首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 78 毫秒
1.
Two experiments were conducted. In the first, 16 crossbred Hereford calves were divided into two equal groups. The first group was vaccinated intranasally with a commercial vaccine against bovid herpesvirus 1 and the second group was unvaccinated. The calves were later exposed to an aerosol of bovid herpesvirus 1 (strain 108) for five minutes. Four calves from each group were subjected to transportation and four calves from each group were kept in an environmental chamber for four days. Four days after viral aerosol all calves were exposed to an aerosol of Pasteurella haemolytica and the same subgroups were again transported or held in the chamber for a further four days.

The calves that did not die from pneumonia were necropsied ten days after the final day of transport. Pulmonary lesions were present in both vaccinated and control animals but were less extensive in the vaccinated calves. Six of eight vaccinated but none of the eight control calves survived.

In the second experiment, eight crossbred Hereford calves were divided into two equal groups. One group was vaccinated with bovid herpesvirus 1 (strain 108) and the other acted as controls. Four weeks later all calves were sequentially exposed to aerosols of bovid herpesvirus 1 (strain 108) and P. haemolytica four days apart. Three of the four controls but none of the vaccinates died from pneumonia. Every lobe of the lungs in all the controls was affected by pneumonia while no pulmonary lesions were found in the vaccinated calves. The differences in efficacy of the modes of vaccination and the possible role of transport stress are discussed.

  相似文献   

2.
In each of 11 experiments, four calves were exposed first to an aerosol of bovine herpesvirus 1 (BHV1, virus of infectious bovine rhinotracheitis) and second to an aerosol of Pasteurella haemolytica. The interval between aerosols was three to five days. In two other experiments, calves were exposed only to a bacterial aerosol. Climate was controlled for all experiments from the day of viral exposure and for eight of the experiments it was also controlled for four to six days before the first aerosol. The concentration of infectious doses of virus in the aerosols and the number of bacteria in the aerosols of each calf were determined. Macroscopically recognizable rhinitis, tonsillitis, laryngitis, tracheitis and pneumonia of lobar distribution in 42 lobes from 11 calves were seen in five experiments in which bacterial aerosol followed the viral aerosol by at least four days. One calf died with marked respiratory disease in each of four experiments within four days of exposure to the bacterial aerosol. Production of pneumonia was dependent on an interval between aerosols of at least four days but not on the condition of controlled climate on the environmental chamber either before or after the viral aerosol nor on the period of habituation allowed calves of some experiments.  相似文献   

3.
Pathological changes in respiratory tracts were studied in 30 calves following exposure to aerosols of Pasteurella multocida or to bovine herpesvirus 1 and P. multocida. Two groups of five calves were exposed to aerosols of one of two types of P. multocida only, which produced lobar pneumonia in one calf of each group. Another five groups of four calves were exposed to aerosols of bovine herpesvirus 1 and four to seven days later to one of the two types or one sub-type of P. multocida. Extensive necropurulent lesions were produced throughout the respiratory tract with each type of P. multocida in all four calves in three groups but none in the remaining two groups. The pathological changes differed from those produced following similar exposures to bovine herpesvirus 1 and P. haemolytica, in that the exudate in air passages and alveoli was more purulent and streaming (oat) cells and large mononuclear eosinophilic granulocytes were absent. This is the first report of experimental respiratory disease in cattle as a result of aerosol exposure to P. multocida alone or in combination with bovine herpesvirus 1.  相似文献   

4.
A total of 36 calves were used in three experiments to test the efficacy of a potassium thiocyanate extract of Pasteurella haemolytica in protecting against experimental pneumonia. In each of experiments A and B, 12 calves were divided into three equal groups. The first group was vaccinated with an aerosol of a potassium thiocyanate extract twice, two weeks apart; the second group was vaccinated subcutaneously once only with the same extract. The third group of calves in both experiments remained as unvaccinated controls. In experiment C, six calves were vaccinated intramuscularly and six were left as controls. Approximately one month after vaccination all calves were challenged with an aerosol of bovine herpesvirus 1 (isolate 108) followed in 4 d by an aerosol of P. haemolytica type A1 (the same strain from which the potassium thiocyanate extract had been made). Varying degrees of protection against subsequent development of experimental pneumonic pasteurellosis in cattle were seen in vaccinated calves as compared to control calves in these experiments. The results indicate that protection of cattle against pneumonic pasteurellosis may prove possible with a sub-cellular extract of P. haemolytica.  相似文献   

