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1.
Five 6-month-old calves were inoculated with bovine viral diarrhea (BVD) virus (n = 3) or Pasteurella haemolytica (n = 2) endobronchially with a fiberoptic bronchoscope. Five additional calves were inoculated sequentially with BVD virus followed by P haemolytica at a 5-day interval. Blood samples were collected daily from the calves for bacterial isolation. Clinical signs of respiratory tract disease in calves were recorded daily. If the calves survived, they were killed for necropsy 3 or 4 days after inoculation with P haemolytica (or 8 days after inoculation with BVD virus). The extent and nature of pulmonary lesions in the calves were determined, and the lower portion of the respiratory tract (lungs and trachea) was examined for both these organisms. The 3 calves, inoculated with BVD virus only, developed mild clinical signs mainly manifested as fever, nasal discharge, and occasional cough. Approximately 2% to 7% of the total lung capacity of these calves was pneumonic. Mild clinical signs and localized lesions involving about 15% of the lung volume developed in the 2 calves exposed to P haemolytica only. However, severe fibrinopurulent bronchopneumonia and pleuritis involving 40% to 75% of lung volume developed in the 5 calves inoculated sequentially with BVD virus and P haemolytica. The possible role BVD virus may have in bovine respiratory tract disease is discussed.  相似文献   

2.
Isolates of non-cytopathogenic bovine viral diarrhoea (BVD) virus from 18 persistently infected calves from one herd were compared by using monoclonal antibodies directed against the major viral glycoprotein gp53. All the isolates displayed an almost identical reaction pattern. Based on this antigenic analysis three cytopathogenic BVD and three non-cytopathogenic BVD viruses closely related to the non-cytopathogenic BVD herd isolate were selected. Six of the persistently infected calves were inoculated with a pool of the three closely related cytopathogenic BVD viruses and two with a pool of the three non-cytopathogenic BVD viruses. In addition three animals were infected with one closely related cytopathogenic BVD strain (Indiana) and two animals with the antigenetically different cytopathogenic BVD viral strain A1138/69. Regardless of the inoculation route all the animals superinfected with closely related cytopathogenic BVD viruses developed the characteristic lesions of mucosal disease within 14 days of infection. Animals which were inoculated with non-cytopathogenic BVD viruses which closely resembled the herd isolate, or with cytopathogenic BVD viruses which did not resemble the herd isolate did not develop any signs of disease. However, the latter group produced antibodies to the superinfecting virus.  相似文献   

3.
In calves inoculated with bovine viral diarrhea (BVD) viruses and soluble antigen, the complement-fixing (CF) antibodies appeared before serum-neutralizing (SN) antibodies and remained at high levels throughout the test period. A rapid rise in SN antibodies occurred after challenge with homologous virus with no apparent effect on CF antibody levels.

The CF antibody responses in calves infected with cytopathogenic NADL-MD and noncytopathogenic CG-1220 viruses were similar whereas SN antibody responses indicated strain specificity by reciprocal cross-neutralization tests.

The CF antibody levels in 5 hog cholera (HC) antisera were assayed using the soluble antigen of NADL-MD BVD virus. No demonstrable SN antibodies were present in four HC antisera tested against NADL-MD virus, but a significant titer was present in the commercially prepared antiserum.

Virus was reisolated from animals infected with BVD viruses by buffy coat culture technique during 3 weeks postinoculation, even when significant levels of CF and SN antibodies were present.

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4.
Three, 5, or 7 days after inoculation with bovine viral diarrhea (BVD) virus (n = 12) or Mycoplasma bovis (n = 12), groups of calves were exposed to aerosols of Pasteurella haemolytica and were euthanatized 4 hours later. Histologic lesions in the lungs and the ratios of neutrophils to alveolar macrophages, collected by bronchoalveolar lavage, were compared with those of clinically healthy calves (n = 8) and calves inoculated with BVD virus only (n = 4), M bovis only (n = 4), or P haemolytica only (n = 2). Inoculation with BVD virus or M bovis did not have a significant (P greater than 0.05) effect on the neutrophil/macrophage ratio in the bronchoalveolar lavage. Aerosol exposure to P haemolytica induced a marked and significant (P less than 0.01) change in the neutrophil/macrophage ratio (from less than 1:9 to greater than 9:1). The reversed neutrophil/macrophage ratio in calves exposed to P haemolytica correlated well with the histologic changes in which small bronchi and bronchioles were plugged with purulent exudate. Inoculation with BVD virus did not induce gross or microscopic lesions in the lungs. Inoculation with M bovis resulted in a severe peribronchial lymphoid hyperplasia with mild exudation of neutrophils and macrophages into the cranioventral parts of the lungs.  相似文献   

