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B Gottstein

Publications and source records attributed to B Gottstein.

At least 19 recordsLinked to original sources
PubMed2006

Expression and diversity of Echinococcus multilocularis AgB genes in secondarily infected mice: evaluating the influence of T-cell immune selection on antigenic variation.

The T-cell-mediated immune response exhibits a crucial function in the control of the intrahepatic proliferation of Echinococcus multilocularis larvae in mice and humans, both being natural intermediate hosts of the parasite. Antigen B (AgB), a metabolized Echinococcus spp. lipoprotein, contributes to the modulation of the T-cell immune response, and distinct sites of the corresponding AgB1, AgB3 and AgB4 genes were shown to be under positive selection pressure. Since several AgB gene variants are present in a single Echinococcus metacestode, we used secondary E. multilocularis infections in BALB/c and in athymic nude mice (devoid of T-cell responses) to analyze the effect of the cellular immune response on the expression and diversity of EmAgB1-EmAgB4 genes. We demonstrated hereby that EmAgB transcripts were less abundant in nude mice during the early phase of infection (at one month post-infection), and that EmAgB2 is simultaneously down-regulated when compared to the other three genes. A negative relationship exists between the level of transcription and diversity of EmAgB genes. Moreover, no excess of non-synonymous substitutions was found among the distinct EmAgB alleles from a single host. Together, these results pointed to the effect of purifying selection, which seemed to eliminate the detrimental AgB variants generated during the development of the metacestode within the peritoneal cavity of its intermediate host.

Animals↗
PubMed2006

Taxonomic position and geographical distribution of the common sheep G1 and camel G6 strains of Echinococcus granulosus in three African countries.

The taxonomic and phylogenetic status of Echinococcus granulosus strains are still controversial and under discussion. In the present study, we investigated the genetic polymorphism of E. granulosus isolates originating from three countries of Africa, including a region of Algeria, where the common G1 sheep and the camel G6 strains coexist sympatrically. Seventy-one hydatid cysts were collected from sheep, cattle, camels, and humans. Two mitochondrial markers (cox1 and nad1) were used for strain identification. Two nuclear markers (actII and hbx2) were used to study the possible occurrence of cross-fertilization. Despite the heterogeneity observed among the G1 isolates, they were all localized within one robust cluster. A second strong cluster was also observed containing all of the G6 isolates. Both strains appeared as two distinct groups, and no cases of interbreeding were found. Thus, the attribution of a species rank can be suggested. We also found the Tasmanian sheep G2 strain for the first time in Africa. Because of the slight variations observed between the common sheep and the Tasmanian sheep strains, further studies should be carried out to elucidate the epidemiological relevance of this genetic discrimination.

Algeria↗
PubMed2006

Immunodiagnosis of Besnoitia besnoiti infection by ELISA and Western blot.

Besnoitia besnoiti, an obligate intracellular apicomplexan protozoan parasite, is the causative agent of bovine besnoitiosis. This infection may dramatically affect body condition and lead to irreversible infertility in males, resulting in important economical losses in livestock production. Identification of serologically positive animals is of major relevance to elaborate appropriate measures of control. While identification of clinical cases is relatively easy to carry out, the finding of subclinical forms of infection is more difficult, thus serology is considered as an appropriate diagnostic tool. In view to improve and validate immunodiagnosis, we evaluated an enzyme-linked immunosorbent assay (ELISA), complemented with a Western blot (both using a somatic B. besnoiti-tachyzoite antigen) to detect anti-B. besnoiti antibodies in bovine sera. The comparative evaluation of the 2 methods, using 13 sera from animals affected by the chronic phase of besnoitiosis and 10 asymptomatic carriers, yielded a diagnostic sensitivity of 87% for ELISA and 91% for Western blot analyses. Specificity was tested with sera from animals with confirmed Toxoplasma gondii (n=5) and Neospora caninum (n=12) infection, and with 64 negative sera from either an endemic or a non-endemic area. The ELISA specificity ranged between 96.4% and 98%, the Western blot specificity between 96.4% and 100%. The present study demonstrated that ELISA and Western blot, using in vitro generated somatic B. besnoiti antigen, is a useful tool combination to reliably detect animals that have been exposed to B. besnoiti infection, including both asymptomatic and symptomatic courses of disease.

