The Genome

Excerpt

The isolation and cultivation of a spiral bacterium in the early 1980s (62) from the gastric biopsies of patients suffering from chronic gastritis and ulcers have since resulted in a wealth of new knowledge about one of the largest worldwide infectious diseases known to mankind. Helicobacter pylori colonizes the gastric mucosa of almost half of the world's population and is associated with gastroduodenal diseases ranging from superficial and chronic gastritis, duodenal and gastric ulcers, to gastric carcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma (18, 43, 55). There is also some evidence that infection with H. pylori may play a role in increasing the severity or risk of infection by other gastrointestinal pathogens and in childhood malnutrition, particularly in less developed countries (17, 20). Consistent with its global significance, a tremendous amount of attention in the last two decades has been directed toward understanding the biology and pathogenesis of H. pylori.

A shift in the paradigm of bacteriology came in 1995 with the release of the first complete genomic sequence of a free-living bacterium, Haemophilus influenzae (30). In the last 5 years, there has been an explosion of microbial genomic sequence data generated from a wide range of organisms, with almost 30 completed microbial genomes now published and over 100 microbial genomic projects under way. A milestone in microbial genomics was set when H. pylori became the first bacterial species to have its genome sequenced and compared from two independent isolates (8, 99). The subsequent comparison has provided the first detailed look at the physical chromosomal organization and has begun to identify a minimal set of common genes that can be used as candidates for therapeutic strategies.