两种鳜病毒的共感染现象及引起感染细胞的超微变化

借助细胞培养和电镜技术,揭示了鳜球形病毒(Siniperca chuatsi spherical virus,SCSV)与鳜弹状病毒(Siniperca chuatsi rhabdovirus,SCRV)在草鱼鳍细胞(Grass carp fins,GCF)中共感染的现象。在筛选到敏感鱼类细胞系和建立了 鳜病毒体外增殖系统的基础上,取息典型病毒感染出血症的鳜组织,制备组织悬液,接种到GCF细胞中传代培养, 在攻毒后间隔不同时间收集细胞,对攻毒细胞的超薄切片进行电镜观察。揭示两种形态的鳜病毒可在同一个GCF 细胞中增殖,并描述和分析了病毒复制引起感染细胞的超微病变。本研究结果有助于阐明鱼类重要病毒病害的发 生过程及致病机理。     

Viral infections of aquatic animals with special reference to Asian aquaculture

Worldwide, the number of communicable diseases of animals raised in aquaculture continue to increase. Viral infections of cultivated shellfish, crustacea, and finfish have been frequently recognized in the past few years. In the Asian regions, penaeid shrimp and several teleost fish underwent epizootics associated with heavy losses in aquaculture. Baculoviruses are particularly harmful to shrimp and prawns. Herpes-, irido-, reo-, or rhabdovirus-like agents can cause outbreaks in fish farms. Viral diseases are important limiting factors in the expansion of aquaculture. However, studies on viral infections of aquatic animals have been focused primarily on economically important farmed fish. Therfore, certain viral diseases of teleost fish are relatively well understood. In contrast, our knowledge of viral infections of farmed aquatic invertebrates is still very spare. Although a great number of viruses have been detected in farmed molluscs and crustaceans, the pathogenicity and epizootiology of most of the agents is not known.     

Significance of Legionella pneumophila in human respiratory pathology

The etiological structure of acute pneumonia and acute respiratory diseases was studied with a view to establishing the proportion of L. pneumophila among other causative agents of such diseases. A total of 299 patients were examined over time. The etiological diagnosis based on the data of serological examination was made in 70.6% of the patients with acute pneumonia and in 65% of the patients with acute respiratory viral infections and influenza. In the etiology of pneumonia, the leading role was found to belong to influenza A (H3N2) and B viruses, as well as to adenovirus, while in the etiology of acute respiratory viral infections and influenza, to influenza B virus, adenovirus and Mycoplasma pneumoniae. The importance of L. pneumophila in the etiology of acute pneumonia and acute respiratory diseases was shown. The proportion of L. pneumophila proved to be, on the average, 9.9% in acute pneumonia and 9.8% in acute respiratory diseases. L. pneumophila occurred most frequently in mixed infections in combination with adenovirus and influenza B virus. Diseases of Legionella etiology were found to have a seasonal character, occurring mostly in winter and spring.     

Genetic resistance to rhabdovirus infection in teleost fish is paralleled to the derived cell resistance status

Genetic factors of resistance and predisposition to viral diseases explain a significant part of the clinical variability observed within host populations. Predisposition to viral diseases has been associated to MHC haplotypes and T cell immunity, but a growing repertoire of innate/intrinsic factors are implicated in the genetic determinism of the host susceptibility to viruses. In a long-term study of the genetics of host resistance to fish rhabdoviruses, we produced a collection of double-haploid rainbow trout clones showing a wide range of susceptibility to Viral Hemorrhagic Septicemia Virus (VHSV) waterborne infection. The susceptibility of fibroblastic cell lines derived from these clonal fish was fully consistent with the susceptibility of the parental fish clones. The mechanisms determining the host resistance therefore did not associate with specific host immunity, but rather with innate or intrinsic factors. One cell line was resistant to rhabdovirus infection due to the combination of an early interferon IFN induction--that was not observed in the susceptible cells--and of yet unknown factors that hamper the first steps of the viral cycle. The implication of IFN was well consistent with the wide range of resistance of this genetic background to VSHV and IHNV, to the birnavirus IPNV and the orthomyxovirus ISAV. Another cell line was even more refractory to the VHSV infection through different antiviral mechanisms. This collection of clonal fish and isogenic cell lines provides an interesting model to analyze the relative contribution of antiviral pathways to the resistance to different viruses.     

