IgG and IgM responses to the Plasmodium falciparum asexual stage antigens reflect respectively protection against malaria during pregnancy and infanthood.

BACKGROUND: Plasmodium falciparum malaria is a public health issue mostly seen in tropical countries. Until now, there is no effective malaria vaccine against antigens specific to the blood-stage of P. falciparum infection. Because the pathogenesis of malarial disease results from blood-stage infection, it is essential to identify the most promising blood-stage vaccine candidate antigens under natural exposure to malaria infection. METHODS: A cohort of 400 pregnant women and their infants was implemented in South Benin. An active and passive protocol of malaria surveillance was established during pregnancy and infancy to precisely ascertain malaria infections during the follow-up. Twenty-eight antibody (Ab) responses specific to seven malaria candidate vaccine antigens were repeatedly quantified during pregnancy (3 time points) and infancy (6 time points) in order to study the Ab kinetics and their protective role. Abs were quantified by ELISA and logistic, linear and cox-proportional hazard model were performed to analyse the associations between Ab responses and protection against malaria in mothers and infants, taking into account socio-economic factors and for infants an environmental risk of exposure. RESULTS: The levels of IgM against MSP1, MSP2 and MSP3 showed an early protective response against the onset of symptomatic malaria infections starting from the 18th month of life, whereas no association was found for IgG responses during infancy. In women, some IgG responses tend to be associated with a protection against malaria risk along pregnancy and at delivery, among them IgG3 against GLURP-R0 and IgG2 against MSP1. CONCLUSION: The main finding suggests that IgM should be considered in vaccine designs during infanthood. Investigation of the functional role played by IgM in malaria protection needs further attention.

Maternal schistosomiasis impairs offspring Interleukin-4 production and B cell expansion.

Epidemiological studies have identified a correlation between maternal helminth infections and reduced immunity to some early childhood vaccinations, but the cellular basis for this is poorly understood. Here, we investigated the effects of maternal Schistosoma mansoni infection on steady-state offspring immunity, as well as immunity induced by a commercial tetanus/diphtheria vaccine using a dual IL-4 reporter mouse model of maternal schistosomiasis. We demonstrate that offspring born to S. mansoni infected mothers have reduced circulating plasma cells and peripheral lymph node follicular dendritic cells at steady state. These reductions correlate with reduced production of IL-4 by iNKT cells, the cellular source of IL-4 in the peripheral lymph node during early life. These defects in follicular dendritic cells and IL-4 production were maintained long-term with reduced secretion of IL-4 in the germinal center and reduced generation of TFH, memory B, and memory T cells in response to immunization with tetanus/diphtheria. Using single-cell RNASeq following tetanus/diphtheria immunization of offspring, we identified a defect in cell-cycle and cell-proliferation pathways in addition to a reduction in Ebf-1, a key B-cell transcription factor, in the majority of follicular B cells. These reductions are dependent on the presence of egg antigens in the mother, as offspring born to single-sex infected mothers do not have these transcriptional defects. These data indicate that maternal schistosomiasis leads to long-term defects in antigen-induced cellular immunity, and for the first time provide key mechanistic insight into the factors regulating reduced immunity in offspring born to S. mansoni infected mothers.

Dynamics of PfEMP1 Antibody Profile From Birth to 12 Months of Age in Beninese Infants.

BACKGROUND: Plasmodium falciparum-infected erythrocytes bind to specific endothelial cell receptors via members of the PfEMP1 family exported onto the erythrocyte surface. These interactions are mediated by different types of cysteine-rich interdomain region (CIDR) domains found in the N-terminal region of all PfEMP1. CIDRα1 domains bind endothelial protein C receptor (EPCR), CIDRα2-6 domains bind CD36, whereas the receptor specificity of CIDRß/γ/δ domains is unknown. METHODS: In this study, we investigated the level of immunoglobulin (Ig)G targeting the different types of PfEMP1 CIDR during the first year of life. We used plasma collected longitudinally from children of pregnant women who had been followed closely through pregnancy. RESULTS: Antibodies to CIDRα1 domains were more frequent in cord blood compared with antibodies to CIDRα2-6 domains. Higher IgG levels to EPCR-binding CIDRα1 variants positively correlated with the timing of first infections. Antibodies to all PfEMP1 types declined at similar rates to the point of disappearance over the first 6 months of life. At 12 months, children had acquired antibody to all types of CIDR domains, mostly in children with documented P falciparum infections. CONCLUSIONS: These observations agree with the notion that the timing and phenotype of first P falciparum infections in life are influenced by the immune status of the mother.

