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1.
The aim of this study was to compare the ability of a live incomplete strain (Strain 48) and a live complete strain (Strain 89) of Toxoplasma gondii to protect against abortion and congenital infection following an oral challenge of T. gondii oocysts. Sixty-nine two-tooth ewes were immunised pre-tupping with live Strain 48 of T. gondii tachyzoites and seventy ewes were immunised with Strain 89. Eighty-two serologically negative ewes served as controls. At mid-pregnancy half of the ewes were challenged orally with T. gondii oocysts (2x10(5)/ewe). The ewes vaccinated with Strain 48 were significantly (p<0.05) protected against the effects of experimental challenge and the rate of congenital infection was also significantly (p<0.15) reduced. The ewes vaccinated with Strain 89 were also significantly (p<0.05) protected. The serological response to challenge as measured by both the Dye test and the Indirect Haemagglutination test varied considerably between the two vaccinated groups.  相似文献   

2.
SUMMARY Ewes were immunised in late pregnancy with killed Staphylococcus aureus vaccines prepared from organisms grown either under in vitro (vaccine T) or in vivo (Vaccine V) cultural conditions; other ewes were immunised with a live S. aureus vaccine and a further group remained non-vaccinated controls. The animals given either of the killed vaccines developed highest titres of agglutinating antibody in serum; there were only trivial levels of agglutinating antibody in milk from ewes in each treatment group. Ewes immunised with the live vaccine developed significantly greater levels of opsonins in serum than did those immunised with the killed vaccines or non-immunised controls. AT 30 to 35 days post-partum the ewes were challenged by intramammary infusion of one million S. aureus of a strain different to the vaccination strain. In 4 of the 5 control ewes this resulted in the development of acute mastitis and a precipitous decline in milk production, whereas there was a considerable degree of resistance recorded in animals in each of the vaccinated groups. On criteria of milk production data, bacteriological status of milk and clinical signs of acute mastitis it was apparent that animals which had been immunised with the live vaccine were better protected from challenge than those immunised with either killed vaccines T or V.  相似文献   

3.
This study assessed the effectiveness of a mutant strain of Toxoplasma gondii (RH strain) lacking the mic1 and mic3 genes (Mic1-3KO) against Toxoplasma abortion in sheep. Ewes were inoculated subcutaneously with 105 Mic1-3KO tachyzoïtes in three independent experiments. Following vaccination, Mic1-3KO induced a mild febrile response and serum IgG antibodies, which persisted throughout the experiments. Tissue cysts formed in the sheep, but were not, under our experimental conditions, infectious when given orally. Ewes were mated two months after vaccination and were orally challenged with the PRU strain of T. gondii at mid-gestation (400 oocysts in Experiments 1 and 2; 100 oocysts in Experiment 3). Challenge of vaccinated pregnant ewes resulted in a slight febrile response, whereas unvaccinated ewes developed a more severe, characteristic febrile response of longer duration. After challenge, all unvaccinated ewes aborted whereas 62%, 91% and 64% (Experiments 1, 2 and 3 respectively) of the lambs from vaccinated ewes were viable, with no clinical signs of infection. Mic1-3KO was as effective as S48, the strain used as a live vaccine for sheep (Toxovax®). A dose of 105 Mic1-3KO tachyzoites was sufficient to induce protection (versus a dose of 2 × 106). Both subcutaneous and intraperitoneal injections were effective. Moreover, preliminary results showed the potential of Mic1-3KO to reduce the development of tissue cysts in lambs born to vaccinated ewes. This study demonstrates that Mic1-3KO is a potent vaccine candidate.  相似文献   

4.
AIMS: To develop a challenge model for Salmonella Brandenburg infection in pregnant ewes. To compare efficacies of a live attenuated Salmonella Typhimurium mutant, a subunit preparation from a virulent S. Brandenburg isolate, and a commercial multivalent inactivated vaccine in their ability to prevent experimental S. Brandenburg infection. To assess the efficacy of the live attenuated S. Typhimurium mutant against natural S. Brandenburg infection in lambs.

