title: Genetic heterogeneity at the beta-giardin locus among human and animal isolates of Giardiaduodenalis and identification of potentially zoonotic subgenotypes.
abstract: Human giardiasis, caused by the intestinal flagellate Giardia duodenalis, is considered a zoonotic infection, although the role of animals in the transmission to humans is still unclear. Molecular characterisation of cysts of human and animal origin represents an objective means to validate or reject this hypothesis. In the present work, cysts were collected in Italy from humans (n=37) and animals (dogs, one cat and calves, n=46), and were characterised by PCR amplification and sequencing of the beta-giardin gene. As expected, only Assemblages A and B were identified among human isolates. The host-specific Assemblages C and D were found in the majority of dog isolates; however, 6 dog isolates were typed as Assemblage A. The cat-specific Assemblage F has been identified in the single feline isolate available. Among calf isolates, most were typed as Assemblages A (n=12) and B (n=5), whereas the host-specific Assemblage E was rarely found (n=3). Sequence heterogeneity in the beta-giardin gene allowed a number of subgenotypes to be identified within Assemblage A (8 subgenotypes), B (6 subgenotypes), D (2 subgenotypes), and E (3 subgenotypes). Five of these subgenotypes, namely A1, A2, A3, A4 and B3, were found to be associated with infections of humans, of dogs and of calves; these data, therefore, supported the role of these animals as a source of infection for humans.
authors.affiliation: Division of Gastroenteric and Tissue Parasitic Diseases, Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Lalle
authors.forename: Edoardo
authors.initials: E
authors.lastname: Pozio
authors.forename: Gioia
authors.initials: G
authors.lastname: Capelli
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Bruschi
authors.forename: Daniele
authors.initials: D
authors.lastname: Crotti
authors.forename: Simone M
authors.initials: SM
authors.lastname: Cacciò
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000469:parasitology / Q000635:transmission; D002415:Cats; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology / Q000635:transmission; D003598:Cytoskeletal Proteins / Q000235:genetics*; D016054:DNA, Protozoan / Q000032:analysis; D004283:Dog Diseases / Q000469:parasitology / Q000635:transmission; D004285:Dogs; D017125:Genes, Protozoan / Q000235:genetics; D018740:Genetic Heterogeneity; D016829:Giardia lamblia / Q000235:genetics* / Q000302:isolation & purification; D005873:Giardiasis / Q000469:parasitology* / Q000635:transmission / Q000662:veterinary; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*; D015047:Zoonoses
chemical_list: D003598:Cytoskeletal Proteins; D016054:DNA, Protozoan; D015800:Protozoan Proteins; C038207:giardin protein, Giardia lamblia