M E S '9 8 - University of Georgia College of Veterinary Medicine

FishGeorgia’s aquaculture industry continues to expand with its greatest increase inchannel catfish. Since 1995, pond acreage for catfish farming has grown from6,000 to 8,000 acres. Major areas of disease concern continue to be losses causedby channel catfish virus and the bacteria Flavobacterium columnare andEdwardsiella ictaluri. Furthermore, there have been extensive losses in Georgiathis spring because of the protozoan parasite Ichthyophthirius multifiliis or Ich.In addition to Georgia’s food fish industry, there is an increasing interest inornamental fish production. As Georgia’s aquaculture industries continue togrow, research aimed at improving the health of aquatic animal species willultimately help growers reduce production costs and improve profits.Role of Signaling Phosphoproteins inCatfish Antibacterial Innate ResistanceNonspecific cytotoxic cells (NCC) are theteleost equivalent of mammalian natural killercells. NCC lyse protozoa and tumor cells andNCC may participate in anti-bacterial resistanceby the release of cytokines and amplificationof inflammatory responses. We haverecently identified an antigen receptor (i.e.,natural killer receptor protein-1/NCCRP-1) onthe membrane of NCC. Cross-linkage of thisreceptor with monoclonal antibody ortumor/protozoan antigen initiates a downstreamsignaling process that eventually activatescytotoxicity. A major consequence of thisactivation/signaling process is the phosphorylationof many different intermediate proteinsnecessary for NCC function. In the presentstudy, we identified different “species” ofphosphoproteins. NCCRP-1 was phosphorylatedon both tyrosine and serine residues. Thiswas identified in Western blots using monoclonalantibodies specific for phosphotyrosineand phosphoserine residues. BOX-1 motifs areproline-rich consensus sequences found on theN-terminus of NCCRP-1 and on differentcytokine receptors, on growth hormone receptors,and so on. These motifs are the knowndocking sites for JAK kinases. NCC membranelysates were treated with the chemical crosslinkerDSS, and it was found that JAK-2 wasphysically associated with NCCRP-1.Additional data suggesting that NCCRP-1 is animportant signaling phosphoprotein was thepresence of STAT-6 in NCC cytosol preparations.Evidence that this protein may be associatedwith transcriptional activation was shownby demonstrating that STAT-6 translocates tothe NCC nucleus. These studies demonstratedthat NCCRP-1 may be responsible for bothsignaling responses and gene transcriptionalactivation.Liliana Jaso-Friedmann and Donald L. Evansdevans@calc.vet.uga.eduCatfish Immune Response to PlasmidVaccinationChannel catfish (Ictalurus punctatus)farming accounts for approximately half thetotal aquaculture production and farm gatevalue in the United States. Compared with terrestrialfood animal production industries, verylittle is known about the health managementaspects of channel catfish, especially withregard to infectious disease. As with mostcommercially important food animals, there isa pressing need for safe, effective, and inexpensivevaccines in the channel catfish cultureindustry. DNA-mediated vaccines, or plasmidvaccines, are a rapidly emerging variation ofsubunit vaccines. The long-range goal of thisresearch is to develop safe, effective, andaffordable plasmid vaccines for infectious diseasesimportant to the channel catfish cultureindustry. The current objective in pursuit ofthis goal is to investigate the catfish immuneresponse, both humoral and cellular, generatedby immunization with a plasmid vaccine. Ourlaboratory has demonstrated that foreign proteingenes under the control of mammaliantranscription promoters will be expressed bychannel catfish cells both in vitro and in vivo.Our expectations are that, at the end of thisproject, we will have demonstrated that channelcatfish will mount a humoral and cellmediatedimmune response against an in vivoexpressed foreign antigen delivered by plasmidvaccination. These observations will providepreliminary data that will facilitate funding forfuture research towards the development ofvaccines targeted against specific channel catfishdisease agents, such as channel catfishvirus and the bacterium Edwardsiella ictaluri.Steven E. Poet and Donald E. Evanspoets@calc.vet.uga.edu12