Animals↗
PubMed2006

Redundancy and recombination in the Echinococcus AgB multigene family: is there any similarity with protozoan contingency genes?

Numerous genetic variants of the Echinococcus antigen B (AgB) are encountered within a single metacestode. This could be a reflection of gene redundancy or the result of a somatic hypermutation process. We evaluate the complexity of the AgB multigene family by characterizing the upstream promoter regions of the 4 already known genes (EgAgB1-EgAgB4) and evaluating their redundancy in the genome of 3 Echinococcus species (E. granulosus, E. ortleppi and E. multilocularis) using PCR-based approaches. We have ascertained that the number of AgB gene copies is quite variable, both within and between species. The most repetitive gene seems to be AgB3, of which there are more than 110 copies in E. ortleppi. For E. granulosus, we have cloned and characterized 10 distinct upstream promoter regions of AgB3 from a single metacestode. Our sequences suggest that AgB1 and AgB3 are involved in gene conversion. These results are discussed in light of the role of gene redundancy and recombination in parasite evasion mechanisms of host immunity, which at present are known for protozoan organisms, but virtually unknown for multicellular parasites.

Alleles↗
PubMed2006

Acute trichinellosis increases susceptibility to Giardia lamblia infection in the mouse model.

The intestinal protozoan parasite Giardia lamblia causes diarrhoea in humans and animals. In the present study, we used the C57BL/6 inbred mouse model to assess the impact of a nematode (Trichinella spiralis) infection on the course of a G. lamblia (clone GS/M-83-H7) infection. Acute trichinellosis coincided with transient intestinal inflammation and generated an intestinal environment that strongly promoted growth of G. lamblia trophozoites although the local anti-Giardia immunoglobulin (Ig) A production was not affected. This increased G. lamblia infection intensity correlated with intestinal mast cell infiltration, mast cell degranulation, and total IgE production. Furthermore, a G. lamblia single-infection investigated in parallel also resulted in intestinal mast cell accumulation but severe infiltration was triggered in the absence of IgE. Recently, intestinal mast cells emerging during a G. lamblia infection were reported to be involved in those immunological mechanisms that control intestinal proliferation of the parasite in mice. This anti-giardial activity was assumed to be related to the capacity of mast cells to produce IL-6. However, this previous assumption was questioned by our present immunohistological findings indicating that murine intestinal mast cells, activated during a G. lamblia infection were IL-6-negative. In the present co-infection experiments, mast cells induced during acute trichinellosis were not able to control a concurrent G. lamblia infection. This observation makes it feasible that the T. spiralis infection created an immunological and physiological environment that superimposed the anti-giardial effect of mast cells and thus favoured intestinal growth of G. lamblia trophozoites in double-infected mice. Furthermore, our findings raise the possibility that intestinal inflammation e.g. as a consequence of a 'pre-existing' nematode infection is a factor which contributes to increased susceptibility of a host to a G. lamblia infection. The phenomenon of a 'pre-existing' nematode infection prior to a G. lamblia infection is a frequent constellation in endemic areas of giardiasis and may therefore have a direct impact on the epidemiological situation of the disease.

Animals↗
PubMed2006

Incidence of Neospora caninum and other intestinal protozoan parasites in populations of Swiss dogs.

