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1.
Forty Friesian one-year-old calves were vaccinated simultaneously with live Babesia bovis and B bigemina vaccines. Three groups of 10 calves each were treated with two, three or four doses of 20 mg kg-1 long-acting oxytetracycline (OTC/LA) at six- to seven-day intervals starting from day 6 after vaccination. Ten animals remained untreated. The treated calves showed considerably fewer days of patency and higher packed cell volumes than the vaccinated untreated calves. All calves developed serum antibodies to both parasites following vaccination. Five months later the 40 vaccinated and 30 new calves were challenged with syringe-transferred virulent parasites of both species. The vaccinated calves showed no parasites or clinical manifestations while calves of the new group exhibited severe clinical babesiosis. These results show that when OTC/LA is administered following anti-babesial vaccination, parasitaemia and red blood cell destruction are significantly reduced without, however, inhibiting the development of immunity.  相似文献   

2.
Cross-bred Bos taurus calves, aged between 6 and 8 months, were inoculated with the Onderstepoort Anaplasma centrale live blood vaccine. One group of 15 calves were inoculated once only, while a 2nd group of 15 were revaccinated 6 months later. All the animals were challenged with approximately 1 X 10(10) Anaplasma marginale parasites of a known virulent strain 8 months after the first vaccination. The results of blood smear examination and the card agglutination test indicated that only 20 out of 30 animals vaccinated contracted A. centrale infections after the first attempt, and 3 out of 5 after the second. The vaccine conferred only partial immunity to challenge with a virulent A. marginale strain.  相似文献   

3.
Three experiments were conducted with calves in which, following intramuscular or intranasal vaccination with virulent or attenuated bovine herpesvirus 1, calves were protected against bovine herpesvirus 1 -- Pasteurella haemolytica challenge. Calves receiving low doses of vaccine had lower levels of antibody and greater evidence of virus replication upon challenge than those receiving higher doses. In contrast 11/13 unvaccinated controls had fibrino-purulent pneumonia following challenge. The immune response developed later in younger calves and those given low doses of vaccine. Neutralizing antibodies to bovine herpes-virus 1 were not found in nasal secretions, but were present in serum seven days after vaccination. Bovine herpesvirus 1 was isolated before challenge from nasal secretions of calves vaccinated intranasally or intramuscularly with virulent virus but not those vaccinated intramuscularly with vaccine virus. It was concluded that both routes of vaccination with either virulent or attenuated bovine herpesvirus 1 provided protection from challenge with homologous or heterologous bovine herpesvirus 1 and that live vaccines should contain at least 10(3) plaque forming units/dose for effective immunization.  相似文献   

4.
A group of four conventional, colostrum-fed calves was vaccinated with live parainfluenza type 3 (PI-3) virus vaccine at 1 and 5 weeks of age. A group of four control calves was treated with cell culture medium at the same time. Two weeks after the second vaccination, both groups of calves were challenged with PI-3 virus by a combined respiratory route. Blood and nasal mucus samples were collected at intervals, and alveolar macrophages were recovered before and after challenge by bronchoalveolar lavage. The results demonstrated that clearance of virus, as indicated by presence of virus antigen was more rapid in previously vaccinated calves. Several alveolar macrophage functions were markedly reduced in all calves 5 to 7 days following virus challenge, although microbicidal activity was unaffected, compared to the controls. The production of neutrophil chemotactic factors by alveolar macrophages occurred more rapidly after virus challenge in the previously vaccinated calves and this correlated with a more rapid neutrophil influx into the lungs in these animals.  相似文献   

