Recent advances in Neospora and neosporosis

Occurrence of antibodies and epidemiological significance of Toxoplasma Gondii and Neospora caninum infections in canine populations of Laguna, State of Santa Catarina

Toxoplasma gondii and Neospora caninum are two species of protozoa that belong to the Apicomplexa phylum and are distributed worldwide. T. gondii is one of the most extensively studied parasites due to its significant health implications. In this study, an investigation on the occurrence of T. gondii and N. caninum antibodies in dogs from a municipality on the southern coast of Santa Catarina, Brazil, and its associated risk factors were conducted. Blood samples were collected from 238 dogs, and a questionnaire was used to gather relevant information about the dogs, including their age, gender, breed, housing and habits. The serum samples were then subjected to indirect fluorescent antibody test (IFAT) using a cutoff of 1:64 and 1:50 to detect antibodies against T. gondii and N. caninum, respectively. The study's findings revealed that the frequency of T. gondii was 23.1% (55/238), and no factors associated with infection in these animals were identified. However, the frequency of N. caninum was 4.2% (10/238), and the study identified the type of housing and environment in which the dogs lived as the factors that were associated with the infection. Stray animals and those that lived exclusively outdoors had a greater frequency of N. caninum. These results indicate that dogs from Laguna, Santa Catarina, Brazil, are exposed to T. gondii and N. caninum. As such, further studies are necessary to enhance the understanding of the nature of these protozoan infections in the municipality.

Molecular and serological prevalence rates of Neospora caninum infection in dogs from Jordan

Neosporosis is a proven disease of farm animals and dogs caused by Neospora caninum. This cross-sectional study investigates N. caninum prevalence and seroprevalence among 268 dogs. Nc5 gene PCR was carried out on dog faeces and confirmed by sequencing. Seroprevalence was detected using an indirect fluorescent antibody test (IFAT). Three age groups, gender, locality (Amman, Irbid, and Zarqa Governorates), dog type (stray, pet, and breeding), place of living (indoor/outdoor), food type (raw/cooked), having diarrhoea, having abortion in the area, and having animals nearby were tested as independent variables for associations with positivity to N. caninum using univariate and multivariable logistic regression analyses. The true prevalence of N. caninum was 34.3% (95% CI 28.4, 40.5) using the Nc5-PCR test. The true seroprevalence rate of N. caninum among dogs in Jordan was 47.9% (95% CI 41.4, 54.5) using IFAT. The sequenced isolates of Nc5-PCR products (n = 85) matched three N. caninum strains, namely, NcHareGre (n = 70, 82.4%, 95% CI 72.6-89), NC MS2 (n = 14, 16.5%, 95% CI 9.3-26.1), and L218 (n = 1, 1.2%, 95% CI 0.03-6.4). The three strains were isolated previously from three different countries and continents. N. caninum shedding is associated with abortion among dogs and animals in the area (odds ratio = 3.6). In Amman and Zarqa, living indoors reduced seroprevalence at 0.45, 0.24, and 0.02 odds ratios, respectively. Jordan shares three molecular N. caninum strains with three different countries and continents.

Seroprevalence and risk factors for Neospora caninum and Toxoplasma gondii in dairy cattle from São Paulo State, Brazil

Neospora caninum is a major cause of reproductive loss in cattle worldwide as it leads to abortion and animal repositioning. Although Toxoplasma gondii does not cause a reproductive problem in cattle, consuming raw or uncooked beef poses the risk of transmission. This study aimed to evaluate the occurrence of anti-N. caninum and anti-T. gondii antibodies in dairy cattle in the West and Northwest regions of São Paulo State, Brazil. A total of 653 serum samples from dairy cows were analyzed using an indirect immunofluorescence assay (IFA). Epidemiological data from the farms were associated with the serological results of the animals by logistic regression based on the presence of antibodies. The frequencies of the antibodies against N. caninum and T. gondii were 41.6% (272/653) and 11.5% (75/653), respectively. A statistically significant association was observed between: the serum anti-N. caninum antibodies and breed, history of food supplementation for calves, introduction of outside animals that later presented reproductive problems, and history of reproductive problems by the trimester of gestation. The present study highlights the importance of neosporosis in dairy cattle in the study regions and that the inclusion of this parasite in the investigation of animals with reproductive disorders is important.

The role of genetic variability of the host on the resistance to Neospora caninum infection in cattle

Neospora caninum is one of the most frequently diagnosed abortifacient pathogens in cattle. There is abundant genomic information about the parasite itself, but very little is known about the genetic variability of resistance in the most common intermediate host. The aim of this review was to compile all the available information about the genetic variability associated with the resistance to N. caninum both between and within cattle breeds. We systematically searched for published studies that investigated the influence of genetics of the host on the prevalence of N. caninum and risk of abortion. Beyond the potential confounding effects of feeding systems, management and animal density, some lines of evidence suggest that Holstein, the most popular breed for milk production, has a comparatively higher risk of abortion due to infections by N. caninum, whereas some beef breeds from Continental Europe seem to be more resistant. It is still not clear if different genetic mechanisms of resistance are involved in the two known routes of infection: postnatal ingestion of oocysts or transplacental transmission from the infected dam to the fetus. Genomic information associated with susceptibility to infection and risk of abortion in different cattle breeds is still scarce. The information reported here could be useful to identify new research alternatives and to define novel strategies to deal with this major problem of animal production.

