Neospora caninum and neosporosis — recent achievements in host and parasite cell biology and treatment

Abstract

Neospora caninum is an apicomplexan parasite, which owes its importance to the fact that it represents the major infectious cause of bovine abortion worldwide. Its life cycle is comprised of three distinct stages: Tachyzoites, representing the proliferative and disease-causing stage, bradyzoites, representing a slowly replicating, tissue cyst-forming stage, and sporozoites, which represent the end product of a sexual process taking place within the intestinal tissue of the final canine host. Tachyzoites are capable of infecting a large variety of host cells in vitro and in vivo, while bradyzoites have been found mainly within the central nervous system. In order to survive, proliferate, and proceed in its life cycle, N. caninum has evolved some amazing features. First, the parasite profits immensely from its ability to interact with, and invade, a large number of host cell types. Secondly, N. caninum exploits its capability to respond to alterations in living conditions by converting into another stage (tachyzoite-to-bradyzoite or vice versa). Thirdly, this parasite has evolved mechanisms that modulate its host cells according to its own requirements, and these must, especially in the case of the bradyzoite stage, involve mechanisms that ensure long term survival of not only the parasite but also of the host cell. These three key events (host cell invasion -stage conversion -host cell modulation) represent potential targets for intervention. In order to elucidate the molecular and cellular bases of these important features of N. caninum, cell culture-based approaches and laboratory animal models are extensively exploited. In this review, we will summarize the present knowledge and achievements related to host cell and parasite cell biology.

Identification ofBesnoitia besnoitiproteins that showed differences in abundance between tachyzoite and bradyzoite stages by difference gel electrophoresis

“…Surface proteins were not identified in the present study, most likely due to their hydrophobic nature. Thus, additional approaches should be conducted to identify the B. besnoiti glycoproteome (Che et al 2011; Luo et al 2011) because most stage-specific proteins described in T. gondii and N. caninum are surface proteins (Boothroyd et al 1998; Hemphill and Gottstein, 2006). Moreover, secreted proteins are also expected to be present in both invasive forms; thus, subcellular fractionation strategies (Bradley et al 2005; Marugán-Hernández et al 2011) could help to identify these minor proteins involved in invasion and proliferation.…”

A model for chronic bovine besnoitiosis: Parasite stage and inoculation route are key factors

“…Based on our results, the bradyzoite stage appears to be a principal key variable in determining the outcome of the chronic infection since all inoculated animals developed tissue cysts regardless of the inoculation route. In Sarcocystidae parasites, the bradyzoite differentiation is an immune evasion mechanism that allows the parasite to persist in the host for a long life (Hemphill & Gottstein, ; Jeffers, Tampaki, Kim, & Sullivan, ). Indeed, B. besnoiti tachyzoites display different antigenic patterns and protein compositions compared with bradyzoites (Fernández‐García et al, ; García‐Lunar, Regidor‐Cerrillo, Gutiérrez‐Expósito, Ortega‐Mora, & Álvarez‐García, ).…”

Modeling the Ruminant Placenta-Pathogen Interactions in Apicomplexan Parasites: Current and Future Perspectives

“…During the course of a natural infection, parasite survival and propagation heavily rely on successful invasion and proliferation within receptive host cells as part of the parasite's lytic cycle ( 130 ). Thus, the study of such processes in target cells appears as an ideal tool to study host-parasite interactions at the placental barrier.…”