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1.
The effects of Mycoplasma gallisepticum (MG) vaccination on egg transmission of MG and egg production were evaluated. Leghorn hens vaccinated with live MG (strain F), with strain F plus MG bacterin, with one dose of MG bacterin, or with two doses of MG bacterin all transmitted MG through the egg at a significantly lower level than unvaccinated controls. Hens vaccinated with two doses of MG bacterin had the longest lag before detectable transmission of MG through the egg. All vaccinated groups were protected against the egg-production drop seen in unvaccinated hens challenged with virulent MG.  相似文献   

2.
Leghorn hens vaccinated twice with an inactivated Mycoplasma gallisepticum (MG) bacterin before egg production and subsequently challenged with virulent MG were protected against transmission of MG through the egg. Unvaccinated control hens transmitted MG through the egg at a high rate. When unvaccinated hens were vaccinated with MG bacterin 2 weeks after challenge with MG, there was no significant decrease in egg transmission. Hens vaccinated twice before laying did not suffer as severe egg-production drops as unvaccinated hens did when challenged with virulent MG. In a natural MG outbreak in a leghorn breeder flock, 50 hens were separated from the remainder of the flock and vaccinated with MG bacterin approximately 3 weeks after initial exposure. The unvaccinated hens transmitted MG through the egg at a rate three times higher than the rate of transmission of the vaccinated hens.  相似文献   

3.
The efficacy of Salmonella enteritidis (SE) oil-emulsion bacterin (a commercially available vaccine) was evaluated in an intravaginal challenge model in hens producing a high rate of SE-contaminated eggs. Hens were vaccinated at 38 wk of age. A second (booster) bacterin injection was administered 4 wk later. Two weeks after the second vaccination, all hens were challenged intravaginally with 10(7) colony-forming units of SE. After challenge, 36 of 189 eggs (19.0%) in the vaccinated hens were positive for SE, and this contamination rate was significantly (P < 0.01) lower than that in the unvaccinated hens (61 of 165 eggs, 37.0%). SE was highly recovered from the cloacal and vaginal swabs of the unvaccinated and vaccinated hens, but the number of SE from the cloaca of the vaccinated hens was significantly (P < 0.05) lower than that in the unvaccinated hens at 7 days post-challenge (PC). The recoveries of SE from the spleen and ovary in the vaccinated hens were significantly (P < 0.05) lower than those in the unvaccinated hens at 7 days PC. At necropsy, SE was recovered from 2 of 15 forming eggs (13.3%) taken from the oviducts of the unvaccinated hens, whereas no SE was recovered from 17 forming eggs in the vaccinated hens. After vaccination, serum antibodies for SE in the vaccinated hens were significantly higher than those in the unvaccinated hens. Antibodies from the oviductal washing, especially immunoglobulin G isotype, in the vaccinated hens were higher than those in the unvaccinated hens after challenge. This intravaginal challenge model produced frequent contaminated eggs and clearly demonstrated the ability of the bacterin to protect against egg contamination. The present model may be a useful tool for further studies to evaluate the protective effect against SE contamination of eggs by potential vaccine candidates.  相似文献   

4.
The efficacy of three commercial Mycoplasma gallisepticum (MG) immunizing agents-a bacterin, a recombinant fowlpox-MG vaccine, and a live F-strain vaccine-was compared in specific-pathogen-free hens in egg production. Three groups of 25 chickens were vaccinated with one of the vaccines at 10 wk of age and 25 birds were not vaccinated. At 25 wk of age (and approximately 50% egg production), 20 birds from each of the three vaccinated groups and 15 nonvaccinated controls were challenged with virulent R-strain via aerosol; the birds were necropsied and evaluated at 10 days post-challenge. The MG bacterin and live F-strain vaccinations were both protective and resulted in significant differences in air sac lesions, tracheal lesions, and ovarian regression compared to the nonvaccinated controls and the recombinant fowlpox-MG vaccine (P < or = 0.05). The evaluation of ovarian regression is a useful method of testing the efficacy of MG vaccines in laying hens.  相似文献   

