Fig. 1

a The location of the different genotypes in the vacA protoxin: signal region(s) and intermediate region (i) on p33 domain. On the p55 domain, we can identify the middle region (m), c region (c) and the incidentally identified “tail-region” (n). This n-region exists as 2 genotypes: n1 (2 amino acid residue deletion) and n2 (without deletion). Between the i- and m- region (currently defined as “d-region”), we found 3 common occurring genotypes, which are denoted by K (K-type), Q (Q-type) and E (E-type). These genotypes are further divided into subtypes due to a high degree of polymorphism. b: Multiple sequence alignment from BioEdit of 18 isolates showing the highly polymorphic (so-called “d-region”) and the newly identified n-region. The high degree of polymorphism indicates that categorizing this region as d1 or d2 could be inadequate. This polymorphic region has a mean length of 34 amino acids. 10 motifs can be identified within these 18 isolates: KDKP, ESKT, KNQT, SQNN, NTQV, ANNN, ANDK, PKND, NTQV, and NNTP. The sequence of amino acid residues in the 3′ end of the p55 domain, denoted by the “n-region” shows two distinct genotypes with n1 (2 amino acid residue deletion) and n2 (without deletion). The most common occurring genotype across the studied 1259 strains is the n1 genotype