Circulating Cytokines Associated with Poor Pregnancy Outcomes in Beninese Exposed to Infection with Plasmodium falciparum.

Malaria during pregnancy is a major cause of maternal morbidity as well as fetal and neonatal mortality. Previous studies, including our own, suggested that placental and peripheral cytokine and chemokine levels measured at delivery can be used as biomarkers for pregnancy outcomes. However, the timing of malaria infection during pregnancy matters, and these studies do not address the effect of different cytokines in peripheral blood plasma samples taken at early and midpregnancy and at delivery. Here, we aimed to investigate whether peripheral plasma cytokine levels were associated with pregnancy outcomes in a cohort of 400 Beninese pregnant women. Using a high-sensitivity cytometry-based method, we quantified the levels of interleukin-4 (IL-4), IL-5, IL-10, IL-12p70, and gamma interferon (IFN-γ) in peripheral plasma samples taken at two time points during pregnancy and at delivery in various groups of pregnant women identified with Plasmodium falciparum infection, with anemia, with preterm births, or giving birth to babies who are small for their gestational age. We found that, consistently at all time points, elevated levels of IL-10 were strongly and significantly associated with P. falciparum infection, while the levels of IFN-γ at inclusion and delivery were weakly but also significantly associated. Low levels of IL-5 at delivery were associated with a greater risk of both preterm births and small-for-gestational-age babies. The immunosuppressive effects of IL-10 likely affect the overall cytokine equilibrium during pregnancy in women harboring P. falciparum infections. Our findings highlight the peripheral signature of pregnancy outcomes and strengthen the idea of using cytokines as diagnostic or prognostic markers.

Pregnancy-specific malarial immunity and risk of malaria in pregnancy and adverse birth outcomes: a systematic review.

BACKGROUND: In endemic areas, pregnant women are highly susceptible to Plasmodium falciparum malaria characterized by the accumulation of parasitized red blood cells (pRBC) in the placenta. In subsequent pregnancies, women develop protective immunity to pregnancy-associated malaria and this has been hypothesized to be due to the acquisition of antibodies to the parasite variant surface antigen VAR2CSA. In this systematic review we provide the first synthesis of the association between antibodies to pregnancy-specific P. falciparum antigens and pregnancy and birth outcomes. METHODS: We conducted a systematic review and meta-analysis of population-based studies (published up to 07 June 2019) of pregnant women living in P. falciparum endemic areas that examined antibody responses to pregnancy-specific P. falciparum antigens and outcomes including placental malaria, low birthweight, preterm birth, peripheral parasitaemia, maternal anaemia, and severe malaria. RESULTS: We searched 6 databases and identified 33 studies (30 from Africa) that met predetermined inclusion and quality criteria: 16 studies contributed estimates in a format enabling inclusion in meta-analysis and 17 were included in narrative form only. Estimates were mostly from cross-sectional data (10 studies) and were heterogeneous in terms of magnitude and direction of effect. Included studies varied in terms of antigens tested, methodology used to measure antibody responses, and epidemiological setting. Antibody responses to pregnancy-specific pRBC and VAR2CSA antigens, measured at delivery, were associated with placental malaria (9 studies) and may therefore represent markers of infection, rather than correlates of protection. Antibody responses to pregnancy-specific pRBC, but not recombinant VAR2CSA antigens, were associated with trends towards protection from low birthweight (5 studies). CONCLUSIONS: Whilst antibody responses to several antigens were positively associated with the presence of placental and peripheral infections, this review did not identify evidence that any specific antibody response is associated with protection from pregnancy-associated malaria across multiple populations. Further prospective cohort studies using standardized laboratory methods to examine responses to a broad range of antigens in different epidemiological settings and throughout the gestational period, will be necessary to identify and prioritize pregnancy-specific P. falciparum antigens to advance the development of vaccines and serosurveillance tools targeting pregnant women.

Macrophage migration inhibitory factor (MIF) and pregnancy may impact the balance of intestinal cytokines and the development of intestinal pathology caused by Toxoplasma gondii infection.

