Multiplex PCR assay for the simultaneous detection and differentiation of clonal lineages of Erysipelothrix rhusiopathiae serovar 1a strains currently circulating in Japan

Human Erysipelothrix rhusiopathiae infection via bath water – case report and genome announcement

Erysipelothrix rhusiopathiae is a facultative anaerobic, environmentally stable, Gram-positive rod that causes swine and avian erysipelas as a zoonotic pathogen. In humans, the main manifestations described are circumscribed erysipeloid, generalized erysipeloid, and endocarditis. Here, we report a 46-year-old female patient who presented to the physician because of redness and marked functio laesa of the hand, in terms of a pain-related restricted range of motion, and was treated surgically. E. rhusopathiae was detected in tissue biopsy. The source of infection was considered to be a pond in which both swine and, later, her dog bathed. The genome of the isolate was completely sequenced and especially the presumptive virulence associated factors as well as the presumptive antimicrobial resistance genes, in particular a predicted homologue to the multiple sugar metabolism regulator (MsmR), several predicted two-component signal transduction systems, three predicted hemolysins, two predicted neuraminidases, three predicted hyaluronate lyases, the surface protective antigen SpaA, a subset of predicted enzymes that potentially confer resistance to reactive oxygen species (ROS), several predicted phospholipases that could play a role in the escape from phagolysosomes into host cell cytoplasm as well as a predicted vancomycin resistance locus (vex23-vncRS) and three predicted MATE efflux transporters were investigated in more detail.

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

Simple Summary

Swine erysipelas caused by the Erysipelothrix rhusiopathiae occurred frequently among pigs in Japan mostly by the serovar 1a variant featured by two amino acids in the surface protective antigen A protein. To determine if current vaccines are effective against the variant infection in pigs, one inactivated vaccine, SER-ME containing serovar 2a as the immunogen, was representatively evaluated. All vaccinated pigs survived without any apparent clinical signs after lethal challenge with the Fujisawa reference strain or the variant. This indicates that the serovar 2a immunogen of SER-ME vaccine effectively protects pigs against the E. rhusiopathiae variant and was not related to the emergences of the variant.

Abstract

Erysipelothrix rhusiopathiae causes swine erysipelas (SE). Sporadic SE outbreaks in Japan are mostly caused by the E. rhusiopathiae serovar 1a variant featured by methionine (M) and isoleucine (I) at amino acid positions 203 and 257 of the surface protective antigen (Spa) A protein (M203/I257 SpaA-type). To determine if current vaccines are effective against infection with this variant in pigs, one representative inactivated vaccine, SER-ME (containing E. rhusiopathiae serovar 2a), was evaluated. All vaccinated pigs survived without any apparent clinical signs after lethal challenge with the Fujisawa reference strain or the variant. This indicates that the SER-ME vaccine effectively protects pigs against the infection of E. rhusiopathiae M203/I257 SpaA-type variant. Current vaccines in Japan, including SER-ME, suggest that outbreaks in Japan are unlikely caused by vaccine failure.

Serovars and SpaA Types of Erysipelothrix rhusiopathiae Isolated from Pigs in Japan from 2012 to 2019

Erysipelothrix rhusiopathiae causes swine erysipelas (SE), which results in considerable economic loss on pig farms. During SE outbreaks that occurred sporadically from 2008 to 2011 in Japan, new E. rhusiopathiae strains were isolated with a specific surface protective antigen (Spa)A protein characterized by methionine at position 203 and isoleucine at position 257 (M203/I257 SpaA type). To determine whether strains with the M203/I257 SpaA type are still prevalent in Japan, we collected 79 strains of E. rhusiopathiae from pigs showing various SE symptoms from 2012 to 2019 and classified them based on serovar typing, spaA gene sequence analysis, and lineage typing. We found that the majority of recent E. rhusiopathiae strains (59/79) belonged to the serovar 1a strain, and that the M203/I257 SpaA type (56/59) was predominant continuing from 2008 to 2011. Furthermore, serovar 1a strains with IVb-1 and IVb-2 lineages that had been isolated in specific regions of Japan were no longer local but were found across Japan. The pathogenicity of recent isolates tested in mice was not significantly changed when compared to that of previously isolated strains. Our results suggest that recent SE outbreaks were not due to changes in the SpaA protein or to altered virulence of E. rhusiopathiae but were rather caused by the persistent presence of E. rhusiopathiae with the M203/I257 SpaA type.

Identification of the Chromosomal Region Essential for Serovar-Specific Antigen and Virulence of Serovar 1 and 2 Strains of Erysipelothrix rhusiopathiae

Erysipelothrix rhusiopathiae causes swine erysipelas, an infection characterized by acute septicemia or chronic endocarditis and polyarthritis. Among 17 E. rhusiopathiae serovars, determined based on heat-stable peptidoglycan antigens, serovars 1 and 2 are most commonly associated with the disease; however, the molecular basis for the association between these serovars and virulence is unknown. To search for the genetic region defining serovar 1a (Fujisawa) strain antigenicity, we examined the 15-kb chromosomal region encompassing a putative pathway for polysaccharide biosynthesis, which was previously identified in the E. rhusiopathiae Fujisawa strain. Six transposon mutants of Fujisawa strain possessing a mutation in this region lost antigenic reactivity with serovar 1a-specific rabbit serum. Sequence analysis of this region in wild-type strains of serovars 1a, 1b, and 2 and serovar N, which lacks serovar-specific antigens, revealed that gene organization was similar among the strains and that serovar 2 strains showed variation. Serovar N strains displayed the same gene organization as the serovar 1a, 1b, or 2 strain and possessed certain mutations in this region. In two of the analyzed serovar N strains, restoration of the mutations via complementation with sequences derived from serovar 1a and 2 strains recovered antigenic reactivity with 1a- and 2-specific rabbit serum, respectively. Several gene mutations in this region resulted in altered capsule expression and attenuation of virulence in mice. These results indicate a functional connection between the biosynthetic pathways for the capsular polysaccharide and peptidoglycan antigens used for serotyping, which may explain variation in virulence among strains of different serovars.