国内鱼类病毒病研究进展

病毒性疾病是危害水生动物最严重的一类疾病,是水产养殖业发展的重大障碍。近年来,中国水生动物病毒病的研究取得了一定成就,但是还有许多方面的研究有待加强,有很多未知领域需要进行探索与研究。本文综述了近年来国内鱼类病毒病的研究进展,主要介绍了草鱼出血病、传染性胰脏坏死病、淋巴囊肿病、传染性脾肾坏死病、鳗鲡病毒病、真鲷病毒病等不同鱼类病毒病的临床症状、流行病学、检测手段、致病机理、防治措施以及引起该病的病原体的形态结构、理化性质等,旨在为鱼类病毒病的防治提供参考。     

Viral diseases in commercially exploited crabs: a review

Viruses and viral diseases of crabs were observed and investigated earlier than the first observation of viruses in shrimp. In fact, crabs were used as biological models to investigate crustacean virology at the beginning of shrimp aquaculture development. More than 30 viruses have been reported in crabs, including those related to the known virus families Reoviridae, Bunyaviridae, Roniviridae and a group of Bacilliform enveloped nuclear viruses. This review reports data on several important viral diseases of crabs, particularly those associated with pathology of organs and tissues of commercially and ecologically significant host species.     

Establishment, characterization, and viral susceptibility of two cell lines derived from goldfish Carassius auratus muscle and swim bladder

Goldfish Carassius auratus are common aquarium fish and have a significant economic and research value, having considerable worth to fisheries as a baitfish and the ability to adapt to a range of habitats. Two cell lines were established from goldfish muscle and swim bladder tissue, in order to create a biological monitoring tool for viral diseases. Cell lines were optimally maintained at 30 degrees C in Leibovitz-15 medium supplemented with 20% fetal bovine serum. Propagation of goldfish cells was serum dependent, with a low plating efficiency (>16%). Karyotyping analysis indicated that both cell lines remained diploid, with a mean chromosomal count of 104. Results of viral challenge assays revealed that both cell lines shared similar patterns of viral susceptibility and production to infectious hematopoietic necrosis virus, infectious pancreatic necrosis virus, snakehead rhabdovirus, and spring viremia carp virus. Both cell lines demonstrated a higher sensitivity and significantly larger viral production than control brown bullhead cells for channel catfish virus. These newly established cell lines will be used as a diagnostic tool for viral diseases in this fish species and also for the isolation and study of goldfish viruses in the future.     

Effect of Cecropin B and a Synthetic Analogue on Propagation of Fish Viruses In Vitro

Abstract Cecropins and other natural antimicrobial peptides are widely distributed in animals from insects to mammals. These proteins have been shown to be major constituents of the innate immune systems of animals for nonspecific defense of the host against various bacteria and parasites. Therefore, exploitation of this natural innate defense system may lead to the development of effective methods for protecting fish from invasion by microbial pathogens. Recently, we have demonstrated that the introduction of cecropin transgenes into Japanese medaka (Oryzias latipes) conferred resistance to infection by fish bacterial pathogens. Aside from a few reports documenting the antiviral effect of antimicrobial peptides including cecropins against mammalian viruses, there is no evidence for the effect of these peptides against fish viruses. In this article we present results of in vitro characterization of native cecropin B and a synthetic analogue, CF17, against several important fish viral pathogens—namely, infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus (VHSV), snakehead rhabdovirus (SHRV), and infectious pancreatic necrosis virus (IPNV). Upon coincubation of these peptides and viruses, the viral titers yielded in fish cells were reduced from several fold to 104-fold. Direct disruption of the viral envelope and disintegration of the viral capsids may be involved in the inhibition of viral replication by the peptides. Results of our studies demonstrate the potential of manipulating antimicrobial peptide genes by transgenesis to combat viral infection in fish.     