Toxoplasma gondii (T. gondii) is an intracellular parasite responsible for causing toxoplasmosis. When infection occurs during pregnancy, it can produce severe congenital infection with ocular and neurologic damage to the infant. From the oral infection parasite reaches the intestine, causing inflammatory response, damage in tissue architecture and systemic dissemination. Macrophage migration inhibition factor (MIF) is a cytokine secreted from both immune and non-immune cells, including gut epithelial cells. MIF is described to promote inflammatory responses, to be associated in colitis pathogenesis and also to play role in maintaining the intestinal barrier. The aim of the present study was to evaluate the influence of the pregnancy and MIF deficiency on T. gondii infection in the intestinal microenvironment and to address how these factors can impact on the intestinal architecture and local cytokine profile. For this purpose, small intestine of pregnant and non-pregnant C57BL/6 MIF deficient mice (MIF-/-) and Wild-type (WT) orally infected with 5 cysts of ME-49 strain of T. gondii were collected on day 8th of infection. Intestines were processed for morphological and morphometric analyses, parasite quantification and for cytokines mensuration. Our results showed that the absence of MIF and pregnancy caused an increase in T. gondii infection index. T. gondii immunolocalization demonstrated that segments preferentially infected with T. gondii were duodenum and ileum. The infection caused a reduction in the size of the intestinal villi, whereas, infection associated with pregnancy caused an increase in villi size due to edema caused by the infection. Also, the goblet cell number was increased in the ileum of MIF-/- mice, when compared to the corresponding WT group. Analyses of cytokine production in the small intestine showed that MIF was up regulated in the gut of pregnant WT mice due to infection. Also, infection provoked an intense Th1 response that was more exacerbated in pregnant MIF-/- mice. We also detected that the Th2/Treg response was more pronounced in MIF-/- mice. Altogether, our results demonstrated that pregnancy and MIF deficiency interferes in the balance of the intestinal cytokines and favors a Th1-immflamatory profile, which in turn, impact in the development of pathology caused by T. gondii infection in the intestinal microenvironment.

Unpasteurised milk consumption as a potential risk factor for toxoplasmosis in females with recurrent pregnancy loss.

In women with a bad obstetric history, certain infections are associated with recurrent foetal loss. One of the common infectious agents is a protozoan parasite, Toxoplasma gondii. The aim of this study was to assess unpasteurised milk consumption as a potential risk factor for toxoplasmosis in females with recurrent pregnancy loss from the province of Khyber Pakhtunkhwa, Pakistan. In this study, we recruited a total of 360 females, comprising a study group of 180 females with previous history of recurrent pregnancy loss and a control group of 180 females with no such history. Blood serum from the participants was analysed for Toxoplasma gondii IgM antibodies by enzyme linked immunosorbent assay. Among the study group, 23 (12.8%) females were serologically positive for IgM antibodies against Toxoplasma gondii, whilst 157 (87.2%) were IgM negative. In the control group, only two (4.8%) females were IgM positive, whilst 178 (95.2%) were IgM negative. Bad pregnancy outcome in the study group and control group was observed to be significantly different (p < .0001). In both of these groups, unpasteurised milk consumption was found as a major risk factor for Toxoplasma gondii infection. A routine serological investigation should be carried out in pregnant women to rule out toxoplasmosis and reduce the risk of recurrent pregnancy loss as well as congenital toxoplasmosis in newborns.Impact statementWhat is already known on this subject? Seropositivity for Toxoplasma gondii antibodies ranges from 7% to 51% in different regions of the world. The prevalence rate varies because of differences in climate, culture, food habits, behaviour, personal hygiene and cooking habits of different societies and ethnic groups. Various risk factors have been identified that contribute to a high prevalence rate of the disease, including consumption of raw or poorly cooked meat, physical contact with cats or cat litter, consumption of unwashed raw vegetables and fruits, drinking of contaminated water and milk. We presumed that consuming unpasteurised milk could be a potential risk factor for developing toxoplasmosis in pregnant women.What the results of this study add? This study demonstrates high seroprevalence of Toxoplasma gondii antibodies in females of child bearing age that have consumed unpasteurised milk and is a potential risk factor for developing toxoplasmosis.What the implications are of these findings for clinical practice and/or further research? Our findings suggest that primary preventive measures (personal hygiene, frequent hand washing and consuming pasteurised milk) should be taken by health surveillance authorities to focus on families, especially pregnant women, to educate them about personal hygiene, contact with cattle or using their milk and milk products. The latter is especially important to aware them about the hazards of consuming unpasteurised and contaminated milk.

Malaria in pregnancy shapes the development of foetal and infant immunity.