5.
Twelve large white turkey hens were immunized with a commercially available Bordetella avium bacterin. Hens and eggs were tested using an enzyme-linked immunosorbent assay (ELISA) to determine the response to the bacterin. Three hundred poults were then obtained from two commercial flocks, the hens of one flock having been immunized with the same bacterin used on the group of 12 turkeys. Titers of the poults were monitored for 7 weeks, and poults were challenged by exposure to infected poults at 1, 7, 14, and 21 days post-hatch. Hens produced an antibody response following immunization, with a parallel antibody response being detected in eggs. Maternal antibodies were present in poults from immunized hens. Poult titers declined to near the level of poults from unimmunized hens by 14 days of age. Poults from immunized hens challenged at 1 and 7 days were resistant to development of clinical disease and gross lesions, whereas all poults from unimmunized hens exhibited clinical signs and gross lesions. After 14 days, the resistance of both groups to development of clinical disease, became near equal, neither group being affected as severely as the unimmunized hens challenged at days 1 and 7. Six commercial turkey breeding flocks and their progeny that had not been vaccinated for B. avium and had no history of B. avium infection were evaluated with the B. avium ELISA. There were variations between the flocks, with poult titers reflecting those found in the hens.  相似文献   

6.
H D Stone 《Avian diseases》1987,31(3):483-490
An experimental avian influenza (AI) oil-emulsion vaccine was formulated with 1 part inactivated A/turkey/Wisconsin/68 (H5N9) AI virus emulsified in 4 parts oil. Broilers were vaccinated subcutaneously (SC) either at 1 or 3 days old or at 4 or 5 wks old. Commercial white leghorn (WL) layers were vaccinated SC at 12 and 20 wks old or at only 20 wks old. Maximum geometric mean hemagglutination-inhibition titers postvaccination (PV) were 1:86-1:320 for broilers, 1:597 for twice-vaccinated layers, and 1:422 for once-vaccinated layers. Ninety to 100% of vaccinated broilers were protected against death and morbidity when challenged with highly pathogenic A/chicken/Penn/83 (H5N2) AI virus 4 weeks PV, and all were protected when challenged 8 wks PV. All controls and most vaccinates were infected by challenge virus, and 90-100% of controls died or exhibited clinical signs. Vaccinated commercial pullets were protected against morbidity, death, and egg-production decline at either peak of lay (25 wks old) or at 55 wks old. All unvaccinated controls became morbid or died, and egg production ceased 72 hours after challenge. The 0.5-ml vaccine dose was determined to contain 251 and 528 mean protective doses (PD50S) in 4-wk-old and 1-year-old SPF WL chickens, respectively, challenged 4 wks PV.  相似文献   

7.
Six groups of white leghorn pullets were studied to determine the ability of beta-propiolactone-inactivated Mycoplasma gallisepticum (MG) oil-emulsion bacterins to counteract reductions in egg production caused by MG infection. The pullets were inoculated with 0.5 ml of MG bacterin subcutaneously in the neck at about 20 weeks of age and were challenged with MG near 28 weeks of age, when they were in peak egg production. Various challenge schemes with infectious bronchitis virus were used at the time of MG challenge to increase the reduction in egg production. MG bacterins afforded protection against moderate drops in egg production in at least three of the studies, where the unvaccinated challenged control hens exhibited reduced egg production.  相似文献   

8.
Effects of administering killed Salmonella enterica serovar enteritidis (SE) vaccines to laying hens prior to induced molting on egg production and on shedding of SE were investigated. Forty hens were vaccinated with one of two SE vaccines available commercially in the United States and Japan. Twenty-five days after vaccination, feed was withdrawn for 2 wk from 20 vaccinated plus 10 unvaccinated hens to induce molt. Four days after molt induction, all hens were challenged with a dose of 2.4 X 10(9) of SE. For the 25 days following administration of the SE bacterins, egg production in vaccinated hens showed approximately a 15% decrease. After molt induction, egg production in molted hens ceased and then returned to normal levels 8 or 9 wk postvaccination. Through the 3-mo experimental period, the decreases in numbers of eggs laid in the unvaccinated/molted group and two vaccinated/molted groups were 225 (26.2%), 245 (28.4%), and 274 (31.9%), respectively, compared with 860 in the unvaccinated/unmolted group. There was no significant difference in egg lay at the P < 0.05 level among the former three groups. Hens in the vaccinated/molted groups shed about two logs less SE than hens in the unvaccinated/molted group 3 14 days postchallenge (P < 0.05 or 0.01). These results indicate that vaccination prior to induced molting might be effective in preventing the exacerbation of SE problems within flocks in which the potential for SE contamination may exist.  相似文献   

