Antibody increases phagocytosis and killing of Lactococcus garvieae by rainbow trout (Oncorhynchus mykiss, L.) macrophages

The eel immune system: present knowledge and the need for research

“…This same effect has also been observed in salmonids and carps (Ottinger, Johnson, Ewart, Brown & Ross 1999; Robertsen 1999; Sakai 1999; John, Chandran, Aruna & Anbarasu 2002). In other studies, the opsonization of bacteria with antibodies has been shown to improve phagocytosis in rainbow trout (Barnes, Guyot, Hansen, Horne & Ellis 2002), tilapia (Leung et al. 1995) and turbot (Figueras, Santarem & Novoa 1997).…”

Lactococcus garvieae: an emerging bacterial pathogen of fish

“…Binding of antibodies by non-immune mechanisms inhibits activation of complement by the classical pathway and allows the bacterium to shield itself from specific antibodies and evade phagocytosis. Barnes et al (2002b) showed that non-capsulated L. garvieae was capable of nonspecifically binding immunoglobulin more efficiently than capsulated isolates, an observation which seems inconsistent with the avirulence of non-capsulated isolates. However, it must be considered that surface proteins play integral roles in adhesion and colonisation of host tissues, and that non-specific binding to host serum proteins might therefore inhibit adhesion of non-capsulated isolates to host cells (Barnes et al 2002a).…”

“…The observed increased bactericidal activity of immune serum was likely not due to complement, as the serum was heattreated. Fluorescence micro scopy of fluorescein-isothiocyanate labelled bacteria incubated with macrophages indicated that 90% of macrophages contained internalised bacteria treated with immune serum, while between 0 and 2% of macrophages internalised bacteria treated with non-immune serum (Barnes et al 2002b). Many Gram-positive bacteria employ non-specific binding of immunoglobulins by their crystallizable fragment region as a virulence factor (Agniswamy et al 2004).…”

Lactococcus garvieae strains from yellowtail Seriola quinqueradiata carry different lengths of fimbriae on their cell surface

“…The capsulated strain is more virulent to yellowtail than the non‐capsulated phenotype strain with resistance to the opsonophagocytosis of the yellowtail phagocytic cells 3,4 and serum killing 8 . Therefore, a cell capsule is thought to be one of the virulence factors in L. garvieae cells from yellowtail 4–9 . Recently, oral or injectable vaccines have been developed for preventing L. garvieae infection in yellowtail.…”