Ascaris: development of selected genotypes in mice

Area of Science:

• Parasitology
• Molecular Biology
• Host-Parasite Interactions

Background:

• Nucleotide variation in the first internal transcribed spacer of nuclear ribosomal DNA identified five Ascaris genotypes (G1-G5).
• Genotype G1 predominates in human-derived worms, while G3 is prevalent in pig-derived worms, suggesting host specificity.
• Previous studies indicated significant differences in infectivity and establishment between G1 and G3 genotypes in mice and pigs.

Purpose of the Study:

• To investigate differences in egg hatching, larval migration, and distribution between Ascaris genotypes G1 and G3 in a mouse model.
• To elucidate the developmental discrepancies that may explain observed differences in host affiliation.

Main Methods:

• Oral infection of C57BL/6 mice with Ascaris eggs of genotype G1 (human-derived) and G3 (pig-derived).
• Systematic examination of eggs/larvae in various tissues (intestines, cavities, blood, liver, lungs) at multiple time points post-infection (2h to 34 days).

Main Results:

• Distinct differences observed in egg hatching patterns, including timing, location, and number of hatched eggs.
• Significant variations noted in larval migration and distribution, encompassing means, ratios, peak recovery times, and intestinal reappearance.
• Genotype G1 exhibited significantly higher larval recovery rates in mice compared to genotype G3.

Conclusions:

• Developmental differences in egg hatching and larval stages between Ascaris genotypes G1 and G3 are evident in mice.
• These findings provide a biological basis for the differential host affiliation observed between Ascaris genotypes.
• The study highlights the importance of genotype in understanding Ascaris-host interactions and epidemiology.