The protozoan parasite Neospora caninum is one of the most important abortifacient organisms in cattle worldwide. The dog is known to act as definitive host although its potential role as infection source for bovines still remains unelucidated. The aim of the present study was to compile initial epidemiological data on the prevalence and incidence of N. caninum in Swiss dogs acting as definitive hosts. Thus, 249 Swiss dogs were investigated coproscopically in monthly intervals over a period of 1 year. A total of 3289 fecal samples was tested by the flotation technique. Among these, 202 were shown to contain Sarcocystis sp. (6.1%), 149 Cystoisospora sp. (=Isospora sp.; 4.5%) and 25 Hammondia/Neospora-like oocysts (HNlO) (0.7%). All but one sample containing HNlO were from different dogs; one dog shed HNlO at two subsequent time points. Calculation of the yearly incidence for HNlO resulted in the surprisingly high value of 9.2%. Farm dogs exhibited a higher incidence for HNlO than urban family dogs. Thirteen out of the 25 HNlO-samples showed sporulation after 5 days incubation at room temperature. HNlO were further differentiated by species-specific PCR. However, all HNlO-samples were negative for N. caninum, Hammondia heydorni and Toxoplasma gondii. One reason may be the low oocyst density found in most fecal samples, which did not permit us to carry out PCR under optimal conditions. Three out of the 25 HNlO-cases contained enough oocysts to allow further enrichment and purification by the flotation technique. Subsequently, twenty to fifty sporulated HNlO-oocysts were orally administered to Meriones unguiculatus. All gerbils were seronegative for N. caninum at 5 weeks p.i. A N. caninum-seroprevalence of 7.8% was determined by ELISA upon 1132 serum samples collected from dogs randomly selected by veterinarians among their clinical patients.

Animals↗
PubMed2006

EmsB, a tandem repeated multi-loci microsatellite, new tool to investigate the genetic diversity of Echinococcus multilocularis.

In order to explore the genetic diversity within Echinococcus multilocularis (E. multilocularis), the cestode responsible for the alveolar echinococcosis (AE) in humans, a microsatellite, composed of (CA) and (GA) repeats and designated EmsB, was isolated and characterized in view of its nature and potential field application. PCR-amplification with specific primers exhibited a high degree of size polymorphism between E. multilocularis and Echinococcus granulosus sheep (G1) and camel (G6) strains. Fluorescent-PCR was subsequently performed on a panel of E. multilocularis isolates to assess intra-species polymorphism level. EmsB provided a multi-peak profile, characterized by tandemly repeated microsatellite sequences in the E. multilocularis genome. This "repetition of repeats" feature provided to EmsB a high discriminatory power in that eight clusters, supported by bootstrap p-values larger than 95%, could be defined among the tested E. multilocularis samples. We were able to differentiate not only the Alaskan from the European samples, but also to detect different European isolate clusters. In total, 25 genotypes were defined within 37 E. multilocularis samples. Despite its complexity, this tandem repeated multi-loci microsatellite possesses the three important features for a molecular marker, i.e. sensitivity, repetitiveness and discriminatory power. It will permit assessing the genetic polymorphism of E. multilocularis and to investigate its spatial distribution in detail.

Animals↗
PubMed2006

14-3-3- and II/3-10-gene expression as molecular markers to address viability and growth activity of Echinococcus multilocularis metacestodes.

The present study aimed to search for and characterize parasite molecules, whose expression levels correlate with the viability and growth activity of Echinococcus multilocularis metacestodes. We focused on the expression profiles of 2 parasite-derived genes, 14-3-3 and II/3-10, as putative molecular markers for viability and growth activity of the larval parasite. In experiments in vivo, gene expression levels of 14-3-3 and II/3-10 were relatively quantified by real-time reverse transcription-PCR using a housekeeping gene, beta-actin, as a reference reaction. All three reactions were compared with growth activity of the parasite developing in permissive nu/nu and in non-permissive wild type BALB/c mice. At 2 months p.i., the transcription level of 14-3-3 was significantly higher in parasites actively proliferating in nu/nu mice compared to parasites moderately growing in wild type mice. Immunoblotting experiments confirmed at the protein level that 14-3-3 was over-expressed in parasites derived from nu/nu mice at 2 months p.i. In vitro treatment of E. multilocularis with an anti-echinococcal drug nitazoxanide resulted in a significant decrease of both 14-3-3 and II/3-10 transcription levels found after 8 days of treatment, which correlated with the kinetics of a housekeeping gene, beta-actin. The conclusion is that 14-3-3, combined with II/3-10, exhibits good potential as a molecular marker to assess viability and growth activity of the parasite.

14-3-3 Proteins↗
PubMed2006

[Travel medicine of parasitic diseases in the dog].

