Experimental Cryptobia salmositica (Kinetoplastida) infections in Atlantic salmon, Salmo salar L.: cell‐mediated and humoral immune responses against the pathogenic and vaccine strains of the parasite

Abstract

Hatchery‐reared Atlantic salmon, Salmo salar L., were vaccinated intraperitoneally (i.p.) with a live attenuated Cryptobia salmositica vaccine (either 100 000 or 5000 parasites fish−1) and 4 weeks later were challenged with the parasite (either 100 000 or 5000 parasites fish−1). Unvaccinated, infected salmon had high parasitaemias and were anaemic. Fish given a high dose (100 000 parasites fish−1) had higher parasitaemias than fish given the lower dose. Vaccinated fish had low parasitaemias and a mild anaemia, but recovered quickly after challenge. Complement‐fixing antibody increased in vaccinated fish after challenge and was highest at 2 weeks post‐challenge. The cell‐mediated response (both T cells and B cells) was depressed in infected fish until 4 weeks after infection. In vaccinated fish, the humoral response (i.e. B‐lymphocytes) was greater than the cell‐mediated response (i.e. T‐lymphocytes). In contrast, infected fish had a greater cell‐mediated than humoral immune response.

Innate cell-mediated immune response and peripheral leukocyte populations in Atlantic salmon, Salmo salar L., to a live Cryptobia salmositica vaccine

“…The live C. salmositica vaccine induced a characteristic parasitemia profile and humoral response in Atlantic salmon (Ardelli and Woo 2002;Chin et al 2004). Antibodies were detected by 4 w.p.v., and the titer continued to increase as parasitemia decreased.…”

“…The kinetics of the humoral immune response has been well characterized over the course of vaccination with C. salmositica (e.g. Sitja-Bobadilla and Woo 1994; Ardelli and Woo 2002;Chin et al 2004), but the cellular immune response, specifically circulating leukocytes, is less well understood.…”

“…Cell-mediated immune responses against C. salmositica have been shown using delayed-type hypersensitivity reactions (Thomas and Woo 1990;Feng and Woo 1996), inhibition of macrophage migration (Thomas and Woo 1990), mixed lymphocyte reactions (Ardelli and Woo 2002), and respiratory burst activity of head kidney macrophages (Mehta and Woo 2002).…”

Acquired cell-mediated protection in rainbow trout, Oncorhynchus mykiss , against the haemoflagellate, Cryptobia salmositica

“…It has also lost some polypeptide bands and others are antigenically different from those of the pathogen (Woo and Thomas 1991). Extensive studies have been carried out on vaccination and the humoral protection in infected or vaccinated fish (reviewed by Woo 2001); there are indications that cell-mediated immunity is activated and may also be involved in protection (Thomas and Woo 1989b;Feng and Woo 1996;Ardelli and Woo 2002).…”

In vitro nutritional requirements and metabolic products of pathogenic and nonpathogenic strains of Cryptobia salmositica: essential carbohydrates and amino acids

“…Thus, in addition to increasing the buffering capacity of media, using galactose or mannose (pathogen) and lactose (nonpathogenic) in place of glucose enhanced multiplication of C. salmositica. This may, in part, explain the multiplication of the nonpathogenic (vaccine) strain in Atlantic salmon (Ardelli & Woo 2002), but not in rainbow trout (Li & Woo 1990). Further studies are necessary to confirm this suggestion.…”