5.
The protective effect of an inactivated whole-virion bovine herpesvirus-1 (BHV-1) immunising inoculum, without adjuvant, against viral-bacterial respiratory disease was studied in three experimental treatment groups of five calves each. One group was boosted 14 days after the first vaccination and at this time the second group received their initial inoculation. Seven days later, calves were challenged with BHV-1 in aerosol and four days after this challenge all calves were exposed to Pasteurella haemolytica A1 in aerosol. Among the three groups, differences in rectal temperature responses four days after viral challenge (P less than 0.01) did not relate to protection. However the main response variable, viral-bacterial pneumonia, was reduced in boosted calves (P less than 0.05).  相似文献   

6.
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   

7.
In two experiments in which 31 calves were used, a bovine herpesvirus 1 subunit vaccine previously shown to elicit a strong immunological response in adult cattle failed to do so in younger animals and failed to protect against pneumonia caused by sequential exposure to virulent bovine herpesvirus 1 and Pasteurella haemolytica aerosols. One of the experimental groups had been previously inoculated with a live commercial vaccine but even this failed to elicit a strong immunological response. These results indicate that the calves were in a refractory state when immunized and may explain why similar vaccine failures occur in the field.  相似文献   

8.
Sixteen six to eight month old beef calves were exposed individually to a five minute aerosol of bovine herpesvirus 1, isolate 108. Aerosol exposure to Pasteurella haemolytica (biotype A, serotype 1) was administered individually for five minutes at either four, ten, 20 or 30 days after the virus. Fibrinous pneumonia and pleuritis occurred in all four groups but were most extensive and severe in those exposed to the virus and bacterium four days apart (the positive controls). Fibrinous pneumonia was associated with persistence of bovine herpesvirus 1 in the respiratory tract despite resolution of virus-induced necrotic lesions of the respiratory mucosa. The results presented here suggest that, although the severity of viral-bacterial synergism may be influenced by virus-induced morphological changes, the continued presence of viral antigens after the resolution of respiratory mucosal lesions may continue to exert some effect on host defenses and disease processes.  相似文献   

9.
Five calves were given live intranasal vaccine against bovid herpesvirus 1 (BHV1) two days after intranasal inoculation of bovine pestivirus (BVDV). Another 5 were vaccinated in the absence of BVDV. Control unvaccinated groups were also maintained. All calves were challenged with virulent BHV1. The unvaccinated calves developed signs of infectious bovine rhinotracheitis (IBR) and both vaccinated groups showed a similar degree of clinical protection from IBR. Those given BVDV before vaccination shed up to 140 times more BHV1 (P<0.01) in the nasal mucus following challenge than those which had received BHV1 vaccine alone. The epidemiological significance of this is discussed.  相似文献   

10.
Three strains of bovid herpesvirus 2, viz. Allerton, bovine mammillitis and 69/1LO were used to infect calves intradermally. Twenty-eight days later the immunity of the calves was challenged by intravenous injection of a homologous or heterologous strain. Challenge control calves developed a fever (greater than 40 degrees C) lasting several days and widespread skin lesions which varied with the strain. Homologous challenge of the primary infection produced neither skin lesions nor febrile response, except in one calf in which fever was noted on one day. Heterologous challenge did not cause skin lesions but fever occurred in 8/12 calves. In particular Allerton virus failed to protect completely against heterologous challenge. Despite minor differences evident in these experiments, it is recommended that these isolates should be considered as strains of the same virus--bovid herpesvirus 2.  相似文献   