9.
A commercially available inactivated Mycoplasma gallisepticum (MG) bacterin was administered to chickens on a multiple-age farm endemically infected with MG. A total of 3400 MG-free pullets were vaccinated with the MG bacterin at 19 weeks of age, and 4300 unvaccinated pullets served as controls. The vaccinated group became serologically positive by the rapid plate agglutination (RPA) test within 3 weeks, and the unvaccinated group became positive in 7 weeks. The hemagglutination-inhibition test responses were observed at approximately the same time as the RPA in both of the groups. Egg production and mortality through 50 weeks of age did not differ significantly between the two groups. MG was isolated from birds of the vaccinated and control groups near the termination of the study.  相似文献   

10.
To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment.  相似文献   

11.
A Mycoplasma gallisepticum bacterin was prepared and used in Mycoplasma gallisepticum (MG)-positive primary breeders to control vertical transmission of MG. Two generations were vaccinated, but the third generation was not vaccinated and was monitored serologically. Results showed no evidence of MG at 1 day, 6 weeks, 11 weeks, 16 weeks, or 31 weeks of age. This procedure may offer small breeder organizations and showbird fanciers a way to eliminate MG.  相似文献   

12.
The protective effect of an inactivated Mycoplasma gallisepticum (MG) bacterin was evaluated in chickens subsequently challenged intratracheally (IT) with the homologous strain. Antibody responses in sera and tracheal washings (TWs) from these chickens were determined by an enzyme-linked immunosorbent assay. A group of chickens was vaccinated intramuscularly (IM) with two doses of the bacterin containing aluminum hydroxide gel (IM + IM). Another group was vaccinated IM with the same bacterin followed by IT with bacterin lacking the adjuvant (IM + IT). Chickens of both vaccinated groups had similar levels of antibody in TWs at the time of challenge. MG was eliminated from the trachea at higher rates and inflammatory lesions in the trachea were less severe in vaccinated chickens than in unvaccinated controls. The protective effect in chickens vaccinated IM + IT was greater than that in chickens vaccinated IM + IM. Perhaps vaccinal immunity is mediated by local rather than systemic antibody responses, or perhaps resistance provided by vaccination IM + IT is conferred partly by another immune mechanism such as cell-mediated immunity.  相似文献   

13.
The development of a classical swine fever (CSF) subunit marker vaccine, based on viral envelope glycoprotein E2, and a companion diagnostic test, based on a second viral envelope glycoprotein E(RNS), will be described. Important properties of the vaccine, such as onset and duration of immunity, and prevention of horizontal and vertical transmission of virus were evaluated. A single dose of the vaccine protected pigs against clinical signs of CSF, following intranasal challenge with 100LD(50) of virulent classical swine fever virus (CSFV) at 2 weeks after vaccination. However, challenge virus transmission to unvaccinated sentinels was not always completely inhibited at this time point. From 3 weeks up to 6 months after vaccination, pigs were protected against clinical signs of CSF, and no longer transmitted challenge virus to unvaccinated sentinels. In contrast, unvaccinated control pigs died within 2 weeks after challenge. We also evaluated transmission of challenge virus in a setup enabling determination of the reproduction ratio (R value) of the virus. In such an experiment, transmission of challenge virus is determined in a fully vaccinated population at different time points after vaccination. Pigs challenged at 1 week after immunization died of CSF, whereas the vaccinated sentinels became infected, seroconverted for E(RNS) antibodies, but survived. At 2 weeks after vaccination, the challenged pigs seroconverted for E(RNS) antibodies, but none of the vaccinated sentinels did. Thus, at 1 week after vaccination, R1, and at 2 weeks, R=0, implying no control or control of an outbreak, respectively. Vertical transmission of CSFV to the immune-incompetent fetus may lead to the birth of highly viraemic, persistently infected piglets which are one of the major sources of virus spread. Protection against transplacental transmission of CSFV in vaccinated sows was, therefore, tested in once and twice vaccinated sows. Only one out of nine once-vaccinated sows transmitted challenge virus to the fetus, whereas none of the nine twice-vaccinated sows did. Finally, our data show that the E(RNS) test detects CSFV-specific antibodies in vaccinated or unvaccinated pigs as early as 14 days after infection with a virulent CSF strain. This indicates that the E2 vaccine and companion test fully comply with the marker vaccine concept. This concept implies the possibility of detecting infected animals within a vaccinated population.  相似文献   

