Identification of a virulence-related surface protein XF in piscine Streptococcus agalactiaeby pre-absorbed immunoproteomics

Abstract

BackgroundSince 2009, large-scale Streptococcus agalactiae infections have broken out in cultured tilapia farms in China, resulting in considerable economic losses. Screening of the surface proteins is required to identify virulence factors or protective antigens involved in piscine S.agalactiae infections in tilapia. Pre-absorbed immunoproteomics method (PAIM) is a useful method previously established in our laboratory for identifying bacterial surface proteins.ResultsA serine-rich repeat protein family 1 (Srr-1), designated XF, was identified by PAIM in piscine S. agalactiae isolate GD201008-001. To investigate the role of XF in the pathogenesis of piscine S. agalactiae, an isogenic xf mutant strain (Δxf) and a complemented strain (CΔxf) were successfully constructed. The Δxf mutant and CΔxf showed no significant differences in growth characteristics and adherence to HEp-2 cells compared with the wild-type strain. However the 50% lethal dose of Δxf was increased (4-fold) compared with that of the parental strain in a zebrafish infection model.ConclusionsThe findings demonstrated that XF is a virulence-related, highly immunoreactive surface protein and is involved in the pathogenicity of S. agalactiae infections in fish.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-014-0259-7) contains supplementary material, which is available to authorized users.

The Novel Streptococcal Transcriptional Regulator XtgS Negatively Regulates Bacterial Virulence and Directly Represses PseP Transcription

“…The fusion fragments were purified, digested with respective endonucleases, and then cloned into the same sites of the thermosensitive suicide vector pSET4S (33). Then, the recombinant plasmids were introduced into competent S. agalactiae GD201008-001 cells by electroporation at 2.35 kV, 200 ⍀, and 25 F. The procedure for the selection of mutants generated by allelic exchange via double-crossover was performed as described previously (34).…”

Impacts of streptococcal infection on Nile tilapia Oreochromis niloticus in Egyptian farms with special reference to diagnosis and prevention

“…Other methods for detecting streptococcus bacteria, such as the RAPID, VITEX, API 20 STREP, and Rapid Strep 32 systems can also be applied (Facklam et al, 2005;Lau et al, 2006).Serological tests, such as the enzyme-linked immunosorbent assay is also used for identification purpose (Liu et al, 2014). For quick detection and identification of S. iniae, a monoclonal antibody-based indirect fluorescent antibody method was also used (Klesius et al, 2006;Souter et al, 2021).…”

Zebrafish and Streptococcal Infections

“…Numerous other studies have also used the natural interaction occurring between GBS and the zebrafish to understand several aspects of GBS virulence and fish immunity . Liu et al .…”

“…Liu et al . identified several GBS surface proteins and protective antigens including the serine‐rich repeat protein (Srr‐1). When injected into adult zebrafish, the GBS mutant lacking an active Srr‐1 had an impaired ability to cause an infection, indicating an important role of the Srr‐1 in GBS virulence .…”

“… identified several GBS surface proteins and protective antigens including the serine‐rich repeat protein (Srr‐1). When injected into adult zebrafish, the GBS mutant lacking an active Srr‐1 had an impaired ability to cause an infection, indicating an important role of the Srr‐1 in GBS virulence . Similarly, the important role of the CpsA, a regulator of the capsule operon, was demonstrated in adult zebrafish, where the ΔCpsA mutant showed significant attenuation compared to the wild‐type GBS .…”