Neospora caninum Infection in a Litter of Labrador Retriever Dogs in Denmark

Neospora caninum is a recently recognized cyst-forming coccidian parasite associated with severe encephalomyelitis and myositis in dogs of different breeds and ages (Bjerkås et al 1984, Bjerkås & Presthus 1988, Dubey et al. 1988), but has for many years been misdiagnosed as Toxoplasma gondii. In some dogs, the main clinical sign has been attributed to polyradiculoneuritis (Dubey et al. 1988, Cuddon et al. 1992). Furthermore, ulcerative dermatitis (Dubey et al. 1988) and megaoesophagus have been reported (Wolf et al. 1991). The life cycle of the parasite and mode of infection have not been clarified, but transplacental infection seems so far to be the natural route of transmission between intermediate hosts (Dubey & Lindsay 1989). It has been speculated that the disease in young and adult dogs might be due to reactivation of a persistent infection because corticosteroid therapy can activate a latent N. caninum infection (Dubey & Lindsay 1993).     

A Case of Neospora Associated Bovine Abortion in Sweden

Neospora caninum is a recently recognized protozoan organism that causes fatal neuromuscular disease in dogs and abortions and stillbirths in cattle and other animals (Dubey & Lindsay 1993). The parasite is morphologically similar and phylogenetically very closely related to the cyst-forming coccidium Toxoplasma gondii (Ellis et al. 1994, Holmdahl et al. 1994). This group of parasites has a two-host life cycle principally involving a carnivorous definitive host and a herbivorous or omnivorous intermediate host. However, with N. caninum, there is as yet no knowledge of any definitive host harbouring sexual stages of the parasite. The only known route of transmission is vertical from mother to foetus (Dubey & Lindsay 1993).     

Neosporosis

Neospora caninum is a recently recognized protozoan parasite of animals, which, until 1988, was misdiagnosed as Toxoplasma gondii. Neospora caninum or Neospora-like parasites, here discussed by J.P. Dubey and David Lindsay, cause paralysis and death in dogs and neonatal mortality and abortion in cattle, sheep, goats and horses.     

A European perspective on Neospora caninum

Since the identification of Neospora caninum in 1984 as a parasite separate from Toxoplasma gondii by Bjerkas et al., and its subsequent characterization and classification in 1988 by Dubey and co-workers, this parasite has attracted increasing attention, primarily as an important causative agent of abortion in cattle and neuromuscular disease in dogs, but also as a complementary model system to T. gondii for investigating the basic biology of intracellular parasitism. During November 11-14, 1999, the COST 820 Annual meeting (Vaccines against coccidioses) took place in Interlaken, Switzerland. Almost half of the papers presented at that meeting were on N. caninum and neosporosis, reflecting the increasing awareness of the importance of this parasite on part of the scientific community in Europe. On the occasion of the meeting, participants in this COST Action involved in Neospora research in Europe were asked to participate in this invited review in order to document the growing interest in N. caninum and the disease it causes. Thus, this paper is a unique collection of contributions provided by several European experts in the field. It is comprised of 10 reviews or original papers on different aspects of Neospora research including epidemiology, immunology, application and development of serological tools, and molecular characterisation of the parasite currently carried out throughout Europe. In addition, two distinguished invited speakers from overseas (Milton McAllister and John Ellis) provided valuable contributions. This invited review demonstrates that the COST 820 Action has brought together scientists from all over Europe and other parts of the world, and has laid the basis for many fruitful collaborations. The studies described here will contribute in assessing the relevance of neosporosis as a potential risk factor not only for animals, but also for human health.     

Small Intestinal Bacterial Overgrowth in Seven Dogs with Gastrointestinal Signs

In small intestinal bacterial overgrowth (SIBO) syndrome the small intestine is colonized by bacteria in excess of 105 colony-forming units (CFU)/ml or g (Batt et al 1983, Williams et al 1987, Strombeck & Guilford 1990). In dogs, SIBO has only recently been recognized as a cause of gastrointestinal signs like diarrhea (Strombeck et al 1981, Batt et al 1983, Batt & McLean 1987, Batt et al 1988). No demonstrable underlying anatomic or functional predisposition is identified in most cases of canine SIBO. However, most of the reported cases have been on German shepherds and dogs suffering from pancreatic insufficiency (Williams etal 1987; Simpson etal 1990).     

Prevalence of agglutinating antibodies to Neospora caninum in raccoons, Procyon lotor.

