Comparative study of the phenotype and virulence of recent serovar 1a, 1b, and 2a isolates of Erysipelothrix rhusiopathiae in Japan

The Swine Erysipelas Vaccine SER-ME Effectively Protects Pigs against Challenge with the Erysipelothrix rhusiopathiae M203/I257 SpaA-Type Variant

“…Death or the humane endpoint was scored as +7. These clinical scores followed our previous study [ 16 ].…”

“…The Fujisawa strain was used as the reference strain of E. rhusiopathiae [ 18 ]. One of the major SpaA-type variants having M203/I257 SpaA-type, 2012 Miyazaki variant that was isolated previously [ 15 , 16 ], was representatively used. The Fujisawa strain and 2012 Miyazaki variant belong to serovar 1a variant.…”

“…The Marienfelde strain was used for the growth agglutination (GA) test as the live antigen ( See below ). Three strains were prepared from the glycerol stock in the brain heart infusion (BHI) medium as previously described [ 16 ].…”

“…Fujisawa strain and 2012 Miyazaki variant were cultured at 37 ◦C in the tryptose phosphate broth (TPB) medium. Marienfelde strain was cultured in BHI medium [ 16 ]. Colony-forming units (CFU) of Fujisawa strain and 2012 Miyazaki variant were measured by counting the colonies on TPB agar plates as previously described [ 15 ].…”

“…This indicates that the serovar 1a M203/I257 SpaA-type variant of E. rhusiopathiae is the major causative strain of SE as ever in Japan. In a previous study, we found that serovar 1a strains have advantages on growth in liquid culture compared with serovar 2a and showed more virulent phenotype than serovar 2a in mice and pigs [ 16 ]. However, the reason why the E. rhusiopathiae serovar 1a M203/I257 SpaA-type variant has become dominant in the field in Japan remains unknown.…”