5.
A noncytopathogenic field strain of bovine viral diarrhea virus (BVDV) was isolated from an Iowa farm brood sow and from her hysterectomy-derived, colostrum-deprived (HDCD) piglets. This field isolant was fully virulent for a neonatal calf. The NADL strain of BVDV was passaged through a series of HDCD piglets with no resultant loss of virulence for neonatal calves. Most of the BVD viral isolants recovered from pigs had been changed from a cytopathogenic biotype to a noncytopathogenic biotype. Circumstantial evidence points to swine as “carrier” hosts of BVDV.  相似文献   

6.
The percentage and absolute numbers of circulating B and T lymphocytes were determined for 10 healthy cattle by labeling mononuclear cells with anti-bovine immunoglobulin or peanut agglutinin. The cattle were then inoculated with a cytopathogenic isolate of bovine viral diarrhea (BVD) virus, and B- and T-lymphocyte populations were again quantitated at given intervals. Seemingly, BVD virus caused a decrease in the absolute numbers of B and T lymphocytes and in the percentage of T lymphocytes. Although these effects lasted through 7 days, all of the cattle recovered from infection and had detectable BVD virus-neutralizing antibodies in their sera 17 days after exposure.  相似文献   

7.
The present study was undertaken to investigate whether sequential exposure to aerosols of parainfluenza-3 virus followed by Pasteurella haemolytica, or P. haemolytica followed by parainfluenza-3 virus, could lead to the production of pulmonary lesions in conventionally-raised calves. Twenty male calves with low serum antibody titres to both organisms were placed in five equal groups. Synergism of parainfluenza-3 virus and P. haemolytica was not demonstrated in any of the sequentially infected groups and pulmonary lesions were mild in all challenged calves. Clinical signs of disease were not present after exposure to parainfluenza-3 virus although the virus was repeatedly isolated from nasal secretions of all inoculated calves. Exposure to P. haemolytica produced a transient response which consisted of increased rectal temperatures and respiratory rates, with a mild neutrophilic leukocytosis and a mild left shift present six hours postinoculation and returning to normal within 24 hours. Results from this study suggest, although do not confirm, that reduced pulmonary clearance of inhaled P. haemolytica in parainfluenza-3 virus infected calves does not necessarily lead to production of severe pulmonary lesions and that previous exposure to aerosols of P. haemolytica may not enhance secondary parainfluenza-3 virus infection.  相似文献   

8.
Five monoclonal antibodies against the bovine viral diarrhoea (BVD) viral strain NADL were isolated and characterized by an indirect immunofluorescence assay. Extensive cross-reactions were detected when the antibodies were tested with 12 heterologous BVD and four hog cholera (HC) viral strains. One antibody reacted with all strains tested. Two antibodies were specific for cytopathogenic BVD viruses, but failed to react with HC virus. The other antibodies reacted to varying degrees with BVD and HC viral strains.  相似文献   

9.
Four male dairy calves, ages 1-9 months, were inoculated intratracheally (IT), with log dilutions (1.5 X 10(3)-1.5 X 10(6)) of an isolate of P. haemolytica A-1. Doses of bacteria varied according to ages of the calves, older calves receiving the larger doses. All four calves became severely ill within 24 h after inoculation and antibiotic treatment was considered essential. Two months later the four calves remained healthy after IT injection of P. haemolytica, again given in log dilution (2.8 X 10(2)-2.8 X 10(5)). The control calf, given a dilution of only 28 viable P. haemolytica (plate count), developed severe respiratory infection 9 days post inoculation. Antibiotic treatment was given to this calf for 7 days, at which time recovery was evident. All five calves developed direct bacterial agglutination titers to P. haemolytica. Persistent leukocyte migration inhibition indexes of all calves were decreased by greater than or equal to 20% compared to their controls. Although the initial doses administered were low, the calves became ill. Most reports refer to massive doses necessary to produce primary disease and significant agglutination titers.  相似文献   