Neospora caninum infection in dairy cattle in Egypt: a serosurvey and associated risk factors

Neospora caninum (N. caninum) is one of the causative agents that causing cattle abortion, and severe economic losses. Due to the scarcity of data on N. caninum infection in Egyptian cattle, the purpose of this study was to estimate the seroprevalence and determine the risk factors for parasite infection. In four governorates in northern Egypt, 540 blood samples from cattle were taken, and tested using a commercial ELISA kit. The overall seroprevalence of N. caninum in examined cattle was 28.89%. A multivariate logistic regression model determined that age (OR = 2.63, P < 0.001), manual milking (OR = 1.39, P = 0.14), abortion history (OR = 2.78, P < 0.0001), repetition of estrus (OR = 2.31, P < 0.0001), and contact with dogs (OR = 2.57, P < 0.0001) were significant risk factors. The findings proved that N. caninum infection was one of the factors contributing to abortion and financial losses in dairy cattle in Egypt. Therefore, the application of sanitary security and control programs is very important in dairy farms.

Unfolded protein response is involved in resistance to Neospora caninum infection via IRE1α-XBP1s-NOD2 Axis

Neospora caninum, an intracellular protozoan parasite, causes neosporosis resulting in major losses in the livestock industry worldwide. However, no effective drugs or vaccines have been developed to control neosporosis. An in-depth study on the immune response against N. caninum could help to search for effective approaches to prevent and treat neosporosis. The host unfolded protein response (UPR) functions as a double-edged sword in several protozoan parasite infections, either to initiate immune responses or to help parasite survival. In this study, the roles of the UPR in N. caninum infection in vitro and in vivo were explored, and the mechanism of the UPR in resistance to N. caninum infection was analyzed. The results revealed that N. caninum triggered the UPR in mouse macrophages, such as the activation of the IRE1 and PERK branches, but not the ATF6 branch. Inhibition of the IRE1α-XBP1s branch increased the N. caninum number both in vitro and in vivo, while inhibition of the PERK branch did not affect the parasite number. Furthermore, inhibition of the IRE1α-XBP1s branch reduced the production of cytokines by inhibiting NOD2 signalling and its downstream NF-κB and MAPK pathways. Taken together, the results of this study suggest that the UPR is involved in the resistance of N. caninum infection via the IRE1α-XBP1s branch by regulating NOD2 and its downstream NF-κB and MAPK pathways to induce the production of inflammatory cytokines, which provides a new perspective for the research and development of anti-N. caninum drugs.

Seropositivity of Anti-Toxoplasma gondii and Anti-Neospora caninum Antibodies in Cattle Intended for Human Consumption in an Amazonian Area of North Brazil

Toxoplasma gondii and Neospora caninum are obligate intracellular intestinal coccidia distributed worldwide, and are causative agents of toxoplasmosis and neosporosis, respectively. The aim of this study was to evaluate the prevalence of anti-T. gondii and anti-N. caninum antibodies and the factors associated with infections in beef cattle intended for human consumption in an Amazonian area of North Brazil. We collected blood samples of 387 cattle from 50 herds located in different municipalities of the State of Rondônia. An epidemiological questionnaire was distributed to farmers, with regard to nutritional, sanitary and reproductive herd management. The samples were identified, refrigerated and sent for serological analyses via IFAT (Immunofluorescent Antibody Test). Among the 387 analyzed animals, 91 (23.5%; CI 95%: 18.8-27.2) were positive for anti-T. gondii antibodies, with titers varying from 1:64 (75.8%) to 1:512 (2.2%). For anti-N. caninum antibodies, only four animals (1%; CI 95%: 0-2.7) were positive, with titers ranging from 1:400 (50%) to 1:1600 (25%). We observed a significant rate of anti-T. gondii antibodies in the variables "pure breed" and "contact with free-range chickens" (p < 0.2). There were no risk factors associated with the presence of anti-T. gondii or anti-N. caninum antibodies. In conclusion, there was a high prevalence of anti-T. gondii antibodies in beef cattle intended for human consumption in the State of Rondônia, Brazil, and a low prevalence of anti-N. caninum antibodies. Longitudinal studies can better elucidate the cause of these prevalence levels and how they could be better prevented and controlled.

Regulation of Mitochondrial Energy Metabolism by Glutaredoxin 5 in the Apicomplexan Parasite Neospora caninum

Iron-sulfur [Fe-S] clusters are one of the most ancient and functionally versatile natural biosynthetic prosthetic groups required by various proteins involved in important metabolic processes, including the oxidative phosphorylation of proteins, electron transfer, energy metabolism, DNA/RNA metabolism, and protein translation. Apicomplexan parasites harbor two possible [Fe-S] cluster assembly pathways: the iron-sulfur cluster (ISC) pathway in the mitochondria and the sulfur formation (SUF) pathway in the apicoplast. Glutaredoxin 5 (GRX5) is involved in the ISC pathway in many eukaryotes. However, the cellular roles of GRX5 in apicomplexan parasites remain to be explored. Here, we showed that Neospora caninum mitochondrial GRX5 (NcGRX5) deficiency resulted in aberrant mitochondrial ultrastructure and led to a significant reduction in parasite proliferation and virulence in mice, suggesting that NcGRX5 is important for parasite growth in vitro and in vivo. Comparative proteomics and energy metabolomics were used to investigate the effects of NcGRX5 on parasite growth and mitochondrial metabolism. The data showed that disruption of NcGRX5 downregulated the expression of mitochondrial electron transport chain (ETC) and tricarboxylic acid cycle (TCA) cycle proteins and reduced the corresponding metabolic fluxes. Subsequently, we identified 23 proteins that might be adjacent to or interact with NcGRX5 by proximity-based protein labeling techniques and proteomics. The interactions between NcGRX5 and two iron-sulfur cluster synthesis proteins (ISCS and ISCU1) were further confirmed by coimmunoprecipitation assays. In conclusion, NcGRX5 is important for parasite growth and may regulate mitochondrial energy metabolism by mediating the biosynthesis of iron-sulfur clusters. IMPORTANCE Iron-sulfur [Fe-S] clusters are among the oldest and most ubiquitous prosthetic groups, and they are required for a variety of proteins involved in important metabolic processes. The intracellular parasites in the phylum Apicomplexa, including Plasmodium, Toxoplasma gondii, and Neospora caninum, harbor the ISC pathway involved in the biosynthesis of [Fe-S] clusters in mitochondria. These cofactors are required for a variety of important biological processes. However, little is known about the role of oxidoreductase glutaredoxins in these parasites. Our data indicate that NcGRX5 is an essential protein that plays multiple roles in several biological processes of N. caninum. NcGRX5 interacts with the mitochondrial iron-sulfur cluster synthesis proteins ISCS and ISCU1 and also regulates parasite energy metabolism. These data provide an insider's view of the metabolic regulation and iron-sulfur cluster assembly processes in the apicomplexan parasites.