Companion animals are increasingly brought along by their owners to foreign countries. Thus, small animal travel medicine is becoming more important. The field includes both prophylaxis and metaphylaxis against various infectious diseases, as well as their diagnosis and treatment. Dogs returning from Southern Europe, but also from more tropical regions, may be infected with exotic pathogens. In addition, imported pedigree or working dogs, and especially stray dogs imported through welfare organisations, are at high risk. The present overview summarises the clinical and practical aspects of exotic parasitic diseases that may affect such dogs, and the risk of such diseases becoming autochthonously transmitted in Switzerland. Furthermore, the zoonotic potential of these infections will be considered.

Animal Welfare↗
PubMed2006

[Methods for investigating Trichinella infections in domestic and wild animals].

Trichinellosis is an important parasitic zoonosis that is caused by the intracellular nematode Trichinella spp.. Infection of humans occurs through consumption of raw (or undercooked) meat containing infectious larvae. In Europe, meat from pork, horse, and wild boar have been identified as most important sources of Trichinella infections in humans. In Switzerland, both the domestic pig and wild boar population are considered free of Trichinella. Conversely, Swiss foxes, lynxs and recently a wolf were found to be infected, the species identified in these animals was always referred to as Trichinella britovi. Although this species rarely infects pork and, compared to Trichinella spiralis, only causes reduced pathogenic effects in humans, the basic presence of Trichinella in Switzerland cannot be neglegted. This fact has gained increasing importance since the responsible authorities in the European Union (EU) are preparing regulations for the official Trichinella-control in meat in order to improve food safety for consumers. These regulations will be implemented as a consequence of the recent association of east European countries with the EU. This new legislation particularly takes into account, that in the past by far most cases of human trichinellosis in the EU were due to consumption of imported east European meat.Within the framework of the bilateral agreements of Switzerland with the EU, the Swiss veterinary public health authorities will have to comply with the foreseen EU regulations. Although diagnostic methods for the direct demonstation of Trichinella in pork meat are already routine practice in several Swiss abattoirs, the implementation of a meat control program for Trichinella for the entire slaughter pig population of the country would lead to an enormous increase in costs for the administration and will require an increased infrastructure in veterinary services. In order to find a reduced testing format for monitoring Trichinella infections in Swiss pork, an infection risk-oriented survey strategy is currently evaluated. In the present article, this minimized survey strategy is discussed regarding its compatibility with the EU regulations laying down rules for the official control of meat for Trichinella.

Animals↗
PubMed2006

[Search for Neospora caninum DNA in bull semen using PCR ].

Neospora caninum represents one of the most frequent abortifaciant organisms worldwide. The parasite is diaplacentally transmitted from the pregnant cow to the fetus, where it normally leads to the delivery of a healthy, however persistently infected calf. Abortion thus is a relative rare event. The transmission of bovine neosporosis occurs in more than 90% of the cases vertically due to the endogenous reactivation of a persistently infected mother. Exogenous infections are therefore responsible for less than 10% of the cases. The question arises about which infection sources may be relevant in this context. In Switzerland, the role of dogs as definitive hosts has been shown to be of low significance in that respect. Recently, discussion focused on the potential of infectious bull semen following natural or artificial insemination. Thus, a few years ago a report documented the detectability of N. caninum-DNA in the semen of naturally infected bulls by nested-PCR. As a consequence, we decided to gain own experience by investigating 5 separate semen specimens per animal, originating from 20 N. caninum-seropositive bulls used for artificial insemination in Switzerland. All probes turned out to be negative by nested PCR. Based upon our laboratory experiences, the potential bull semen-associated Neospora-problem seems not to affect the Swiss bull population, thus there is no evidence to include further respective means of control.

Abortion, Veterinary↗
PubMed2006

Intraperitoneal Echinococcus multilocularis infection in C57BL/6 mice affects CD40 and B7 costimulator expression on peritoneal macrophages and impairs peritoneal T cell activation.

