Multilocus genotyping of Giardia duodenalis isolates from breeding cattery cats in Japan

Objectives The present study reports the multilocus genotyping of Giardia duodenalis isolates from cats maintained in breeding catteries in Japan and discusses their potential for zoonotic transmission. Methods A total of 41 faecal samples positive for Giardia-specific antigen were procured from cats maintained in five breeding catteries and subjected to PCR to amplify four gene loci, namely small subunit ribosomal RNA (SSU rRNA), glutamate dehydrogenase (gdh), beta-giardin (bg) and triose phosphate isomerase (tpi ). The PCR-amplified DNA fragments were sequenced to determine the G duodenalis genotypes (synonym for assemblages). Results The most commonly occurring single assemblage was assemblage F (68.3%; n = 28/41), followed by assemblage A (12.2%; n = 5/41) and assemblage C (2.4%; n = 1/41). The mixed assemblages were identified as follows: assemblages F and A (9.8%; n = 4/41), assemblages F and C (4.9%; n = 2/41) and assemblages C and D (2.4%; n = 1/41). Additional sub-genotyping of assemblage A isolates based on three of the sequenced loci (gdh, bg and tpi ) revealed that all eight isolates were identified as sub-assemblage AI and/or AII. Conclusions and relevance The present study is the first to report the detection of dog-adapted assemblages C and D in feline isolates from Japan. In addition, zoonotic sub-assemblage AI and human-adapted sub-assemblage AII were also identified. Thus, we concluded that the risk of transmission of G duodenalis from breeding cattery cats to humans is considerable and cannot be ignored.