[Reaction of bovine endothelial cells in vitro to coccidia (Eimeria bovis, Toxoplasma gondii, Neospora caninum) infections as the expression of a non-adaptive immune response]

Abstract

Eimeria (E.) bovis sporozoites as well as Toxoplasma (T.) gondii and Neospora (N.) caninum tachyzoites can invade bovine endothelial cells (BUVEC) in vitro and develop to next stage meronts within 15-20 and 3-4 days, respectively. The latter differences suggest different immune evasion strategies, particularly concerning innate reactions. Realtime RT-PCR techniques were used to determine transcript levels of genes relevant in this sense, i.e. adhesion molecule, chemokine, growth factor GM-CSF, cyclooxygenase 2 (COX-2) and iNOS genes in infected cells. In addition, adhesion of neutrophils (PMN) to infected BUVEC monolayers was quantified. Effects differed between E. bovis and T. gondii/N. caninum as the latter two species strongly enhance the transcription of all genes in question and induce PMN adhesion to infected BUVEC whereas E. bovis either caused only weak responses or failed to enhance gene transcription as in case of CXC chemokines and COX-2. It even down regulates adhesion molecule expression in response to cytokines. The differences between the species may reflect differing immune evasion strategies, in case of E. bovis favouring its long lasting development to macromeronts.