Streptococccus parauberis is etiologic agent of Streptococcosis in olive flounder, Paralichthys olivaceus. Formalin-inactivated S. paraubeirs vaccine currently marketed in the Korea are authorized for use in olive flounder from 2009.
The present study serotype distribution and multilocus sequence typing (MLST) of S. parauberis isolated from olive flounder cultured in Korea. Eighty S. parauberis isolates were analyzed by biochemical, serological and molecular analyses.
Of these 80 S. parauberis isolates, serotype Ia, Ib, Ic, II, non-typeable were 38, 29, 8, 4 and 2 strains respectively. The sequences of the six chosen loci were determined for MLST. The S. parauberis strains were divided to 2 MLST genogroups, which were highly related with those of serotypes. Serotype replacement by non-vaccine serotype (Ia and Ic) has been detected in Korea since S. parauberis vaccination began. The serotype Ib of S. parauberis strains were dominantly isolated from flounder before 2009, but the prevalence of S. parauberis serotype Ia and Ic had been increased from 2010 in Korea.