14.
Six-week-old broilers were fed 50 g tylosin/ton, 400 g chlortetracycline (CTC)/ton, or unmedicated feed and then challenged intratracheally with R strain Mycoplasma gallisepticum (MG). Feed-grade antibiotic medication did not prevent infection, but medication did lower the number of isolations from treated birds compared with controls. Only tylosin significantly lowered MG counts in the trachea. The log10 ID50 of birds receiving tylosin, CTC, or unmedicated feed were 5.8, 4.4, and 2.9, respectively. Six-week-old leghorns were placed on the three diets described previously and challenged with the R strain of MG. Birds were sacrificed at various times up to 10 weeks postchallenge (PC). Compared with the control diet, the tylosin-medicated diet significantly reduced the tracheal MG count from day 1 to 4 weeks PC, whereas the CTC-medicated diet significantly lowered the tracheal MG count only at 3 days PC. In all groups, the MG count gradually declined after 1 week PC; by 8 weeks PC it was essentially the same in all groups. It was concluded that continuous medication has the potential for reducing MG tracheal populations only during the initial phase of an outbreak.  相似文献   

15.
S H Kleven 《Avian diseases》1985,29(4):1012-1017
Chickens vaccinated once or twice with inactivated oil-emulsion vaccine against Mycoplasma gallisepticum (MG) or left unvaccinated were challenged intratracheally with the R strain of MG. The population of MG organisms was determined by enumerating tracheal cultures periodically up to 28 weeks postchallenge (PC). The number of organisms in the respiratory tract increased rapidly after 4 days PC, and the number tended to decrease after 4 weeks PC. Tracheal populations of MG varied considerably among individual chickens. Bacterin-vaccinated chickens had numerically lower populations of MG in their tracheas up to 8 weeks PC, but the differences were small and considered of little practical significance.  相似文献   

16.
Ochratoxin A (OA) was administered to 13-day-old chicken embryos via the chorioallantoic membrane. The 7-day LD50 value (day 20 incubation) of OA was calculated at 7.9 micrograms of OA. Ochratoxin-treated embryos (2.5 micrograms) had slight but significant changes in numbers of immunoglobulin-bearing cells in the bursa but not in the spleen. Chicks hatched from in ovo-treated eggs were challenged with 9 X 10(4) colony-forming units (CFU) of beta-hemolytic Escherichia coli (O1:K1) at 7 days of age via the thoracic air sac. Lesion scores of OA-treated chicks were equal to or less severe than those of controls. Hatchmates of the above chicks were vaccinated with a homologous killed E. coli bacterin (O1:K1) at both 2 and 4 weeks of age and challenged with 10(4) CFU of E. coli at 7 weeks. Post-challenge lesions were present in three vaccinated untreated controls and no OA-treated chicks. We conclude that although in ovo exposure to OA may marginally suppress immunoglobulin-bearing cells of bursa, chicks hatched from OA-treated eggs respond as well as controls to an antigen and resist infection by a virulent organism.  相似文献   

17.
OBJECTIVE: To evaluate immune responses induced by administration of Mycoplasma hyopneumoniae bacterin to pigs. Animals-60 healthy 7- to 10-day-old cross-bred boars. PROCEDURE: Pigs were assigned to 1 of 4 pig groups (15 pigs/group): vaccinated, challenged; vaccinated, nonchallenged; nonvaccinated, challenged; nonvaccinated, nonchallenged. Vaccinated pigs received IM injections of a mycoplasma bacterin on days 0 and 14, whereas nonvaccinated pigs received saline (0.9% NaCl) solution. Pigs in the challenged groups were inoculated intratracheally with M hyopneumoniae on day 42. Pigs were euthanatized and necropsied 41, 44, 48, and 70 days after the first vaccination, and proportion of lung surface with pneumonic lesions was determined. Percentage of lymphocyte subpopulations and number of interferon-gamma (IFN-gamma) secreting lymphocytes in blood and tissues, cytokine and antibody concentrations in bronchoalveolar lavage (BAL) fluid, and serum antibody concentrations were determined. RESULTS: Vaccination against and infection with M hyopneumoniae induced a local mucosal immune response in the respiratory tract of pigs. Proportion of lung surface with pneumonic lesions in vaccinated challenged pigs was reduced on day 70, compared with nonvaccinated challenged pigs. Vaccination stimulated the production of M hyopneumoniae-specific IFN-gamma secreting blood lymphocytes. Tumor necrosis factor-alpha concentration in BAL fluid on day 70 was increased in nonvaccinated challenged pigs, compared with vaccinated challenged pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination against M hyopneumoniae induced local, mucosal, humoral, and cellular immune responses. Moreover, vaccination reduced the severity of lung lesions in challenged pigs, suggesting that mucosal antibodies, mediation of the inflammatory response, and cell-mediated immune responses are important for control of mycoplasmal pneumonia in pigs.  相似文献   