11.
Five calves were given live intranasal vaccine against bovid herpesvirus 1 (BHV1) two days after intranasal inoculation of bovine pestivirus (BVDV). Another 5 were vaccinated in the absence of BVDV. Control unvaccinated groups were also maintained. All calves were challenged with virulent BHV1. The unvaccinated calves developed signs of infectious bovine rhinotracheitis (IBR) and both vaccinated groups showed a similar degree of clinical protection from IBR. Those given BVDV before vaccination shed up to 140 times more BHV1 (P less than 0.01) in the nasal mucus following challenge than those which had received BHV1 vaccine alone. The epidemiological significance of this is discussed.  相似文献   

12.
Five groups of range bred calves (four calves per group) were used to investigate the effect of stress on susceptibility to aerosol exposures with bovine herpesvirus-1 or Pasteurella haemolytica. Twelve calves were weaned, transported, processed at a commercial feedlot and transported to isolation facilities three days later. An aerosol challenge of either 10 colony forming units of P. haemolytica or 10 plaque forming units of bovine herpesvirus-1 virus was given to two groups of calves and the third group was not challenged. The fourth group was transported directly to the isolation facilities after weaning and aerosol challenged with P. haemolytica. The fifth group remained at the farm after weaning and was not challenged. All transported animals had elevated plasma cortisol levels which remained above normal for at least three days postchallenge. The blastogenic response of all calves was depressed after leaving the farm and remained depressed throughout the experiment. The suppression correlated well with elevated serum cortisol levels. Calves processed through the feedlot encountered bovine herpesvirus-1 because eight out of 12 animals seroconverted to this antigen. Most calves seroconverted to P. haemolytica whether they were experimentally challenged or not. Where the unchallenged calves encountered P. haemolytica is unknown. Calves challenged with bovine herpesvirus-1 but not with P. haemolytica, had significant clinical signs of pneumonia and two animals died due to bovine herpesvirus-1 infection.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
The effect of various aerosol doses of bovine herpesvirus 1, followed four days later by aerosol exposure to a constant level of Pasteurella haemolytica, was studied in 16 crossbred Hereford range calves. A Collision nebulizer was used to generate aerosols from virus suspensions with concentrations of 10(8.2) (high), 10(5.2) (moderate) or 10(2.2) (low) TCID50/mL. The bacterial suspension contained 10(7) colony forming units/mL. Control calves exposed only to P. haemolytica developed no pulmonary lesions. Calves in the low, moderate and high virus exposure groups developed lobular areas of atelectasis; in addition, one calf in the moderate and all four in the high virus exposure group developed fibrinous pneumonia. One of the latter calves died. The 50% effective dose for fibrinous pneumonia under these experimental conditions was 10(6.0) TCID50 bovine herpesvirus 1/mL of suspension in the nebulizer reservoir, and approximately 10(4.0) infectious units inhaled per calf.  相似文献   

14.
Immunity against pneumonic pasteurellosis was studied in calves after recovery from experimental respiratory disease with Pasteurella haemolytica. Nine calves were exposed to aerosols of parainfluenza-3 virus and Pasteurella haemolytica A1 six days apart to produce respiratory disease. After recovery from the disease, these nine principal and four control calves were challenged with aerosols of bovine herpesvirus 1 and P. haemolytica A1 four days apart. With this viral-bacterial challenge, the nine principal animals failed to develop clinical responses to this bacterial challenge and their lungs did not show the growth of P. haemolytica on cultures, whereas two of four control calves had elevated temperatures and developed necropurulent pneumonia with the isolation of P. haemolytica from the lungs. The principal calves had developed high levels of cytotoxin neutralizing antibodies in their sera following parainfluenza-3 virus-P. haemolytica infection. This demonstrated that immunity against pneumonic pasteurellosis can be achieved, with a suggestion that further search for an effective vaccine for P. haemolytica is warranted.  相似文献   

15.
Six strains of bovid herpesvirus 1 isolated from British cases of infectious bovine rhinotracheitis (IBR) were inoculated intranasally into calves. The clinical, virological and serological responses were measured and comparisons made between virus strains. Calves infected with viruses of subtype 1 developed more severe clinical signs and excreted higher titres of virus than calves infected with subtype 2b strains. The findings could be related to the history of IBR in Great Britain.  相似文献   