One of the most important immunopathological consequence of intraperitoneal alveolar echinococcosis (AE) in the mouse is suppression of T cell-mediated immune responses. We investigated whether and how intraperitoneal macrophages (MØs) are, respectively, implicated as antigen-presenting cells (APCs). In a first step we showed that peritoneal MØs from infected mice (AE-MØs) exhibited a reduced ability to present a conventional antigen (chicken ovalbumin, C-Ova) to specific responder lymph node T cells. In a subsequent step, AE-MØs as well as naïve MØs (positive control) proved their ability to uptake and process C-Ova fluorescein isthiocyanate (FITC). Furthermore, in comparison with naïve MØs, the surface expression of Ia molecules was up-regulated on AE-MØs at the early stage of infection, suggesting that AE-MØs provide the first signal via the antigen-Ia complex. To study the accessory activity of MØs, AE-MØs obtained at the early and late stages of infection were found to decrease Con A-induced proliferation of peritoneal naïve T cells as well as of AE-sensitized peritoneal T cells, in contrast to stimulation with naïve MØs. The status of accessory molecules was assessed by analysing the expression level of costimulatory molecules on AE-MØs, with naïve MØs as controls. It was found that B7-1 (CD80) and B7-2 (CD86) expression remained unchanged, whereas CD40 was down-regulated and CD54 (= ICAM-1) was slightly up-regulated. In a leucocyte reaction of AE-MØs with naïve or AE-T cells, both types of T cells increased their proliferative response when CD28 - the ligand of B7 receptors - was exposed to anti-CD28 in cultures. Conversely to naïve MØs, pulsing of AE-MØs with agonistic anti-CD40 did not even partially restore their costimulatory activity and failed to increase naïve or AE-T cell proliferation. Neutralizing anti-B7-1, in combination with anti-B7-2, reduced naïve and AE-T cell proliferation, whereas anti-CD40 treatment of naïve MØs increased their proliferative response to Con A. These results point at the key role of B7 receptors as accessory molecules and the necessity of the integrity of CD40-expression by naïve MØs to improve their accessory activity. Taken together, the obstructed presenting-activity of AE-MØs appeared to trigger an unresponsiveness of T cells, contributing to the suppression of their clonal expansion during the chronic phase of AE-infection.

Animals↗
PubMed2005

Coprological study on intestinal helminths in Swiss dogs: temporal aspects of anthelminthic treatment.

Coproscopic examination of 505 dogs originating from the western or central part of Switzerland revealed the presence (prevalence data) of the following helminthes: Toxocara canis (7.1%), hookworms (6.9%), Trichuris vulpis (5.5%), Toxascaris leonina (1.3%), Taeniidae (1.3%), Capillaria spp. (0.8%), and Diphyllobothrium latum (0.4%). Potential risk factors for infection were identified by a questionnaire: dogs from rural areas significantly more often had hookworms and taeniid eggs in their feces when compared to urban family dogs. Access to small rodents, offal, and carrion was identified as risk factor for hookworm and Taeniidae, while feeding of fresh and uncooked meat did not result in higher prevalences for these helminths. A group of 111 dogs was treated every 3 months with a combined medication of pyrantel embonate, praziquantel, and febantel, and fecal samples were collected for coproscopy in monthly intervals. Despite treatment, the yearly incidence of T. canis was 32%, while hookworms, T. vulpis, Capillaria spp., and Taeniidae reached incidences ranging from 11 to 22%. Fifty-seven percent of the 111 dogs had helminth eggs in their feces at least once during the 1-year study period. This finding implicates that an infection risk with potential zoonotic pathogens cannot be ruled out for the dog owner despite regular deworming four times a year.

Animals↗
PubMed2005

Toltrazuril treatment to control diaplacental Neospora caninum transmission in experimentally infected pregnant mice.

We addressed the question whether diaplacental transmission of Neospora caninum can be controlled by metaphylactic chemotherapy using toltrazuril or enrofloxacin. Female C57/BL6 mice, infected on day 10 of pregnancy, were medicated for 6 consecutive days p.i. with 52.5 mg toltrazuril or - as an out-group control medication--16.7 mg enrofloxacin per kg body weight per day. Other control groups received either infection but no medication or vice versa. Toltrazuril treatment significantly reduced pre- and perinatal losses (10 deliveries of healthy newborns, versus 1 abortion and 4 failures) when compared to control-enrofloxacin (2 deliveries, versus 1 abortion, 7 failures and 2 pre-parturient deaths of dams) and non-treated animals (3 deliveries, versus 6 abortions, 8 failures and 4 pre-parturient deaths). Simultaneously, PCR-based parasite detection in the brain of mothers, histopathological findings as well as clinical fatality were significantly less frequent in toltrazuril-treated dams. The overall toltrazuril treatment efficacy was determined as 87 %, that of enrofloxacin-treatment as 17 %. The progenies of toltrazuril-treated dams also exhibited a very low rate of PCR-positivity in their brain (3 out of 39), whereas untreated dams delivered litters with mostly PCR-positive brains (12 out of 14) and a relatively high death rate post-partum (5 out of 19 newborns died). Mice subjected to a second mating delivered newborns all negative by N. caninum-PCR, indicating that diaplacental tachyzoite passage does not occur in a later, repeated pregnancy. Overall, our experiments showed that toltrazuril-treatment of an acute N. caninum-infection--induced during pregnancy--results in a clear reduction of fetal losses and a marked reduction of diaplacental passage of the parasite to the fetal brain, whereas enrofloxacin, as an out-group control substance, failed to show the same effect.