METHODS: Two-year-old ewes were immunised with either a live attenuated vaccine (eye-drop; n=20), a subunit vaccine (n=20) or an inactivated bacterin vaccine (n=20), both administered subcutaneously, or served as unvaccinated controls (n=21). Four weeks later, the sensitising regime was repeated as a booster vaccination, and the ewes were challenged 6 weeks later with a virulent S. Brandenburg isolate, approximately 6 weeks prior to lambing. The presence of clinical signs, abortion or death was noted following challenge. The presence and number of Salmonella spp in faecal samples taken throughout the trial, and in organs collected post mortem, were determined using an enrichment selection procedure, and confirmed by serology and pulsed-field gel electrophoresis (PFGE). Half of the surviving lambs were vaccinated with the live attenuated vaccine and all (n=39) were exposed to natural infection from contaminated pasture.

RESULTS: There was no significant protection against mortality and abortion following vaccination with the live attenuated, subunit and inactivated vaccines following experimental challenge with S. Brandenburg. There was a significant but transient decrease in the number of ewes shedding S. Brandenburg (live attenuated, p=0.05; subunit, p=0.05; inactivated, p=0.01), and in the quantity of these bacteria in the sheep from the vaccinated groups (p<0.05) compared with controls, 6 weeks after challenge. Lambs from the challenged ewes did not shed Salmonella spp after being vaccinated with the live attenuated vaccine, in contrast to some of the controls, when grazed on pasture contaminated with S. Brandenburg.

CONCLUSIONS: The use of live attenuated, subunit and inactivated vaccines did not significantly protect sheep against lethal experimental challenge with S. Brandenburg.  相似文献   

5.
SUMMARY Eleven pregnant Merino ewes were immunised with either a killed Staphylococcus aureus cell-toxoid vaccine (intramuscularly) or a living culture of the same organism (subcutaneously). A further 3 animals were used as non-immunised controls. There were no significant differences between the vaccinated groups for agglutinating antibody to staphylococci or for anti-α-haemolysin in either serum or whey. Three weeks after lambing the ewes were challenged by intramammary infusion of virulent staphylococci. All animals developed an acute mastitis with significant decreases in milk yields being recorded 48 hours post-challenge. Seven days after challenge the mean milk production of ewes given the live vaccine had recovered to within 5% of the pre-challenge mean yield. However, milk productions of controls and ewes given the killed vaccine had further decreased and were significantly lower than for animals vaccinated with live staphylococci. There were no significant differences between the two vaccinated groups for numbers of bacteria or leucocytes in milk samples collected after challenge. The ewes were killed 7 days postchallenge and mammary tissues were examined for immunoglobulin-containing cells. Large numbers of IgA-containing cells, and few IgM-containing cells were found, but there were no significant differences between the treatment groups for these parameters.  相似文献   

6.
Two-tooth ewes (n=48) were immunized pre-tupping with a live Toxoplasma gondii vaccine. At midpregnancy these ewes were challenged intravenously with 1 x 105 live T. gondii tachyzoites. The strain of T. gondii used for vaccination was an incomplete strain that did not produce oocysts. It was derived by continuous twice weekly passage in mice. The lambing percentage for ewes immunized with the live vaccine was significantly higher (P<0.001 normal score) than non-vaccinated control ewes. However, vaccination did not prevent foetal or placental infection. The serological response to vaccination and challenge was measured by both the Dye test and the Indirect Haemagglutination test. No significant relationship between titre of antibody and protection in the vaccinated ewes was observed.  相似文献   

