Investigation of the Genomic and Pathogenic Features of the Potentially Zoonotic Streptococcus parasuis

Abstract

Recently, Streptococcus suis reference strains of serotype 20, 22, and 26 were reclassified as Streptococcus parasuis. The public health significance of S. parasuis is underestimated due to the lack of clinical isolates. In the present study, we first reported two sporadic S. parasuis infections in humans, after using full-length 16S rRNA and housekeeping genes’ phylogeny and ANI values of genome sequence comparisons to determine the species of their isolates BS26 and BS27. Compared to highly pathogenic S. suis strain P1/7, S. parasuis strains BS26 and BS27 possessed a delayed capacity to initiate lethal infection, which may attribute to the later production of higher level of pro-inflammatory cytokines. Differed to S. suis strain P1/7, S. parasuis strains did not induce significant inflammatory response in the brain of mice. Histopathological changes in liver and lungs were widely present in mice infected with S. parasuis strains. Our data indicated that the pathogenic mechanism of S. parasuis may be different from that of S. suis. Three lineages in the core-genome phylogenetic tree and ten types of cps gene cluster were found in 13 S. parasuis genomes, indicating high heterogeneity of this species. The similarity of CPS structure and antibiotic-resistant genes relative to S. suis indicated the evolutionary affinity between the two species. Our data suggested S. parasuis is a potential zoonotic pathogen and poses severe threat to health of susceptible people. Further study on the epidemiology and public health significance of S. parasuis is urgently necessary.

Genomic characterization of Streptococcus parasuis, a close relative of Streptococcus suis and also a potential opportunistic zoonotic pathogen

“…First, the species of these isolates were checked at the genomic level. The ANI and Tetra of one isolate, 2843, also named 2674 in a previous study [ 8 ] (recognised by the same Genbank number), are highly different from the other 14 S. parasuis isolates. Further, we analysed the genome composition and found that 79% genes (1736/2198) of this isolate are unique and the size core-genome has a huge reduction after adding this isolate to analyses (from 1043 to 264) (Additional file 5 ).…”

“…The CPS biosynthesis gene cluster drives the formation of streptococcal capsule of Streptococci . Previously Wang et al aligned the cps locus difference between S. parasuis and S. suis and found that there were frequent interspecies horizontal transfers between the cps locus of S. parasuis and S. suis , and verified that both S. parasuis and S. suis synthesised their CPS using the WZX/WZY pathway [ 8 ]. In this study, the intraspecies difference of S. parasuis was explored, and we found 11 different cps types.…”

“…The first and last cps flanking genes of S. parasuis from the published cps locus were used to screen for their presence in 14 S. parasuis genomes [ 8 ]. In addition.…”

“…S. parasuis has been isolated from both healthy and diseased pigs and cows and can cause symptoms and diseases similar to S. suis , including meningitis, pneumonia, septicemia, endocarditis and arthritis [ 6 , 7 ]. Recently, two human S. parasuis infection cases were reported in China, making S. parasuis a potential opportunistic zoonotic pathogen and hazardous to public health [ 8 ].…”

Streptococcus parasuis, an Emerging Zoonotic Pathogen, Possesses the Capacity to Induce Cerebral Inflammatory Responses

“…Although most S. parasuis strains have been isolated from the saliva of clinically healthy pigs, the presence of S. parasuis in diseased pigs and calves with pneumonia or systemic infection (meningitis, arthritis, endocarditis, or septicemia) indicates that this species may be pathogenic in pigs and calves [3][4][5][6]. In our previous study, two S. parasuis clinical strains, BS26 and BS27, were isolated from a patient with peritonitis and a patient with pneumonia and arthritis, respectively [7]. In the present study, a third S. parasuis clinical strain, NN1, was isolated from a patient with pneumonia.…”