5.
The intestinal and systemic antibody response of calves vaccinated and/or challenged with rotavirus was studied employing isotype-specific ELISAs for the detection of IgG1, IgG2, IgM and IgA antibodies to rotavirus. Monoclonal antibodies to bovine immunoglobulin isotypes of proven specificity were used as conjugated or catching antibody. Five days after oral inoculation (dpi) of a 5-day-old gnotobiotic calf with rotavirus, IgM rotavirus antibodies were excreted in faeces, followed 5 days later by IgA rotavirus antibodies. The increase in IgM rotavirus antibody titre coincided with the inability to detect further rotavirus excretion. Faeces IgM and IgA rotavirus antibody titres fell to low levels within 3 weeks post infection. IgG1 and IgG2 rotavirus antibodies were not detected in faecal samples. In serum, antibodies to rotavirus of all four isotypes were detected, starting with IgM at 5 dpi. Two SPF-calves, which were fed colostrum free of rotavirus antibodies, were vaccinated with a modified live rotavirus vaccine and challenged with virulent rotavirus 6 days later. Upon vaccination, the calves showed an antibody response similar to the response of the infected gnotobiotic calf. Intestinal IgM rotavirus antibodies were excreted before or on the day of challenge and appeared to be associated with protection against challenge infection with virulent virus and rotavirus-induced diarrhoea. In 3 control calves, which were challenged only, the antibody patterns also resembled that of the gnotobiotic calf and again the appearance of IgM rotavirus antibodies coincided with the end of the rotavirus detection period. Two other groups of 3 SPF-calves were treated similarly, but the calves were fed colostrum with rotavirus antibodies during the first 48 h of life. These calves excreted passively acquired IgG1 and IgG2 rotavirus antibodies in their faeces from 2 to 6 days after birth. After vaccination, no IgM or IgA antibody activity in serum or faeces was detectable. Upon challenge, all calves developed diarrhoea and excreted rotavirus. Seven to 10 days after challenge low levels of IgM rotavirus antibody were detected for a short period. These data indicate that the intestinal antibody response of young calves to an enteric viral infection is associated with the excretion of IgM antibodies, immediately followed by IgA antibodies. This response is absent or diminished in calves with passively acquired specific antibodies which may explain the failure to induce a protective intestinal immune response by oral vaccination with modified live rotavirus of calves fed colostrum containing rotavirus antibodies.  相似文献   

6.
Calves were vaccinated orally, subcutaneously or intraperitoneally with a smooth, plasmid-cured strain of Salmonella enterica serovar typhimurium, strain 81. Oral vaccination was not effective, as only 1/5 calves survived challenge with virulent S. typhimurium. Strain 81 was attenuated for calves, as only a slight rise in rectal temperatures was detected after vaccination. The organism was excreted by some calves in the faeces, but no signs of diarrhoea were observed after vaccination. After parenteral vaccination, strain 81 was able to reach the intestines, gastric associated lymphoid tissues and other internal lymphoid tissues and remained viable for up to 14 days in the bovine host. After oral challenge with a virulent strain, 9/10 vaccinated calves survived challenge as opposed to 4/10 control calves (p<0.5). Diarrhoea was present in all calves of the control groups, but in only 4/10 of the vaccinated calves. The clinical reactions of the vaccinated calves were milder than in the control calves, as the rises in rectal temperatures were lower, diarrhoea was less severe, and the challenge strain was present in fewer organs from vaccinated calves than control calves. This study showed that parenterally administered Salmonella vaccines can induce both mucosal and systemic immunity, and it is postulated that this capability of strain 81 is related to its colonisation of lymphoid tissues and other systemic and intestinal tissues. This study confirmed that plasmid-cured strains were attenuated in the bovine host and conferred significant protection after parenteral vaccination, but not oral vaccination.  相似文献   