7.
Sixty-four ewes were vaccinated with tachyzoites of an incomplete strain (S48) of Toxoplasma gondii grown either in the peritoneal cavity of mice (group 1) or vero cell culture (group 2) and 30 ewes (group 3) were not vaccinated. All the ewes were mated 77 days later and challenged orally with 2000 sporulated oocysts at 89 to 90 days of gestation. Ten additional unvaccinated (group 4) and 10 vaccinated (group 5) control ewes were not challenged. The unvaccinated ewes developed a characteristic febrile response to challenge while in the vaccinated ewes the fever commenced earlier but was less severe and of shorter duration. After challenge, the antibody titres against T gondii rose rapidly to high values in the vaccinated ewes while the ewes in group 3 responded more slowly. Only eight of the 45 fetuses/lambs (17.8 per cent) from group 3 were viable compared with 72.3 per cent of those in group 1 and 80.8 per cent of those in group 2. Gestation in the unvaccinated challenged ewes was shortened and the mean birthweight of their single, viable offspring was significantly lower than the weight of single lambs from the vaccinated (groups 1 and 2) and control ewes (groups 4 and 5). Examination of precolostral sera showed that almost two-thirds of the lambs from the vaccinated ewes were infected in utero. The 20 control ewes appeared clinically normal at all times and lambed normally. The two vaccine preparations were equally effective.  相似文献   

8.
Sows were immunised subcutaneously with a live Salmonella cholerae suis (SCS) vaccine prior to farrowing. Serological tests demonstrated a high level of SCS colostral antibodies at parturition. Piglet sera negative for antibodies at birth contained a high level of SCS antibodies 24 h after the ingestion of vaccinated sow colostrum. Experiments were carried out to establish if these maternally derived antibodies could protect the piglets against an intranasal (IN) challenge with a field isolate of SCS. It was concluded that pregnant sows could be safely immunised with a live SCS vaccine thus providing their piglets with a passive immunity which protected them against an intranasal challenge.  相似文献   

9.
Pregnant ewes were vaccinated twice, seven weeks and three weeks before lambing, with a multivalent formalin-killed Escherichia coli vaccine containing an added K99, F41 antigen preparation. Lambs born to vaccinated and unvaccinated ewes were exposed to oral infection with E coli B44 (09:K30, K99, F41). All 10 lambs from vaccinated ewes were protected whereas all 10 control lambs developed severe diarrhoea and five died or were killed in extremis. In the following year, previously immunised ewes were given a single dose of the vaccine two weeks before lambing. Eleven of their 12 lambs were protected against a similar challenge, which caused the death of six of eight control lambs and severe diarrhoea in the two survivors. Higher levels of antibody to the K99, F41 preparation were detected by enzyme-linked immunosorbent assay in the serum and colostrum from vaccinated ewes and in the serum of their lambs when compared with similar samples from control ewes and lambs.  相似文献   

10.
Sixty ewes, divided randomly into four groups of 15, were immunised subcutaneously against sporidesmin (sdm) — bovine thyroglobulin (BTG) or 2-amino-5-chIoro-3,4-dimethoxy benzyl alcohol (ACDMBA) coupled to heat killed staphylococci or to bovine gamma globulin. Fifteen ewes served as untreated controls. Approximately 10 weeks after inoculation ewes were dosed orally with sdm at a rate of 0.1 mg/kg body weight/day for three consecutive days. Sdm antibody binding values, in plasma collected before dosing were higher in ewes immunised with sdm-BTG than ewes given the ACDMB A-complexes. Levels in the 15 untreated ewes were all very low. However, despite the presence of antibodies, the immunised ewes were not protected against sdm challenge; and cholesterol and bilirubin levels in serum and liver and urinary bladder damage scores, at slaughter, were all significantly higher (P<0.05) in the immunised compared to the control ewes six weeks after dosing. It is concluded from these results that subcutaneous immunisation against sdm or the structurally related substance used did not protect sheep against sdm dosing.  相似文献   