Temporal transcriptomic changes in microRNAs involved in the host immune response and metabolism during Neospora caninum infection

BACKGROUND

Neospora caninum infection is a major cause of abortion in cattle, which results in serious economic losses to the cattle industry. However, there are no effective drugs or vaccines for the control of N. caninum infections. There is increasing evidence that microRNAs (miRNAs) are involved in many physiological and pathological processes, and dysregulated expression of host miRNAs and the biological implications of this have been reported for infections by various protozoan parasites. However, to our knowledge, there is presently no published information on host miRNA expression during N. caninum infection.

METHODS

The expression profiles of miRNAs were investigated by RNA sequencing (RNA-seq) in caprine endometrial epithelial cells (EECs) infected with N. caninum at 24 h post infection (pi) and 48 hpi, and the functions of differentially expressed (DE) miRNAs were predicted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The transcriptome data were validated by using quantitative real-time polymerase chain reaction. One of the upregulated DEmiRNAs, namely chi-miR-146a, was selected to study the effect of DEmiRNAs on the propagation of N. caninum tachyzoites in caprine EECs.

RESULTS

RNA-seq showed 18 (17 up- and one downregulated) and 79 (54 up- and 25 downregulated) DEmiRNAs at 24 hpi and 48 hpi, respectively. Quantitative real-time polymerase chain reaction analysis of 13 randomly selected DEmiRNAs (10 up- and three downregulated miRNAs) confirmed the validity of the RNA-seq data. A total of 7835 messenger RNAs were predicted to be potential targets for 66 DEmiRNAs, and GO and KEGG enrichment analysis of these predicted targets revealed that DEmiRNAs altered by N. caninum infection may be involved in host immune responses (e.g. Fc gamma R-mediated phagocytosis, Toll-like receptor signaling pathway, tumor necrosis factor signaling pathway, transforming growth factor-β signaling pathway, mitogen-activated protein kinase signaling pathway) and metabolic pathways (e.g. lysine degradation, insulin signaling pathway, AMP-activated protein kinase signaling pathway, Rap1 signaling pathway, calcium signaling pathway). Upregulated chi-miR-146a was found to promote N. caninum propagation in caprine EECs.

CONCLUSIONS

This is, to our knowledge, the first report on the expression profiles of host miRNAs during infection with N. caninum, and shows that chi-miR-146a may promote N. caninum propagation in host cells. The novel findings of the present study should help to elucidate the interactions between host cells and N. caninum.

Decisive points for pregnancy losses in beef cattle

Beef cattle producers rely on each of their cows to produce a marketable calf each year to maintain a sustainable operation. Within the first month of gestation, pregnancy failures have been recorded to be upwards of 40-50%. From fertilisation to birth, there are numerous factors contributing to pregnancy failure. From the beginning of gestation oocyte competence is often a large factor impacting fertility as the dam contributes all mRNA for initial embryo development. Other factors contributing to early embryonic infertility include hormonal concentration and heat stress. After the embryo enters the uterus, it becomes critical for the uterus to be receptive to the developing conceptus. The embryo then begins to elongate and secrete interferon-tau to initiate maternal recognition of pregnancy; a requirement to establish and maintain bovine pregnancies. After a pregnancy completes these steps, placentation actively begins around day 22 of pregnancy and lasts until organogenesis. The fetal phase follows the embryonic phase where disease and/or toxins are often the cause of pregnancy failure at this period. However, fetal mortality has been reported to occur in less than 10% of pregnancies. Understanding of the many factors influencing infertility needs to be further investigated to increase pregnancy success in beef cattle.

Seroprevalence of Neospora caninum in Goats from Korkuteli District of Antalya

OBJECTIVE

This study aimed to determine the seroprevalence of Neospora caninum in goats from the Korkuteli district of Antalya.

METHODS

During the study, sera samples were obtained from 184 female goats and analyzed for the presence of antibodies against N. caninum using a commercial ELISA kit.

RESULTS

Seroprevalence of N. caninum was determined as 4.89%. Seropositivity of N. caninum in goats was not statistically significant (p>0.05) in terms of study centers, age groups, and abort situation.

CONCLUSION

This study reports the first data on the presence and seroprevalence of N. caninum in the goats in the region.

Neospora caninum infection in aborting bovines and lost fetuses: A systematic review and meta-analysis

Background

Neospora caninum (N. caninum) is known to be a major cause of reproductive failure in cattle herds around the world. Therefore, the current comprehensive study was performed to estimate the global prevalence of N. caninum infection in bovines that had an abortion and aborted fetuses.

Methods

In this study, PubMed, ScienceDirect, Web of Science, Scopus, and ProQuest databases were systematically searched for relevant studies up until November 4, 2021. Pooled prevalence and corresponding 95% confidence intervals (CI) were estimated using a random effect model. Other analyzes performed on the data of this study include sensitivity analysis, publication bias test, and quality assessment.

