Isolation of Neospora caninum from the brain of a naturally infected adult dairy cow

Isolation of Neospora caninum from a beef cattle fetus from Argentina: Immunopathological and molecular studies

Neospora caninum is an important abortifacient agent affecting mainly cattle worldwide. The aim of the present work was to describe the histopathological findings in a naturally infected beef cow and its midterm fetus caused by a genetically defined N. caninum isolate in Argentina. A N. caninum seropositive multiparous Aberdeen Angus pregnant cow and its fetus in the sixth month of gestation were submitted for histopathological, immunohistochemical, serological, and molecular studies and parasite isolation. The cow belonged to a beef herd under extensive management, with a N. caninum seroprevalence of 11%, and low level of annual abortion rate (≤ 5%). The dam had mild lymphocytic infiltrate in CNS, heart and uterus and no parasites were detected by Immunohistochemistry (IHC). No parasitic DNA was detected in the dam's brain, and gamma interferon knockout mice inoculated with brain material did not become infected. Clusters of tachyzoites and parasitic DNA were detected in the placenta by IHC and PCR, respectively. However, isolation from the placenta was unsuccessful. The fetus developed specific antibodies and an inflammatory response was detected in multiple organs. Furthermore, in vitro and in vivo isolation was achieved from gamma interferon knockout mice inoculated with CNS from the fetus. Multilocus-microsatellite typing revealed a genetically defined N. caninum isolate similar to the previously reported as MLG 72. We report the first N. caninum isolate from beef cattle in Argentina.

From Signaling Pathways to Distinct Immune Responses: Key Factors for Establishing or Combating Neospora caninum Infection in Different Susceptible Hosts

: Neospora caninum is an intracellular protozoan parasite affecting numerous animal species. It induces significant economic losses because of abortion and neonatal abnormalities in cattle. In case of infection, the parasite secretes numerous arsenals to establish a successful infection in the host cell. In the same context but for a different purpose, the host resorts to different strategies to eliminate the invading parasite. During this battle, numerous key factors from both parasite and host sides are produced and interact for the maintaining and vanishing of the infection, respectively. Although several reviews have highlighted the role of different compartments of the immune system against N. caninum infection, each one of them has mostly targeted specific points related to the immune component and animal host. Thus, in the current review, we will focus on effector molecules derived from the host cell or the parasite using a comprehensive survey method from previous reports. According to our knowledge, this is the first review that highlights and discusses immune response at the host cell-parasite molecular interface against N. caninum infection in different susceptible hosts.

Neosporosis, Toxoplasmosis, and Sarcocystosis in Ruminants: An Update

Neospora caninum, Toxoplasma gondii, and Sarcocystis spp. are related Apicomplexan parasites that have 2 hosts in their life cycles. The definitive hosts excrete unsporulated (Neospora caninum, T gondii) or sporulated (Sarcocystis spp.) oocysts in their feces after ingesting tissue cysts from the tissues of ruminant intermediate hosts. These coccidians can cause abortion and neonatal mortality in ruminants. T gondii and Sarcocystis hominis (from cattle) are zoonotic. This article reviews information on the etiology, life cycle, diagnosis, control and prevention of these parasites and the diseases they cause in ruminants.

Histological and immunohistochemical characterization of the inflammatory and glial cells in the central nervous system of goat fetuses and adult male goats naturally infected with Neospora caninum

Background

Neospora caninum is an apicomplexan protozoan that is considered one of the main agents responsible for abortion in ruminants. The lesions found in the central nervous system (CNS) of aborted fetuses show multifocal necrosis, gliosis, and perivascular cuffs of mononuclear cells, but the inflammatory and glial cells have not been immunophenotypically characterized. The lesions in the CNS of infected adult animals have rarely been described. Therefore, in this study, we characterized the lesions, the immunophenotypes of the inflammatory and glial cells and the expression of MHC-II and PCNA in the CNS of goats infected with N. caninum. The CNS of eight aborted fetuses and six adult male goats naturally infected with N. caninum were analyzed with lectin histochemistry (RCA1) and immunohistochemistry (with anti-CD3, −CD79α, −GFAP, −MHC-II, and -PCNA antibodies). All animals were the offspring of dams naturally infected with N. caninum.