Animals↗
PubMed2005

Organotypic slice cultures from rat brain tissue: a new approach for Naegleria fowleri CNS infection in vitro.

The free-living amoeba Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis (PAM), a disease leading to death in the vast majority of cases. In patients suffering from PAM, and in corresponding animal models, the brain undergoes a massive inflammatory response, followed by haemorrhage and severe tissue necrosis. Both, in vivo and in vitro models are currently being used to study PAM infection. However, animal models may pose ethical issues, are dependent upon availability of specific infrastructural facilities, and are time-consuming and costly. Conversely, cell cultures lack the complex organ-specific morphology found in vivo, and thus, findings obtained in vitro do not necessarily reflect the situation in vivo. The present study reports infection of organotypic slice cultures from rat brain with N. fowleri and compares the findings in this culture system with in vivo infection in a rat model of PAM, that proved complementary to that of mice. We found that brain morphology, as present in vivo, is well retained in organotypic slice cultures, and that infection time-course including tissue damage parallels the observations in vivo in the rat. Therefore, organotypic slice cultures from rat brain offer a new in vitro approach to study N. fowleri infection in the context of PAM.

Amebiasis↗
PubMed2005

Alveolar echinococcosis in the zoological garden Basle.

Alveolar echinococcosis (AE) is a rare, but potentially severe zoonotic disease caused by Echinococcus (E.) multilocularis. Recent findings indicated an increasing importance of AE for non-human primates living in regions endemic for E. multilocularis. The death of five cynomolgus monkeys (Macaca fascicularis) and a lowland gorilla (Gorilla g. gorilla) due to AE raised concern about the incidence of this parasite in the Basle Zoo. Consequently, a project was initiated to investigate the prevalence amongst an affected group of cynomolgus monkeys, as well as in foxes and mice. Three out of 46 monkeys were seropositive for E. multilocularis antigen. In two of these monkeys and in another three animals, which were seronegative, structures compatible with metacestodal cysts were observed using ultrasonography. Seven out of 35 free roaming foxes caught at the zoo were positive for an intestinal E. multilocularis copro-antigen ELISA, four of them shed taeniid eggs simultaneously. No lesions compatible with AE were present in 50 necropsied mice from the zoo area. These results indicate that the fox population is a potential source to introduce E. multilocularis and may thus represent a risk for the zoo animals.

Animals↗
PubMed2005

[First documentation of a neospora-induced "abortion storm" (exogenous transplacental transmission of neospora caninum) in a Swiss dairy farm].

In a Swiss dairy farm (canton of Geneva) consisting of 73 animals 8 abortions were observed within 2 weeks. Serological and molecular biological analyses (PCR) on aborting dams, and abortion materials, respectively, revealed that the protozoan parasite Neospora caninum was the causative agent. Besides the 8 aborting animals, 12 other non-aborting heifers were found to be serologically positive for this parasite. All positive sera were further tested in an avidity-ELISA to elucidate the recency of infection. All seropositive animals but one showed low avidities at the time the abortion storm started. This indicated at a recent N. caninum-infection within the herd. Thus, the animals most probably were exposed to N. caninum-oocysts (e.g. by dog feces-contaminated forage) and the resulting abortion storm was due to an exogenous (formerly known as "horizontal") parasite transmission into a naive herd. This is the first documented record of such an event in Switzerland.

Abortion, Veterinary↗