%0 Journal Article %T Differential Effects on Survival, Humoral Immune Responses and Brain Lesions in Inbred BALB/C, CBA/CA, and C57BL/6 Mice Experimentally Infected with Neospora caninum Tachyzoites %A Tanja Mols-Vorstermans %A Andrew Hemphill %A Thierry Monney %A Dick Schaap %A Eveline Boerhout %J ISRN Parasitology %D 2013 %R 10.5402/2013/830980 %X C57BL/6, BALB/c, and CBA/Ca mouse strains with different MHC-I haplotypes were compared with respect to susceptibility to Neospora caninum infection. Groups of 5 mice received , , or tachyzoites of the NC-Liverpool isolate by intraperitoneal injection and were observed for disease symptoms. Humoral responses, splenocyte interferon-¦Ã (IFN-¦Ã) production, cerebral parasite loads, and histopathology were evaluated at human end points or the latest at 34 days postinfection (PI). The mortality rates in C57BL/6 mice were the highest, and relatively high levels of IgG1 antibodies were detected in those mice surviving till 34 days PI. In lymphocyte proliferation assays, spleen cells from C57BL6 mice stimulated with N. caninum antigen extract exhibited large variations in IFN-¦Ã production. In BALB/c mice mortality was 0% at the lowest and 100% at the highest infection dose. Serologically they responded with high levels of both IgG2a and IgG1 subclasses, and lymphocyte proliferation assays of surviving mice yielded lower IFN-¦Ã levels. CBA/Ca mice were the most resistant, with no animal succumbing to infection at a dose of and tachyzoites, but 100% mortality at tachyzoites. High IgG2a levels as well as increased IFN-¦Ã in lymphocyte proliferation assays were measured in CBA/Ca mice infected with tachyzoites. 1. Introduction Neospora caninum is an apicomplexan protozoan, infecting a large range of mammals. In cattle, this parasite represents a major cause of abortion [1¨C3]. Several studies focussing on the specific immune response to N. caninum in cattle have shown that the time of gestation is important with regard to the outcome of the infection. This may be explained on the basis of hormone levels and cytokine profiles [4]. Proinflammatory cytokines, produced by lymphocytes, are crucial for controlling a variety of intracellular pathogens, including N. caninum. These cytokines are produced by natural killer (NK) cells, as well as by CD4+£¿£¿T-cells and CD8+£¿£¿T-cells. CD4+ cells mediate the humoral response and their involvement is associated with increased IgG1 levels, whereas CD8+ cells are involved in the cellular immune response, which is characterized by increased production of IgG2a. Indeed, both has been observed in experimentally and naturally infected animals [5]. N. caninum is an intracellular parasite and resides within a specialized compartment, a parasitophorous vacuole, surrounded by a parasitophorous vacuole membrane (PVM). Following egress from a host cell, these parasites immediately search for a new host cell to invade, and the direct accessibility %U http://www.hindawi.com/journals/isrn.parasitology/2013/830980/