New multilocus genotypes of Giardia lamblia human isolates

Area of Science:

• Medical Parasitology
• Molecular Biology
• Genetics

Background:

• Giardia lamblia is a species complex with significant genetic variability.
• Understanding genetic diversity is crucial for epidemiological studies and control strategies.

Purpose of the Study:

• To investigate inter- and intra-assemblage genetic variation of Giardia lamblia in human clinical samples from Rio de Janeiro.
• To characterize genetic assemblages and subtypes using multilocus sequence typing (MLST).

Main Methods:

• Parasitological examination of fecal samples.
• DNA extraction from positive Giardia lamblia samples.
• Multilocus sequence typing (MLST) using beta-giardin (bg), triose phosphate isomerase (tpi), and glutamate dehydrogenase (gdh) gene loci.

Main Results:

• Fourteen assemblage A samples were genotyped, revealing two known (AII-1, AII-4) and two novel multilocus genotypes (AII-8, AII-9).
• Assemblage B isolates exhibited higher nucleotide variation than assemblage A, with novel sequences and heterogeneous nucleotides preventing clear genotype definition in most cases.
• MLST successfully identified novel subtypes in both assemblages and two new multilocus genotypes within assemblage A.

Conclusions:

• This study provides the first MLST characterization of Giardia lamblia from clinical samples in Rio de Janeiro.
• MLST is a valuable tool for detecting novel Giardia lamblia subtypes and genotypes, offering new insights into assemblage A's genetic diversity.
• The findings underscore the importance of MLST for characterizing Giardia lamblia globally and in Brazil.