Results

The final analyses included 71 studies conducted on 2965 abortive cattle and 4805 aborted fetuses. The overall prevalence rates of N. caninum infection in bovines that had an abortion were 47% and 1% using serological and molecular methods. Furthermore, overall prevalence rates of N. caninum infection in bovine aborted fetuses globally were 35% (95% CI: 8%–62%) and 43% (95% CI: 35%–52%) using serological and molecular methods.

Conclusions

The results of this study showed the high prevalence of N. caninum infection in bovines that had an abortion and aborted fetuses. It is hoped that the results of this study will help prevent abortion in bovines around the world and encourage further studies to determine the impact of this parasite on the occurrence of abortion that may help reduce the economic damage caused by abortion worldwide.

Neurological Infection, Kynurenine Pathway, and Parasitic Infection by Neospora caninum

Neuroinflammation is one of the most frequently studied topics of neurosciences as it is a common feature in almost all neurological disorders. Although the primary function of neuroinflammation is to protect the nervous system from an insult, the complex and sequential response of activated glial cells can lead to neurological damage. Depending on the type of insults and the time post-insult, the inflammatory response can be neuroprotective, neurotoxic, or, depending on the glial cell types, both. There are multiple pathways activated and many bioactive intermediates are released during neuroinflammation. One of the most common one is the kynurenine pathway, catabolizing tryptophan, which is involved in immune regulation, neuroprotection, and neurotoxicity. Different models have been used to study the kynurenine pathway metabolites to understand their involvements in the development and maintenance of the inflammatory processes triggered by infections. Among them, the parasitic infection Neospora caninum could be used as a relevant model to study the role of the kynurenine pathway in the neuroinflammatory response and the subset of cells involved.

Comparison of serum creatine kinase and aspartate aminotransferase activity in dogs with Neospora meningoencephalitis and noninfectious meningoencephalitis

Background

Creatine kinase (CK) and aspartate aminotransferase (AST) activity can be increased with myositis associated with Toxoplasma and Neospora infection in dogs.

Hypothesis/Objectives

Serum activity of CK and AST can be used as a rapid screen for predicting positive serology in meningoencephalitis caused by Toxoplasma gondii or Neospora caninum in dogs compared to dogs with noninfectious meningoencephalitis.

Animals

Eighty dogs with meningoencephalitis based on magnetic resonance imaging and cerebrospinal fluid analysis.

Methods

Retrospective case‐control study. Serological cutoffs (≥1:800 immunofluorescence for Neospora and ≥1:400 IgG or ≥1:64 IgM or both for Toxoplasma) categorized dogs as infected (n = 21, all neosporosis) or noninfected (n = 59). Activities of CK and AST between infected and noninfected groups were compared using a Mann‐Whitney U test and receiver operating characteristic curve analysis.

Results

No dogs were diagnosed with toxoplasmosis. Serum CK and AST activities were significantly increased (P < .001) in dogs with positive serology for Neospora (CK: median, 1334 U/L; range, 281‐3633 U/L and AST: median, 124 U/L; range, 59‐333 U/L) compared to noninfectious cases (CK: median, 215 U/L; range, 69‐683 U/L and AST: median, 36 U/L; range, 19‐139 U/L). A CK cutoff of 485 U/L had 95.24% sensitivity and 96.61% specificity with a negative predicative value of >99%. An AST cutoff of 57 U/L had 94.44% sensitivity and 85.71% specificity with an estimated negative predicative value of 99%.

Conclusions and Clinical Importance

High serum CK and AST activity can increase suspicion for neosporosis while awaiting serological tests for dogs with meningoencephalitis.

Identification and Function of Apicoplast Glutaredoxins in Neospora caninum

Glutaredoxins (GRXs), important components of the intracellular thiol redox system, are involved in multiple cellular processes. In a previous study, we identified five GRXs in the apicomplexan parasite, Neospora caninum. In the present study, we confirmed that the GRXs S14 and C5 are located in the apicoplast, which suggests unique functions for these proteins. Although single-gene deficiency did not affect the growth of parasites, a double knockout (Δgrx S14Δgrx C5) significantly reduced their reproductive capacity. However, there were no significant changes in redox indices (GSH/GSSG ratio, reactive oxygen species and hydroxyl radical levels) in double-knockout parasites, indicating that grx S14 and grx C5 are not essential for maintaining the redox balance in parasite cells. Key amino acid mutations confirmed that the Cys²⁰³ of grx S14 and Cys^253/256 of grx C5 are important for parasite growth. Based on comparative proteomics, 79 proteins were significantly downregulated in double-knockout parasites, including proteins mainly involved in the electron transport chain, the tricarboxylic acid cycle and protein translation. Collectively, GRX S14 and GRX C5 coordinate the growth of parasites. However, considering their special localization, the unique functions of GRX S14 and GRX C5 need to be further studied.

Glutaredoxin 1 Deficiency Leads to Microneme Protein-Mediated Growth Defects in Neospora caninum