10.
A streptomycin-dependent, live Pasteurella haemolytica vaccine was given in 1 or 2 doses to 2 groups of weaned calves; 2 other groups of calves were not vaccinated. All calves in the vaccinated groups and calves in 1 of the nonvaccinated groups were stressed by transport, intratracheally inoculated with bovine herpesvirus type-1 (Cooper strain), and then intratracheally inoculated with P haemolytica type A1. The 4th group of calves (nonvaccinated controls) was not stressed and were not intratracheally inoculated with virus or bacteria. Mean daily weight gains, total clinical sign scores, lung lesion scores, plasma fibrinogen concentrations, and antibody titers against P haemolytica were determined at various intervals. Calves that had been vaccinated twice had greater mean daily weight gains and lower total clinical sign scores and lung lesion scores than did nonvaccinated, challenge-exposed calves, but the difference was not significant (P greater than 0.05). Calves vaccinated once had the greatest mean daily weight gains, the lowest total clinical sign scores, and the lowest lung lesion scores when compared with the other 2 challenge-exposed groups of calves. Mean daily weight gains and total clinical sign scores of calves vaccinated once were significantly different (P less than 0.05) than those of calves vaccinated twice. Nonvaccinated, nonchallenge-exposed control calves did not develop clinical signs of disease, did not develop lung lesions, and had consistently positive daily weight gains, and had scores in these areas that were significantly different (P less than 0.05) from those of all challenge-exposed groups of calves. Increases in plasma fibrinogen concentrations corresponded to infection with P haemolytica.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

11.
Healthy nonstressed calves were inoculated intranasally with or subjected to aerosol exposure to Pasteurella haemolytica serotype 1. Only 4 of 28 calves harbored the bacterium in enough numbers to be isolated from the nasal passages for more than 7 days. After apparent clearing from the nasal passages, 8 calves were inoculated intranasally with infectious bovine rhinotracheitis virus; 2 of these calves shed the P haemolytica during clinical illness due to the virus. The remaining 20 calves were aerosol-exposed to parainfluenza-3 virus; 6 of these calves shed P haemolytica during clinical illness due to the parainfluenza-3 virus.  相似文献   

12.
This study was initiated to determine the etiologic and pathogenic significance of an American strain of bovine viral diarrhea (BVD) virus (strain NADL-MD) in enteritis of neonatal calves (calf scours).

Three colostrum-fed calves from dams exposed intravenously to BVD virus at 6, 16 and 25 days prepartum, respectively, had moderate diarrhea persisting until the eighth day of life. The BVD virus was isolated from all 3 calves and persisted up to 93 days in 1 calf, indicating either that BVD was transmitted in utero or via the dam's milk.

Three specific pathogen free (SPF) calves permitted dams' colostrum for the first 4 feedings and then given milk replacer were exposed orally on the day of birth to BVD virus. One calf died of neonatal enteritis 28 hours post-exposure and at necropsy the BVD virus was isolated from several of its organs. The remaining 2 calves had a mild diarrhea persisting to the eighth day of age.

Two calves permitted dams' colostrum ad lib. for 72 hours, and then weaned, were exposed orally to BVD virus. Both calves had a mild persistent diarrhea and BVD virus was isolated from their blood for 56 days post-exposure.

Of 13 SPF, colostrum-deprived calves exposed orally or intranasally at birth to the BVD virus, 4 had severe diarrhea and died of neonatal enteritis from 38 hours to 13 days postexposure. Isolations of BVD virus were made from several of the organs of the calves at necropsy. All of the 9 surviving calves had a moderate to severe diarrhea frequently persisting for 7 to 10 days, and BVD virus was isolated from the survivors up to 103 days postexposure.

