Original Articles
Copyright ©The Author(s) 1998. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 15, 1998; 4(6): 485-488
Published online Dec 15, 1998. doi: 10.3748/wjg.v4.i6.485
Coexistence of Helicobacter pylori spiral and coccoid forms in experimental mice
Jiesong Hua, Bow Ho, Pengyuan Zheng, Khay Guan Yeoh, Han Chong Ng, Seng Gee Lim
Jiesong Hua, Bow Ho, Pengyuan Zheng, Han Chong Ng, NUS H. pylori Recearch Group, Department of Microbiology, National University of Singapore, Lower kent Ridge Road, Singapore 119260, Repbulic of Singapore
Khay Guan Yeoh, Seng Gee Lim, Medicine, National University of Singapore, Lower kent Ridge Road, Singapore 119260, Repbulic of Singapore
Author contributions: All authors contributed equally to the work.
Correspondence to: Associate Professor Bow Ho, Department of Microbiology, National University of Singapore, Lower Kent Ridge Road, Singapore 119260, Republic of Singapore. michob@nus.edu.sg
Telephone: +65-8743672 Fax: +65-7766872
Received: November 9, 1998
Revised: November 22, 1998
Accepted: December 5, 1998
Published online: December 15, 1998
Abstract

AIM: To infect mice with Helicobacter pylori and detect immune response against two form of H. pylori.

METHODS: An isolate of H. pylori obtained from a patient with gastric cancer was used to infect mice. Fifty mice were divided into eight groups. Two groups served as negative control without any inoculation and internal negative control with 0.5 M NaHCO3 and brain heart infusion (HBI), respectively. Mice in each experimental group were first inoculated with 0.5 M NaHCO3 and then H. pylori suspension for 3 times at a 2-d interval. Mice from controls and infectious groups were sacrificed at a weekly interval postinfection. Gastric samples were trimmed, inoculated onto chocolate blood agar and then incujbated in microaerophilic atmosphere at 37¡æ for 14 d. Sera were examined for immunoglobulins against H. pylori spiral and coccoid antigens by ELISA.

RESULTS: After inoculation H. pylori was isolated in one mouse from one week postinfection. No H. pylori was detected in control mice. However, urease test was positive in 50% (5/10) control mice, 70% (7/10) mice inoculated with NaHCO3 and BHI and 77% (23/30) mice infected with H. pylori. The systemic immune responses of the mice to H. pylori strain were determined by ELISA. The mice showed immune responses to both H. pylori spiral and coccoid antigens one week after infection with H. pylori. The peak mean absorbances of antibodies against spiral and coccoid forms were four weeks postinfection which showed 6 and 18 times higher than that of negative control group respectively (P < 0.01).

CONCLUSION: Spiral and coccoid forms of H. pylori coexist in experimental mice studied.

Keywords: Helicobacter pylori, antibodies; ELISA; spiral form; coccoid form; mouse