7.
Cows were vaccinated with formalin-killed Salmonella typhimurium approximately seven weeks and two weeks before parturition to investigate whether passive immunity could protect their calves against experimental S typhimurium infection. After birth the calves were left with their dam for 48 hours and then separated and fed cold, stored colostrum from their own dam for a further eight days. Oral challenge five days after birth with 10(8) S typhimurium did not result in the death of these calves even when they had absorbed little colostrum. Mortality was reduced to 22 per cent in calves which sucked from vaccinated dams and were then fed colostrum from unvaccinated cows and to 50 per cent in calves born to unvaccinated cows and later fed colostrum from vaccinated animals. Calves which sucked from a vaccinated dam and then received stored colostrum from the same cow excreted salmonellas for significantly shorter periods after challenge and were less often infected at necropsy 28 days after inoculation. Protection was not correlated with the levels of O or H agglutinating antibodies in serum, which were at a maximum 24 hours after sucking and then slowly declined. There was no evidence of an active antibody response in the serum. Measurement of the O and H response of cows after vaccination indicated that the vaccination schedule could be improved. The highest levels of agglutinating antibody were measured between two and three weeks after the first vaccination and there was only a minimal response to the second vaccination before parturition.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
Calves were vaccinated orally, subcutaneously or intraperitoneally with a smooth, plasmid-cured strain of Salmonella enterica serovar typhimurium, strain 81. Oral vaccination was not effective, as only 1/5 calves survived challenge with virulent S. typhimurium. Strain 81 was attenuated for calves, as only a slight rise in rectal temperatures was detected after vaccination. The organism was excreted by some calves in the faeces, but no signs of diarrhoea were observed after vaccination. After parenteral vaccination, strain 81 was able to reach the intestines, gastric associated lymphoid tissues and other internal lymphoid tissues and remained viable for up to 14 days in the bovine host. After oral challenge with a virulent strain, 9/10 vaccinated calves survived challenge as opposed to 4/10 control calves (p<0.5). Diarrhoea was present in all calves of the control groups, but in only 4/10 of the vaccinated calves. The clinical reactions of the vaccinated calves were milder than in the control calves, as the rises in rectal temperatures were lower, diarrhoea was less severe, and the challenge strain was present in fewer organs from vaccinated calves than control calves. This study showed that parenterally administered Salmonella vaccines can induce both mucosal and systemic immunity, and it is postulated that this capability of strain 81 is related to its colonisation of lymphoid tissues and other systemic and intestinal tissues. This study confirmed that plasmid-cured strains were attenuated in the bovine host and conferred significant protection after parenteral vaccination, but not oral vaccination.  相似文献   

9.
Lymphocytic responses in peripheral blood and visceral lymph to Cooperia oncophora antigen and skin tests were determined in 35 Holstein male calves that were inoculated orally with single or multiple doses of C oncophora infective larvae. Several calves were vaccinated or given immune serum before larvae were inoculated. Antigen-specific in vitro blastogenesis of blood and lymph lymphocytes and delayed-type hypersensitivity reactions were observed in several inoculated, vaccinated, and/or passively immunized calves. Most calves that had delayed skin reactions also had in vitro lymphocyte responses to C oncophora antigen. The lymphocyte and skin responses were inconsistent and variable in time of onset--the earliest lymphocyte response occurring 7 days after calves were inoculated. A cellular immune response was induced by both dermal vaccination and oral inoculation; however, passive immunization by IV administration of immune serum simultaneously with inoculation did not have an apparent effect on the cellular response, as measured by the lymphocyte blastogenesis test or dermal testing. Although cellular immune responses were observed in several calves infected with C oncophora, there was no apparent relationship between the specific responses and number of nematodes establishing infection in calves after either single- or multiple-dose oral inoculations.  相似文献   

10.
Calves not vaccinated with infectious bovine rhinotracheitis virus (IBRV) became latently infected when challenge exposed and treated with dexamethasone (DM). Calves that shed IBRV after DM treatment were considered to be latently infected. Vaccination with a temperature-sensitive intranasal vaccine or with formalinized IBRV in Freund's complete adjuvant (IBRV-FCA) protected some, but not all, calves against latent infection--indicating a role for the immune response in preventing latent infection. That all latently infected calves were not detected after DM treatment was indicated by the fact that after a 2nd DM treatment of 3 calves treated 6 months previously and not found to shed virus, 1 of the calves was latently infected. Latently infected calves were inoculated with successive doses of IBRV-FCA and treated with DM. Nonvaccinated calves shed virus, whereas vaccinated calves similarly treated did not shed virus. Because both groups had a comparable cell-mediated immune response, as determined by blastogenic response to IBRV, but the vaccinated group had significantly higher virus-neutralizing antibody titers, a role for humoral antibody in preventing viral shedding was indicated.  相似文献   

