Viral Diseases Infecting Finfishes and Ornamental Fishes: A Review of Relevance to Sustainable Aquaculture (original) (raw)

Challenges and Solutions to Viral Diseases of Finfish in Marine Aquaculture

Pathogens

Aquaculture is the fastest food-producing sector in the world, accounting for one-third of global food production. As is the case with all intensive farming systems, increase in infectious diseases has adversely impacted the growth of marine fish farming worldwide. Viral diseases cause high economic losses in marine aquaculture. We provide an overview of the major challenges limiting the control and prevention of viral diseases in marine fish farming, as well as highlight potential solutions. The major challenges include increase in the number of emerging viral diseases, wild reservoirs, migratory species, anthropogenic activities, limitations in diagnostic tools and expertise, transportation of virus contaminated ballast water, and international trade. The proposed solutions to these problems include developing biosecurity policies at global and national levels, implementation of biosecurity measures, vaccine development, use of antiviral drugs and probiotics to combat viral infect...

Countermeasures against viral diseases of farmed fish

Antiviral Research, 2012

Farmed fish provide an increasing fraction of the human food supply, and are of major economic importance in many countries. As in the case of terrestrial agriculture, bringing together large numbers of animals of a single species (i.e., monoculture) increases the risk of infectious disease outbreaks, including viral infections. Aquaculture, in which farmed fish are kept at high population densities in close proximity with wild fish reservoirs, is ideal for the emergence of wild-type pathogens that exist benignly in local wild fish and/or the spreading of aquatic pathogens to wild fish that enter into or come into close proximity with net cages and with fish escaping from them. This paper provides a general review for the nonspecialist of viral diseases of farmed fish and how they could be prevented or treated. It has five principal objectives: (1) to provide an update on the most important and emerging viral diseases of salmonid aquaculture; (2) to review general aspects of innate antiviral defense against virus infections in fish, including recent advances in antiviral signaling; (3) to discuss current principles and practices of vaccinating fish; (4) to review antiviral drugs that have activity against viruses of farmed fish, and current barriers to employing them in aquaculture; and (5) to discuss the growing use of ''functional feeds'' in salmonid aquaculture to mitigate viral diseases. In conclusion, despite the challenging aquatic environment, it is expected that well thought-out combinations of vaccination and immunostimulants and/or antiviral drugs could provide solid protection against viral diseases of farmed fish.

Viruses of Fish: An Overview of Significant Pathogens

Viruses, 2011

The growing global demand for seafood together with the limited capacity of the wild-capture sector to meet this demand has seen the aquaculture industry continue to grow around the world. A vast array of aquatic animal species is farmed in high density in freshwater, brackish and marine systems where they are exposed to new environments and potentially new diseases. On-farm stresses may compromise their ability to combat infection, and farming practices facilitate rapid transmission of disease. Viral pathogens, whether they have been established for decades or whether they are newly emerging as disease threats, are particularly challenging since there are few, if any, efficacious treatments, and the development of effective viral vaccines for delivery in aquatic systems remains elusive. Here, we review a few of the more significant viral pathogens of finfish, including aquabirnaviruses and infectious hematopoietic necrosis virus which have been known since the first half of the 20th century, and more recent viral pathogens, for example betanodaviruses, that have emerged as aquaculture has undergone a dramatic expansion in the past few decades.

Viral vaccines for aquaculture

Annual Review of Fish Diseases

A description of the types of viral vaccines that are being developed for fish is presented in this review. All three types of vaccines, i.e. killed, attenuated, and subunit vaccines, have worked to some extent in fish under controlled laboratory conditions. However, with the exception of a killed vaccine for spring viremia of carp, there are no commercially available viral vaccines for fish. The introduction of these vaccines to aquaculture will require an understanding of immune recognition in fish and the development of cost-effective ways of producing a safe, immunogenic vaccine. A review of available information on vaccines for infectious pancreatic necrosis virus, viral hemorrhagic septicemia virus, infectious hematopoietic necrosis virus, spring viremia of carp virus, and channel catfish virus is presented. These are the main viruses that have been investigated for vaccine development. Very little information is available on vaccines for other viral diseases of fish.