18.
K Karaca  K M Lam 《Avian diseases》1987,31(1):202-203
One-week-old chickens were vaccinated with commercial Mycoplasma gallisepticum bacterin subcutaneously and challenged with the S6 strain by the intra-air-sac route 3 weeks later. Significantly fewer vaccinated chickens had air-sac lesions than controls.  相似文献   

19.
Two commercial marker vaccines against classical swine fever virus (CSFV) and companion diagnostic tests were examined in 160 conventional pigs. To test the vaccines in a "worst case scenario", group of 10 weaners were vaccinated using a single dose of an E2 (gp55) based vaccine at days -21, -14, -10 or -7, and subsequently challenged at day 0. The challenge virus was CSFV 277, originating from a recent outbreak of classical swine fever (CSF) in Germany. In all groups, only 5 out of 10 pigs were challenged; the remaining 5 pigs served as vaccinated contact controls. Also, three control groups, each consisting of 10 non-vaccinated pigs, were challenged in parallel to the vaccinated animals. CSFV could be isolated from all non-vaccinated pigs. Among these pigs 40% displayed a chronic course of the infection (virus positive for more than 10 days). Pigs vaccinated 21 or 14 days before challenge displayed no clinical signs of CSFV after challenge. However, they were still able to replicate CSFV when challenged, as measured by reisolation of CSFV from leukocytes of the directly challenged pigs. CSFV could be isolated from the leucocytes of 25% of the pigs vaccinated 21 days before challenge and 50% of the pigs vaccinated 14 days before challenge. Chronic infection was not observed, but transmission to one vaccinated contact pig occurred. From all pigs vaccinated 10 or 7 days before challenge, CSFV could be reisolated. We observed a chronic course of infection in 5% of pigs vaccinated 10 days before challenge and in 30% of pigs vaccinated 7 days before challenge. The mortality rate was 20% in the pigs vaccinated 10 days before challenge, and varied between 20 and 80% in pigs vaccinated 7 days prior to challenge. The contact animals had lower mortality (0-20%) than directly challenged pigs, probably mirroring the delayed time point of infection. There was thus some protection against clinical illness by both marker vaccines, but not a solid protection against infection and virus shedding. The efficacy of the vaccine was best if used 3 weeks before challenge and a clear correlation between time interval from vaccination to challenge and the level of virus shedding was observed. Each vaccine had its own accompanying discriminatory ELISA, but 18% of the virus positive pigs never seroconverted in these tests.  相似文献   

20.
OBJECTIVE: To compare the efficacy of a Salmonella bacterin and a modified live Salmonella ser. Choleraesuis vaccine on a commercial dairy. ANIMALS: 450 cows in late gestation and 80 calves. PROCEDURE: Group-1 cows (n = 150) were vaccinated once with a modified live S. Choleraesuis (serogroup C1) strain 54 (SC54) vaccine, group-2 cows (150) were vaccinated on enrollment and 30 days later with a Salmonella ser. Montevideo (serogroup C1) bacterin, and group-3 cows (150) served as unvaccinated controls. One gallon of colostrum harvested from the first 80 cows to calve was fed to each calf. Outcome assessments included fecal shedding of Salmonella spp for the first 10 days after parturition (cows) or birth (calves), milk production, involuntary culling rate, mastitis incidence, antimicrobial use, and mortality rate. RESULTS: Salmonellae were isolated from 306 of 309 (99%) cows and 64 of 74 (86.5%) calves. Shedding frequency was less in SC54-vaccinated cows and calves that received colostrum from those cows, compared with the other groups, and vaccination was specifically associated with less shedding of serogroup C1 salmonellae. Production data were similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination of pregnant cows with an autogenous Salmonella bacterin had no effect on fecal shedding of salmonellae, whereas vaccination with a modified live S. Choleraesuis vaccine reduced the frequency of fecal shedding of serogroup C1 salmonellae during the peripartum period. A commercial S. Choleraesuis vaccine licensed for use in swine may be more efficacious than autogenous Salmonella bacterins on dairies infected with serogroup C1 salmonellae.  相似文献   

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