VACCINES: PREVENTION OF DISEASES IN AQUATIC ANIMALS

Authors: Klesius, Phillip; Shoemaker, Craig; Evans, Joyce; Lim, Chhorn

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/30/1999
Publication Date: 6/1/2001
Citation: KLESIUS, P.H., SHOEMAKER, C.A., EVANS, J.J., LIM, C.E. VACCINES: PREVENTION OF DISEASES IN AQUATIC ANIMALS. In: CHHORN LIM, CARL D. WEBSTER eds. NUTRITION AND FISH HEALTH. FOOD PRODUCTS PRESS AN INPRINT OF THE HAWORTH PRESS, INC BINGHAMTON, NY. 2001:317-335.

Interpretive Summary: VACCINES: PREVENTION OF DISEASES IN AQUATIC ANIMALS Phillip H. Klesius, Craig A. Shoemaker, Joyce J. Evans and Chhorn Lim Fish Diseases and Parasites Research Laboratory USDA ARS Auburn, AL The use of vaccines to prevent diseases of cultured food fish is increasing with the rapid growth in the numbers of fish species cultured worldwide. Vaccines provide life long and cost-effective protection against specific infectious agents by stimulating the fish=s defense system. Health management practices that include the use of vaccines are significantly reducing the use of antibiotics and chemicals that have caused environmental and human health problems. In the past five years, the number of vaccines available has significantly increased for use in Atlantic salmon, rainbow trout, channel catfish, turbot, sea-bass, sea bream and cod. Vaccines are needed for tilapia and hybrid bass that are subjected to significant losses due to certain infectious bacteria in intensive culture systems. Currently, the majority of fish vaccines are killed products that require the use of adjuvants for boostering their efficacy and duration of protection. Modified live or attenuated vaccines are improved products that are being tested for licensing and use in channel catfish against enteric septicemia of catfish. Attenuated vaccines are more advantageous because they stimulate both cellular and humoral defenses, do not require adjuvants and are more easily administrated at low cost. Certain types of adjuvants cause adverse reactions and loss of the product. Licensed vaccines in use today are designed to provide protection against bacterial diseases. Vaccines against Vibrio anguilarum, V. ordalii, V. salmonicida, Yersinia ruckeri, Aeromonas salmonicidia and Edwardsiella ictaluri are commercially available. They are administrated by either injection, immersion or incorporation in the feed. Salmonid vaccines are commonly administrated by injection of individual fish, the most costly and time-consuming method. An immersion route is both less costly and time consuming. Immunization of very young fish in large numbers is better accomplished by immersion vaccines, in minutes, with less stress on the fish. Oral immunization is still in the experimental stage, but is a route that offers distinct advantages, if problems with manufacturing and shelf life can be solved. The optimal age to immunize fish was believed to be not before 30 days post-hatch. Our research has demonstrated that an E. ictaluri attenuated vaccine works in fish as young as 1-2 days post- hatch, when challenged at 40 days post- hatch with virulent E. ictaluri. In the channel catfish industry, 7-10 day fry are released into ponds where they are exposed and susceptible to E. ictaluri without protection provided through vaccination in the hatchery. DNA vaccines and recombinant vaccines are being developed and experimentally tested. Problems in the use of these types of vaccines need to be solved, but it is hoped that viral and parasite vaccines can be developed from gene designed and attenuated vaccines. Fish vaccinology will encounter similar problems associated with vaccines used in other animal species that include lack of protection against all serovars and the emergence of new serovars in intensive culture systems. The use of fish vaccines is justified economically by significantly reducing the production cost. These benefits include reduced mortality, prevention of decreased growth and performance due to infection, reduction in wasted feed and reduced use of chemicals and antibiotics. The practice of fish vaccination is a major tool in effective fish health management programs designed to improved product safety and prevent pollution of environment.

Technical Abstract: The use of vaccines to prevent diseases of cultured food fish is increasing with the rapid growth in the numbers of fish species cultured worldwide. Vaccines provide life long and cost-effective protection against specific infectious agents by stimulating the fish's defense system. Health management practices that include the use of vaccines are significantly reducing the use of antibiotics and chemicals that have caused environmental and human health problems. Vaccines are needed for tilapia and hybrid bass that are subjected to significant losses due to certain infectious bacteria in intensive culture systems. A modified live or attenuated vaccine is licensed and used in channel catfish against enteric septicemia. Attenuated vaccines are more advantageous because they stimulate both cellular and humoral defenses, do not require adjuvants and are more easily administrated at low cost. The optimal age to immunize fish was believed to be not before 30 days post-hatch. Our research has demonstrated that an E. ictaluri attenuated vaccine works in fish as young as 1-2 days post-hatch, when challenged at 40 days post-hatch with virulent E. ictaluri. In the channel catfish industry, 7-10 day fry are released into ponds where they are exposed and susceptible to E. ictaluri without protection provided through vaccination in the hatchery. Economically, fish vaccine use reduces the production cost. These benefits include reduced mortality, prevention of decreased growth and performance due to infection, reduction in wasted feed and reduced use of chemicals and antibiotics. The practice of fish vaccination is a major tool in effective fish health management programs designed to improved product safety and prevent pollution of environment.