Malaria, particularly Plasmodium falciparum, continues to disproportionately affect pregnant women. In addition to the profoundly deleterious impact of maternal malaria on the health of the mother and foetus, malaria infection in pregnancy has been shown to affect the development of the foetal and infant immune system and may alter the risk of malaria and nonmalarial outcomes during infancy. This review summarizes our current understanding of how malaria infection in pregnancy shapes the protective components of the maternal immune system transferred to the foetus and how foetal exposure to parasite antigens impacts the development of foetal and infant immunity. It also reviews existing evidence linking malaria infection in pregnancy to malaria and nonmalarial outcomes in infancy and how preventing malaria in pregnancy may alter these outcomes. A better understanding of the consequences of malaria infection in pregnancy on the development of foetal and infant immunity will inform control strategies, including intermittent preventive treatment in pregnancy and vaccine development.

How does toxoplasmosis affect the maternal-foetal immune interface and pregnancy?

Toxoplasma gondii is a zoonotic parasite which, depending on the geographical location, can infect between 10% and 90% of humans. Infection during pregnancy may result in congenital toxoplasmosis. The effects on the foetus vary depending on the stage of gestation in which primary maternal infection arises. A large body of research has focused on understanding immune response to toxoplasmosis, although few studies have addressed how it is affected by pregnancy or the pathological consequences of infection at the maternal-foetal interface. There is a lack of knowledge about how maternal immune cells, specifically macrophages, are modulated during infection and the resulting consequences for parasite control and pathology. Herein, we discuss the potential of T. gondii infection to affect the maternal-foetal interface and the potential of pregnancy to disrupt maternal immunity to T. gondii infection.

Early Neospora caninum infection dynamics in cattle after inoculation at mid-gestation with high (Nc-Spain7)- or low (Nc-Spain1H)-virulence isolates.

Early Neospora caninum infection dynamics were investigated in pregnant heifers intravenously inoculated with PBS (G-Control) or 107 tachyzoites of high (G-NcSpain7)- or low (G-NcSpain1H)-virulence isolates at 110 days of gestation. Serial culling at 10 and 20 days post-infection (dpi) was performed. Fever was detected at 1 dpi in both infected groups (P < 0.0001), and a second peak was detected at 3 dpi only in G-NcSpain7 (P < 0.0001). At 10 dpi, Nc-Spain7 was detected in placental samples from one animal related to focal necrosis, and Nc-Spain7 transmission was observed, although no foetal lesions were associated with this finding. The presence of Nc-Spain1H in the placenta or foetuses, as well as lesions, were not detected at 10 dpi. At 20 dpi, G-NcSpain7 animals showed almost 100% positive placental tissues and severe focal necrosis as well as 100% transmission. Remarkably, foetal mortality was detected in two G-NcSpain7 heifers. Only one animal from G-NcSpain1H presented positive placental samples. No foetal mortality was detected, and lesions and parasite transmission to the foetus were not observed in this group. Finally, 100% of G-NcSpain7 heifers at 20 dpi presented specific antibodies, while only 60% of G-NcSpain1H animals presented specific antibodies at 20 dpi. In addition, earlier seroconversion in G-Nc-Spain7 was observed. In conclusion, tachyzoites from Nc-Spain7 reached the placenta earlier and multiplied, leading to lesion development, transmission to the foetus and foetal mortality, whereas Nc-Spain1H showed delayed infection of the placenta and no lesional development or transmission during early infection.

Detection of Toxoplasma gondii B1 Gene and IgM in IgG Seropositive Pregnant Women.

BACKGROUND: The onset of acute toxoplasmosis in pregnant women may pose a risk to their growing fetuses. The timely diagnosis of infection in managing the disease and preventing its harmful consequences on the fetus is very important. Therefore, the study was conducted to identify acute toxoplasmosis in the pregnant women by detecting the specific IgM antibody and Toxoplasma gondii B1 gene. METHODS: A total of 653 serum samples of women who attended to Fatemieh Hospital of Hamadan University of Medical Sciences were tested for IgG antibodies against Toxoplasma gondii by enzyme-linked immunosorbent as-say (ELISA). The IgG positive specimens were further examined for IgM by ELISA and polymerase chain reaction (PCR) for B1 gene. In the second phase, change in IgG titers was evaluated on 47 IgG positive samples after two weeks. RESULTS: ELISA data showed that 167 out of 653 and 2 out of 167 samples were positive for IgG (25.6%) and IgM (1.2%), respectively. However, PCR detection showed that 36 cases (21.6%) were positive for the B1 gene. Seven out of 47 IgG positive samples showed an increase in the antibody titer and positive for the B1 gene. The most cases of IgG positives and the B1 gene samples were associated with the third trimester of pregnancy with 49.7% and 14%, respectively, and the most common abundance of the B1 gene was 14.4% in the age group of 26 - 35. The most commonly reported clinical symptoms in the B1 gene-positive women were nausea 15 (41.7%), cough 13 (36.1%), headache 12 (33.3%), and vomiting 11 (30.5%). CONCLUSIONS: Using PCR and the B1 gene in serum samples of pregnant women to detect acute toxoplasmosis is a more appropriate and accurate method than IgM antibody.

