Activation of the alternative complement pathway in canine normal serum by Paracoccidioides brasiliensis

Abstract

The dimorphic fungus Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis, a human granulomatous disease. Recently the first case of natural disease in dogs was reported. The complement system is an important effector component of humoral immunity against infectious agents. Therefore, the aim of this study was to evaluate the activation of the dog alternative complement pathway by P. brasiliensis. Initially, the ability of erythrocytes of guinea pig, rabbit, sheep, chicken and swine to activate the dog alternative pathway was evaluated. The guinea pig erythrocytes showed the greatest capacity to activate dog alternative pathway. The alternative (AH50) hemolytic activity was evaluated in 27 serum samples from healthy dogs and the mean values were 87.2 AH50/ml. No significant differences were observed in relation to sex and age. The alternative pathway activation by P. brasiliensis was higher in serum samples from adult dogs when compared to puppies and aged dogs (p ≤ 0.05). This is the first report of dog alternative complement pathway activation by P. brasiliensis and suggests that it may play a protective role in canine paracoccidioidomycosis.

Innate immunity in chicken lines developed by EMBRAPA Suínos e Aves: antimicrobial activity of macrophages and serum

“…The complement system is one of the main effector mechanisms of innate and humoral immunity. It is activated by the presence of the microorganism and results in the destruction of the pathogen through activation of the inflammatory response, by facilitating phagocytosis or by direct lysis (Bianchini et al, 2009;Shokal and Eleftherianos, 2017). Therefore, one of the main mechanisms of virulence of bacteria is the ability to resist the lytic action of the complement system (Barbieri et al, 2015).…”