Viral vaccines for farmed finfish

VirusDisease, 2013

Over the past decade, aquaculture has grown at an average annual growth rate of approximately 6 % worldwide despite many challenges. Viral diseases are one of the major challenges that are threatening a sustainable growth of finfish farming globally. Vaccination of farmed fish plays an important role in commercial fish farming to mitigate viral diseases. In this review, we summarized the major viral diseases that have caused serious economic losses, and emerging diseases that pose a potential threat to aquaculture. The current status of viral vaccines in farmed fish are discussed, particularly the different types of vaccines that were licensed in recent years and are now commercially available, and the routes of delivery of those vaccines including the merits and demerits of each of these delivery method. Furthermore, the article provides an overview of different experimental vaccines that have been reported in the literatures in recent years besides highlighting the future need for developing cost-effective, oral vaccines that can be easily applicable at farm level.

Viral Diseases of Fish and Shellfish in Australia

1997

Except for table and pearl oyster culture, marine aquaculture in Australia has only a short history. This, together with the less intensive culture methods which are usually employed, probably explains why relatively few viral diseases have been detected and even fewer are of significance. However, we predict that, as more species are brought into aquaculture and management practices intensify, viral diseases of both fin and shellfish will assume greater significance. The one exception is salmonid mariculture which is based on stocks which are uniquely free of the major, pathogenic salmonid viruses as a result of their effective quarantine from northern hemisphere populations. In Australian finfish mariculture the major pathogen is the nodavirus which causes mass mortality in larval barrumundi (Lates calcarifer). The recent massive mortality of pilchards (Sardinops sagax) is also discussed as are lymphocystis and a number of less important viral diseases. No viruses of com mercial significance have been detected in Australian molluscs, although a herpesvirus infecting juvenile clams Katelysia sp. has been a significant impediment to commercialisation of these shellfish. The situation with shrimps is somewhat different as a new syndrome called mid-crop mortality syndrome (MCMS) has caused major losses. This syndrome appears to be a multifactorial disease with at least four viruses being visualised by electronmicoscopy. Of these, two are regarded as the most important; a parvo-like virus (spawner-isolated mortality virus) and a possible rhabdo-like virus (gill-associated virus) which resembles yellowhead virus.

Viral Diseases of Fish and Shellfish in Australian Mariculture

Fish Pathology, 1998

Except for table and pearl oyster culture, marine aquaculture in Australia has only a short history. This, together with the less intensive culture methods which are usually employed, probably explains why relatively few viral diseases have been detected and even fewer are of significance. However, we predict that, as more species are brought into aquaculture and management practices intensify, viral diseases of both fin and shellfish will assume greater significance. The one exception is salmonid mariculture which is based on stocks which are uniquely free of the major, pathogenic salmonid viruses as a result of their effective quarantine from northern hemisphere populations. In Australian finfish mariculture the major pathogen is the nodavirus which causes mass mortality in larval barrumundi (Lates calcarifer). The recent massive mortality of pilchards (Sardinops sagax) is also discussed as are lymphocystis and a number of less important viral diseases. No viruses of com mercial significance have been detected in Australian molluscs, although a herpesvirus infecting juvenile clams Katelysia sp. has been a significant impediment to commercialisation of these shellfish. The situation with shrimps is somewhat different as a new syndrome called mid-crop mortality syndrome (MCMS) has caused major losses. This syndrome appears to be a multifactorial disease with at least four viruses being visualised by electronmicoscopy. Of these, two are regarded as the most important; a parvo-like virus (spawner-isolated mortality virus) and a possible rhabdo-like virus (gill-associated virus) which resembles yellowhead virus.

Reassortant viruses threatening fish aquaculture

Reviews in Aquaculture

Aquaculture provides more than half of fish destined for human consumption worldwide. In aquaculture, infectious diseases triggered by viruses are amongst the major cause of mortality of farmed fish. The cohabitation of different virus strains in the same geographical area opens the possibility to natural reassortment. Virus reassortment is a characteristic recombination process of segmented viruses in which different viruses merge their genome by the shuffling of complete segments. This is