Association of Antibodies to VAR2CSA and Merozoite Antigens with Pregnancy Outcomes in Women Living in Yaoundé, Cameroon.

Plasmodium falciparum infections are serious in pregnant women, because VAR2CSA allows parasitized erythrocytes to sequester in the placenta, causing placental malaria (PM). In areas of endemicity, women have substantial malarial immunity prior to pregnancy, including antibodies to merozoite antigens, but produce antibodies to VAR2CSA only during pregnancy. The current study sought to determine the importance of antibodies to VAR2CSA and merozoite antigens in pregnant women in Yaoundé, Cameroon, where malaria transmission was relatively low. A total of 1,377 archival plasma samples collected at delivery were selected (at a 1:3 ratio of PM-positive [PM+] to PM-negative [PM-] women) and screened for antibodies to full-length VAR2CSA and 7 merozoite antigens. Results showed that many PM+ women and most PM- women lacked antibodies to VAR2CSA at delivery. Among PM+ women, antibodies to VAR2CSA were associated with a reduced risk of having high placental parasitemia (odds ratio [OR], 0.432; confidence interval [CI], 0.272, 0.687; P = 0.0004) and low-birth-weight (LBW) babies (OR = 0.444; CI, 0.247, 0.799; P = 0.0068), even during first pregnancies. Among antibodies to the 7 merozoite antigens, i.e., AMA1, EBA-175, MSP142, MSP2, MSP3, MSP11, and Pf41, only antibodies to MSP3, EBA-175, and Pf41 were associated with reduced risk for high placental parasitemias (P = 0.0389, 0.0291, and 0.0211, respectively) and antibodies to EBA-175 were associated with reduced risk of premature deliveries (P = 0.0211). However, after adjusting for multiple comparisons significance declined. Thus, in PM+ women, antibodies to VAR2CSA were associated with lower placental parasitemias and reduced prevalence of LBW babies in this low-transmission setting.

Chronic schistosomiasis during pregnancy epigenetically reprograms T-cell differentiation in offspring of infected mothers.

Schistosomiasis is a nontransplacental helminth infection. Chronic infection during pregnancy suppresses allergic airway responses in offspring. We addressed the question whether in utero exposure to chronic schistosome infection (Reg phase) in mice affects B-cell and T-cell development. Therefore, we focused our analyses on T-cell differentiation capacity induced by epigenetic changes in promoter regions of signature cytokines in offspring. Here, we show that naïve T cells from offspring of schistosome infected female mice had a strong capacity to differentiate into TH 1 cells, whereas TH 2 differentiation was impaired. In accordance, reduced levels of histone acetylation of the IL-4 promoter regions were observed in naïve T cells. To conclude, our mouse model revealed distinct epigenetic changes within the naïve T-cell compartment affecting TH 2 and TH 1 cell differentiation in offspring of mothers with chronic helminth infection. These findings could eventually help understand how helminths alter T-cell driven immune responses induced by allergens, bacterial or viral infections, as well as vaccines.

Decidual macrophage M1 polarization contributes to adverse pregnancy induced by Toxoplasma gondii PRU strain infection.

