CLONING AND CHARACTERIZATION OF HEMOLYTIC GENES FROM HELICOBACTER-PYLORI

Strains of Helicobacter pylori, the bacterium associated with gastriti s, peptic ulcer disease, and gastric cancer in humans, express differe nt degrees of hemolysis on agar containing erythrocytes (RBC). Here we report the isolation and characterization of six recombinant clones f rom a genomic library of H. pylori ATCC 49503 that confer on Escherich ia coli the ability to lyse sheep RBC. DNA hybridizations indicated no sequence homology among these hemolytic clones. Hybridization mapping of them to an ordered H. pylori cosmid library identified their separ ate chromosomal locations. One clone hybridized to two regions separat ed by approximately 200 kb. The specificities of the hemolytic activit ies of these clones were tested with RBC from humans, monkeys, cattle, horses, guinea pigs, rabbits, and chickens as well as with RBC from s heep. One clone conferred the ability to lyse RBC from five species, a second clone allowed the lysis of RBC from four of these species, thr ee other clones allowed the lysis of RBC from three of these species, and the sixth clone allowed the lysis of RBC from just two species. We propose that some or all of the genes that confer these various hemol ytic activities contribute to pathogen-host tissue interactions and th at the different specificities seen here are important for H. pylori i nfections of humans of different genotypes or disease states.