[Expression of helicobacter pylori alpA gene in lactococcus lactis and its immunogenicity analysis].
OBJECTIVE
To express Helicobacter pylori (Hp) alpA gene in a live delivery vehicle of lactococcus lactis (L. lactis) and assay the efficacy of the L. lactis-alpA oral vaccine in recipient mice.


METHODS
The alpA gene of Hp was amplified by PCR and cloned into the prokaryotic expression vector pNICE: sec. The recombinant vector pNICE: sec-alpA was transformed into Lactococcus lactis strain NZ9000. Then the engineered strain was induced to express recombinant alpA as shown by SDS-PAGE and Western blot. Female ICR mice (CV Grade) were randomly divided into 4 groups and administrated orally with PBS, L. lactis pNICE: sec, L. lactis pNICE: sec-alpA, and the inactivated Hp, respectively. After immunized seven times, the mice were detected for their alpA-specific IgG and IgA.


RESULTS
The alpA gene was obtained and successfully cloned into the vector pNICE: sec. The recombinant alpA protein (56,000) was accumulated in L. lactis after the induction of the nisin, accounting for 9.6% of the total bacterial protein. Western bolt confirmed that the alpA protein could be recognized specifically by the anti-Hp serum. The titer of anti-alpA IgG in the pNICE: sec-alpA group, comparable to that in the inactivated Hp group, was higher than that in the pNICE: sec group. The titer of anti-alpA IgA in the pNICE: sec-alpA group was higher than all other groups (P<0.05).


CONCLUSIONS
The oral administration of the engineered alpA-expressing L. lactis induced protective immunity against Hp. Our study provides a certain experimental basis for the use of L. lactis as an antigen-delivering vehicle for the development of Hp oral vaccines.
Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China. sunluyu1007@126.com
Zhen-lu
ZL
Sun
Yan-wei
YW
Bi
Cai-ming
CM
Bai
Dan-dan
DD
Gao
Zhi-hua
ZH
Li
Zong-xiang
ZX
Dai
Jian-feng
JF
Li
Wei-ming
WM
Xu
D018829:Adhesins, Bacterial / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D005260:Female; D015870:Gene Expression; D016481:Helicobacter Infections / Q000097:blood / Q000276:immunology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000276:immunology*; D006801:Humans; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR
D018829:Adhesins, Bacterial; C470179:AlpA protein, Helicobacter pylori; D000907:Antibodies, Bacterial