Neospora caninum is an obligate intracellular protozoan parasite that infects a wide range of mammalian species and causes spontaneous abortion in cattle. N. caninum is exposed to oxidative stress during its life cycle. Oxidoreductase is crucial for parasite response to the environmental stresses. Glutaredoxins (Grxs) are small oxidoreductases of the thioredoxin family proteins that catalyze thiol-disulfide exchange reactions by utilizing electrons from the tripeptide glutathione (γGlu-Cys-Gly; GSH). Grxs are key elements in redox signaling and cell signal transduction. However, Grxs are an unexplored set of oxidoreductases in N. caninum. Here, we identified two cytoplasm located glutaredoxin domain-containing proteins (NcGrx1 and NcGrx3) in N. caninum. To better understand the functions of these Grx proteins, we generated NcGrx1 and NcGrx3 deficiency and overexpression strains. The deletion or overexpression of NcGrx3 had no significant effect on the growth of N. caninum in vitro and in vivo. NcGrx1 knockout parasites displayed a significant growth defect, which was due to the influence on invasion and egress abilities. Moreover, NcGrx1 deficiency decreased the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) (GSH/GSSG ratio), caused a significant accumulation of hydroxyl radical in parasites, and an increase in apoptotic cells under oxidative stress (H₂O₂) condition. To determine the cause of growth defects in ΔNcGrx1, we examined the transcription levels of various invasion-egress related genes as measured by qPCR. We found a significant decrease in MIC1, MIC4, and MIC6 genes. Further investigation found that the secretion of MIC1, MIC4, and MIC6 proteins was significantly affected. Collectively, Ncgrx1 is important for microneme protein-mediated parasite growth, and maybe a potential intervention target for the N. caninum.

Evidence of infection with Toxoplasma gondii and Neospora caninum in South Australia: using wild rabbits as a sentinel species

OBJECTIVE

The aim of this study was to utilise wild rabbits (Oryctolagus cuniculus) as a sentinel species to study levels of environmental contamination with N. caninum and T. gondii in South Australia, and to examine associations with rainfall, climate and land use.

DESIGN

Toxoplasma gondii (T. gondii), an apicomplexan parasite, causes the clinical disease toxoplasmosis, which can affect sheep as well as humans and many other animals. Neosporosis, the clinical disease caused by closely related Neospora caninum (N. caninum), causes abortions in cattle, with large economic impacts to cattle industries.

METHODS

Aliquots of wild rabbit (Oryctolagus cuniculus) serum were obtained from twelve sites across South Australia over a period of eighteen years, with a total of 2114 samples. An in-house Modified Agglutination Test (MAT) was developed, and samples were screened for the specific antibodies against both T.gondii and N. caninum.

RESULTS

Overall, 9.9% of samples screened for T. gondii tested positive and 6.1% of samples screened for N. caninum tested positive. There was no difference observed in seroprevalence of T.gondii specific antibodies between samples collected throughout summer, autumn, winter or spring. By contrast, a significantly higher (p=0.030) seroprevalence of N. caninum specific antibodies was observed in spring than any other season. T. gondii and N. caninum antibodies were discovered at sites across a broad area of South Australia, indicating these environments maybe infected with both parasites.

CONCLUSION

Results provide evidence that suggests N. caninum oocysts may have different survival characteristics, such as varying tolerances to low relative humidity, than T. gondii oocysts.

Seroprevalence of Neospora caninum and Toxoplasma gondii in dogs from an urban area of North-eastern Brazil: a spatial approach

INTRODUCTION

The present study aimed to assess the seroprevalence and spatial distribution of Neospora caninum and Toxoplasma gondii in dogs.

METHODS

Blood samples (n = 241) were collected and analyzed for the presence of anti-N. caninum and anti-T. gondii antibodies. The spatial distribution was evaluated using kernel density estimation (KDE).

RESULTS

Anti-N. caninum and anti-T. gondii antibodies were detected in 24.06% (58/241) and 9.54% (23/241) of samples, respectively. A heterogeneous spatial distribution of positive dogs was observed across the city.

CONCLUSIONS

These data are pivotal for better understanding the dynamics of infection caused by these protozoa in the canine population.

Occurrence of anti-Neospora caninum antibodies in cattle in the dairy farming region of the state of Piauí, Brazil

This study focused on the detection of anti-Neospora caninum IgG antibodies in cows in the dairy farming region of the state of Piauí, Brazil. To this end, serum samples were collected from 255 dairy cows on 17 farms located in the dairy farming region of the municipality of Parnaíba, Piauí, Brazil. The indirect fluorescence antibody test (IFAT) was employed to detect anti-N. caninum IgG antibodies, using anti-bovine IgG (Sigma®) conjugated to fluorescein isothiocyanate (FITC) and a cutoff point of 1:200. Of the 255 samples analyzed, 69 (27.06%) were positive for anti- N. caninum IgG antibodies, the relative frequency found by property was: 1 (20.00%), 2 (53.33%), 3 (46.66%), 4 (53.33%), 5 (26.66%), 6 (6.66%), 7 (6.66%), 8 (20.00%), 9 (26.66%), 10 (26.66%), 11 (20.00%), 12 (20.00%), 13 (46.66%), 14 (26.66%), 15 (26.66%), 16 (20.00%) and 17 (13.33%). with titers of 200 (15.94%), 400 (20.30%), 800 (24.63%), 1600 (23.18%) and 3200 (15.94%), being the highest frequency for the titer of 800. This study demonstrates for the first time that cows from dairy herds of Parnaíba municipality, state of Piauí, are exposed to N. caninum.

Genome Wide Identification of Mutational Hotspots in the Apicomplexan Parasite Neospora caninum and the Implications for Virulence

Neospora caninum is an apicomplexan parasite responsible for neosporosis, a disease causing hind limb paralysis in dogs and abortion in cattle, resulting in substantial economic losses to beef and dairy industries. Marked differences in pathogenicity exist between N. caninum strains suggesting that intrinsic genetic differences exist between them. These differences likely exist in genes expressed during the tachyzoite lifecycle stage which is responsible for the pathogenesis of neosporosis. An improved understanding of these genetic differences is essential to understanding N. caninum virulence, though such knowledge is scarce. Using a variant detection workflow we compared the tachyzoite transcriptomes of two N. caninum strains with different virulence properties: NC-Liverpool (virulent) and NC-Nowra (avirulent). This workflow identified 3130 SNPs and 6123 indels between the strains, and nine markers capturing 30 variants were Sanger sequenced for both strains. Sequencing of these loci was extended to an additional eight strains and subsequent phylogenetic analysis supported a genetic population structure comprised of two major clades with no geographical segregation. Sequence polymorphisms within coding regions of tachyzoite-associated genes were concentrated on chromosomes XI and XII, with 19 distinct tachyzoite-associated SNP hotspot regions identified within coding regions of the N. caninum nuclear genome. The variants were predominantly located in loci associated with protein binding, protein-protein interactions, transcription, and translation. Furthermore, 468 nonsynonymous SNPs identified within protein-coding genes were associated with protein kinase activity, protein binding, protein phosphorylation, and proteolysis. This work may implicate these processes and the specific proteins involved as novel effectors of N. caninum tachyzoite virulence.

