Characterization of Dr20/22: Molecular Insights and Antibody Response in Naturally Infected Dogs with Dirofilaria repens

Subcutaneous dirofilariasis, caused by the parasitic nematode Dirofilaria repens, is a growing concern in Europe, affecting both dogs and humans. This study focused on D. repens Dr20/22, a protein encoded by an alt (abundant larval transcript) gene family. While well-documented in L3 larvae of other filariae species, this gene family had not been explored in dirofilariasis. The research involved cloning Dr20/22 cDNA, molecular characterization, and evaluating its potential application in the diagnosis of dirofilariasis. Although Real-Time analysis revealed mRNA expression in both adult worms and microfilariae, the native protein remained undetected in lysates from both developmental stages. This suggests the proteins specificity for L3 larvae and may be related to a process called SLTS (spliced leader trans-splicing), contributing to stage-specific gene expression. The antigens apparent specificity for invasive larvae makes it a strong candidate for an early dirofilariasis marker. ELISA tests using sera from infected and healthy dogs detected specific IgG antibody responses in both groups, indicating that specific IgG in healthy dog sera may contribute to dirofilariasis immunity. Although further research is necessary, the molecular and immunological characterization of Dr20/22 can enhance our understanding of host-parasite interactions and provide insights into the mechanisms that facilitate immune system evasion.