Fish Streptococcus agalactiae (S. agalactiae) seriously harms the world's aquaculture industry and causes
huge economic losses.This study aimed to develop a potential live attenuated vaccine of S. agalactiae.
Pre-screened vaccine candidate strain S. agalactiae HN016 was used as starting material to generate an
attenuated strain S. agalactiae YM001 by continuous passage in vitro.