我国西尼罗病毒和Tahyna病毒的发现与流行

已发现100余种蚊传虫媒病毒在世界各地流行,其引发的人兽共患病是全世界关注的公共卫生问题。长期以来我国仅发现乙型脑炎和登革热两种蚊传虫媒病毒病,但近年来新发现西尼罗病毒和Tahyna病毒及其感染疾病流行。从我国新疆维吾尔自治区采集的蚊虫标本中分离到西尼罗病毒,大量血清学研究证明当地不仅存在西尼罗病毒感染所致疾病,还发生过西尼罗病毒感染引发的病毒性脑炎流行。目前已从新疆维吾尔自治区、青海省和内蒙古自治区采集的蚊虫标本中分离到Tahyna病毒,并发现其在自然界动物中的循环和导致的人类感染流行。西尼罗病毒和Tahyna病毒及其相关感染性疾病的发现为我国虫媒病毒及虫媒病毒病的预防与控制提出了新的挑战。     

Histological, serological and virulence studies on rainbow trout experimentally infected with recombinant infectious hematopoietic necrosis viruses

Several recombinant infectious hematopoietic necrosis viruses (IHNV) were produced by reverse genetics and their pathogenicity in trout was evaluated and compared to that of the wild type (wt) viruses IHNV and viral haemorrhagic septicemia virus (VHSV). Recombinant IHNVs used in this study were: rIHNV, identical to the wtIHNV; rIHNV-Gvhsv, a recombinant virus expressing the VHSV G gene instead of the IHNV G gene; rIHNV-Gmut, which possesses 2 targeted mutations in the glycoprotein; and rIHNVmut-Gmut, which is similar to the rIHNV-Gmut, but exhibits additional mutations along the genome. Results obtained in experimental infections showed that the rIHNV and rIHNV-Gmut were the most virulent recombinant viruses. Severity of the lesions induced by the different recombinant viruses was in agreement with mortality data. The kidney and the liver were the organs most affected by the most pathogenic viruses, and the lesions observed resembled those produced by wtIHNV. The introduction of mutations did not alter the tissue tropism of the virus. The recombinant viruses were able to replicate in fish, as shown by immunoperoxidase assay and RT-PCR. Antibodies against IHNV were detected in the fish inoculated with IHNV, rIHNV, rIHNV-Gmut and rIHNVmut-Gmut, and antibodies against VHSV were also found in fish infected with rIHNV-Gvhsv. Finally, antibody production was highest in fish infected with the rIHNVmut-Gmut even though this virus was the least virulent.     

Current trends in large‐scale viral surveillance methods in mosquitoes

Vector‐borne and zoonotic infectious diseases are serious public health concerns that affect approximately half of the world's population. In particular, arthropod‐borne viruses (arboviruses) have contributed to more mortality and morbidity worldwide with the emergence of dengue, chikungunya, yellow fever, and Zika virus diseases. The infections have scaled up due to urbanization, globalization, and international mobility. Traditionally, the spread of mosquito‐borne viral diseases to humans was considered a low health priority concern. However, their categorization as emerging infectious diseases and public health emergencies of international concern has heightened the attention given by the government, academia, research, and industry for the development of timely, cost‐efficient, and sustainable solutions. The urgency has increased in the wake of global climate change. The focus on effective interventions includes epidemiological monitoring, vector control measures, molecular diagnostics, vaccines, and environmental determinants. In this review, we discuss the etiology and predisposition of mosquito‐borne viruses that are detrimental to public health and economically damaging when disseminated as epidemics. We focus on the large‐scale virus surveillance methods with special reference to innovations and interventions in molecular detection science and technologies that include viral nucleic acid isolation, polymerase chain reaction (PCR)‐based diagnostics, and high‐throughput sequencing technologies. In addition, we discuss the development of a viral RNA extraction and PCR‐based diagnostic kit (Invirustech) that can extract viral RNA from mosquitoes with verified applications in PCR‐based molecular diagnostics of Pan‐flavivirus.     

