This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, X. Articles by Dickerson, H. W. Search for Related Content PubMed PubMed Citation Articles by Wang, X. Articles by Dickerson, H. W.

Surface Immobilization Antigen of the Parasitic Ciliate Ichthyophthirius multifiliis Elicits Protective Immunity in Channel Catfish (Ictalurus punctatus)

Department of Medical Microbiology and Parasitology, College of Veterinary Medicine, The University of Georgia, Athens, Georgia 30602-7371

Received 12 July 2001/ Returned for modification 21 September 2001/ Accepted 17 October 2001

Channel catfish (Ictalurus punctatus) that survive infection with the parasitic ciliate Ichthyophthirius multifiliis acquire immunity to subsequent challenge and produce specific antibodies in serum that immobilize the parasite in vitro. Cellular surface protein antigens targeted by these antibodies are referred to as immobilization antigens (i-antigens). By using an immobilizing mouse monoclonal antibody as a ligand, the i-antigen of I. multifiliis isolate G5 was purified to homogeneity by immunoaffinity chromatography, and its immunogenicity was confirmed by inoculating rabbit and channel catfish to produce immobilizing antisera. To test the purified i-antigen as a subunit vaccine, channel catfish fingerlings were injected intraperitoneally (i.p.) with purified i-antigen at a dose of 10 µg/fish in complete Freund’s adjuvant on day 1, followed by a second i.p. injection of the same amount of i-antigen in incomplete Freund’s adjuvant on day 15. Negative control fish were immunized similarly with either bovine serum albumin (BSA) or an immobilization-irrelevant I. multifiliis protein. On day 84, the fish were challenged with live I. multifiliis G5 theronts at a dose of 15,000 cells per fish. Seventy-two percent of the fish immunized with i-antigen survived the challenge. All negative control fish died within 16 days of exposure. There was a significant difference in the median days to death between the negative control fish injected with BSA and the fish that died following vaccination with i-antigen. Fish injected with i-antigen developed high immobilizing antibody titers in serum. This is the first demonstration of a direct role for i-antigens in the elicitation of protective immunity, suggesting that these proteins by themselves serve as effective subunit vaccines against I. multifiliis.

This article has been cited by other articles:

• Maki, J. L., Dickerson, H. W. (2003). Systemic and Cutaneous Mucus Antibody Responses of Channel Catfish Immunized against the Protozoan Parasite Ichthyophthirius multifiliis. CVI 10: 876-881 [Abstract] [Full Text]