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Insight into the specific virulence related genes and toxin-antitoxin virulent pathogenicity islands in swine streptococcosis pathogen Streptococcus equi ssp. zooepidemicus strain ATCC35246.

Ma Z, Geng J, Yi L, Xu B, Jia R, Li Y, Meng Q, Fan H, Hu S - BMC Genomics (2013)

Bottom Line: Analysis of the genome identified potential Sz35246 virulence genes.Genes of the Fim III operon were presumed to be involved in breaking the host-restriction of Sz35246.Genome wide comparisons of Sz35246 with three other strains and transcriptome analysis revealed novel genes related to bacterial virulence and breaking the host-restriction.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.

ABSTRACT

Background: Streptococcus equi ssp. zooepidemicus (S. zooepidemicus) is an important pathogen causing swine streptococcosis in China. Pathogenicity islands (PAIs) of S. zooepidemicus have been transferred among bacteria through horizontal gene transfer (HGT) and play important roles in the adaptation and increased virulence of S. zooepidemicus. The present study used comparative genomics to examine the different pathogenicities of S. zooepidemicus.

Results: Genome of S. zooepidemicus ATCC35246 (Sz35246) comprises 2,167,264-bp of a single circular chromosome, with a GC content of 41.65%. Comparative genome analysis of Sz35246, S. zooepidemicus MGCS10565 (Sz10565), Streptococcus equi. ssp. equi. 4047 (Se4047) and S. zooepidemicus H70 (Sz70) identified 320 Sz35246-specific genes, clustered into three toxin-antitoxin (TA) systems PAIs and one restriction modification system (RM system) PAI. These four acquired PAIs encode proteins that may contribute to the overall pathogenic capacity and fitness of this bacterium to adapt to different hosts. Analysis of the in vivo and in vitro transcriptomes of this bacterium revealed differentially expressed PAI genes and non-PAI genes, suggesting that Sz35246 possess mechanisms for infecting animals and adapting to a wide range of host environments. Analysis of the genome identified potential Sz35246 virulence genes. Genes of the Fim III operon were presumed to be involved in breaking the host-restriction of Sz35246.

Conclusion: Genome wide comparisons of Sz35246 with three other strains and transcriptome analysis revealed novel genes related to bacterial virulence and breaking the host-restriction. Four specific PAIs, which were judged to have been transferred into Sz35246 genome through HGT, were identified for the first time. Further analysis of the TA and RM systems in the PAIs will improve our understanding of the pathogenicity of this bacterium and could lead to the development of diagnostics and vaccines.

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Survival curves for ICR mice infected with the wild-type Sz35246 and ∆Island3-Sz35246. Two groups of eight-week-old ICR mice were inoculated i.p. with 2.5×105 CFU bacteria, and mouse survival was monitored over a 5-day period. Data are expressed as the mean percentage of live animals in each group (n = 10). The virulences of these two strains were significantly different (P<0.05).
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Figure 10: Survival curves for ICR mice infected with the wild-type Sz35246 and ∆Island3-Sz35246. Two groups of eight-week-old ICR mice were inoculated i.p. with 2.5×105 CFU bacteria, and mouse survival was monitored over a 5-day period. Data are expressed as the mean percentage of live animals in each group (n = 10). The virulences of these two strains were significantly different (P<0.05).

Mentions: To prove that the genes located within the PAIs affect the virulence of Sz35246, we deleted part of SeseCisland_3 from SeseC_01869 to SeseC_01898. PCR was used to confirm the deletion (Figure 9A and Additional file8: Table S8), sequencing results showed that exactly 28,606 bp of SeseCisland_3 was deleted, including the genes belong to the ϵ /ζ TA system (Figure 9B). The deleted region started with Tn5252 transposon gene (SeseC_01869), and two repeat sequences, including transposase genes (SeseC_01867 and SeseC_01901), were located at the flank of the deleted region. These two repeat sequences and the Tn5252 transposon gene formed the structural basis for deleting such a long fragment. The mutant strain ∆Island3-Sz35246 and wild-type Sz35246, were used to infect ICR mice to evaluate the influence of partial PAI deletion on bacterial virulence. The percent survival significantly increased in ∆Island3-Sz35246 infected mice (Figure 10), 5 days post-infection, only one of the ten mice was dead; however, of the mice infected with wild-type Sz35246, only one was alive. The survival curve indicated that partial deletion of a PAI did affect the virulence of Sz35246, and that some of these genes in the PAI are important for bacterial pathogenicity. Genes located in the other three PAIs require further study to determine their role in bacterial virulence.


