[Construction of RevS gene knock-out mutant of Streptococcus suis serotype 2].
OBJECTIVE
To construct a gene knock-out mutant of response regulator named RevS in Streptococcus suis serotype 2 virulent strain 05ZYH33, and to investigate the effects of its deletion on the biological characters of this pathogen and the pathogenesis to mice and piglets.


METHODS
Recombinant gene knock-out vector consisting of Spc(r) cassette was constructed and flanking was constructed consisting of Spc(r) cassette with flanking homology regions to the RevS genes while the isogenic RevS-deficient mutant was screened by allelic replacement. The effects of RevS deletion on the basic biological characters of 05ZYH33 including growth stability, colonial morphology, haemolysis, Gram staining, growth curve and protein expression were examined in vitro. The mice and piglets were infected with 10(8) CFU wild virulent and mutant isolates.


RESULTS
PCR analysis confirmed that the coding genes of RevS were replaced completely by Spc(r) cassette and the basic biological characters of 05ZYH33 did not undergo any apparent change. Balb/c mice infection assay indicated that RevS play a role in the pathogenesis of Streptococcus suis infections, while no remarkable difference was observed in the piglets' pathogenesis infection rates between mutant isolates deltaA05ZYH33 and wild-type isolates 05ZYH33.


CONCLUSIONS
The mutant of Streptococcus suis 05ZYH33 response regulator was successfully constructed, while the mutation did not obviously affect the bacterial biological characters, while the knock-out mutant of RevS was shown to be attenuated in pathogenesis to mice and piglets.
Ju
Ai-ping
AP
Institute of Military Medical Sciences, Nanjing Command, Nanjing 210002, China.
Wang
Chang-jun
CJ
Li
Ming
M
Cheng
Gong
G
Zheng
Feng
F
Pan
Xiu-zhen
XZ
Lu
Cheng-ping
CP
Tang
Jia-qi
JQ
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D055786:Gene Knockout Techniques / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000382:microbiology; D017011:Streptococcus suis / Q000235:genetics* / Q000472:pathogenicity*
D001426:Bacterial Proteins