African Journal of Microbiology Research Vol. 6(23), pp. 5015-5019, 21 June, 2012 Available online at http://www.academicjournals.org/AJMR DOI: 10.5897/AJMR12.303 ISSN 1996-0808 ©2012 Academic Journals Full Length Research Paper Relationship between Helicobacter pylori infection and Multiple sclerosis (MS) in South-east Iran Nourollah Ramroodi 1 , Nima Sanadgol 2 *, Leyla Vafadar Ghasemi 2 and Somaye Namroodi 3 1 Department of neurology, Zahedan University of Medical Sciences, Zahedan, Iran. 2 Department of Biology, College of Science, Zabol University, Zabol, Iran. 3 Department of Clinical Sciences, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran. Accepted 8 March, 2012 Helicobacter pylori (H. pylori) are one of the most common, well-known pathogenic agents in the development of peptic ulcers. Some investigators have shown a relationship between H. pylori and Multiple sclerosis (MS). However, this relationship is controversial. The aim of this study was to determine the association between H. pylori infection and MS. In a prospective case-control study, we studied 78 patients with MS and 123 healthy blood donors (HBDs) for bacterial DNA detection and antibody assay. DNA extracted from samples (serum and saliva) and real-time polymerase chain reaction (PCR) was employed in the detection of H. pylori genome. The presence of anti H. pylori CagA and VacA Immunoglobulin G (IgG) was measured in serum by Western blot technique. We found H. pylori DNA in both samples of the 32.05% (25/78) and 32.52% (40/123) of patients and HBDs, respectively (P=NS). Furthermore, anti H. pylori IgG for both antigens were detected in 21.95% (27/123) of HBDs in contrast with 25.64% (20/78) of patients (P=NS). Moreover, genome copy number of H. pylori was not significantly changed in patients (140 copies/ml) and HBDs (147 copies/ml). There was no significant correlation between H. pylori infection in both groups, but H. pylori CagA/VacA-IgG was found in patient quite more than HBDs (P<0.05) and these patients showed more positively for serum H. pylori genome. Although, these results indicate a lack of connection between the Helicobacter pylori infection and multiple sclerosis, the role of immune response against H. pylori in the modulation of MS requires further study. Key words: Helicobacter. pylori, multiple sclerosis (MS), real time- polymerase chain reaction (PCR), Western blot. INTRODUCTION Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). The factors thought to contribute to the debilitating symptoms of MS are poorly understood. While general consensus seems to be that environmental and genetic factors are the *Corresponding author. E-mail: n.sanadgol@uoz.ac.ir/ sanadgol.n@gmail.com. Tel: +98-915-7444696. Fax: +98-542- 2240696. predominant risk-determining elements, a multi-faceted view incorporating many other factors is probably more accurate (Fox et al., 2006; Kantarci and Wingerchuk 2006). Helicobacter pylori (H. pylori) are spiral, gram- negative, micro-aerophilic bacteria that are important pathogens causing infections in human gastrointestinal system. The bacteria spread through oral-oral and oral- fecal ways, and virulence factors are related to pathogenicity, as well as host factors were defined (Dunn et al., 1997; Gatti et al., 2005). The outcome of H. pylori infection is dependent on host, environmental, and