Peripheral white blood cell counts throughout pregnancy in non-aborting Neospora caninum-seronegative and seropositive high-producing dairy cows in a Holstein Friesian herd

Parasitemia and Associated Immune Response in Pregnant and Non-Pregnant Beef Cows Naturally Infected With Neospora caninum

The aim of this longitudinal study was to characterize the parasitemia of Neospora caninum and the associated immunological parameters in naturally infected beef cows for 10 months. The following groups were established: Neospora caninum seropositive pregnant cows (+Preg, n = 7), seropositive non-pregnant cows (+Npreg, n = 7), seronegative pregnant cows (−Preg, n = 4), and seronegative non-pregnant cows (−Npreg, n = 4). Several samples were obtained for absolute and relative leukocyte counting, cytokines IL-10, IL-12, α-TNF, and γ-IFN quantification, specific IgG, IgG1, and IgG2 and avidity and N. caninum DNA molecular detection and quantification. The +Preg group had a higher frequency and concentration of N. caninum DNA in PBMC in the last third of pregnancy compared to +Npreg (p <0.05), with 22 and 8% of detection, respectively. Parasitemia correlated positively with IgG titers and negatively with IgG1/IgG2 ratio (p <0.05). On day 222 of the assay, the +Preg group had the lowest total leukocyte counting (p <0.05). The +Preg group had a higher concentration of IgG and higher avidity in the last third of gestation compared to +Npreg (p <0.05). Avidity correlated with total IgG and IgG2 (p <0.05). All +Preg cows gave birth to clinically healthy but seropositive calves before colostrum intake, therefore, the congenital transmission was 100% efficient. Only a complete N. caninum genotype from a placenta and a partial genotype from cow #3 of the group +Preg were achieved by multilocus microsatellite analysis. Overall, N. caninum parasitemia is frequent in seropositive beef cows during the last third of gestation. This correlates with higher antibody levels and a decrease in total leukocyte counting. The precise timing of the parasitemia may be used for diagnosis purposes and/or for design strategies to avoid vertical transmission. Further studies are needed to identify the immune molecular mechanisms that favor parasitemia during gestation in chronically infected cattle.

Experimental infection of tachyzoites of the NC1 strain of Neosporacaninum in female swine

Neospora caninum is a protozoan that can cause reproductive problems in several animal species. Although N. caninum infection has been reported in swine, the pathogenesis and clinical signs are not fully known in this species. The objective of this work was to evaluate the effect of experimental infection with tachyzoites of the N. caninum strain Nc1 in swine matrices at different stages of gestation. For that purpose, 12 gilts, seronegative for N. caninum and T. gondii, were selected and allocated into four groups of three animals each. Animals in group A were not inoculated (control) and animals in groups B, C, and D were inoculated intravenously with of 2.9 × 10⁷ tachyzoites, 30 days before conception, and at 45 and 90 days of gestation, respectively. Temperature, heart rate, blood, saliva, and vaginal mucus samples from the animals were collected periodically until the time of delivery for the investigation of IgG and IgM antibodies against N. caninum using IFAT and PCR to detect the parasite DNA. All gilts sero-converted from 5 and 7 DPI (days postinoculation) to IgM and IgG, respectively. Two gilts showed hypothermia on the 5th and 7th DPI, and five inoculated animals had leukocytosis on the 7th DPI. It was possible to detect DNA of N. caninum in samples of saliva (33/84), vaginal mucus (17/84), and blood (2/84). Based on serology (IgM) and PCR, three animals in group B showed evidence of reappearance of the infection during pregnancy. It is concluded that N. caninum can cause clinical signs in infected swine females, in addition to indicating saliva as a suitable diagnostic biological material for the detection of N. caninum DNA in this animal species.

Caprine Monocytes Release Extracellular Traps against Neospora caninum In Vitro

Neospora caninum is an obligate intracellular apicomplexan parasite that causes reproductive loss and severe economic losses in dairy and goat industry. In the present study, we aim to investigate the effects of N. caninum tachyzoites on the release of extracellular traps (ETs) in caprine monocytes and furthermore elucidated parts of its molecular mechanisms. N. caninum tachyzoite-induced monocytes-derived ETs formation was detected by scanning electron microscopy. H3 and myeloperoxidase (MPO) within monocyte-ETs structures were examined using laser scanning confocal microscopy analyses. The results showed that N. caninum tachyzoites were not only able to trigger ETs formation in caprine monocytes, but also that monocyte-released ETs were capable of entrapping viable tachyzoites. Histones and MPO were found to be decorating the DNA within the monocytes derived-ETs structures thus proving the classical components of ETs. Furthermore, inhibitors of NADPH oxidase-, MPO-, ERK 1/2-, or p38 MAPK-signaling pathway significantly decreased N. caninum tachyzoite-triggered caprine monocyte-derived ETosis. This is the first report of ETs release extruded from caprine monocytes after N. caninum exposure and thus showing that this early innate immune effector mechanism might be relevant during the acute phase of caprine neosporosis.

Metabolic footprinting of extracellular metabolites of brain endothelium infected with Neospora caninum in vitro

BACKGROUND

The survival of the intracellular protozoan parasite Neospora caninum depends on its ability to adapt to changing metabolic conditions of the host cell. Thus, defining cellular and metabolic changes in affected target tissues may aid in delineating pathogenetic mechanism. We undertook this study to assess the metabolic response of human brain microvascular endothelial cells (HBMECs) to N. caninum infection in vitro.

METHODS

HBMECs were exposed to N. caninum infection and the cytotoxic effects of infection were analyzed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromidin (MTT) assay and lactate dehydrogenase (LDH) release assay. Metabolic footprinting of the extracellular metabolites of parasite-infected and non-infected culture supernatant was determined by using targeted (Randox RX Imola clinical chemistry analyser) and unbiased RS (Raman microspectroscopy) approaches.

RESULTS

The MTT assay did not reveal any cytotoxic effect of N. caninum challenge on host cell viability. Measurement of LDH activity showed that N. caninum significantly induced loss of cell membrane integrity in a time-dependent and dose-dependent manner compared to control cells. Targeted biochemical analysis revealed that beta hydroxybutyrate, pyruvate, ATP, total protein, non-esterified fatty acids, and triglycerides are significantly different in infected cells compared to controls. RS-based footprinting with principal component analysis (PCA) were able to correctly distinguish extracellular metabolites obtained from infected and control cultures, and revealed infection-related spectral signatures at 865 cm-1, 984 cm-1, 1046 cm-1, and 1420 cm-1, which are attributed to variations in the content of lipids and nucleic acids in infected cultures.

CONCLUSIONS

The changing pattern of extracellular metabolites suggests that HBMECs are target of metabolic alterations in N. caninum infection, which seem to reflect the changing metabolic state of infected cells and constitute a level of information exchange that host and parasite use to coordinate activities.