Genetic polymorphism in Dirofilaria immitis.

Area of Science:

• Veterinary Parasitology
• Molecular Genetics
• Drug Resistance Studies

Background:

• Dirofilaria immitis causes heartworm disease in dogs.
• Reports of macrocyclic lactone inefficacy highlight the need to investigate genetic polymorphism in D. immitis.
• Limited genetic information exists for D. immitis, impacting understanding of drug resistance.

Purpose of the Study:

• To investigate genetic polymorphism and heterogeneity in D. immitis populations.
• To assess baseline genetic variability in relation to potential macrocyclic lactone resistance.
• To compare genetic profiles of D. immitis from the USA and Japan.

Main Methods:

• Analysis of single nucleotide polymorphisms (SNPs) in key genes: β-tubulin, heat shock protein 60 (Hsp60), P-glycoprotein (Pgp), sarco-endoplasmic reticulum Ca(2+)ATPase (Serca), and phosphofructokinase (PFK).
• Genotyping using combined SNPs from β-tubulin, Hsp60, Pgp, and Serca.
• Calculation of F coefficients to assess genetic equilibrium and differences between populations.

Main Results:

• Significant SNP frequency differences were observed across all investigated genes except PFK.
• Combined genotypes revealed unique and shared profiles among US (lab/field) and Japanese field samples.
• F coefficients indicated genetic disequilibrium and variations between sample groups, confirming genetic heterogeneity.

Conclusions:

• Dirofilaria immitis populations exhibit significant genetic heterogeneity.
• This genetic diversity has implications for the development of drug-resistant parasite strains.
• Understanding genetic variability is essential for effective heartworm disease management and treatment strategies.