Extra cellular pH governs the entry and phenotypic plasticity of Neospora caninum

Conference Paper

• اسم المؤتمر: Saudi Scientific International Conference
• عنوان المؤتمر: Brunel, UK
• تاريخ المؤتمر: الخميس, تشرين اﻷول (أكتوبر) 11, 2012

مستخلص المنشور

Neospora caninum, a strictly intracellular protozoan, is a major leading cause of parasitic-induced abortion in cattle.  Despite this prevalence, very little is known about the pathogenesis of N. caninum infection.  A widely held view of N. caninum infection is that both cellular proliferation and stage interconversion (tachyzoite-bradyzoite switching) are triggered, perhaps even modulated by, changes in culture conditions. The present study aimed to examine the effects of modification of the growth medium pH on N. caninum entry, proliferation and transformation in cultured K-652 and Vero cell lines. Materials and methods: The entry pathway of N. caninum in K-562 cells was studied by using a cell membrane potential-sensitive probe. Parasite invasion and proliferation of Vero cells was assessed by plaque formation assay. Stage transformation was studied using indirect double immunofluorescence and electron microscopy approaches. Results: Here we report that a major pathway for N. caninum entry into the K-562 cell line is dependent on endocytosis and exposure to a low pH. Also, N. caninum proliferation in Vero cells was highest when pH level was optimum and parasite encystation increased when the pH level was alkaline or acidic. Conclusions: These data suggest that external pH has a determinable effect on the host cells and free N. caninum parasites and provide evidence that the extracellular pH regulates the colonisation and phenotypic plasticity of N. caninum in mammalian cells.