ARS | Publication request: Multilocus genotyping of Giardia duodenalis in lambs from Spain reveals a high hetrogeneity

Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 16, 2011
Publication Date: October 2, 2012
Citation: Gomez-Munoz, M., Camara-Badenes, C., Martinez-Herrero, M., Dea-Ayuela, M., Perez-Gracia, M., Fernandez-Barredo, S., Santin, M., Fayer, R. 2012. Multilocus genotyping of Giardia duodenalis in lambs from Spain reveals a high hetrogeneity. Research in Veterinary Science. 93(2):836-842.

Interpretive Summary: This study examined feces from 120 lambs in Valencia (Spain) for the presence of the parasite Giardia duodenalis using microscopy and molecular methods for detection. Fragments for four different genes (beta giardin, glutamate dehydrogenase, triose phosphate isomerise, and small subunit ribosomal RNA) were amplify using the polymerase chain reaction (PCR). The highest prevalence was obtained using the PCR for the small subunit ribosomal RNA gene (89.2%), whereas values from other techniques ranged from 64.1 to 69.2%. Two genetic types were found, Assemblage E which is known to infect only hooved livestock, and Assemblage A which infects many animals and humans. Sequences of the small subunit ribosomal RNA gene showed a high proportion of assemblage A or mixed assemblage A/E samples (55.1 and 25.2%, respectively). When the other 3 genes were analyzed, between 6.5and 15.4% were found to be assemblage A or A/E, respectively. Multilocus genotyping resulted in 63 patterns from the 71 samples sequenced at the four genes. The results of this study suggested that a multilocus analysis is critical to understand the epidemiology giardia infectious. The high degree of diversity found in indicated that attempts to utilize a single locus to track G. duodenalis to determine the source of environmental contamination is not practical.

Technical Abstract: Fecal specimens from 120 lambs in Valencia (Spain) were analyzed for Giardia duodenalis by IFA and nested-PCR using the beta giardin, glutamate dehydrogenase (gdh), triose phosphate isomerase (tpi) and small subunit ribosomal RNA (ssurRNA) genes. The highest prevalence was obtained using the ssurRNA gene (89.2%), whereas values from other techniques ranged from 64.1 to 69.2%. Sequences of the ssurRNA showed a high proportion of assemblage A or mixed assemblage A/E samples (55.1 and 25.2%, respectively). When the other 3 loci were analyzed, between 6.5and 15.4% were found to be assemblage A or A/E, respectively. Nested PCR for the tpi gene was the most variable of the targets employed. Twelve new sequences of gdh and tpi from sheep were found. Multilocus genotyping resulted in 63 patterns from the 71 samples sequenced at the four loci. This high variability among isolates possibly reflects the high frequency of mixed infections.