16.
Seven experiments with four calves each were conducted in which the calves spent at least four days of adaptation in an environmental chamber and then were subjected to climatic stress in the form of a number of constant ambient temperature and humidity combinations. On the second day of climatic stress the calves were individually exposed to measured numbers of infectious units of bovine herpesvirus 1 (BHV1, virus of infectious bovine rhinotrachetis) in aerosol. The calves were killed seven or eight days later. Mycoplasma were found in some nasal swabs and in one lung. Certain bacteria but no Pasteurella were often isolated from the lungs. Bovine herpesvirus 1 was isolated from chamber air and from most postinoculation nasal swabs, tracheas and lungs. The number of macro- and microscopic lesions did not appear to be influenced by the climatic conditions of the experiments. The histopathological changes in epithelium at all levels of the respiratory tract were described in detail.  相似文献   

17.
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   

18.
Studies have been made of antiviral inhibitors produced by bovine tracheal organ cultures inoculated with strains of bovid herpesvirus 1. The inhibitors, which had properties of interferon, were assayed by a plaque-reduction method in bovine turbinate cell cultures with vesicular stomatitis virus as challenge virus. Each of the four strains of bovid herpesvirus 1 studied induced interferon in bovine tracheal organ cultures.  相似文献   

19.
A subunit vaccine in the form of immunostimulating complex (iscom) was prepared to contain the envelope glycoproteins of bovine herpesvirus type 1 (BHV-1). This iscom preparation was tested in a vaccination experiment on 4-month-old calves seronegative to BHV-1. In this experiment, four groups with three animals per group were used. Two groups were vaccinated with the iscom preparation twice, four weeks apart, one group with 50 micrograms and the other with 100 micrograms per calf. The third group received a commercial inactivated whole-virus vaccine applying the same vaccination program. The fourth group served as control. Two weeks after the second vaccination, all the animals were challenge-infected intranasally with a virulent BHV-1 strain and four days later with a virulent Pasteurella multocida--this in order to mimic hard field conditions. When exposed to challenge infection, all the animals vaccinated with the iscom were fully protected, i.e., no virus could be recovered from their nasal secretions and no clinical symptoms were recorded. In contrast, the animals vaccinated with the commercial vaccine, responded to challenge with moderate fever and loss of appetite, and virus was isolated from the nasal secretions. The animals in the control group developed severe clinical symptoms. In the sera of iscom-vaccinated animals, the virus neutralization titers reached levels of 1/3500 or higher.  相似文献   

20.
Groups of six male goats were inoculated intratracheally and intranasally with either caprine herpesvirus followed 6 days later by Pasteurella haemolytica, canine herpesvirus alone or P. haemolytica alone. Pneumonic lesions were observed in five of the six goats inoculated with caprine herpesvirus followed by P. haemolytica and in three of the six goats inoculated with P. haemolytica alone, but were not observed in goats inoculated with caprine herpesvirus alone or in non-infected controls. Pasteurella haemolytica was isolated from seven of eight lungs with pneumonia, but only from one of sixteen lungs without pneumonia. The lesions ranged from fatal acute exudative necrotising pneumonia to predominantly proliferative pneumonia. Half of the caprine herpesvirus-inoculated goats developed a clinical catarrhal rhinitis five days post-inoculation and the only virus-specific histopathological lesion was a mild tracheitis. Canine herpesvirus was recovered from the nasal swabs of all caprine herpesvirus- inoculated goats developed a clinical catarrhal rhinitis five days post-inoculation and the only virus-specific histopathological lesion was a mild tracheitis. Canine herpesvirus was recovered from the nasal swabs of all canine herpesvirus-inoculated goats and from the lungs of three goats inoculated with caprine herpesvirus alone. The experimental inoculations demonstrated that P. haemolytica alone can produce pneumonia in goats. In addition, the study showed that caprine herpesvirus readily proliferates in the upper respiratory tract and lungs of goats but the role of caprine herpesvirus in the aetiology of pneumonia remains uncertain.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号