Intestinal growth and pathology ofGiardia duodenalisassemblage subtype AI, AII, B and E in the gerbil model

Abstract

SUMMARYThis study investigated the significance of the genetic differences between assemblages A, B and E on intestinal growth and virulence. Intestinal growth and virulence were studied in 2 laboratory (AI: WB and B: GS/M-83-H7) and 6 field isolates of assemblage subtype AI, AII, B and EIII. Intestinal trophozoite burdens, body weight and faecal consistency were monitored until day 29 post-infection (p.i.), morphological (mucosal architecture and inflammation) and functional (disaccharidase and alkaline phosphatase enzyme activity) damage to the small intestine were evaluated on days 7 and 18 p.i. The assemblage subtypes AIand B were more infectious and produced higher trophozoite loads for a longer period compared to the subtypes AIIand EIII. The body weight of infected gerbils was significantly reduced compared to uninfected controls, but did not differ between the assemblage subtypes. Consistent softening of the faeces was only observed with assemblage B. Assemblage B next to assemblage subtype AIelicited relatively higher pathogenicity, characterized by more extensive damage to mucosal architecture, decreased brush-border enzyme function and infiltration of inflammatory cells. Assemblage EIIIand AIIisolates showed relatively low virulence. TheGiardiaassemblage subtypes exhibit different levels of growth and virulence in the gerbil model.