Internal Transcribed Spacer 1 (ITS1) based sequence typing reveals phylogenetically distinct Ascaris population

Area of Science:

• Molecular biology
• Parasitology
• Genetics

Background:

• Taxonomic differentiation of morphologically similar Ascaris species remains a challenge for Ascariasis epidemiology.
• Genome information from Ascaris strains in endemic regions is crucial for understanding disease patterns and species classification.

Purpose of the Study:

• To genetically characterize the Ascaris population from India using the ITS1 marker.
• To investigate the phylogenetic position and genetic diversity of Indian Ascaris isolates.

Main Methods:

• Genetic characterization of Ascaris using the internal transcribed spacer 1 (ITS1) genetic marker.
• Identification of sequence variants and phylogenetic analysis.
• Intragenic linkage disequilibrium (LD) analysis.

Main Results:

• Eight new ITS1 sequence variants were identified, in addition to the prevalent genotype G1.
• Genotype G1 was significantly associated with female patients aged 10-15 years.
• Indian Ascaris isolates formed a distinct phylogenetic cluster, separate from global populations.
• Incomplete LD values indicated potential recombination events within the Ascaris population.

Conclusions:

• The study provides the first molecular epidemiological insights into the Indian Ascaris population.
• Recombination is suggested as a driving force behind the high genetic diversity and emergence of new sequence variants.
• Distinct genetic clustering of Indian isolates highlights their unique phylogenetic position.