Insight into the specific virulence related genes and toxin-antitoxin virulent pathogenicity islands in swine streptococcosis pathogen Streptococcus equi ssp. zooepidemicus strain ATCC35246.

Ma Z, Geng J, Yi L, Xu B, Jia R, Li Y, Meng Q, Fan H, Hu S - BMC Genomics (2013)

Survival curves for ICR mice infected with the wild-type Sz35246 and ∆Island3-Sz35246. Two groups of eight-week-old ICR mice were inoculated i.p. with 2.5×105 CFU bacteria, and mouse survival was monitored over a 5-day period. Data are expressed as the mean percentage of live animals in each group (n = 10). The virulences of these two strains were significantly different (P<0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750634&req=5

Figure 10: Survival curves for ICR mice infected with the wild-type Sz35246 and ∆Island3-Sz35246. Two groups of eight-week-old ICR mice were inoculated i.p. with 2.5×105 CFU bacteria, and mouse survival was monitored over a 5-day period. Data are expressed as the mean percentage of live animals in each group (n = 10). The virulences of these two strains were significantly different (P<0.05).
Mentions: To prove that the genes located within the PAIs affect the virulence of Sz35246, we deleted part of SeseCisland_3 from SeseC_01869 to SeseC_01898. PCR was used to confirm the deletion (Figure 9A and Additional file8: Table S8), sequencing results showed that exactly 28,606 bp of SeseCisland_3 was deleted, including the genes belong to the ϵ /ζ TA system (Figure 9B). The deleted region started with Tn5252 transposon gene (SeseC_01869), and two repeat sequences, including transposase genes (SeseC_01867 and SeseC_01901), were located at the flank of the deleted region. These two repeat sequences and the Tn5252 transposon gene formed the structural basis for deleting such a long fragment. The mutant strain ∆Island3-Sz35246 and wild-type Sz35246, were used to infect ICR mice to evaluate the influence of partial PAI deletion on bacterial virulence. The percent survival significantly increased in ∆Island3-Sz35246 infected mice (Figure 10), 5 days post-infection, only one of the ten mice was dead; however, of the mice infected with wild-type Sz35246, only one was alive. The survival curve indicated that partial deletion of a PAI did affect the virulence of Sz35246, and that some of these genes in the PAI are important for bacterial pathogenicity. Genes located in the other three PAIs require further study to determine their role in bacterial virulence.

Bottom Line: Analysis of the genome identified potential Sz35246 virulence genes.Genes of the Fim III operon were presumed to be involved in breaking the host-restriction of Sz35246.Genome wide comparisons of Sz35246 with three other strains and transcriptome analysis revealed novel genes related to bacterial virulence and breaking the host-restriction.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.

ABSTRACT

Background: Streptococcus equi ssp. zooepidemicus (S. zooepidemicus) is an important pathogen causing swine streptococcosis in China. Pathogenicity islands (PAIs) of S. zooepidemicus have been transferred among bacteria through horizontal gene transfer (HGT) and play important roles in the adaptation and increased virulence of S. zooepidemicus. The present study used comparative genomics to examine the different pathogenicities of S. zooepidemicus.

Results: Genome of S. zooepidemicus ATCC35246 (Sz35246) comprises 2,167,264-bp of a single circular chromosome, with a GC content of 41.65%. Comparative genome analysis of Sz35246, S. zooepidemicus MGCS10565 (Sz10565), Streptococcus equi. ssp. equi. 4047 (Se4047) and S. zooepidemicus H70 (Sz70) identified 320 Sz35246-specific genes, clustered into three toxin-antitoxin (TA) systems PAIs and one restriction modification system (RM system) PAI. These four acquired PAIs encode proteins that may contribute to the overall pathogenic capacity and fitness of this bacterium to adapt to different hosts. Analysis of the in vivo and in vitro transcriptomes of this bacterium revealed differentially expressed PAI genes and non-PAI genes, suggesting that Sz35246 possess mechanisms for infecting animals and adapting to a wide range of host environments. Analysis of the genome identified potential Sz35246 virulence genes. Genes of the Fim III operon were presumed to be involved in breaking the host-restriction of Sz35246.

Conclusion: Genome wide comparisons of Sz35246 with three other strains and transcriptome analysis revealed novel genes related to bacterial virulence and breaking the host-restriction. Four specific PAIs, which were judged to have been transferred into Sz35246 genome through HGT, were identified for the first time. Further analysis of the TA and RM systems in the PAIs will improve our understanding of the pathogenicity of this bacterium and could lead to the development of diagnostics and vaccines.

Show MeSH
Related in: MedlinePlus