11.
As clinical toxoplasmosis is not considered a problem in pigs, the main reason to implement a control strategy against Toxoplasma gondii (T. gondii) in this species is to reduce the establishment of T. gondii tissue cysts in pork, consequently reducing the risk of the parasite entering the human food chain. Consumption of T. gondii tissue cysts from raw or undercooked meat is one of the main sources of human infection, with infected pork being considered a high risk. This study incorporates a mouse bioassay with molecular detection of T. gondii DNA to study the effectiveness of vaccination (incomplete S48 strain) in its ability to reduce tissue cyst burden in pigs, following oocyst (M4 strain) challenge. Results from the mouse bioassay show that 100% of mice which had received porcine tissues from vaccinated and challenged pigs survived compared with 51.1% of mice which received tissues from non-vaccinated and challenged pigs. The presence (or absence) of T. gondii DNA from individual mouse brains also confirmed these results. This indicates a reduction in viable T. gondii tissue cysts within tissues from pigs which have been previously vaccinated with the S48 strain. In addition, the study demonstrated that the main predilection sites for the parasite were found to be brain and highly vascular muscles (such as tongue, diaphragm, heart and masseter) of pigs, while meat cuts used as human food such as chop, loin, left tricep and left semitendinosus, had a lower burden of T. gondii tissue cysts. These promising results highlight the potential of S48 strain tachyzoites for reducing the number of T. gondii tissues cysts in pork and thus improving food safety.  相似文献   

12.
AIMS: To develop a challenge model for Salmonella Brandenburg infection in pregnant ewes. To compare efficacies of a live attenuated Salmonella Typhimurium mutant, a subunit preparation from a virulent S. Brandenburg isolate, and a commercial multivalent inactivated vaccine in their ability to prevent experimental S. Brandenburg infection. To assess the efficacy of the live attenuated S. Typhimurium mutant against natural S. Brandenburg infection in lambs. METHODS: Two-year-old ewes were immunised with either a live attenuated vaccine (eye-drop; n=20), a subunit vaccine (n=20) or an inactivated bacterin vaccine (n=20), both administered subcutaneously, or served as unvaccinated controls (n=21). Four weeks later, the sensitising regime was repeated as a booster vaccination, and the ewes were challenged 6 weeks later with a virulent S. Brandenburg isolate, approximately 6 weeks prior to lambing. The presence of clinical signs, abortion or death was noted following challenge. The presence and number of Salmonella spp in faecal samples taken throughout the trial, and in organs collected post mortem, were determined using an enrichment selection procedure, and confirmed by serology and pulsed-field gel electrophoresis (PFGE). Half of the surviving lambs were vaccinated with the live attenuated vaccine and all (n=39) were exposed to natural infection from contaminated pasture. RESULTS: There was no significant protection against mortality and abortion following vaccination with the live attenuated, subunit and inactivated vaccines following experimental challenge with S. Brandenburg. There was a significant but transient decrease in the number of ewes shedding S. Brandenburg (live attenuated, p=0.05; subunit, p=0.05; inactivated, p=0.01), and in the quantity of these bacteria in the sheep from the vaccinated groups (p<0.05) compared with controls, 6 weeks after challenge. Lambs from the challenged ewes did not shed Salmonella spp after being vaccinated with the live attenuated vaccine, in contrast to some of the controls, when grazed on pasture contaminated with S. Brandenburg. CONCLUSIONS: The use of live attenuated, subunit and inactivated vaccines did not significantly protect sheep against lethal experimental challenge with S. Brandenburg.  相似文献   

13.
To evaluate transplacental transmission of Toxoplasma gondii in naturally infected ewes, blood samples were collected from 55 pregnant ewes and their offspring, before ingestion of colostrum. From 16 offspring of positive ewes and nine offspring from negative ewes, blood samples were obtained after 48 h and 7, 14, 21, 28, 35, 42, 49 and 56 days after birth. T. gondii antibodies were detected in serum samples using the indirect fluorescence antibody test (IFAT ≥ 64). Four of the 30 positive ewes (13.3 %) had offspring positive for T. gondii before ingesting colostrum (vertical transmission). The colostrum antibody titers decreased every week, and only 20 % (2/10) of the lambs in continued to present detectable antibody titers until day 56 after birth. Therefore, vertical transmission of T. gondii in lambs was indication of occur and is an important route for transferring and maintaining the agent in sheep herds in the Brazilian semiarid region.  相似文献   