Survival of enteric viruses under natural conditions in a subarctic river.

The survival of enteric viruses was studied in the vicinity of Fairbanks, Alaska at selected stations along a 317-km section of the Tanana River. This section was located downstream from all known domestic wastewater sources and was effectively sealed by a total ice cover. The mean flow time through the region was 7.1 days, during which initial viral population showed a relative survival rate of 34%. The tracing of native viruses at such great distances in the complete absence of other point and nonpoint viral sources has not been previously reported. Of the two methods of virus concentration used, viral recoveries from the disk adsorption virus elution procedure were far greater than those achieved with the Aquella system employed at that time. The fact the ratio of enteric viruses to fecal indicator bacteria was not constant clearly inferred that these bacteria were not an effectual measure of virus concentration. The persistence of fecal coliforms and fecal streptococci, however, attested to the microbiological health risk involved.     

Survival of enteric viruses under natural conditions in a subarctic river.

The survival of enteric viruses was studied in the vicinity of Fairbanks, Alaska at selected stations along a 317-km section of the Tanana River. This section was located downstream from all known domestic wastewater sources and was effectively sealed by a total ice cover. The mean flow time through the region was 7.1 days, during which initial viral population showed a relative survival rate of 34%. The tracing of native viruses at such great distances in the complete absence of other point and nonpoint viral sources has not been previously reported. Of the two methods of virus concentration used, viral recoveries from the disk adsorption virus elution procedure were far greater than those achieved with the Aquella system employed at that time. The fact the ratio of enteric viruses to fecal indicator bacteria was not constant clearly inferred that these bacteria were not an effectual measure of virus concentration. The persistence of fecal coliforms and fecal streptococci, however, attested to the microbiological health risk involved.     

Metagenomic Analysis of RNA Viruses in a Fresh Water Lake

Freshwater lakes and ponds present an ecological interface between humans and a variety of host organisms. They are a habitat for the larval stage of many insects and may serve as a medium for intraspecies and interspecies transmission of viruses such as avian influenza A virus. Furthermore, freshwater bodies are already known repositories for disease-causing viruses such as Norwalk Virus, Coxsackievirus, Echovirus, and Adenovirus. While RNA virus populations have been studied in marine environments, to this date there has been very limited analysis of the viral community in freshwater. Here we present a survey of RNA viruses in Lake Needwood, a freshwater lake in Maryland, USA. Our results indicate that just as in studies of other aquatic environments, the majority of nucleic acid sequences recovered did not show any significant similarity to known sequences. The remaining sequences are mainly from viral types with significant similarity to approximately 30 viral families. We speculate that these novel viruses may infect a variety of hosts including plants, insects, fish, domestic animals and humans. Among these viruses we have discovered a previously unknown dsRNA virus closely related to Banna Virus which is responsible for a febrile illness and is endemic to Southeast Asia. Moreover we found multiple viral sequences distantly related to Israeli Acute Paralysis virus which has been implicated in honeybee colony collapse disorder. Our data suggests that due to their direct contact with humans, domestic and wild animals, freshwater ecosystems might serve as repositories of a wide range of viruses (both pathogenic and non-pathogenic) and possibly be involved in the spread of emerging and pandemic diseases.     

