Helicobacter. 2020;00:e12758. wileyonlinelibrary.com/journal/hel | 1 of 9 https://doi.org/10.1111/hel.12758 © 2020 John Wiley & Sons Ltd 1 | INTRODUCTION Helicobacter pylori (H. pylori ) is a gram-negative, microaerophilic bac- teria containing between 2 and 6 unipolar flagella. The bacterium has rounded ends and measures 2.5-4 µm in length and 0.5-1 µm width. H. pylori selectively colonize the surface of the gastric mucosa of humans. 1-3 Since the discovery of H. pylori by Marshall and Warren, 4 numerous studies have demonstrated that this human gastric patho- gen is present in approximately 50% of the world's population, and up to 55.8% in the Chinese population. 5,6 Until now, humans stomach have been recognized as the main reservoir for this pathogen. 7 Also, H. pylori have been isolated from nonhuman primates and domestic cats. 8-10 Sero-epidemiological surveys carried out on H. pylori reveal that the frequency of infection changes regionally, and it is lower in developed countries (30%-40%) than in developing countries (in some regions, >85%). 11,12 Most individuals remain asymptomatic. 13 However, long-term carriage of H. pylori considerably increase the risk of developing gastric diseases, such as gastritis (20%), peptic ulceration (10%), gastric adenocarcinoma (2%), and gastric mucosa- associated lymphoid tissue (MALT) lymphoma is less than 0.1% of those infected. 14,15 The routes of transmission of H. pylori are not yet fully understood. However, most infections are thought to be contracted in childhood via the oral-oral or fecal-oral routes. 16-19 H. pylori have been classified as a class I carcinogen in humans by a working group of the International Agency for Research on Cancer (IARC) of the World Health Organization(WHO). 20 So far, to fight H. Received: 16 May 2020 | Revised: 14 August 2020 | Accepted: 1 September 2020 DOI: 10.1111/hel.12758 REVIEW Helicobacter pylori adhesins: HpaA a potential antigen in experimental vaccines for H. pylori Jo-Lewis Banga Ndzouboukou | Qing Lei | Nadeem Ullah | Yandi Zhang | Ling Hao | Xionglin Fan Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China Correspondence Xionglin Fan, Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. Email: xlfan@hust.edu.cn Abstract Background: Helicobacter pylori is a gram-negative bacterium involved in many gas- tric pathologies such as ulcers and cancers. Although the treatment for this infection has existed for several years, the development of a vaccine is nevertheless necessary to reduce the severe forms of the disease. For more than three decades, many ad- vances have been made particularly in the understanding of virulence factors as well as the pathogenesis of gastric diseases caused by H. pylori. Among these key viru- lence factors, specific antigens have been identified: Urease, Vacuolating cytotoxin A (VacA), Cytotoxin-associated gene A (CagA), Blood group antigen-binding adhesin (BabA), H. pylori adhesin A (HpaA), and others. Objectives: This review will focus on H. pylori adhesins, in particular, on HpaA and on the current knowledge of H. pylori vaccines. Methods: All of the information included in this review was retrieved from published studies on H. pylori adhesins in H. pylori infections. Results: These proteins, used in their native or recombinant forms, induce protection against H. pylori in experimental animal models. Conclusion: H. pylori adhesins are known to be promising candidate vaccines against H. pylori. Future research should be carried out on adhesins, in particular, on HpaA. KEYWORDS adhesion, H. pylori adhesins, Helicobacter pylori, HpaA, vaccines