14.
The IgG antibody responses of sheep vaccinated by the subcutaneous injection of live tachyzoites of ‘incomplete’ strain S48 toxoplasma (Toxovax) were analysed by Western blotting. Antibodies corresponding to a range of tachyzoite antigens (13 to 48 kD) were detected, but the response was dominated by antibody recognising a 30 to 32 kD band. Unvaccinated ewes challenged orally with oocysts of the ‘complete’ M3 toxoplasma strain had a more complex IgG response that recognised antigens in six dominant bands of similar intensity as those in sheep vaccinated with S48 tachyzoites and then challenged with M3 oocysts. No differences were detected between the antigenic structures of the S48 tachyzoites and RH strain tachyzoites when the antigens were probed with immune ovine sera. Many of the anitgens of the S48 tachyzoites that were recognised had molecular weights similar to those of antigens that have been identified in other strains of toxoplasma.  相似文献   

15.
Trial of a novel experimental Toxoplasma iscom vaccine in pregnant sheep   总被引：1，自引：0，他引：1  
Fifteen vaccinated ewes (group 1) and 13 unvaccinated ewes (group 2) were each challenged orally with 2000 sporulated Toxoplasma gondii oocysts at 91 (+/- 1) days' gestation. Another four pregnant ewes acted as unvaccinated unchallenged controls. Lamb mortality in group 1 was 36.4% after a mean gestation of 141 days while in group 2 it was 64.7% after a mean gestation of 131.5 days. These differences were not statistically significant. However, substantially more specific antibody was detected in precolostral sera from live lambs from vaccinated ewes than in live lambs from unvaccinated ewes in group 2.  相似文献   

16.
Toxoplasma gondii, a ubiquitous parasitic protozoan, is emerging as an aquatic biological pollutant. Infections can result from drinking water contaminated with environmentally resistant oocysts. However, recommendations regarding water treatment for oocyst inactivation have not been established. In this study, the physical method of radiofrequency (RF) power was evaluated for its ability to inactivate T. gondii oocysts in water. Oocysts were exposed to various RF energy levels to induce 50, 55, 60, 70 and 80°C temperatures maintained for 1 min. Post‐treatment oocyst viability was determined by mouse bioassay with serology, immunohistochemistry and in vitro parasite isolation to confirm T. gondii infections in mice. None of the mice inoculated with oocysts treated with RF‐induced temperatures of ≥60°C in an initial experiment became infected; however, there was incomplete oocyst activation in subsequent experiments conducted under similar conditions. These results indicate that T. gondii oocysts may not always be inactivated when exposed to a minimum of 60°C for 1 min. The impact of factors such as water heating time, cooling time and the volume of water treated must be considered when evaluating the efficacy of RF power for oocyst inactivation.  相似文献   

17.
Cats are important in the epidemiology of Toxoplasma gondii because they are the only hosts that can excrete environmentally resistant oocysts. T.gondii is a major zoonotic agent which infects up to one-third of the world population. Toxoplasmosis in neonates and immunocompromised patients can lead to severe disease and death. A cross- sectional parasitological and serological survey with latex agglutination test (LAT) to detect anti-T. gondii antibodies was conducted on 100 serum samples collected from stray cats in five urban areas of Sari, Northern Iran, from April to November 2004. Classification by age, sex, weight, season and region was made. Results analyzed according to specific variables. The overall prevalence of T. gondii IgG antibodies (LAT titre ≥1:1) were found in 40 of 100(40%) of stray cats, with regional variations. Overall 16 of 100(16%) of stray cats had diagnostically significant antibody titres (LAT ≥ 1:64). Prevalence was significantly higher in adult cats (1.5–3.0 kg, 54.5% of 66) than in juvenile cats and kittens (≤1.4 kg, 11.8% of 34) and higher in female stray cats (44.4% of 72) than in male stray cats (28.6% of 28). Toxoplasma seroprevalence was highest in the season of spring (22.4%). There was a significant difference in the prevalence of infection relative to host age and weight (P < 0.05). No significant difference was found between the prevalence of infection relative to host gender, urban sites and season (P > 0.05). Prevalence of T. gondii oocyst was also analyzed by a routine coprological method in 100 cats. T. gondii oocysts were not found in any faecal samples analyzed. Only 2 out of 100 smear preparations of intestinal mucosa showed trophozoites of T. gondii.  相似文献   