Within you, without you: HIV-1 Rev and RNA export

There are hundreds of viruses that infect different human organs and cause diseases. Some fatal emerging viral infections have become serious public health issues worldwide. Early diagnosis and subsequent treatment are therefore essential for fighting viral infections. Current diagnostic techniques frequently employ polymerase chain reaction (PCR)-based methods to quickly detect the pathogenic viruses and establish the etiology of the disease or illness. However, the fast PCR method suffers from many drawbacks such as a high false-positive rate and the ability to detect only one or a few gene targets at a time. Microarray technology solves the problems of the PCR limitations and can be effectively applied to all fields of molecular medicine. Recently, a report in Retrovirology described a multi-virus DNA array that contains more than 250 open reading frames from eight human viruses including human immunodeficiency virus type 1. This array can be used to detect multiple viral co-infections in cells and in vivo. Another benefit of this kind of multi-virus array is in studying promoter activity and viral gene expression and correlating such readouts with the progression of disease and reactivation of latent infections. Thus, the virus DNA-chip development reported in Retrovirology is an important advance in diagnostic application which could be a potent clinical tool for characterizing viral co-infections in AIDS as well as other patients.     

Koch's postulates and the etiology of AIDS: an historical perspective.

This paper examines the debate over the human immunodeficiency virus (HIV) as the cause of acquired immunodeficiency syndrome (AIDS) from an historical perspective. The changing criteria for proving the link between putative pathological agents and diseases are discussed, beginning with Robert Koch's research on anthrax in the late nineteenth century. Various versions of 'Koch's postulates' are analyzed in relation to the necessity and sufficiency arguments of logical reasoning. In addition, alterations to Koch's postulates are delineated, specifically those required by the discovery of rickettsiae and viruses in the early twentieth century and by the immunological testing developed after mid-century to demonstrate the links between elusive viral agents and two diseases, hepatitis B and infectious mononucleosis. From this perspective, an examination of the AIDS debate is constructed. Molecular biologist Peter Duesberg's argument that HIV is not the cause of AIDS is analyzed in light of his contention that a version of Koch's postulates has not been satisfied. Additional research findings through 1990 relating to the etiology of AIDS are also noted.     

Development of DNA diagnostic methods for the detection of new fish iridoviral diseases

A new disease of epidemic proportions caused by fish viruses within the Iridoviridae family inflicts serious damage on red sea breams (Pagrus major) and striped jack (Caranx delicatissimus) populations grown in aquacultures in Japan. A partial segment of the fish iridoviral DNA was directly amplified using the polymerase chain reaction (PCR) with synthetic primers designed from well conserved nucleotide sequences between the frog virus 3 (Ranavirus) and the silkworm iridescent virus type 6. The deduced amino acid sequence from the nucleotide sequence of the PCR fragment demonstrates a high correlation with a partial sequence from the frog virus 3. Using the PCR method with specific primers, we could detect three of four different known types of fish iridoviruses in diseased fishes. To construct more reliable detection methods specific for this viral family, DNA fragments which can specifically hybridize with all of the four known iridoviridae viral DNAs were screened from the genomic library of one iridoviridae strain. The hybridization assay, using a specific fragment which contains regions which are highly homologous with a characterized partial sequence from the frog virus 3, proved to be a reliable diagnostic tool for fish iridoviral diseases.     

Interactions between commensal bacteria and viral infection: insights for viral disease control in farmed animals

Viral diseases cause serious economic loss in farmed animals industry. However, the efficacy of remedies for viral infection in farmed animals is limited, and treatment strategies are generally lacking for aquatic animals. Interactions of commensal microbiota and viral infection have been studied in recent years, demonstrating a third player in the interaction between hosts and viruses. Here, we discuss recent developments in the research of interactions between commensal bacteria and viral infection,including both promotion and inhibition effect of commensal bacteria on viral pathogenesis, as well as the impact of viral infection on commensal microbiota. The antiviral effect of commensal bacteria is mostly achieved through priming or regulation of the host immune responses, involving differential microbial components and host signaling pathways, and gives rise to various antiviral probiotics. Moreover, we summarize studies related to the interaction between commensal bacteria and viral infection in farmed animals, including pigs, chickens, fish and invertebrate species. Further studies in this area will deepen our understanding of antiviral immunity of farmed animals in the context of commensal microbiota, and promote the development of novel strategies for treatment of viral diseases in farmed animals.