Neospora caninum in properties in the west region of Paraná, Brazil: prevalence and risk factors

Abstract Neospora caninum is a heteroxenous protozoa, whose definitive hosts are canids and intermediate hosts are herbivores, and is of great importance in cattle. The objectives of this study were to determine the prevalence of N. caninum in dairy cattle and dogs, to detect the presence of the protozoa at the molecular level in aborted fetuses, and to identify the risk factors associated with infection in properties in the western region of the state of Paraná. For this study, 600 bovine serum samples from 60 properties, 163 canine serum samples from 52 properties and 17 bovine fetuses from nine properties were collected. Data were collected using an epidemiological questionnaire to verify the risk factors. Serum samples were analyzed using the indirect fluorescent antibody test. Fetal tissues were analyzed using polymerase chain reaction and subsequent DNA sequencing. Of the bovine samples, 23.67% were positive for N. caninum. Among the canine samples, 11.66% were positive for N. caninum. Risk factors in cattle were history of abortion, low milk production, extensive breeding, and Jersey breed (p<0.05). Protozoan DNA was detected in 52.94% of the 17 fetuses and the sequencing presented high similarity with N. caninum.

Parasitemia due to Sarcocystis neurona-like infection in a clinically ill domestic cat

An 8-year-old, 6-kg, male neutered Domestic Shorthair cat was presented to The Ohio State University Veterinary Medical Center (OSU-VMC) for difficulty breathing. Physical examination and thoracic radiographs indicated pneumonia, a soft-tissue mass in the left caudal lung lobe, and diffuse pleural effusion. The effusion was classified as modified transudate. Rare extracellular elongated (~5-7 μm × 1-2 μm) zoites with a central round to oval-shaped purple to deep purple vesicular nucleus with coarsely stippled chromatin and light blue cytoplasm were seen on a peripheral blood smear. Serum IgG and IgM were positive for Sarcocystis sp. antibodies and negative for Toxoplasma gondii antibodies, suggesting that the infection was acute rather than a recrudescence of prior infection. This organism was most consistent with either Sarcocystis neurona or Sarcocystis dasypi based on DNA sequence analysis of PCR products using COC ssRNA, ITS-1, snSAG2, and JNB25/JD396 primer sets. This is the first report to visualize by light microscopy circulating Sarcocystis sp. merozoites in the peripheral blood of a domestic cat. Therefore, Sarcocystis should be considered as a differential diagnosis in cats with suspected systemic protozoal infection.

Risk factors for Neospora caninum infection in dairy cattle and their possible cause-effect relation for disease

Neospora caninum causes reproductive problems in cattle such as abortion, premature birth, retention of fetal membranes, and metritis. Therefore, this study aimed to verify possible risk factors for N. caninum infection in dairy cattle and their cause-effect relation to neosporosis. Serum samples of 1518 dairy cows from the West of Santa Catarina State, Southern Brazil were analyzed by indirect immunofluorescence assay (IFA) for N. caninum, where 466 were found to be positives (30.69%-CI_95%; 28.3-33.0). In addition, an epidemiological survey was conducted in order to verify possible risk factors for neosporosis and their relation to the disease. The presence of dogs in the farm was strongly associated with IFA positive results for N. caninum, and lack of history for neosporosis in the farm increased the chances of positivity in 66%. It was found a significant cause-effect relation between the occurrence of reproductive problems and the presence of antibodies against N. caninum (p = 0.05). It is possible to conclude that N. caninum is widely distributed in dairy farms of the Western part of Santa Catarina state, Brazil, and that the occurrence of reproductive problems is directly related to the disease with the presence of dogs as a risk factor for N. caninum infection.

NLRP3 inflammasome activation in murine macrophages caused by Neospora caninum infection

Background

Neospora caninum is an intracellular parasite that causes significant economic losses in cattle industry. Understanding the host resistance mechanisms in the innate immune response to neosporosis could facilitate the exploration of approaches for controlling N. caninum infection. The NLR inflammasome is a multiprotein platform in the cell cytoplasm and plays critical roles in the host response against microbes.

Methods

Neospora caninum-infected wild-type (WT) macrophages and Nlrp3^−/− macrophages, and inhibitory approaches were used to investigate inflammasome activation and its role in N. caninum infection. Inflammasome RT Profiler PCR Arrays were used to identify the primary genes involved in N. caninum infection. The expression of the sensor protein NLRP3, processing of caspase-1, secretion of IL-1β and cell death were detected. Neospora caninum replication in macrophages was also assessed.

Results

Many NLR molecules participated in the recognition of N. caninum, especially the sensor protein NLRP3, and further study revealed that the NLRP3 distribution became punctate in the cell cytoplasm, which facilitated inflammasome activation. Inflammasome activation-mediated caspase-1 processing and IL-1β cleavage in response to N. caninum infection were observed and were correlated with the time of infection and number of infecting parasites. LDH-related cell death was also observed, and this death was regarded as beneficial for the clearance of N. caninum. Treatment of N. caninum-infected macrophages with caspase-1, pan-caspase and NLRP3 inhibitors led to the impaired release of active IL-1β and a failure to restrict parasite replication. And Neospora caninum infected peritoneal macrophages from Nlrp3-deficient mice displayed greatly decreased release of active IL-1β and the failure of caspase-1 cleavage.