Neospora caninum is an apicomplexan parasite that causes neonatal neuromuscular disease in dogs and abortions in cattle. Dogs are the only proven definitive host. Little is known about the prevalence of antibodies to this parasite in wildlife. Sera from 99 raccoons (Procyon lotor) were examined for agglutinating antibodies to N. caninum using the modified agglutination test employing formalin-fixed tachyzoites as antigen. Raccoons originated in Florida (n = 24, collected in 1996), New Jersey (n = 25, collected in 1993), Pennsylvania (n = 25, collected in 1999), and Massachusetts (n = 25, collected in 1993 and 1994). Ten (10%) had antibodies to N. caninum; 9 had titers of 1:50, and 1 (1%) had a titer of 1:100. The present study indicates that raccoons have minimal exposure to N. caninum. The sera were also tested for agglutinating antibodies to Toxoplasma gondii and 46 (46%) were positive; 16 had titers of 1:50, 8 had titers of 1:100, and 22 had titers of > or = 1:500.     

Evaluation of a Direct Agglutination Test for Detection of Antibodies Against Toxoplasma gondii in Cat,Pig and Sheep Sera

The protozoan parasite Toxoplasma gondii is the causative agent of the zoonosis toxoplasmosis. In sheep and goats, it is one of the most prevalent causes of infectious abortion. Also in pregnant women, a primary infection can result in miscarriage. Humans acquire the infection either by ingestion of oocysts excreted by cats, the definitive host of the parasite, or by eating raw or undercooked meat from latently infected animals (Dubey & Beattie 1988). In Sweden, toxoplasmosis is a notifiable disease, and cases of clinical disease in humans as well as animals must be reported. In both veterinary and human medicine serological assays based on detecting the humoral antibody response of the host against the parasite are used as diagnostic tools. So far, solid phase assays, such as the indirect fluorescent antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA), have been widely used to diagnose T. gondii infection in many species including cats, pigs and sheep (Dubey & Beattie 1988). However, both IFAT and ELISA require appropriate anti-species specific immunoglobulins (Ig) that must be carefully evaluated for each species prior to use. This makes these assays complicated and time consuming. Consequently, alternative, simpler methods that do not require specific antisera would be of great value. The direct agglutination test (DA), which is based on the principle that formalin-treated organisms agglutinate in the presence of specific IgG antibodies, is such an assay (Fulton & Turk 1959). The DA-test is widely used in human medicine as a screening test for T gondii infection but it has not yet been thoroughly evaluated for use in veterinary medicine (Uggla & Buxton 1990).     

CAEV Infection does not Affect Prevalence of Bacterial Mastitis in Goats

Like other lentiviruses, caprine arthritis-encephalitis virus (CAEV) causes persistent infection. The majority of CAEV-infected goats is clinically healthy. Signs of disease are associated with progressive inflammation in one or more organ or tissue systems such as joints, bursae, brain, spinal cord, lungs, and udder (Bulgin 1990, Dawson 1987). In most CAEV- infected females, the mammary gland, which is a target for the virus, is likely to be infected (Kennedy-Stoskopf et al. 1985, Lerondelle et al. 1989). The infection may cause increased somatic cell counts (Post et al. 1984, Nord & Adnoy to be published). The milk mostly appears normal and mastitis may not be suspected. Ryan et al. (1993) and Smith & Cutlip (1988) suggested that susceptibility to bacterial udder infection is enhanced in CAEV-infected goats, in particular with regard to infections due to non-haemolytic Staphylococci. In this study, the prevalence of bacterial udder infections in CAEV-antibody positive goats is compared with that in negative animals.     

Vertical transmission of Neospora caninum in BALB/c mice determined by polymerase chain reaction detection.

Vertical transmission of Neospora caninum was evaluated in BALB/c mice using an N. caninum-specific polymerase chain reaction (PCR) assay as a means of detecting parasite transmission to offspring. BALB/c mice were infected with the NC-1 isolate of N. caninum during pregnancy (days 8-15 gestation). Transmission of parasite, detected by PCR, was determined in 2- to 23-day-old offspring. When dams were infected on days 13-15 of gestation, transfer of parasites was detected in only a proportion of the litter. Infection between days 8 and 12 of gestation resulted in a high frequency of parasite transmission; every offspring from all litters was infected. The tissue locations of parasites in pups of different ages were determined. In young pups (2- to 4-days-old), the predominant sites of infection were the lungs and the brain. In older pups (7- and 23-days-old) the predominant site of infection was the brain. This study shows that PCR may be useful for evaluation of candidate vaccines against horizontal N. caninum infection, vertical transmission, or both.     

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.     

