Helicobacter pylori HopE and HopV porins present scarce expression among clinical isolates.
OBJECTIVE
To evaluate how widely Helicobacter pylori (H. pylori) HopE and HopV porins are expressed among Chilean isolates and how seroprevalent they are among infected patients in Chile.


METHODS
H. pylori hopE and hopV genes derived from strain CHCTX-1 were cloned by polymerase chain reaction (PCR), sequenced and expressed in Escherichia coli AD494 (DE3). Gel-purified porins were used to prepare polyclonal antibodies. The presence of both genes was tested by PCR in a collection of H. pylori clinical isolates and their expression was detected in lysates by immunoblotting. Immune responses against HopE, HopV and other H. pylori antigens in sera from infected and non-infected patients were tested by Western blotting using these sera as first antibody on recombinant H. pylori antigens.


RESULTS
PCR and Western blotting assays revealed that 60 and 82 out of 130 Chilean isolates carried hopE and hopV genes, respectively, but only 16 and 9, respectively, expressed these porins. IgG serum immunoreactivity evaluation of 69 H. pylori-infected patients revealed that HopE and HopV were infrequently recognized (8.7% and 10.1% respectively) compared to H. pylori VacA (68.1%) and CagA (59.5%) antigens. Similar values were detected for IgA serum immunoreactivity against HopE (11.6%) and HopV (10.5%) although lower values for VacA (42%) and CagA (17.4%) were obtained when compared to the IgG response.


CONCLUSIONS
A scarce expression of HopE and HopV among Chilean isolates was found, in agreement with the infrequent seroconversion against these antigens when tested in infected Chilean patients.
Lienlaf
Maritza
M
Microbial Pathogenesis and Vaccine Biotechnology Laboratory, Department of Molecular Genetics and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Alameda 340, Santiago 651-3492, Chile.
Morales
Juan Pablo
JP
Díaz
María Inés
MI
Díaz
Rodrigo
R
Bruce
Elsa
E
Siegel
Freddy
F
León
Gloria
G
Harris
Paul R
PR
Venegas
Alejandro
A
D000907:Antibodies, Bacterial / Q000097:blood; D002677:Chile; D005838:Genotype; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori / Q000302:isolation & purification* / Q000378:metabolism*; D006801:Humans; D010641:Phenotype; D018272:Porins / Q000235:genetics / Q000378:metabolism*; D012189:Retrospective Studies
D000907:Antibodies, Bacterial; D018272:Porins