title: Non-invasive genotyping of Helicobacter pylori cagA, vacA, and hopQ from asymptomatic children.
abstract: BACKGROUND
  Helicobacter pylori infection is usually acquired in childhood, but little is known about its natural history in asymptomatic children, primarily due to the paucity of non-invasive diagnostic methods. H. pylori strains harboring cagA and specific alleles of hopQ and vacA are associated with increased risk for gastric cancer. Many studies of H. pylori virulence markers in children have the bias that symptomatic subjects are selected for endoscopy, and these children may harbor the most virulent strains. Our aim is to genotype cagA, hopQ, and vacA alleles in stool DNA samples of healthy Colombian children residing in an area with high incidence of gastric cancer, to avoid selection bias resulting from endoscopy.
  
  
  METHODS
  H. pylori status of 86 asymptomatic children was assessed by (13) C-urea breath test (UBT) and PCR. H. pylori 16S rRNA, cagA, hopQ, and vacA genes were amplified from stool DNA samples and sequenced.
  
  
  RESULTS
  UBT was positive in 69 (80.2%) of 86 children; in stool DNA analysis, 78.3% were positive by 16S rRNA PCR. cagA, vacA, and hopQ were detected in 66.1%, 84.6%, and 72.3% of stool DNA samples from 16S rRNA-positive children. Of the children's DNA samples, which revealed vacA and hopQ alleles, 91.7% showed vacA s1 and 73.7% showed type I hopQ. Type I hopQ alleles were associated with cagA positivity and vacA s1 genotypes (p < 0.0001).
  
  
  CONCLUSIONS
  Using stool DNA samples, virulence markers of H. pylori were successfully genotyped in a high percentage of the asymptomatic infected children, revealing a high prevalence of genotypes associated with virulence. Type I hopQ alleles were associated with the presence of cagA and the vacA s1 genotype.
authors.affiliation: Division of Gastroenterology, Dept. of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Liviu A
authors.initials: LA
authors.lastname: Sicinschi
authors.forename: Pelayo
authors.initials: P
authors.lastname: Correa
authors.forename: Luis E
authors.initials: LE
authors.lastname: Bravo
authors.forename: Richard M
authors.initials: RM
authors.lastname: Peek
authors.forename: Keith T
authors.initials: KT
authors.lastname: Wilson
authors.forename: John T
authors.initials: JT
authors.lastname: Loh
authors.forename: Maria C
authors.initials: MC
authors.lastname: Yepez
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Gold
authors.forename: Dexter T
authors.initials: DT
authors.lastname: Thompson
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Cover
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Schneider
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D003105:Colombia / Q000453:epidemiology; D005243:Feces / Q000382:microbiology; D005838:Genotype; D016481:Helicobacter Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology*; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D012424:Rural Population
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori