Differences in virulence between two serotypes of Ichthyophthirius multifiliis.
Naive channel catfish Ictalurus punctatus were infected by 2 isolates of the parasitic ciliate Ichthyophthirius multifiliis that differed in virulence. The isolates, NY1 and G5, Serotypes A and D, respectively, express different surface immobilization-antigens. The virulence of the 2 isolates was compared using tail-fin infections to quantitate parasite numbers and by analysis of the survival of infected fish. Although NY1 infected fish at a lower level than G5, all NY1-infected fish died, but 51% of G5-infected fish survived. The greater virulence of NY1 is apparently a consequence of its shorter life cycle, which results in overwhelming reinfection of fish before they can develop a protective immune response. This report represents the first experimental evidence for differences in virulence between serotypes of I. multifiliis.
Swennes
Alton G
AG
Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Noe
Jane G
JG
Findly
R Craig
RC
Dickerson
Harry W
HW
D000818:Animals; D016770:Ciliophora Infections / Q000145:classification / Q000401:mortality / Q000469:parasitology / Q000662:veterinary*; D005393:Fish Diseases / Q000453:epidemiology / Q000401:mortality / Q000469:parasitology*; D016803:Hymenostomatida / Q000145:classification* / Q000276:immunology / Q000472:pathogenicity*; D007059:Ictaluridae / Q000469:parasitology*; D007249:Inflammation / Q000469:parasitology / Q000662:veterinary; D012703:Serotyping / Q000662:veterinary; D013997:Time Factors; D014774:Virulence