ARS | Publication request: Antigens provide immunity against Ich in channel catfish trials

Submitted to: Global Aquaculture Advocate
Publication Type: Popular Publication
Publication Acceptance Date: July 1, 2009
Publication Date: September 1, 2009
Citation: Xu, D., Klesius, P.H., Shoemaker, C.A. 2009. Antigens provide immunity against Ich in channel catfish trials. Global Aquaculture Advocate.12(4): 70-71.

Technical Abstract: Studies were conducted to determine effects of 1) types of Ich antigens and routes of immunization, 2) methods of inactivated trophonts, and 3) antigen doses on fish immune protection against Ichthyophthirius multifiliis Fouquet (Ich). All catfish immunized with live theronts by immersion, live theronts by IP injection, or 90% of catfish immunized by IP injection with sonicated trophonts survived theront challenge. Sonicated trophonts administered by immersion, BSA by IP injection, or non-immunized controls were not protected and all of the fish died after 2 weeks post parasite challenge. The fish immunized with 1) 1% formalin-inactivated trophonts, 2) 3% formalin-inactivated trophonts and 3) freeze-thawed trophonts at a dose of 20 trophonts/g of fish showed survival rates from 33.3% to 44.3% and had significantly higher survival than control fish (no survival). Fish immunized with the higher doses of trophonts (10-20 trophonts/g fish) showed higher survival (60-63%) than those receiving 5 trophonts/g fish (23%) or no trophont control (<7%). Vaccination against the parasite Ich is an alternative to chemical treatment especially the Ich infection which is difficult to treat by chemotherapy.