11.
Calves at the age of one month were vaccinated with a lyophilized vaccine against bovine trichophytosis, or with an avirulent vaccine against bovine trichophytosis (mfd by Bioveta, Ivanovice in Haná). Prophylactic doses of the vaccines (15 mil. CFU of production strain Trichophyton verrucosum per calf) were used for immunization, and doses 10 times, 100 times and 1000 times lower. The calves were revaccinated with the same doses in 12 days after the first vaccination. Twenty-eight days later since revaccination, the vaccinated calves and a group of control nonvaccinated calves was challenged epicutaneously with a virulent strain of T. verrucosum. The protectiveness of both vaccines implanted at doses of 2 x 15 mil. and 2 x 1.5 mil. CFU per test animal was very good. No dermal lesion were observed in the challenged calves of these groups, or if any, they were not clear and could be observed for a short time. If the vaccines were used diluted at a ratio 10(-2) (150 thousand CFU of production strain), trichophytic lesions persisting for the whole period of observation were found in four of the seven calves vaccinated with a lyophilized vaccine against bovine trichophytosis and in two of the eight calves implanted an avirulent vaccine after challenge. Mycotic lesions were formed after challenge in all test animals in the groups vaccinated with doses of 2 x 15 thousand CFU of production strain per calf. The extent of these lesions was practically the same as in all nonvaccinated controls--on the surface of infected skin the hair was shed and scales and crusts were formed. A challenge strain of T. verrucosum was cultivated from these lesions.  相似文献   

12.
OBJECTIVE: To determine the efficacy of a modified-live virus vaccine containing bovine herpes virus 1 (BHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza virus 3, and bovine viral diarrhea virus (BVDV) types 1 and 2 to induce neutralizing antibodies and cell-mediated immunity in na?ve cattle and protect against BHV-1 challenge. ANIMALS: 17 calves. PROCEDURES: 8 calves were mock-vaccinated with saline (0.9% NaCl) solution (control calves), and 9 calves were vaccinated at 15 to 16 weeks of age. All calves were challenged with BHV-1 25 weeks after vaccination. Neutralizing antibodies and T-cell responsiveness were tested on the day of vaccination and periodically after vaccination and BHV-1 challenge. Specific T-cell responses were evaluated by comparing CD25 upregulation and intracellular interferon-gamma expression by 5-color flow cytometry. Titration of BHV-1 in nasal secretions was performed daily after challenge. Results-Vaccinated calves seroconverted by week 4 after vaccination. Antigen-specific cell-mediated immune responses, by CD25 expression index, were significantly higher in vaccinated calves than control calves. Compared with control calves, antigen-specific interferon-gamma expression was significantly higher in calves during weeks 4 to 8 after vaccination, declining by week 24. After BHV-1 challenge, both neutralizing antibodies and T-cell responses of vaccinated calves had anamnestic responses to BHV-1. Vaccinated calves shed virus in nasal secretions at significantly lower titers for a shorter period and had significantly lower rectal temperatures than control calves. CONCLUSION AND CLINICAL RELEVANCE: A single dose of vaccine effectively induced humoral and cellular immune responses against BHV-1, BRSV, and BVDV types 1 and 2 and protected calves after BHV-1 challenge for 6 months after vaccination.  相似文献   

13.
Sixty calves, 3 to 6 months old, were vaccinated once against Babesia bovis in groups of 10, by the following methods: (a) tick infestation; (b) inoculation of virulent parasites obtained from the tick-infested animals immediately after infection; (c) inoculation of the parasites used in (b) attenuated by passage through splenectomised calves; (d) inoculation of commercially-available, living, attenuated vaccine; (e) inoculation of virulent parasites obtained from the tick-infested animals in (a) one year after infection; (f) inoculation of the parasites used in (e) attenuated by passage. All vaccinated animals were maintained tick-free and were strongly immune to challenge with a heterologous strain of B. bovis approximately 4 years after vaccination. There was no difference in immunogenicity between any of the B. bovis populations.  相似文献   

