metapopulation model with a central patch. We give the detailed derivation of the target reproduction number under three public health interventions and provide the corresponding biological insights. Moreover, using the next-generation approach, we calculate the basic reproduction numbers associated with subsystems of our models and determine algebraic connections to the target reproduction number of the complete model. The analysis presented here illustrates that understanding the topological structure of the infection process and partitioning it into simple cycles is useful to design and evaluate the control strategies.