An experimental model for canine visceral leishmaniasis

Area of Science:

• Veterinary Immunology
• Parasitology
• Canine Infectious Diseases

Background:

• Leishmania donovani infantum is a significant pathogen causing canine leishmaniasis.
• Understanding the host-parasite interactions is crucial for disease management and prevention in dogs.

Purpose of the Study:

• To compare the effects of promastigote and amastigote stages of Leishmania donovani infantum in dogs.
• To evaluate humoral and cellular immune responses, clinical signs, and parasitological outcomes following experimental infection.

Main Methods:

• Seven mixed-breed dogs were experimentally infected with Leishmania donovani infantum strains via different routes and parasite numbers.
• Immune responses were assessed using antibody level measurements (ELISA, IF, CIE, Western blotting) and lymphocyte stimulation assays.
• Clinical, haematological, and parasitological parameters were monitored for at least one year post-infection.

Main Results:

• Dogs infected with amastigotes demonstrated a more pronounced humoral immune response and more apparent clinical signs (hypergammaglobulinaemia, enlarged lymph nodes, parasite presence).
• Antibody responses appeared 1.5–3 months post-infection and correlated with clinical manifestations and parasite detection.
• Strong antigen-specific lymphocyte proliferation was detected in only one dog; transient antibody responses were observed in limited cases.

Conclusions:

• The amastigote stage of Leishmania donovani infantum induces a more significant clinical and immunological response in dogs compared to the promastigote stage.
• While experimental infection did not result in mortality, sustained antibody production and clinical signs indicate chronic infection.
• Further research into the immunopathogenesis of canine leishmaniasis is warranted, considering the infective stage of the parasite.