Laboratory validation of an ELISA method to measure circulating immune complexes levels in canine visceral leishmaniasis.

Susceptible dogs suffering from canine leishmaniasis (CanL) develop an ineffective humoral immune response that leads to the formation of circulating immune complexes (CIC). These CIC are aggregates of Leishmania proteins and anti-Leishmania immunoglobulins. Their deposition in different tissues is considered the main cause of mortality.

Vaccination with LetiFend® reduces circulating immune complexes in dogs experimentally infected with L. infantum.

Domestic dogs constitute the main reservoir of Leishmania infantum and play a key role in transmission to humans. The main tool for controlling infection spread is a safe and effective vaccine, as successful immunization of dogs could significantly reduce the incidence of human visceral leishmaniosis (VL) and is the most cost-effective control strategy. The factors that determine disease progression in canine leishmaniosis (CanL) remain poorly understood, though a previous study in naturally infected dogs has demonstrated a clear relationship between the presence of circulating immune complexes (CIC) in the blood and disease progression.

Circulating immune complexes levels correlate with the progression of canine leishmaniosis in naturally infected dogs.

Dogs are the main domestic reservoir of Leishmania infantum, and in cases of uncontrolled infection, a strong humoral immune response is elicited, which is inefficient against the parasites. Previous studies have suggested that an adequate antigen/antibody ratio, with a moderate prevalence of antigens with respect to the antibodies, could result in the formation of circulating immune complexes (CIC) in canine leishmaniosis (CanL). Deposition of these complexes in tissues has been associated with vasculitis, uveitis, arthritis, dermatitis and especially glomerulonephritis and renal failure.