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Helicobacter pylori oipA, vacA and dupA genetic diversity in individual hosts

¹ Departamento de Microbiologia, Parasitologia e Inmunologia, Facultad de Medicina, UBA;

² Servicio de Gastroenterologia, Hospital Escuela 'Don Jose de San Martin' Facultad De Medicina, UBA;

³ Servicio de Endoscopia, Hospital General de Agudos Juan A Fernandez, Buenos Aires, Argentina

⁴ E-mail: catalano{at}fmed.uba.ar

Received April 7, 2009
Accepted July 26, 2009

Helicobacter pylori putative virulence factors can undergo a continuous evolving mechanism as an approach to bacterial adaptation to host changing environment during chronic infection. oipA, vacA and dupA genetic diversity among isolates from multiple biopsies (niches) from antrum and corpus of 40 patients was investigated. A set of 229 isolates was examined. Direct DNA sequence analysis of amplified fragments was used to study oipA 'on/off' expression status as well as the presence of C or T insertion in jhp0917 that originates a continuous (jhp0917-jhp0918) dupA gene. vacA alleles were identified by PCR-multiplex. Different inter-niches oipA CT repeat patterns were observed in 9 patients; in 6 of these, 'on'and 'off' mixed patterns were found. In 3 of these 9 patients, different vacA alleles were also observed in a single host. Inter-niches dupA differences involved absence and presence of jhp0917 and/or jhp0918 or mutations in dupA, including those that may originate a non-functional gene, and they were also present in 2 patients with mixed oipA CT patterns and in other 7 patients. Evidence of mixed infection was observed in 2 patients only. In conclusion, oipA and dupA genes showed similar inter-niches variability, close to 1/4 patients. Conversely, vacA allele microevolution seems to be a less common event, close to 1/10 patients, probably due to the mechanism this gene evolves 'in vivo'.