Location: Aquatic Animal Health Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1 - Determine population and strain responses to vaccines and infectious pathogens (e.g., Edwardsiella ictaluri, Flavobacterium columnare), using genetically characterized fish. Objective 2 - Determine characteristics of coinfections and their role in disease processes in aquaculture and aquatic environments. Objective 3 - Identify microbial pathogen genes and pathways critical for host pathogenesis and immunity. Objective 4 - Develop and validate new and novel pathogen detection tests for Edwardsiella ictaluri, Flavobacterium columnare, Streptococcus iniae and S. agalactiae using genomic, proteomic, microbiological and immunological approaches.
1b. Approach (from AD-416):
Fish farmers continue to identify disease as a significant negative impact on profitability. Therefore, the goal of this project is to improve fish health and reduce this negative impact. Using a multi-disciplinary approach, we will accomplish four objectives that address important questions about bacterial diseases that affect the catfish (e.g., Edwardsiella ictaluri, Flavobacterium columnare) and tilapia (e.g., Streptococcus iniae, S. agalactiae) industries. Studies will be conducted at the gene, protein, individual, and/or population levels. Questions remain about some barriers to optimum vaccine efficacy in the field and about the responses of current and future strains of fish to pathogens and vaccines. Therefore, Objective 1 will determine population and strain responses to vaccines and infectious pathogens (e.g., E. ictaluri, F. columnare), using genetically characterized fish. In most intensive aquaculture production systems, multiple pathogens are present and result in mortality. Objective 2 will determine characteristics of coinfections and their role in disease processes in aquaculture and aquatic environments. Objective 3 will identify microbial pathogen genes and pathways critical for host pathogenesis and immunity that will provide important information for future vaccine development. Objective 4 will develop and validate new and novel pathogen detection tests for E. ictaluri, F. columnare, S. iniae and S. agalactiae so that these can be used in fish health management. The results from this work will contribute to present and future vaccine development, provide useful management information about farm use of vaccines and coinfections, and leverage development of future catfish strains being developed for the industry.
3. Progress Report:
Substantial progress was made to evaluate channel catfish families that were selectively bred for resistance against Edwardsiella (E.) ictaluri for susceptibility to Flavobacterium (F.) columnare infection. Data demonstrated that there may be a negative correlation between the resistance of catfish to F. columnare and their resistance to E. ictaluri. Substantial progress was made on the co-infection of Gyrodactylus and F. columnare. Research results revealed that the infection of Gyrodactylus increased the susceptibility of fish to infection of F. columnare. Substantial progress was made to determine factors influencing the vectoring ability of parasites for bacterial pathogens. The influence of 20 different lectins on the ability to affect the attachment of bacteria E. ictaluri to the theront Ichthyophthirius (Ich) was evaluated. Substantial progress was made to expand proteomic work for a large panel of F. columnare isolates for comparative proteomics. No clear association between virulence to tilapia and genomovar type of these isolates were found. Significant progress was made to identify immune genes of channel catfish in response to infection or vaccination of Aeromonas (A.) hydrophila. Significant progress was made to characterize the extracellular proteins of A. hydrophila. Significant progress was made to develop and evaluate attenuated vaccines to protect catfish and tilapia against Edwardsiella tarda and A. hydrophila. Attenuated vaccines have been developed and invention disclosures have been filed. Significant progress was made to develop and evaluate recombinant Deoxyribonucleic acid (DNA) vaccine against the protozoan parasite Ich. The efficacy studies on these recombinant DNA vaccines were determined.
1. Attenuated polyvalent vaccine developed to protect tilapia against Streptococcus agalactiae. Streptococcosis caused by Streptococcus (S.) agalactiae is a hyperacute systematic disease that affects both cultured and wild fish species in various aquatic environments (freshwater, estuarine, and marine). ARS researchers at Auburn, Alabama, developed an attenuated polyvalent vaccine to protect tilapia against infections by both biotype I and biotype II strains of S. agalactiae. The attenuated polyvalent vaccine offered significant protection to tilapia against infections of S. agalactiae. The use of this polyvalent vaccine will protect tilapia against streptococcosis caused by S. agalactiae.
2. Attenuated vaccine developed to protect catfish and tilapia against Edwardsiella tarda. Bacterial diseases caused by Edwardsiella (E.) tarda are plaguing the aquaculture industry, causing losses to be estimated in millions of dollars annually. ARS researchers at Auburn, Alabama, developed an attenuated vaccine Eta30305NOVO that was found to be safe and highly efficacious in protecting fish against infection of E. tarda. The use of this vaccine will prevent future disease outbreaks in catfish and tilapia caused by E. tarda.
3. Attenuated vaccine developed to protect catfish against Aeromonas hydrophila. Disease outbreaks caused by Aeromonas (A.) hydrophila is causing economic loss in millions of dollars annually. ARS researchers at Auburn, Alabama, have developed an attenuated vaccine AH11NOVO to protect catfish against A. hydrophila infection. AH11NOVO was found to offer 100% protection to catfish against infections of A. hydrophila. The use of this vaccine will prevent future disease outbreaks in catfish caused by A. hydrophila.
4. Virulence factors identified in the highly virulent West Alabama isolate of Aeromonas hydrophila. Disease outbreaks caused by Aeromonas (A.) hydrophila have led to an estimated loss of more than $3 million annually in West Alabama. ARS researchers at Auburn, Alabama, identified virulence factors of these highly virulent isolates of A. hydrophila, including hemolysin, aerolysin, elastase (metalloprotease), nuclease, and nucleotidase. The identification of these virulence factors will provide novel strategies to control disease outbreaks caused by these highly virulent A. hydrophila.
5. Compare immune responses against parasite Ichthyophthirius between channel catfish and hybrid catfish. The hybrid catfish (female channel catfish x male blue catfish) has been reported to exhibit many commercially desirable characteristics, including faster growth, better feed conversion, and resistance to diseases. There is limited information available on the immune protection of hybrid catfish against parasite Ichthyophthirius (Ich). ARS scientists in Auburn, Alabama, compared immune response and host protection between channel catfish and hybrid catfish to evaluate a fish immune protection against the parasite. The immunized channel catfish and hybrid catfish showed a higher anti-Ich antibody level and higher survival (90-100%) than non-immunized controls (0%). Overall results indicated that hybrid catfish could develop the same strong immune protection against Ich as its parent channel catfish. These study results will help fish farmers and fish breeders to select disease resistant fish to minimize the impact of disease on cultured fish.
Yeh, H., Klesius, P.H. 2012. Channel catfish (Ictalurus punctatus Rafinesque, 1818) tetraspanin membrane protein family: Identification, characterization and phylogenetic analysis of tetraspanin 3 and tetraspanin 7 (CD231) transcripts. Fish Physiology and Biochemistry Journal. 38:1553-1563.