Conclusions

The NLRP3 inflammasome can be activated in N. caninum-infected macrophages, and plays a protective role in the host response to control N. caninum.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2197-2) contains supplementary material, which is available to authorized users.

Antibodies to Neospora caninum in sheep from slaughterhouses in the state of São Paulo, Brazil

Neosporosis is an emergent disease responsible for considerable economic impact due to reproductive losses. Its zoonotic potential remains unknown. This study involved a survey of antibodies to Neospora caninum in slaughtered sheep and their association with epidemiological variables. Serum samples from 596 sheep from the states of São Paulo and Rio Grande do Sul, Brazil, were collected in two slaughterhouses located in São Paulo and evaluated by indirect fluorescence antibody test (IFAT), using cut-off titers of 25. Among these samples, 353/596 (59.23%; 95%CI 55.23-63.10) were positive and 263/353 (74.50%; 95%CI 69.71-78.77%) were from Rio Grande do Sul. Statistical associations were determined in the univariate analysis between the serological results and sex, breed and municipality of origin. Sheep that came from extensive breeding system showed higher chance (OR=2.09) of presenting antibodies to N. caninum in relation to those from semi-intensive system. Higher chance was also observed for the different studied breeds, except Bergamácia, in relation to Hampshire Down. The results revealed the presence of infection by N. caninum in sheep from slaughterhouses.

Rhoptry protein 5 (ROP5) Is a Key Virulence Factor in Neospora caninum

Neospora caninum, of the Apicomplexa phylum, is a common cause of abortions in cattle and nervous system dysfunction in dogs. Rhoptry proteins of Apicomplexa play an important role in virulence. The objectives of this study were to study functions of NcROP5 in N. caninum by deleting the NcROP5 gene from the wild Nc-1 strain. We selected NcROP5 in ToxoDB and successfully constructed an NcROP5 gene-deleted vector, pTCR-NcROP5-CD KO. Then we screened the NcROP5 knockout strains (ΔNcROP5) at the gene, protein and transcription levels. Plaque assay, host cell invasion assay and intracellular proliferation test showed that the ΔNcROP5 strain had less plaque space, weakened invasion capacity and slower intracellular growth. Animal testing showed significantly lower cerebral load of ΔNcROP5 than the load of the Nc-1 strain, as well as a loss of virulence for the ΔNcROP5 strains. Phenotypic analyses using the label-free LC-MS/MS assay-based proteomic method and KEGG pathway enrichment analysis showed a reduction of NcGRA7 transcription and altered expression of multiple proteins including the apicomplexan family of binding proteins. The present study indicated that ROP5 is a key virulence factor in N. caninum in mice. The proteomic profiling of Nc-1 and ΔNcROP5 provided some data on differential proteins. These data provide a foundation for future research of protein functions in N. caninum.

Seroepidemiological survey of Neospora caninum and its risk factors in farm dogs in Nakuru district, Kenya

Aim:

The objective of this study was to determine the seroprevalence of Neospora caninum (NC) and its risk factors in farm dogs in Kenya.

Materials and Methods:

As part of a longitudinal study on dairy cattle abortion in 2010 in Kenya, serum samples were collected from 84 dogs in 53 randomly selected dairy cattle farms to determine the seroprevalence and risk factors of seropositivity for NC.

Results:

15 (17.9%) of the dogs were seropositive to NC antibodies, and at least one seropositive dog was found in 12 (22.6%) of the 53 farms. The final multivariable logistic regression model identified free-roaming as the only factor significantly associated with seropositivity (odds ratio=4.48; p=0.03).

Conclusion:

The findings of this study indicate that canine neosporosis does exist in Kenya and that farmers should restrict their dogs from roaming to reduce the risk of their dogs becoming a reservoir for NC. More studies need to be carried out to determine the reproductive effects of NC on dairy cattle in Kenya.

Canine neosporosis: perspectives on pathogenesis and management

Canine neosporosis is a worldwide disease caused by the obligate intracellular parasite protozoan Neospora caninum, manifesting mainly neurological symptoms. N. caninum has a heteroxenous life cycle and affects a wide range of warm-blooded animals. The domestic and wild canids are the definitive host of the parasite. They shed oocysts after ingestion of tissue cysts from infected intermediate hosts (ovine, equine, bovine, canine, and many other species), containing bradyzoites, or oocyst-contaminated water and food. The presence of dogs in farms is considered a risk factor for production animals. A wide range of diagnostic methods are currently available, but the most used is serology, ie, indirect fluorescent antibody test specific to the antibody detection in blood serum samples. No vaccine is available, but control strategies should be focused on the vertical and horizontal transmission of the parasite, ie, avoid feeding dogs with raw or undercooked meat, and taking care with water for human and animal consumption. No medicines to control the transplacental transmission are available yet.

Suspected neospora-associated myocarditis in a dog

Neosporosis was diagnosed in an American Staffordshire Terrier with collapse and arrhythmia episodes by serological and cardiovascular examination. Clinical signs, diagnosis and treatment ofNeospora caninumare described. The dog did not develop any neurological abnormality, which is the most common manifestation. Furthermore, the dog was also serologically positive for antibodies toToxoplasma gondiiand negative forBartonella henselaeandBorrelia burgdorferi. Serological diagnosis was achieved by indirect immunofluorescence. The arrhythmia, cardiac markers, biochemistry, complete blood count and clinical signs gradually improved following therapy with clindamycin and antiarrhythmic therapy. After 3 months of therapyToxoplasma gondiititres persisted low butNeospora caninumtitres changed to negative values. According to the veterinary literature and to the authors’ knowledge this was one of the few cases successfully treated for this condition. These observations demonstrated that neosporosis should be considered in the differential diagnosis of myocarditis in dogs and can be successfully treated by supportive therapy and clindamycin.

