Comparative genomics of Streptococcus parauberis: new target for molecular identification of serotype III

Abstract

This paper describes the predicted structure for the cps loci involved in capsule biosynthesis for Streptococcus parauberis serotypes III, IV, and V. Based on the specific serotype regions I, II, and III, a multiplex PCR protocol (mPCR) was designed to differentiate the main serotypes causing fish diseases. A real-time PCR method (qPCR) is also described to identify S. parauberis of serotype III in bacterial cultures and fish tissues. In silico and in vitro analyses revealed that both methods have a 100% specificity. The mPCR assay was optimized for the detection of S. parauberis strains of subtypes Ia (amplicon size 213 bp), subtypes Ib and Ic (both amplicon size 303 bp), serotype II (amplicon size 403 bp), and serotype III (amplicon size 130 bp) from bacterial cultures. The qPCR assay was optimized for the identification and quantification of S. parauberis serotype III strains in bacterial cultures and fish tissues. This assay achieved a sensitivity of 2.67 × 10 2 gene copies (equivalent to 3.8 × 10 −9 ng/μl) using pure bacterial cultures of S. parauberis serotype III and 1.76 × 10 2 gene copies in fish tissues experimentally and naturally infected with S. parauberis of the serotype III. The specificity and sensitivity of the protocols described in this study suggest that these methods could be used for diagnostic and/or epidemiological purposes in clinical diagnostic laboratories. Key Points• Structure of loci cps for S. parauberis of serotypes III, IV and V was described.• mPCR to differentiate S. parauberis serotypes causing disease in fish was optimized.• qPCR assay to quantify strains of S. parauberis serotype III in fish tissues.

Genomic characterization of Tenacibaculum maritimum O‐antigen gene cluster and development of a multiplex PCR‐based serotyping scheme

“…Hence, because traditional serotyping is costly, labour‐intensive and requires significant technical expertise, molecular serotyping relying of the presence/absence of relevant genes is a promising alternative. In full expansion for the molecular serotyping of human pathogens (Howell et al., 2015; Ludwig et al., 2020; Nakaue et al., 2021), such schemes were recently developed for animal and especially fish pathogenic bacteria (Rochat et al., 2017; Torres‐Corral & Santos, 2020). The strategy is based on the genomic identification of molecular markers that determine the serotype.…”

Prevalence, antibiotic susceptibility and serotyping of Streptococcus parauberis isolates from diseased marine fish

“…Streptococcus parauberis could be classified into five serotypes which divided three subtypes of serotype I (Ia, Ib and Ic), serotype II, III, IV and V according to capsular polysaccharides gene structure (Gao et al, 2021; Yolanda et al, 2019; Torres‐Corral & Santos, 2020). Among these, serotypes Ia and Ib/Ic are found to be the most prevalent in streptococcosis in Paralichthys olivaceus , while serotype II does not induce mortality (Woo & Park, 2013).…”

Pathogenicity and drug resistance of animal streptococci responsible for human infections

“…Cultural, morphological, biochemical or serological characterizations do not distinguish them sufficiently [61]. S. parauberis was initially recognized as an aetiological agent of mastitis in cattle but is now rarely isolated from these clinical cases [63,64].…”

“… S. parauberis was initially recognized as an aetiological agent of mastitis in cattle but is now rarely isolated from these clinical cases [63, 64].…”