Results

The microscopic lesions in the CNS of the aborted fetuses consisted of perivascular cuffs composed mainly of macrophages (RCA1⁺), rare T lymphocytes (CD3⁺), and rare B lymphocytes (CD79α⁺). Multifocal necrosis surrounded by astrocytes (GFAP⁺), gliosis composed predominantly of monocytic-lineage cells (macrophages and microglia, RCA1⁺), and the cysts of N. caninum, related (or not) to the lesions were present. Similar lesions were found in four of the six male goats, and multinucleate giant cells related to focal gliosis were also found in three adult goats. Anti-GFAP immunostaining showed astrocytes characterizing areas of glial scarring. Cysts of N. caninum were found in three adult male goats. The presence of N. caninum was evaluated with histopathology, immunohistochemistry, and PCR. Immunohistochemistry demonstrated anti-PCNA labeling of macrophages and microglia in the perivascular cuffs and the expression of MHC-II by microglia and endothelial cells in the CNS of the aborted fetuses and adult male goats.

Conclusions

Macrophages and microglia were the predominant inflammatory cells in the CNS of aborted fetuses and healthy adult male goats infected with N. caninum. Activated astrocytes were mainly associated with inflamed areas, suggesting that astrocytes were involved in the resolution of the lesions.

Isolation and molecular characterisation of Neospora caninum in cattle in New Zealand

AIM

To isolate Neospora caninum from the brains of naturally infected cattle and use molecular techniques to characterise the isolates.

METHODS

Neospora caninum tachyzoites were isolated in Vero cell culture from the brains of a cow and two calves. The isolates were characterised using polymerase chain reaction (PCR) methods, DNA sequencing, an immunofluorescent antibody test (IFAT), transmission electron microscopy (TEM), and immunohistochemistry (IHC). The brains of the three cattle were subjected to histopathological examination. A pathogenicity study was conducted in 120 BALB/c mice.

RESULTS

Neospora caninum tachyzoites were isolated from all three cases and first observed in vitro between 14 and 17 days post-inoculation. Parasites were sub-cultured and maintained in Vero cell culture for more than 6 months. PCR products were generated for all three isolates, using two different primers. Sequencing of the PCR products and a subsequent BLAST search identified the isolates as N. caninum. In addition, the isolates tested positive using IFAT and IHC, and ultrastructure revealed by TEM was characteristic of N. caninum. Histopathological examination revealed lesions characteristic of N. caninum in 1/3 brains. In the pathogenicity study using BALB/c mice, the mortality rate was 3-7%.

CONCLUSION

This was the first successful isolation of N. caninum in New Zealand confirmed using molecular characterisation tests.

Isolation and genetic characterization of Neospora caninum from asymptomatic calves in Spain

Neospora caninum is a cyst-forming parasite that causes abortion in cattle. Despite this parasite's ubiquitous distribution and wide host range, the number of N. caninum isolates obtained to date is limited. In vitro isolation of the parasite is arduous and often unsuccessful. In addition, most isolates have been obtained from clinically affected hosts and therefore could be biased towards more virulent isolates. In this report, an improved isolation approach from transplacentally infected newborn calves was undertaken and 9 new isolates were obtained. Moreover, a microsatellite technique was applied to investigate the genetic diversity of these isolates. Most isolates showed specific genetic profiles. However, the Nc-Spain10 isolate was identical to the previously described Nc-Spain1H isolate and Nc-Spain3H was identical to Nc-Spain4H. These isolates were likely to have identical genotypes because they were isolated from distinct calves of the same herd. Future pathogenic characterization of these isolates will contribute to the investigation of the relationship between isolate virulence and the outcome of infection, as well as other epidemiological features, such as transmission.

Epidemiology and control of neosporosis and Neospora caninum

Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.

Neosporosis, Toxoplasmosis, and Sarcocystosis in Ruminants

Neospora caninum, Sarcocystis spp, and Toxoplasma gondii are related coccidian parasites that can cause abortion and neonatal mortality in animals. In addition, T gondii and certain species of Sarcocystis are zoonotic. This article reviews information on the etiology, diagnosis, control, and prevention of these diseases.

Diagnosis of bovine neosporosis

The protozoan parasite Neospora caninum is a major cause of abortion in cattle. The diagnosis of neosporosis-associated mortality and abortion in cattle is difficult. In the present paper we review histologic, serologic, immunohistochemical, and molecular methods for dignosis of bovine neosporosis. Although not a routine method of diagnosis, methods to isolate viable N. caninum from bovine tissues are also reviewed.

