Recognition of Helicobacter pylori by protein-targeting aptamers

Helicobacter pylori (H pylori) is a disease-causing pathogen capable of surviving under acidic conditions of the human stomach. Almost half of the world's population is infected with H pylori, with gastric cancer being the most unsatisfactory prognosis. Although H pylori has been discovered 30 years ago, the effective treatment and elimination of H pylori continue to be problematic.

In our study, we screened nucleic acid aptamers using H pylori surface recombinant antigens as targets. Trypsin was used for separating aptamers that were bound to proteins. Following nine rounds of screening, we performed sequence similarity analyses to assess whether the aptamers can recognize the target protein. Two sequences with desirable recognition ability were selected for affinity detection. Aptamer Hp4 with the strongest binding ability to the H pylori surface recombinant antigen was chosen. After optimization of the binding conditions, we conducted specificity tests for Hp4 using Escherichia coli, Staphylococcus aureus, Vibrioanguillarum, and H pylori.

The data indicated that the aptamer Hp4 had an equilibrium dissociation constant (K_d ) of 26.48 ± 5.72 nmol/L to the target protein. This aptamer was capable of exclusively detecting H pylori cells, without displaying any specificity for other bacteria.

We obtained a high-affinity aptamer for H pylori, which is expected to serve as a new molecular probe for detection of H pylori.