14.
The onset of protection offered by intranasal vaccination with attenuated bovine herpesvirus-1 (BHV-1) was studied in 18 calves given a virulent BHV-1 aerosol challenge inoculum and an aerosol challenge exposure to Pasteurella haemolytica. Calves challenge exposed with virus 3, 7, 11, 15, or 19 days after vaccination and challenge exposed 4 days later with Pasteurella haemolytica did not develop viral-bacterial pneumonia, whereas 2 of 3 control calves died of fibrinous bronchopneumonia 40 and 60 hours after the bacterial aerosol and the 3rd control calf had similar lesions. All vaccinated and control calves had detectable amounts of interferon at the time of viral challenge exposure. Protection was observed before detection of neutralizing antibodies to BHV-1 in nasal secretions or in serum. Protection was therefore present from day 3 through day 19 after vaccination, but the mechanism could not be explained completely by neutralizing antibody or interferon.  相似文献   

15.
Ten Holstein calves were divided into 2 groups. Five calves served as nonvaccinated controls, and 5 calves were vaccinated IM at 2 and 3 weeks of age with 10(9) aromatic-dependent (aro-) Salmonella typhimurium strain SL1479 containing O antigens 1, 4, 12. Serious adverse reactions to vaccination were not observed in the calves. Mean maximum rectal temperature increase in the vaccinated calves was 1.5 C. One calf had diarrhea and depressed appetite for 1 day after vaccination. At 5 weeks of age, all calves were challenge exposed orally with 1.5 X 10(11) virulent S dublin strain SL1367 (O antigens 9,12). After challenge-exposure inoculum was given, 1 of 5 vaccinated calves died and 4 of the 5 nonvaccinated calves died (P less than 0.05). Thus, some cross serotype protection against S dublin was induced by parenteral vaccination of calves with aro- S typhimurium strain SL1479, although protection was not complete.  相似文献   

16.
Using 6- to 8-month-old beef calves, 3 experiments were conducted to compare the effect of vaccination with live or killed Pasteurella haemolytica on resistance to a transthoracic challenge exposure with the organism and to correlate serum antibody response with resistance. In each experiment, calves were vaccinated twice at 1-week intervals and were challenge exposed 21 days after the first inoculation. Lung lesions were evaluated by a system, such that higher scores indicated the more severe lesions. In each experiment, calves immunized with live P haemolytica had lower lesion scores than calves vaccinated with saline solution or bacterin. In 2 of the experiments, the differences were significant (P less than 0.05). In all experiments, calves vaccinated parenterally with a commercial P haemolytica/P multocida bacterin or with a formalin-killed P haemolytica bacterin had lesion scores that were not significantly different (P greater than 0.05) than for control calves vaccinated with saline solution. Live and killed bacterial preparations induced a significant serum antibody response to P haemolytica as measured by a quantitative fluorometric immunoassay. The antibody response to vaccination was not affected by preexisting titers to P haemolytica. Serum antibody titers were not consistently as high for calves vaccinated with bacterins as for calves vaccinated with live organisms. Although high antibody titers correlated with low lesion scores when calves vaccinated with saline solution or live organisms were analyzed collectively, there was not a significant correlation between the 2 variables when calves, vaccinated with saline solution or with bacterin, were analyzed collectively. These data indicate that, although bacterins may induce a detectable serum antibody response, they do not induce protection against transthoracic challenge exposure to P haemolytica.  相似文献   

17.
Three experiments were conducted on calves in which the efficacy of vaccination with live Pasteurella haemolytica in aerosol was tested by challenge with sequential aerosol exposure to bovine herpesvirus 1 and P. haemolytica. Neither single nor multiple aerosol vaccinations protected against the experimental disease. Macroscopically recognizable rhinitis, tonsillitis, tracheitis and pneumonia occurred in both controls and vaccinates. In one experiment as many as three aerosol vaccinations with live P. haemolytica for up to 20 minutes failed to elicit clinical signs in exposed calves. Pasteurella haemolytica was isolated less frequently from tissues of vaccinated calves than from those of nonvaccinated calves. Pasteurella haemolytica was isolated from deep nasal swabs of 4/14 vaccinated calves five and six days after viral exposure. It was concluded that although bovine herpesvirus 1 vaccination has been shown previously to prevent the experimental disease produced by bovine herpesvirus 1-P. haemolytica, live P. haemolytica vaccination by aerosol will not provide the same protection.  相似文献   

