Table 3. Transformation of isogenic and non-isogenic H.pylori strains by chromosomal DNA containing selectable markers of different sizes.

Recipient H.pylori strain	Transformation frequency (× 10–7)
	Transfer of a point mutation (1 bp)a from RA4	Transfer of aphA cassette (1.3 kb)b from RA3	Transfer of hpyIIRM::aphA cassette (4.8 kb) from RA1
6cc	141 ± 32	100 ± 19	49 ± 40
J166d	98 ± 7e	4 ± 0.9	<0.4
CH4d	106 ± 38e	3 ± 2	<0.4
HPK1d	222 ± 160e	1 ± 0.7	<0.5
7767d	113 ± 67e	3 ± 2	<0.4

^aStrep^r point mutation.

^baphA present in vacA.

^cStrain 6c has the same clonal origin as strain 6a.

^dStrain has different origin to strain 6a.

^eStrain was transformed by the point mutation in rpsL (A128G) conferring Strep^r at a significantly higher frequency (P < 0.05) than by the aphA cassette or by the hpyIIRM::aphA cassette.