Occurrences of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from four districts of Tocantins state, Brazilian Legal Amazon Region

Toxoplasmosis and neosporosis have been recognized as economically important diseases with considerable impact on the livestock industry. Little is known concerning the occurrence of Toxoplasma gondii and Neospora caninum in sheep from Tocantins state, Brazil. Here, we investigated antibodies against these parasites and associated factors in 182 sheep from Araguaína, Santa Terezinha do Tocantins, Arguianópolis and Palmeiras do Tocantins districts, Tocantins. Sheep sera were assayed for T. gondii and N. caninum IgG antibodies by indirect fluorescence antibody test (IFAT), using cut-off point at a dilution of 1:40 and 1:25 respectively. The prevalence of seropositive animal for T. gondii was 13.74% and 13.74% for N. caninum. None of the characteristics studied including reproductive problems, presence of cats, presence of dogs and veterinary care (p>0.05) was associated with occurrence of T. gondii or N. caninum infection. Only breed was identified as associated factor for the occurrence of toxoplasmosis in sheep (p<0.05). The present study is the first report on serum occurrence of T. gondii and N. caninum in sheep from the state of Tocantins, Brazil.

Susceptibility to experimental infection of the invertebrate locusts (Schistocerca gregaria) with the apicomplexan parasite Neospora caninum

Neuropathogenesis is a feature of Neospora caninum infection. In order to explore this in the absence of acquired host immunity to the parasite, we have tested infection in locusts (Schistocerca gregaria). We show for the first time that locusts are permissive to intra-hemocoel infection with N. caninum tachyzoites. This was characterized by alteration in body weight, fecal output, hemoparasitemia, and sickness-related behavior. Infected locusts exhibited progressive signs of sickness leading to mortality. Also, N. caninum showed neuropathogenic affinity, induced histological changes in the brain and was able to replicate in the brain of infected locusts. Fatty acid (FA) profiling analysis of the brains by gas chromatography and multi-variate prediction models discriminated with high accuracy (98%) between the FA profiles of the infected and control locusts. DNA microarray gene expression profiling distinguished infected from control S. gregaria brain tissues on the basis of distinct differentially-expressed genes. These data indicate that locusts are permissible to infection with N. caninum and that the parasite retains its tropism for neural tissues in the invertebrate host. Locusts may facilitate preclinical testing of interventional strategies to inhibit the growth of N. caninum tachyzoites. Further studies on how N. caninum brings about changes in locust brain tissue are now warranted.

Role of IFN-γ and LPS on neuron/glial co-cultures infected by Neospora caninum

Neospora caninum causes cattle abortion and neurological symptoms in dogs. Although infection is usually asymptomatic, classical neurological symptoms of neosporosis may be associated with encephalitis. This parasite can grow in brain endothelial cells without markedly damages, but it can modulate the cellular environment to promote its survival in the brain. In previous studies, we described that IFN-γ decreased the parasite proliferation and down regulated nitric oxide (NO) production in astrocyte/microglia cultures. However, it remains unclear how glial cells respond to N. caninum in the presence of neurons. Therefore, we evaluated the effect of 300 IU/mL IFN-γ or 1.0 mg/mL of LPS on infected rat neuron/glial co-cultures. After 72 h of infection, LPS did not affect the mitochondrial dehydrogenase activity. However, IFN-γ decreased this parameter by 15.5 and 12.0% in uninfected and infected cells, respectively. The number of tachyzoites decreased 54.1 and 44.3% in cells stimulated with IFN-γ and LPS, respectively. Infection or LPS treatment did not change NO production. On the other hand, IFN-γ induced increased nitrite release in 55.7%, but the infection reverted this induction. IL-10 levels increased only in infected cultures (treated or not), meanwhile PGE₂ release was improved in IFN-γ/infected or LPS/infected cells. Although IFN-γ significantly reduced the neurite length in uninfected cultures (42.64%; p < 0.001), this inflammatory cytokine reverted the impairment of neurite outgrowth induced by the infection (81.39%). The results suggest a neuroprotective potential response of glia to N. caninum infection under IFN-γ stimulus. This observation contributes to understand the immune mediated mechanisms of neosporosis in central nervous system (CNS).

Control options for Neospora caninum--is there anything new or are we going backwards?

Recent work has highlighted and enumerated the economic annual losses due to Neospora caninum abortions worldwide, which should provide strong motivation for the control of bovine neosporosis. However, with the recent withdrawal from sale of the only commercially available vaccine, control options for N. caninum have become more restricted. While researchers continue to work on developing alternative efficacious vaccines, what are the control options presently available for the cattle industries? At the practical level, recommendations for 'Test-and-cull', or 'not breeding from seropositive dams' stand diametrically opposed to alternative options put forward that suggest a primary producer is better advised to keep those cows in the herd that are already seropositive, i.e., assumed to be chronically infected, and indeed those that have already aborted once. Treatment with a coccidiostat has been recommended as the only economically viable option, yet no such treatment has gained official, regulatory approval. Dogs are central to the life cycle of N. caninum and have repeatedly been associated with infection and abortions in cattle by epidemiological studies. Knowledge and understanding of that pivotal role should be able to be put to use in control programmes. The present review canvasses the relevant literature for evidence for control options for N. caninum (some of them proven, many not) and assesses them in the light of the authors' knowledge and experience with control of N. caninum.

Vaccines against neosporosis: what can we learn from the past studies?

Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against N. caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.