X. FU ET AL.
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Fi gur e 4. Purified CpsE on a 12.5%SDS-PAGE gel eluted from
Ni-NTA column using 250mM imidazole. Expression of all lanes
ar e a cco mplished at optimal co nditions (at 37℃ for 1h with 0.2mM
Table 1. Purification of cpse protein from 1l culture.
Cru de ext ractd 67.5 15.48 1,214 23
Immobilized metal affinity
chromatography 1.90 1.62 480 85
aTotal protein was isolated from 1liter of culture medium in optimal expression
condition; b Protein concentration was estimated by the Bradford method using
BSA as standard; c The purity was determined as the amount of the stain asso-
ciated with the CpsE band as a fraction of the stain associated with all the bands
on the SDS-PAGE; d The pellets containing the insoluble fraction (crude
extract) obta ine d from 1liter of culture.
To date, there are no reports in literature that ap proached the
expression optimization allowing the development of a process
to produce recombinant CpsE in E.coli. Our work is able to
present conditions that are optimal for production of recombi-
nant protein. Distribution of B cell epitopes is largely related to
the secondary structures of the protein because regions of turn
and coil can easily change in shape that benefits combination of
protein with antibodies. Hydrophilic regions of the protein
would serve as likely B cell epitopes. Prediction results of hy-
drophilicity character and transmembrane region indicate that
there may have certain B cell epitopes in the CpsE protein.
Comprehensive analysis of turn regions, coil regions, surface
probability regions and hydrophilic regions presented here
suggest that the most possible sites for B cell epitopes are
Phe52-Asn57, Gly7-Gly11, Ser83-Gly84 and Asp112-Pro 114.
This speculate is able to locate B cell epitopes, which could
help to find sp ecific antigen and furth er benefit development of
subunit vaccin e.
This work was supported by grant from Program for Chang-
jiang Scholars and Innovative Research Teamin in University
(PCSIRT) (Grant no. IRT0848 ); Science and Technology
project of Sichuan Province (No.08ZA082). Kaiyu Wang is the
corresponding author. Fish Disease Research Center & Key
Laboratory of Animal Disease and Human Health of Sichuan
Province, College of Veterinary Medicine of Sichuan Agri-
cultural University, 46# Xinkang Road, Yucheng District, Yaan
62501 4, Si c h ua n Pr ovince of Chi na .
 S.J.Schrag, D.Phil, E.R.Zell, M.Stat, R.Lynfield, A.Roome,
K.E.Arnold, A.S.Craig, L.H.Harrison, A.Reingold, K.Stefonek,
G.Smith, M.Gamble, A.Schuchat, “A population-based compar-
ison of strategies to prevent early-onset group B streptococcal
disease in neonates,” N. Engl. J. Med. New York, vol.347,
pp.233-239, July 2002.
 M.S.Edwards, C.J.Baker, “Group B streptococcal infections in
elderly adults,” Clin. Infect. Dis. New York, vol.41 pp.839-847,
 T.H.Skoff, M.M.Farley, S.Petit, A.S.Craig, W.Schaffner,
K.Gershman, L.H.Harrison, R.Lynfield, J.M.Boetani, S.Zansky,
B.A.Albanese, K.Stefonek, E.R.Zell, D.Jackson, T.Thompson,
S.J.Schrag, “Increas ing bu rden of in vasive group B streptoc occal
dis ease in nonpregna nt adults 199 0-2007,”Clin. Infect. Dis. New
York,vol.49 pp.85-92, February 2009.
 G.P.Keefe, “Streptococcus agalactiae mastitis: a review,”
Can.Vet.J. Canada,vol.38, pp.429-437,July 1997.
 J.J.Evans, P.H.Klesius, P.M.Gilbert, C.A.Shoemaker,
M.A.A.Sarawi, J.Landsberg, R.Duremdez, “Characterization of
β-haemolytic group B streptococcus agalactiae in cultured sea-
bream, Sparus auratus L., and wild mullet, Liza klunzingeri
(Day), in Kuwait,” J.Fish. Dis.Wiley, New York, vol.25,
pp.505-513, September 2 002.
 R.Salvador, E.E.Muller, J.C.Freitas, J.H.Leonhadt, “Isolation and
characterization of Streptococcus spp. group B in Nile tilapia
(Oreochromis niloticus) reared in hapas nets and earth nurseries
in the northern region of Parana State,Brazil,” Ciência Rural
Santa Mar ia, vol.35,pp.1374-1378, November 2005.
 A.Eldar, Y.Bejerano, H.Bercovier, “Streptococcus shiloi and
Streptococcus difficile: two new streptococcal species causing a
meningoencephalitis in fish,” Curr.Microbiol.New York, vol.28,
pp.139-143, March 1 994.
 E.R.Moxon, J.S.Kroll, “The role of bacterial polysaccharide
capsules as virulence factors,” Curr.Top.Microbiol. Immu-
nol.Berlin, vol.150, pp.65-85, May 199 0.
 A.S.Cross,“The biologic significance of bacterial encapsula-
tion, ” Curr.Top. Microbiol. Immunol. Berlin , vol.150, pp.87-95,
 D.O.Chaffin, S.B.Beres, H.H.Yim, C.E.Rubens, “The serotype of
type Ia and III group B streptococci is determined by the poly-
merase gene within the polycistronic capsule operon,”
J.Bacteriol.Washington DC, vol.182, pp.4466-4477, May 2000.
 E.Persson, S.Berg, B.Trollfors, P.Larsson, E.Ek, E.Backhaus,
B.E.B.Claesson, L.Jonsson, G.Radberg, T.Ripa, S.Johansson,
“Serotypes and clinical manifestations of invasive group B
streptococcal infections in western Sweden 1998–2001,”
Clin.Microbiol.Infect.Wiley, New York, vol.10, pp.791-796,
 H.C.Slotved, F.Kong, L.Lambertsen, S.Sauer, G.L.Gilbert, “Se-
rotype IX, a proposed new Streptococcus agalactiae se r o type ,” J.
Clin. Microbiol. Washington DC, vol.45, pp.2929-2936, Sep-
 M.E.Hickman, M.A.Rench, P.Ferrieri, C.J.Baker, “Changing
epid emiology of group B strep tococcal coloni zation,” Pediatrics.
American Academy of Pediatrics, New York, vol.104,
pp.203-209, August 1999.
 M.Waqner, T.Murai, B.Waqner, E.Gunther, J.Jelinkova, “JM9
strains, a new type of group B streptococci from Japan,” Zen-
tra lbl.Bakteriol. Elsevier, Amsterdam, vol.280, pp.488-496,
Marc h 1994.