A novel high-resolution multilocus sequence typing of Giardia intestinalis Assemblage A isolates reveals zoonotic transmission, clonal outbreaks and recombination

Recirculation of Giardia lamblia Assemblage A After Metronidazole Treatment in an Area With Assemblages A, B, and E Sympatric Circulation

“…As the genes used for genotyping are considered conserved, a good discriminatory potential among the assemblages is expected (Ryan and Cacciò, 2013). However, the low nucleotide variability observed among subassemblages A questions the efficiency of these gene targets to characterize isolates in AI and AII, mainly (Lebbad et al, 2010(Lebbad et al, , 2011Ankarklev et al, 2018). Few nucleotide changes could be insufficient or sufficient to differentiation into subassemblages.…”

Giardia duodenalis in small animals and their owners in Germany: A pilot study

“…In fact, the analysis of single trophozoites from the axenic culture of an assemblage B isolate (GS isolate) revealed allelic sequence heterogeneity (ASH) and further analysis of single cysts of assemblage B type infections suggested mixed infections with subassemblage types (Ankarklev et al, ). Moreover, possible recombination events in Giardia may also contribute to ASH that could hamper typing efficiency (Andersson, ; Ankarklev et al, ). Altogether, our example confirms that a zoonotic potential cannot be excluded per se (Lalle et al, ; Marangi et al, ), but it also shows that advanced molecular tools are necessary to trace strains unambiguously to deduce a definitive conclusion.…”

“…Detection of subassemblages, especially of assemblage A, could be problematic with gdh, tpi and bg genes due to the low variability of those genes, too (Ankarklev et al, 2018;Ankarklev, Svard, & Lebbad, 2012). Therefore, high-resolution multilocus sequence typing as published recently should be performed in future for a better estimation of the zoonotic potential of Giardia (Ankarklev et al, 2018). Additionally, recombination processes could also lead to a reduced sensitivity of PCR analysis (Andersson, 2012).…”

“…In fact, the analysis of single trophozoites from the axenic culture of an assemblage B isolate (GS isolate) revealed allelic sequence heterogeneity (ASH) and further analysis of single cysts of assemblage B type infections suggested mixed infections with subassemblage types (Ankarklev et al, 2012). Moreover, possible recombination events in Giardia may also contribute to ASH that could hamper typing efficiency (Andersson, 2012;Ankarklev et al, 2018Ankarklev et al, , 2012 al., 2010), but it also shows that advanced molecular tools are necessary to trace strains unambiguously to deduce a definitive conclusion. Thus, future studies should focus on the establishment of more efficient typing strategies for those difficult-to-type samples including possibly more advanced MLST methods as recently introduced for assemblage A (Ankarklev et al, 2018), or whole-genome sequencing-based analysis on enriched or single cysts as shown for Cryptosporidium spp.…”

“…Moreover, possible recombination events in Giardia may also contribute to ASH that could hamper typing efficiency (Andersson, 2012;Ankarklev et al, 2018Ankarklev et al, , 2012 al., 2010), but it also shows that advanced molecular tools are necessary to trace strains unambiguously to deduce a definitive conclusion. Thus, future studies should focus on the establishment of more efficient typing strategies for those difficult-to-type samples including possibly more advanced MLST methods as recently introduced for assemblage A (Ankarklev et al, 2018), or whole-genome sequencing-based analysis on enriched or single cysts as shown for Cryptosporidium spp. (Troell et al, 2016).…”