Pathogenesis of bovine neosporosis

The protozoan parasite Neospora caninum is a major pathogen of cattle and dogs, being a significant cause of abortion in cattle in many countries. It is one of the most efficiently transmitted parasites, with up to 90% of cattle infected in some herds. The pathogenesis of abortion due to Neospora is complex and only partially understood. Losses occur after a primary infection during pregnancy but more commonly as the result of recrudescence of a persistent infection during pregnancy. Parasitaemia is followed by invasion of the placenta and fetus. It is suggested that abortion occurs when primary parasite-induced placental damage jeopardises fetal survival directly or causes release of maternal prostaglandins that in turn cause luteolysis and abortion. Fetal damage may also occur due to primary tissue damage caused by the multiplication of N. caninum in the fetus or due to insufficient oxygen/nutrition, secondary to placental damage. In addition, maternal immune expulsion of the fetus may occur associated with maternal placental inflammation and the release of maternal pro-inflammatory cytokines in the placenta. Thus N. caninum is a primary pathogen capable of causing abortion either through maternal placental inflammation, maternal and fetal placental necrosis, fetal damage, or a combination of all three. The question of how N. caninum kills the fetus exposes the complex and finely balanced biological processes that have evolved to permit bovine and other mammalian pregnancies to occur. Defining these immunological mechanisms will shed light on potential methods of control of bovine neosporosis and enrich our understanding of the continuity of mammalian and protozoal survival.

Shedding of Neospora caninum oocysts by dogs fed tissues from naturally infected water buffaloes (Bubalus bubalis) from Brazil

Attempts were made to isolate Neospora caninum from naturally infected water buffaloes (Bubalus bubalis) from Brazil. Brains from six buffaloes with indirect fluorescent antibodies (>1:100) to N. caninum were used to isolate the parasite by bioassay in dogs and gerbils followed by in vitro culture. Shedding of Neospora-like oocysts was noticed in dogs fed brains from three buffaloes (isolate designation NcBrBuf-1, 2 and 4). Two more isolates (NcBrBuf-3 and 5) were obtained by in vitro culture of the brains of gerbils previously infected with brains of two other buffaloes. The identity of the isolates was confirmed by biological and molecular methods. The isolates were found to be non-pathogenic to gerbils. All five isolates amplified the gene 5 amplicons using Neospora-specific PCR assay. The sequences of gene 5 fragments and the common toxoplasmatiid ITS-1 fragments were analyzed. The dynamics of oocyst production in the dogs indicate that water buffaloes are natural intermediate hosts for N. caninum. This is the first report of isolation of N. caninum from water buffaloes.

Parelaphostrongylus tenuis and other parasitic diseases of the ruminant nervous system

There are many parasites that affect the ruminant central nervous system. Clinical signs can vary dramatically based on the location and mobility of the parasite. Clinical disease can occur due to the physical presence of the parasite and the resulting host immune response or the toxin produced by the parasite. Differentiating the cause of disease is particularly important because prognosis,treatment, and subsequent control measures vary dramatically depending on the disease process. This article focuses on the pathogenesis,treatment, and control of some of the more common parasitic diseases of the ruminant central nervous system.

Neospora caninum antigens recognized by mouse IgG at different stages of infection including recrudescence

Western blotting was performed to analyze Neospora caninum tachyzoite antigens recognized by mouse IgG at different stages of infection including recrudescence. At the early stage of infection, a 36-38 kDa antigen was clearly recognized by the mouse antisera. After day 48 postinoculation, the signal of the 36-38 kDa antigen gradually weakened. Meanwhile, a 43 kDa antigen was intensely and continuously recognized from 48 to 125 days postinoculation. This 43 kDa antigen was clearly detectable with the antisera from the mice under immunosuppression. Sera from naturally infected cattle strongly reacted with the 43 kDa antigen. Therefore, the 43 kDa antigen may be useful for immunological reactions to detect infected animals except in the early stage of the infection.

Review of Neospora caninum and neosporosis in animals

Neospora caninum is a coccidian parasite of animals. It is a major pathogen for cattle and dogs and it occasionally causes clinical infections in horses, goats, sheep, and deer. Domestic dogs are the only known definitive hosts for N. caninum. It is one of the most efficiently transmitted parasite of cattle and up to 90% of cattle in some herds are infected. Transplacental transmission is considered the major route of transmission of N. caninum in cattle. Neospora caninum is a major cause of abortion in cattle in many countries. To elicit protective immunity against abortion in cows that already harbor a latent infection is a major problem. This paper reviews information on biology, diagnosis, epidemiology and control of neosporosis in animals.

Redescription of Neospora caninum and its differentiation from related coccidia

Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.