Canine and bovine Neospora caninum control sera examined for cross-reactivity using Neospora caninum and Neospora hughesi indirect fluorescent antibody tests

Neospora caninum is a well known protozoan parasite of domestic and wild animals. Neospora hughesi is a closely related protozoan with an unknown life cycle, host range, and infection prevalence. Many serologic surveys of N. caninum have been performed without consideration of potential cross-reactions with N. hughesi, which could confound results. The aim of this study was to investigate whether postexposure sera from animals experimentally infected with N. caninum exhibit significant reactivity differences when tested using N. caninum and N. hughesi Immunofluorescent Antibody Tests (IFAT). Pre- and postinfection serum samples from 10 dogs, 20 calves, and 17 cows were tested by dual IFATs. All pre-exposure samples for N. caninum tested seronegative for both organisms. All postexposure samples that were seropositive for N. caninum were also positive for N. hughesi, although N. hughesi antibody titers were usually 1 dilution lower (P < 0.02). Serologic surveys for N. caninum may be confounded by cross-reacting titers with N. hughesi, but true positive N. caninum antibody titers are greater than, or equal to, cross-reacting N. hughesi antibody titers.     

Oocyst excretion in dogs fed mouse brains containing tissue cysts of a cloned line of Neospora caninum

Neospora caninum is an apicomplexan parasite that causes neonatal neuromuscular disease in dogs and abortions in cattle. Bovine neosporosis is a major production problem worldwide. The parasite is transmitted to cattle via oocysts excreted by dogs or by transplacental transmission. Dogs are the only proven definitive host for N. caninum. One of 3 dogs fed mouse brains containing tissue cysts of a wild-type N. caninum strain CK0160SC3B (CKO) excreted oocysts in its feces. Two of 3 dogs fed mouse brains containing tissue cysts from a cloned line of the CKO strain excreted N. caninum oocysts in their feces. The results indicate that a single N. caninum tachyzoite contains all the genetic information needed to produce the asexual and sexual cycles in the canine intestine.     

Immunization of dogs with a canine herpesvirus vector expressing Neospora caninum surface protein, NcSRS2

In order to develop a vaccine against Neospora caninum in dogs, we constructed recombinant canine herpesvirus (CHV) expressing N. caninum surface protein, NcSRS2. Indirect immunofluorescence indicated that the antigenic structure of the recombinant NcSRS2 was similar to the authentic parasite protein. The dogs immunised with recombinant virus produced IgG antibody to N. caninum, and their sera recognised the parasite protein on Western blot. The dogs inoculated with recombinant virus showed no clinical symptoms and infectious CHV was not recovered from the dogs, suggesting that recombinant CHV expressing N. caninum proteins may lead to a vaccine against neosporosis in dogs.     

Transmission of Neospora caninum between wild and domestic animals

To determine whether deer can transmit Neospora caninum, brains of naturally infected white-tailed deer (Odocoileus virginianus) were fed to 4 dogs; 2 of these dogs shed oocysts. Oocysts from 1 of the dogs were tested by polymerase chain reaction and found to be positive for N. caninum and negative for Hammondia heydorni. The internal transcribed spacer 1 sequence of the new strain (designated NC-deer1) was identical to N. caninum from domestic animals, indicating that N. caninum is transmitted between wild and domestic animals, often enough to prevent divergent evolution of isolated populations of the parasite. NC-deerl oocysts were administered to a calf that developed a high antibody titer, providing evidence that N. caninum from wildlife can infect cattle. In addition, N. caninum antibody seroprevalence was detected in 64/164 (39%) free-ranging gray wolves (Canis lupus), 12/113 (11%) coyotes (Canis latrans), 50/193 (26%) white-tailed deer, and 8/61 (13%) moose (Alces alces). These data are consistent with a sylvatic transmission cycle of N. caninum between cervids and canids. We speculate that hunting by humans favors the transmission of N. caninum from deer to canids, because deer carcasses are usually eviscerated in the field. Infection of canids in turn increases the risk of transmitting the parasite to domestic livestock.     

The antigenic composition of Neospora caninum

Neospora caninum is an apicomplexan parasite which causes neosporosis, namely stillbirth and abortion in cattle, and neuromuscular disease in dogs. Although N. caninum is phylogenetically and biologically closely related to Toxoplasma gondii, it is antigenically clearly distinct. In analogy to T. gondii, three stages have been identified. These are: (i) asexually proliferating tachyzoites; (ii) tissue cysts harbouring slowly dividing bradyzoites; and (iii) oocysts containing sporozoites. The sexually produced stage of this parasite has only recently been identified, and has been shown to be shed with the faeces from dogs orally infected with N. caninum tissue cysts. Thus dogs are definitive hosts of N. caninum. Tachyzoites can be cultivated in vitro using similar techniques as previously described for T. gondii. Methods for generating tissue cysts containing N. caninum bradyzoites in mice, and purification of these cysts, have been developed. A number of studies have been undertaken to identify and characterise at the molecular level specific antigenic components of N. caninum in order to improve serological diagnosis and to enhance the current view on the many open questions concerning the cell biology of this parasite and its interactions with the host on the immunological and cellular level. The aim of this paper is to provide an overview on the approaches used for detection of antigens in N. caninum. The studies discussed here have had a great impact in the elucidation of the immunological and pathogenetic events during infection, as well as the development of potential new immunotherapeutic tools for future vaccination against N. caninum infection.     

