Analysis of protective antigen and virulence factors of Lactococcus garvieae, fish bacterial pathogen

点击翻译按钮获取中文摘要

ABSTRACT : Strains of Lactococcus garvieae were examined for the presence of cell surface structures. Two types of cell capsular strains such as highly developed capsule (KG9408) and micro-capsule (MS93003) of L. garvieae were found, carrying fimbrie-like components, projecting from cell surface. While one stain (NSS9319) has neither cell capsular nor fimbrie-like structures on its cell surface. Highly developed cell capsular strain indicated higher virulence to fish than that of micro-capsular or non-capsular strain. Bacteriphage susceptibilities to these three strains were clearly distinguished from KG9408 to MS93003 and NSS9310 strains. Immune protection against Lactococcus garvieae infection was induced in yellowtail, Seriola guinqueradiata immunized with formalin-killed L. garvieae KG9408 and MS93003. However immune protection was also induced by immunization of NSS9310, the level of protection was significantly lower than that of KG9408 andMS93003. protection was induced by immunization of NSS9310. Passive immunization with yellowtail immune sera raised against KG9408 and MS93003 conferred strong protection to yellowtail with the rapid bacterial clearance after the infection of L. garvieae. Immunoblotting analysis of proteins extracted from L. garvieae strains using rabbit anti-KG9408 and MS93003 serum, and yellowtail anti-KG9408 and MS93003 serum indicated that some bands from NSS9310 were not detected as seen in KG9408 and MS93003 strains.