Identification of surface protective antigen (spa) types in Erysipelothrix reference strains and diagnostic samples by spa multiplex real-time and conventional PCR assays

Abstract

Aim: To develop spa multiplex real‐time and conventional PCR assays to detect and differentiate between spaA, spaB and spaC genes within Erysipelothrix spp. Methods and Results: For evaluation of the assays, 28 Erysipelothrix spp. reference strains, 25 tissues from pigs inoculated with reference strains of serotypes 1, 2, 5, 10 or 18, and 15 diagnostic samples were used. SpaA was found to be present in Erysipelothrix rhusiopathiae serotypes 1a, 1b, 2, 5, 9, 12, 15, 16, 17, 23 and N; spaB was detected in E. rhusiopathiae serotypes 4, 6, 8, 11, 19 and 21 and spaC was detected in E. sp. strain 2 serotype 18. Spa‐related genes were not detected in E. tonsillarum strains (serotypes 3, 7, 10, 14, 20, 22, 24, 25, 26) or E. sp. strain 1 (serotype 13). With the spa multiplex real‐time PCR assay, it was also possible to further differentiate spaB into spaB1 (serotypes 4, 6, 8, 19 and 21) and spaB2 (serotype 11). Overall, spaA was detected in seven experimental tissue samples and six diagnostic tissue samples, and spaC in two experimental tissue samples. The detection limits were determined to be five colony‐forming units (CFU) per reaction for the spa multiplex real‐time PCR assay and 4000 CFU per reaction for the conventional PCR assay. Conclusions: Both spa PCR assays were specific and reproducible in the identification of spa types in Erysipelothrix spp. Significance and Impact of the Study: The described spa PCR assays may be useful tools for investigating spa prevalence among strains isolated from field tissues and to determine the role of the Spa proteins in vaccine protection and pathogenesis.

Erysipelothrix Spp. Genotypes, Serotypes, and Surface Protective Antigen Types Associated with Abattoir Condemnations

“…references strains banked several decades ago, which include spaA, spaB1, spaB2, and spaC. 8,14,20 A cross protection study reported complete protection with homologous spa but only partial protection was observed with heterologous spa strains. 20 Recently, it was determined that a certain spa type is not confined to a specific serotype.…”

“…14 The isolation results of 70 condemned cases collected at the regional abattoir are summarized in Table 1. Of 70 cases examined, 84.3% (59/70) were found to be culture positive for Erysipelothrix spp.…”

“…is called erysipelas in birds and mammals or erysipeloid in humans. 24 Current taxonomy recognizes the genus Erysipelothrix with 2 species, each with differentiable serotypes: Erysipelothrix rhusiopathiae (serotypes 1a, 1b, 2, 4, 5, 6, 8, 9, 11, 12, 15, 16, 17, 19, 21, N) and Erysipelothrix tonsillarum (serotypes 3,7,10,14,20,22,23). 15,17,19 Two proposed Erysipelothrix spp.…”

Characterization of Erysipelothrix Species Isolates from Clinically Affected Pigs, Environmental Samples, and Vaccine Strains from Six Recent Swine Erysipelas Outbreaks in the United States

“…The SpaA protein was identified in E. rhusiopathiae serotypes 1a, 1b, 2,5,8,9,12,15,16,17, and N, the SpaB protein was identified in E. rhusiopathiae serotypes 4, 6, 11, 19, and 21, and the SpaC protein was identified only in serotype 18 (29). Additional work further differentiated SpaB into subtypes SpaB1 (serotypes 4,6,8,19,21) and SpaB2 (serotype 11) (21).…”

“…have been isolated from domestic and wild species of both birds and mammals and have been identified as the causative agent of the clinical disease known as "erysipelas" in animals and "erysipeloid" in humans (2). The genus Erysipelothrix consists of four species and 25 associated serotypes: E. rhusiopathiae (serotypes 1a, 1b, 2, 4, 5,6,8,9,11,12,15,16,17,19,21, N), E. tonsillarum (serotypes 3,7,10,14,20,22,23), Erysipelothrix sp. strain 1 (serotype 13), and Erysipelothrix sp.…”