Cell-surface properties of Lactococcus garvieae strains and their immunogenicity in the yellowtail Seriola quinqueradiata

Abstract

The cell-surface properties of strains of Lactococcus garvieae were examined. Two capsular types were found, one with a highly developed capsule (KG9408) and one with a micro-capsule (MS93003) carrying fimbriae-like components projecting from the cell surface. One strain (NSS9310) had neither cell capsular nor fimbriae-like structures on its cell surface. The strains with the highly developed capsule were more virulent to fish than either the micro-capsular or non-capsular strains. The KG9408, MS93003 and NSS9310 strains could be clearly differentiated by their susceptibility to bacteriophages. Protection against L. garvieae infection was induced in the yellowtail Seriola quinqueradiata by immunization with formalin-killed L. garvieae KG9408 and MS93003 cells. Although protection was also induced by immunization with NSS9310, the level of protection was significantly lower than that with KG9408 and MS93003 vaccines. Passive immunization with yellowtail immune sera raised against KG9408 and MS93003 conferred strong protection on yellowtail with rapid bacterial clearance after challenge with L. garvieae. Immunoblotting analysis of protein antigens extracted from L. garvieae strains using rabbit anti-KG9408 and anti-MS93003 sera and yellowtail anti-KG9408 and anti-MS93003 sera indicated that some bands in KG9408 and MS93003 strains were not detectable in NSS9310.KEY WORDS: Immunogenicity ⋅ Lactococcus garvieae ⋅ Seriola quinqueradiata ⋅ Cell capsule ⋅ Fimbriae Resale or republication not permitted without written consent of the publisherDis Aquat Org 51: [169][170][171][172][173][174][175][176][177] 2002 thought to play roles in the pathogenicity of L. garvieae infection, possibly by increasing resistance to fish phagocytosis (Yoshida et al. 1996(Yoshida et al. , 1997.Control of Lactococcus garvieae infection in yellowtail culture has depended on chemotherapy with macrolides. The identification of multiple drug-resistant strains has indicated future problems in controlling the pathogen (Aoki et al. 1990). Recently, oral and injectable vaccines against L. garvieae infection in Seriola quinqueradiata have been developed and commercialized in Japan. Experimental vaccination against L. garvieae has been described (Iida et al. 1982, Sato et al. 1996 and has been reported to provide immunity and increased opsonic activity in the fish. However, no detailed information on the antigenicity of L. garvieae phenotypes nor the duration of the immunity was given. The protective mechanisms of the L. garvieae vaccine remains unknown.In a previous study, Ooyama et al. (1999) reported that formalin-killed Lactococcus garvieae KG-phenotype (capsulated phenotypes) cells and KG+ phenotype (noncapsulated) cells induced strong immunity in Seriola quinqueradiata against artificial infection and longlasting agglutinating titres against non-capsulated cells (avirulent KG+ phenotype). Furthermore, appendages (fimbriae-like structures) were seen extending from the cell surface of L. garvieae KG-phenotype, with some destruction of...

Immunoprotection of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Lactococcus garvieae against Lactococcosis in tilapia

“…malin-killed Streptococcus and Lactococcus spp. vaccine (Evans et al, 2004;Klesius et al, 2000;Ooyama et al, 2002;Vendrell et al, 2007). However, a subunit vaccine for L. garvieae has seldom been investigated.…”

“…Although L. garvieae is susceptible to several chemotherapeutic agents in vitro (Kawanishi et al, 2005), therapeutic measures are normally ineffective under field conditions, thus increasing the number of antibiotic-resistant bacterial strains and the amount of drug residues in food (Thompson et al, 2007). Therefore, related pathogen vaccines have been developed to control lactococcosis (Ooyama et al, 1999(Ooyama et al, , 2002Sato et al, 1996). While most of them are tested using formalin-killed bacteria, vaccines for controlling lactococcosis provide immunity and increased opsonic activity in fish (Ooyama et al, 2002;Sato et al, 1996;Vendrell et al, 2007).…”

“…Therefore, related pathogen vaccines have been developed to control lactococcosis (Ooyama et al, 1999(Ooyama et al, , 2002Sato et al, 1996). While most of them are tested using formalin-killed bacteria, vaccines for controlling lactococcosis provide immunity and increased opsonic activity in fish (Ooyama et al, 2002;Sato et al, 1996;Vendrell et al, 2007).…”

Purification of Two Different Immunoglobulins (Igs) from Olive Flounder Paralichthys olivaceus and Analysis of Lactococcus garvieae Antigens by the Igs

“…In spite of importance as a fish pathogen, there were few studies about antigens of this bacterium recognized by host fish (Kang et al, 2006;Ooyama et al, 2002). Recently, we constructed partial 2-DE reference map for L. garvieae (Shin et al, 2006b) which might be highly useful in identifying antigenic proteins on 2-DE immunoblotting profile.…”

Lactococcosis in Reared Fish in Brazil and Control Strategies

“…In addition, the immunogenicity of susceptible species has been investigated, and variations in protective responses have been observed among different species of fish, which has important implications for the formulation of a vaccine and the vaccination route [22][23][24][25][26]. On economic, environmental and ethical grounds, disease prevention by vaccination is the most appropriate method for pathogen control that is currently available to the aquaculture sector [27,28].…”