18.
OBJECTIVE: To determine whether a combination viral vaccine containing modified-live bovine herpesvirus-1 (BHV-1) would protect calves from infection with a recent field isolate of BHV-1. DESIGN: Randomized controlled trial. ANIMALS: Sixty 4- to 6-month-old beef calves. PROCEDURE: Calves were inoculated with a placebo 42 and 20 days prior to challenge (group 1; n = 10) or with the combination vaccine 42 and 20 days prior to challenge (group 2; 10), 146 and 126 days prior to challenge (group 3; 10), 117 and 96 days prior to challenge (group 4; 10), 86 and 65 days prior to challenge (group 5; 10), or 126 days prior to challenge (group 6; 10). All calves were challenged with BHV-1 via aerosol. Clinical signs, immune responses, and nasal shedding of virus were monitored for 14 days after challenge. RESULTS: Vaccination elicited increases in BHV-1-specific IgG antibody titers. Challenge with BHV-1 resulted in mild respiratory tract disease in all groups, but vaccinated calves had less severe signs of clinical disease. Extent and duration of nasal BHV-1 shedding following challenge was significantly lower in vaccinated calves than in control calves. In calves that received 2 doses of the vaccine, the degree of protection varied with the interval between the last vaccination and challenge, as evidenced by increases in risk of clinical signs and extent and duration of viral shedding. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that this combination vaccine provided protection from infection with virulent BHV-1 and significantly reduced nasal shedding of the virus for at least 126 days after vaccination.  相似文献   

19.
Groups of 10-12 Romney and Merino wethers were challenged simultaneously with homologous experimental footrot infection after having received the second of 2 doses of Bacteroides nodosus (strain 198) vaccine 0, 4, 8, 12, 16 and 20 weeks previously. Inoculations were carried out 28 days apart and unvaccinated sheep of both breeds were challenged as controls. Most Romneys that had been vaccinated up to 16 weeks prior to challenge were resistant to footrot whereas 8 of 10 controls were susceptible. This resistance was lost by about 20 weeks after vaccination. By contrast, protection against challenge in vaccinated Merinos lasted only about 4-5 weeks, although residual benefits of vaccination were apparent after longer intervals from the reduced number and severity of foot lesions among vaccinates compared with controls. Agglutinin titres, which did not differ markedly after similar intervals between Romneys and Merinos, reached maximum levels between 4 and 8 weeks after the second vaccine dose and subsequently declined. Although peak titres were generally recorded at the time of maximum protection in Merinos, the relationship between agglutinin levels and resistance in the Romneys was ill-defined.  相似文献   

20.
The interaction of the morantel sustained release bolus with the development of immunity in calves vaccinated with two doses of gamma irradiated (40 Kr) Dictyocaulus viviparus larvae was investigated under laboratory conditions. A total of 37 helminth-naive calves were used. Eight calves were used in the first part of the study to test the efficacy of a larval vaccine prepared by using gamma rays delivered from a cobalt source. In the second part of the study, four groups of four groups of four calves each were vaccinated and of these, all the animals in two groups each received a bolus. The remaining three groups (two groups of four and one group of five calves each) remained nonvaccinated with each animal in one group receiving a bolus. All the calves were challenged with approximately 2000 lungworm larvae four months postvaccination. In order to simulate possible field conditions, two of the vaccinated groups and two of the nonvaccinated groups were given a trickle infection of 800 lungworm larvae over a four-week period, three months prior to challenge. Based on a comparison of clinical signs, pathology and lungworm burdens at necropsy, the vaccination of the calves conferred a significant degree of protection (P less than 0.001) to a subsequent challenge compared with controls. The introduction of a morantel sustained release bolus and/or a trickle infection had no effect on the high degree of protection engendered by the vaccination. Nonvaccinated calves given a trickle infection, with or without a bolus, were also highly immune to challenge.  相似文献   

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