3D holotomographic monitoring of Ca++ dynamics during ionophore-induced Neospora caninum tachyzoite egress from primary bovine host endothelial cells

Abstract

Neospora caninum represents an obligate intracellular parasite that belongs to the phylum Apicomplexa and is a major abortive agent in bovines. During merogony, N. caninum tachyzoites invade and proliferate in host cells in vivo, including endothelial cells of lymphatic and blood vessels. The egress at the end of the lytic cycle is tightly regulated in apicomplexans. Evidence in Toxoplasma gondii shows that Ca++ signalling governs tachyzoite egress. Much less is known on egress mechanisms of N. caninum. Here, we show, using 3D live cell holotomographic microscopy in fluo-4 AM-loaded N. caninum-infected BUVEC, that treatments with the calcium ionophore A23187 at 24- and 42-h post-infection (h p. i.) induced a fast and sustained increase in Ca++ signals in parallel to tachyzoite egress. A23187 treatments exclusively triggered tachyzoite release at 42-h p. i. but failed to do so at 24-h p. i. indicating a role for meront maturation in calcium-induced tachyzoite egress. Overall, we show that live cell 3D holotomographic analysis in combination with epifluorescence is a suitable tool to study calcium dynamics related to coccidian egress or other important cell functions.

The Cellular Innate Immune Response of the Invasive Pest Insect Drosophila suzukii against Pseudomonas entomophila Involves the Release of Extracellular Traps

“…D. suzukii robust cellular immune responses might have facilitated its rapid worldwide spread by allowing it to overcome pathogen infections in newly colonized environments [ 55 , 56 , 57 ]. Such immunological diversity can help invasive species deal with unfamiliar pathogens [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ], as recently shown for the invasive harlequin ladybird Harmonia axyridis [ 48 , 55 , 56 , 57 ...…”

“…Further, 3D rendering and digital staining were performed based on RI values and thereafter illustrated. Additionally, each channel was exported separately using Steve ® software v.2.6 (Nanolive ® , Tolochenaz, Switzerland) and managed with Image J Fiji v1.7 (NIH, Bethesda, MD, USA) as described elsewhere [ 38 , 39 ].…”

The State of Art of Extracellular Traps in Protozoan Infections (Review)

“…Neospora caninum ( N. caninum ) belongs to the class Aconoidasida and order Eucoccidia. It is an obligate intracellular protozoan parasite that causes serious reproductive disorders in ruminants worldwide ( 78 ). N. caninum can infect a wide range of hosts.…”