18.
Lambs which received colostrum from ewes vaccinated with contagious ecthyma (CE) virus and other lambs vaccinated with CE virus were compared for serum anti-CE immunoglobulin (Ig)G levels, delayed-type hypersensitivity (DTH) responses to CE viral antigen, and protective immunity to challenge with CE virus. Ewes vaccinated 3-4 weeks prior to parturition transferred CE antibody to lambs via colostrum. Although these lambs had higher levels of antibody at challenge than lambs vaccinated when 1-4 days old, only the vaccinated lambs were protected against challenge with CE virus at 1 month of age. Furthermore, the presence of colostrum-derived maternal antibody prevented an active antibody response in lambs to vaccination and/or challenge with CE virus, except where pre-inoculation titres were low. In contrast, the DTH response to CE viral antigen and induction of protective immunity by CE vaccination were not impaired by passively-acquired antibody. Actively immunised lambs could be distinguished from those only receiving passively-acquired antibody by the DTH response to heat-killed CE viral antigen.  相似文献   

19.
Maternal periconceptional undernutrition is associated with altered development and increased risks of adverse outcomes in the offspring. The aim of this work was to determine the effect of periconceptional undernutrition on behavioural and reproductive aspects of the offspring. Fifty ewes were synchronized in oestrus (day 0) and allocated to two groups (n = 25) to be fed diets that provided 1.5 (C) or 0.5 (L) times the requirements for maintenance until day 15. Ewes were mated and fed the control diet from day 16 until lambing. Two months after lambing, 26 lambs were exposed to tests to determine their cognitive/emotional responses. Six ewe lambs were euthanized and in vitro oocyte maturation and fertilization procedures performed. The experimental diets produced no changes of mean live weight (LW) of C ewes, L ewes presenting a reduction in their initial LW with significant differences at day 15, in comparison with C ewes (p < 0.05). L ewes experienced a significant reduction in their body condition (BC) in comparison with C ewes (p < 0.05). Fourteen days after the onset of the experimental diets, mean LW and BC of L ewes was significantly lower than those of C ewes (p < 0.05). Undernourished ewes presented a trend to a reduction of prolificacy and fecundity (p < 0.10) in comparison with C ewes. Emotional and cognitive test revealed a similar response between groups. Ewe lambs from the undernourished ewes presented a population of oocytes 1.7 times higher than ovaries from control ewe lambs (66.0 ± 0.73 vs. 113.7 ± 15.6 oocytes; p < 0.05) and had more oocytes in the ‘good’ (p < 0.05) and ‘healthy’ (p < 0.05) categories. In conclusion, a low plane of nutrition around conception significantly increases quantity and quality of the oocyte population of 60‐day‐old female descendants. Modifications of the cognitive and emotional responses of the progeny have not been evidenced.  相似文献   

20.
A total of 50 two-tooth ewes were immunized pre-tupping using a killed vaccine of disintegrated Toxoplasma tachyzoites with Freunds incomplete adjuvant. At mid-pregnancy, the ewes were challenged intravenously with 1 x 10(4) live T. gondii tachyzoites. There was no difference in the lambing percentage between ewes vaccinated once and unvaccinated ewes. The lambing percentage for ewes vaccinated twice was significantly lower (p<0.05 normal score) than unvaccinated ewes. The serological response to vaccination and challenge was measured by the Toxoplasma dye test. The level of dye test antibodies at the time of challenge suggests that effective immunity to Toxoplasma n abortion is not dependent on dye test antibody titre. These results suggest that a killed vaccine would Toxoplasma on fertility and lambing performance in not be an effective tool to estimate the effects of commercial flocks.  相似文献   

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