Expanding allelic diversity of Helicobacter pylori vacA.
The diversity of the gene encoding the vacuolating cytotoxin (vacA) of Helicobacter pylori was analyzed in 98 isolates obtained from different geographic locations. The studies focused on variation in the previously defined s and m regions of vacA, as determined by PCR and direct sequencing. Phylogenetic analysis revealed the existence of four distinct types of s-region alleles: aside from the previously described s1a, s1b, and s2 allelic types, a novel subtype, designated s1c, was found. Subtype s1c was observed exclusively in isolates from East Asia and appears to be the major s1 allele in that part of the world. Three different allelic forms (m1, m2a, and m2b) were detected in the m region. On the basis of sequence alignments, universal PCR primers that allow effective amplification of the s and m regions from H. pylori isolates from all over the world were defined. Amplimers were subsequently analyzed by reverse hybridization onto a line probe assay (LiPA) that allows the simultaneous and highly specific hybridization of the different vacA s- and m-region alleles and tests for the presence of the cytotoxin-associated gene (cagA). This PCR-LiPA method permits rapid analysis of the vacA and cagA status of H. pylori strains for clinical and epidemiological studies and will facilitate identification of any further variations.
Delft Diagnostic Laboratory, 2625 AD Delft, The Netherlands. L.J.van.Doorn@ddl.nl
L J
LJ
van Doorn
C
C
Figueiredo
R
R
Sanna
S
S
Pena
P
P
Midolo
E K
EK
Ng
J C
JC
Atherton
M J
MJ
Blaser
W G
WG
Quint
D000595:Amino Acid Sequence; D001208:Asia; D001315:Australia; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics; D003364:Costa Rica; D017931:DNA Primers; D005798:Genes, Bacterial; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D016480:Helicobacter pylori / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D009426:Netherlands; D009520:New Zealand; D015345:Oligonucleotide Probes; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014481:United States
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017931:DNA Primers; D015345:Oligonucleotide Probes; C074689:VacA protein, Helicobacter pylori