Recent evidence indicates that macrophages at the maternal-fetal interface adapt to a phenotype characterized by alternative activation (M2 polarization) and exhibit immunosuppressive functions that favor the maintenance of pregnancy. The bias of M2 decidual macrophages toward M1 has been clinically linked to pregnancy-related complications, such as preeclampsia and preterm delivery. The aim of this study was to investigate the effect of Toxoplasma gondii PRU strain infection on the bias of decidual macrophage polarization and its contribution to adverse pregnancy outcomes. A mouse model with adverse pregnancy outcome was established by infection with T. gondii PRU strain and the expression levels of functional molecules in decidual macrophages of mice were measured. The results showed that T. gondii infection caused seriously adverse pregnancy outcome in mice. The placentae of infected mice showed obvious congestion and inflammatory cell infiltration. The expression of CD206, MHC-II, and arginase-1 considered as M2 markers was decreased in decidual macrophages after T. gondii infection, whereas the expression of CD80, CD86, iNOS, and cytokines TNF-α and IL-12 considered as M1 markers was increased. Furthermore, iNOS-positive expression was observed in the decidua basalis of infected mice. Our results indicated that T. gondii infection was responsible for the bias of M2 decidual macrophages toward M1, which changes the immunosuppressive microenvironment at the maternal-fetal interface and contributes to adverse pregnancy outcomes.

Cellular immunopathogenesis in primary Toxoplasma gondii infection during pregnancy.

Congenital toxoplasmosis is caused by the vertical transmission of infection from mother to foetus through the placenta when a pregnant woman is infected with Toxoplasma gondii (T. gondii). Congenital infection can have serious consequences, such as intrauterine abortion, foetal death and severe neurological, ocular or other organ damage in the foetus. In this review, we focus on recent publications investigating vertical transmission of T. gondii infection, cellular immunopathogenesis and protective immunity in primary toxoplasmosis during pregnancy.

High production of pro-inflammatory cytokines by maternal blood mononuclear cells is associated with reduced maternal malaria but increased cord blood infection.

BACKGROUND: Increased susceptibility to malaria during pregnancy is not completely understood. Cellular immune responses mediate both pathology and immunity but the effector responses involved in these processes have not been fully characterized. Maternal and fetal cytokine and chemokine responses to malaria at delivery, and their association with pregnancy and childhood outcomes, were investigated in 174 samples from a mother and child cohort from Mozambique. Peripheral and cord mononuclear cells were stimulated with Plasmodium falciparum lysate and secretion of IL-12p70, IFN-γ, IL-2, IL-10, IL-8, IL-6, IL-4, IL-5, IL-1ß, TNF, TNF-ß was quantified in culture supernatants by multiplex flow cytometry while cellular mRNA expression of IFN-γ, TNF, IL-2, IL-4, IL-6, IL-10 and IL-13 was measured by quantitative PCR. RESULTS: Higher concentrations of IL-6 and IL-1ß were associated with a reduced risk of P. falciparum infection in pregnant women (p < 0.049). Pro-inflammatory cytokines IL-6, IL-1ß and TNF strongly correlated among themselves (ρ > 0.5, p < 0.001). Higher production of IL-1ß was significantly associated with congenital malaria (p < 0.046) and excessive TNF was associated with peripheral infection and placental lesions (p < 0.044). CONCLUSIONS: Complex network of immuno-pathological cytokine mechanisms in the placental and utero environments showed a potential trade-off between positive and negative effects on mother and newborn susceptibility to infection.

Influence of dose and route of administration on the outcome of infection with the virulent Neospora caninum isolate Nc-Spain7 in pregnant sheep at mid-gestation.

Experimental infections in pregnant sheep have been focused on studying the effect of the time of challenge on the outcome of N. caninum infection, whereas the impact of the dose and route of challenge has not been studied in depth. Therefore, clinical outcome, immune responses, parasite detection and burden, and lesion severity in placental tissues and foetal brains were investigated in 90-day-pregnant sheep inoculated intravenously with 105 (G1), 104 (G2), 103 (G3), or 102 (G4) tachyzoites or subcutaneously with 104 (G5) tachyzoites of the virulent Nc-Spain7 isolate and an uninfected group (G6). Comparing challenge doses, G1 was the only group that had 100% abortion. Likewise, IFNγ levels in G1 increased earlier than those in other intravenously infected groups, and IgG levels on day 21 post-infection (pi) were higher in G1 than those in other intravenously infected groups. Concerning vertical transmission, G1 shows a higher parasite burden in the foetal brain than did G2 and G3. Comparing routes of administration, no differences in foetal survival rate or parasite load in the foetal brain were found. Although G2 had higher IFNγ levels than G5 on day 10 pi, no differences were found in humoral immune responses. Because the outcome after intravenous infection with 105 tachyzoites was similar to that observed after intravenous infection with 106 tachyzoites used in a previous work (100% abortion and vertical transmission), we conclude that it may be reasonable to use 105 tachyzoites administered by the intravenous route in further experiments when assessing drugs or vaccine candidates.

Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes.

The influence of the physiological stage of a Blackbelly flock against natural infection by gastrointestinal parasitic nematodes (GIN) was investigated. Data on serum and saliva IgA levels and peripheral cellular immune response were recorded in 51 sheep for 6 months. The flock was divided based on their physiological stage as follows: a) pregnant ewes, b) lactating ewes, c) non-pregnant ewes, d) pre-weaning lambs, e) growing lambs and f) replacement sheep. Additionally, sheep were classified based on the parasite infection as stabled or grazing management system as follows: g) non-infected stabled sheep, h) infected and stabled sheep and i) infected grazing sheep. Faeces and blood samples were collected every fifteen days. The percentage of packed cell volume (PCV), plasma protein, (PP) and leucocyte differential counts (LDC) were recorded. Likewise, serum and saliva IgA levels were measured by the indirect ELISA technique. The number of GIN eggs excreted per g of faeces (EPG) was also determined using the McMaster technique. Data were analysed using the SAS program to identify fixed effect of physiological stages, infection time and interactions. Results showed high EPG values in stabled lactating ewes (2764) and in growing lambs (2950-4550 EPG). Pregnant ewes had higher PCV values (27%) than lactating ewes (23.5%). Infected lambs showed low PCV values (28.5%) and high PP values (5.9 g/dL) compared with non-infected lambs (31% PCV and 5.6 g/dL PP). The two most abundant GIN species identified were Haemonchus contortus (91%) and Trichostrongylus colubriformis (81%). Pregnant and non-pregnant ewes showed 29% and <20% of IgA values, respectively. High EPG, low IgA and eosinophils counts were observed until 180 days of age in infected lambs. In conclusion, the group of infected lactating ewes and lambs showed susceptibility to GIN than the other groups, including the pregnant ewes.

Experimental Malaria in Pregnancy Induces Neurocognitive Injury in Uninfected Offspring via a C5a-C5a Receptor Dependent Pathway.

The in utero environment profoundly impacts childhood neurodevelopment and behaviour. A substantial proportion of pregnancies in Africa are at risk of malaria in pregnancy (MIP) however the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Complement activation, in particular C5a, may contribute to neuropathology and adverse outcomes during MIP. We used an experimental model of MIP and standardized neurocognitive testing, MRI, micro-CT and HPLC analysis of neurotransmitter levels, to test the hypothesis that in utero exposure to malaria alters neurodevelopment through a C5a-C5aR dependent pathway. We show that malaria-exposed offspring have persistent neurocognitive deficits in memory and affective-like behaviour compared to unexposed controls. These deficits were associated with reduced regional brain levels of major biogenic amines and BDNF that were rescued by disruption of C5a-C5aR signaling using genetic and functional approaches. Our results demonstrate that experimental MIP induces neurocognitive deficits in offspring and suggest novel targets for intervention.

Immune response in bovine neosporosis: Protection or contribution to the pathogenesis of abortion.

Neospora caninum is a protozoan parasite with a preference for cattle and dogs as hosts. When N. caninum infection occurs in cattle it induces abortion, bovine neosporosis being a main cause of abortion worldwide. In dairy cattle, the economic burden of neosporosis-associated abortion is so great that it might results in closure of a farm. However, not all infected cows abort and it is not yet understood why this occurs. At present there is no effective treatment or vaccine. This review provides insights on how immune response against the parasite determines protection or contribution to abortion. Aspects on markers of risk of abortion are also discussed. Humoral immune responses are not protective against N. caninum but seropositivity and antibody level can be good markers for a diagnosis of bovine neosporosis and its associated abortion risk. In addition, humoral mechanisms against N. caninum infection and abortion differ in pure-breed and cross-breed pregnant dairy and beef cattle. Concentrations of Pregnancy Associated glycoprotein -2 (PAG-2) can also be used to predict abortion. A partially protective immune response encompasses increased IFN-γ expression, which has to be counterbalanced by other cytokines such as IL-12 and IL-10, especially towards the end of pregnancy. Although IFN-γ is required to limit parasite proliferation a critical threshold of the IFN-γ response is also required to limit adverse effects on pregnancy. In clinical terms, it may be stated that IFN-γ production and cross-breed pregnancy can protect Neospora-infected dairy cows against abortion.