Clinical Toxoplasma gondii, Hammondia heydorni, and Sarcocystis spp. infections in dogs

Concurrent infections with coccidians Toxoplasma gondii, Sarcocystis spp., and a Hammondia heydorni-like parasite were identified in tissues of three littermate pups on a Kelpie dog breeding farm in Australia. In total, 20 pups in four litters had died following vaccination with an attenuated distemper virus vaccine. Toxoplasma gondii tachyzoites were identified immunohistochemically in tissues of two dogs. Sarcocystis sp. sporocysts were seen in the intestinal lamina propria of two dogs. Asexual and sexual stages of H. heydorni-like parasite were found in enterocytes of the small intestine of two dogs. Ultrastructural development of schizonts and gamonts of this parasite is described. None of the protozoa in these dogs reacted with antibodies to Neospora caninum. Feeding of uncooked tissue of sheep was considered to be the likely source of infection for these coccidians in dogs.     

Epidemiology of intestinal helminth parasites in stray dogs from markets in south-eastern Nigeria

A survey of gastrointestinal helminth parasites of stray dogs (Canis familiaris) was conducted at Obollo-Afor and Ekwulobia markets, in Enugu and Anambra States, south-eastern Nigeria, respectively, to determine the patterns of infection among dogs in different parts of south-eastern Nigeria. Faecal samples collected, using long forceps, from every dog encountered in the markets between June 2007 and December 2008 were analysed by the Kato-Katz technique. Out of 413 dogs examined in both markets, 217 (52.6%) were infected with at least one of five parasites (Toxocara spp., Dipylidium caninum, Ancylostoma caninum, Taenia spp. and Trichuris vulpis). Overall faecal egg intensity of infection was 49.9?±?58.7 eggs/g (epg). The prevalence of infection was comparable between the markets and between the male and female dogs, but varied significantly (P?相似文献   

Multiple Forms and Distribution of Calcium/Calmodulin-Stimulated Protein Kinase II in Brain

In recent years, the enzyme Ca²⁺/calmodulin-stimulated protein kinase II¹ (CaM-PK II) as attracted a great deal of interest. CaM-PK II is the most abundant calmodulin-stimulated protein kinase in brain, where it is particularly enriched in neurons (Ouimet et al., 1984; Erondu and Kennedy, 1985; Lin et al., 1987; Scholz et al., 1988). Neuronal CaM-PK II has been suggested to be involved in several phenomena associated with synaptic plasticity (Lisman and Goldring, 1988; Kelly, 1992), including long-term potentiation (Malinow et al., 1988; Malenka et al.,1989), neurotransmission (Nichols et al., 1990; Siekevitz, 1991), and learning (for review, see Rostas, 1991). This enzyme has also been postulated to be selectively vulnerable in several pathological condition, including epilepsy/kindling (Bronstein et al.,1990; Wu et al., 1990), cerebral ischemia (Taft et al., 1988), and organophosphorus toxicity (Abou-Donia and Lapadula, 1990).     

Adaptation of Neospora caninum isolates to cell-culture changes: an argument in favor of its clonal population structure

Neospora caninum, a recently recognized protozoan parasite of animals, is considered to be a major cause of bovine abortion worldwide. Although its life cycle is not completely known, recent studies suggest that the sexual stage occurs in dogs. The prevalence of sexual reproduction in N. caninum, however, is unknown. We investigated the ability of 3 N. caninum isolates (NC-1, NC-SweB1, and NC-Liverpool) to propagate asexually for approximately 250 parasite generations in a cell line in which they had not been cultured previously. The malthusian parameter of fitness was estimated for each isolate from 10 independent replicates of tachyzoites at the beginning as well as at the end of the experimental period. Derived and ancestral values for mean fitness were compared both within and among NC-1, NC-SweB1, and NC-Liverpool isolates. Results showed a significant increase in mean fitness for the 3 N. caninum isolates at the end of the experimental period. These findings indicate that N. caninum can adapt to new environmental conditions without the help of sexual recombination, supporting the idea that this parasite has, at least potentially, the capacity for maintaining clonal propagation in nature.