Several strains of Escherichia coli were isolated from calves after the second day of life, but were neither pathogenic for mice, nor serologically related to strains of E. coli usually associated with outbreaks of calf scours. Four colostrum-deprived SPF calves were exposed orally at birth to a strain of E. coli isolated from the intestine of the calf with the most acute symptoms and fatal neonatal enteritis. None of the four calves receiving the E. coli had diarrhea. One calf, however, had respiratory distress and died on day 5.

Two SPF colostrum-deprived control calves had neither diarrhea nor respiratory distress.

The above findings support the conclusion that BVD virus should not be overlooked as a primary cause of the neonatal calf enteritis complex.

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13.
Two trials were conducted to investigate the effects of supplemental chromium (Cr) from organic sources (Cr chelate and high Cr yeast) on antibody responses of newly arrived feeder calves following vaccination with infectious bovine rhinotracheitis (IBR), para-influenza-3 (PI3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea (BVD) and Pasteurella haemolytica and ovalbumin (OVA). Using cross bred steer calves purchased at sales in Ontario, vaccines and OVA were given on d 0 and 21 after arrival in the feedlot. Immune responses of calves were measured as serum specific antibody titres against all antigens on d 0 and 28 or d 35. The anti-OVA antibody responses (trial 2) were further investigated by measuring antibody concentrations of calves weekly until d 55 after arrival in the feedlot. Supplemental Cr (0.14 ppm) from an amino acid-chelated source had no effect on antibody responses to IBR, P13 and BRSV, but enhanced (P < 0.05) antibody titres of calves in response to the BVD vaccine on d 28 or d 35. Supplemental Cr from Cr yeast had no effect on antibody titres of calves to any vaccines. Chromium from both sources (trial 1 and 2) had no effect on antibody responses of calves following vaccination with P. haemolytica. However, supplemental Cr (0.75 ppm) from Cr yeast enhanced (P < 0.05) serum antibody responses of calves to OVA during the primary response (d 14) and secondary response (d 35) following immunization. These data confirmed our previous finding that supplemental Cr can enhance humoral immune response of market-transit stressed calves, but its enhancement on vaccine efficacy was antigen-dependent and variable.  相似文献   

14.
A subcutaneous soft tissue infection model in calves was used to study the in vivo response of Pasteurella haemolytica to erythromycin and dexamethasone. Two tissue chambers were implanted SC in each of 12 calves. At 45 days after implantation, all tissue chambers were inoculated with an erythromycin-sensitive strain of P haemolytica. Starting 24 hours after inoculation, calves were allotted to 4 groups of equal size and a 2 x 2-factorial arrangement of treatments was applied: 3 calves were given erythromycin (30 mg/kg of body weight, IM, for 5 days), 3 calves were given dexamethasone (0.05 mg/kg, IM, for 2 days), 3 calves were given erythromycin and dexamethasone, and the remaining calves served as nontreated controls. Chamber fluids were tested daily, and the response to treatment was measured. Neither erythromycin nor dexamethasone affected viability or growth of bacteria within tissue chambers. Dexamethasone had no effect on the influx of neutrophils into infected chambers. Despite repeated administration of a high dose of erythromycin and attainment of adequate concentration in serum, erythromycin concentration in chamber fluids did not exceed the minimal inhibitory concentration established in vitro. These results indicate that the clinical efficacy of erythromycin against P haemolytica sequestered in consolidated pneumonic lesions may not be well correlated with predictions based on serum pharmacokinetic and in vitro susceptibility data.  相似文献   

15.
Eight healthy nonstressed calves were inoculated with Pasteurella haemolytica serotype 1, by instilling a broth culture into the middle nasal meatus of the left nostril. The inoculated left nostrils shed P haemolytica from the ventral nasal meatus at a steady rate for a mean of 7 days, whereas the uninoculated right nostrils of the same calves shed P haemolytica sporadically and in lower concentrations. The duration, frequency, and concentration of P haemolytica shed from the inoculated nostrils was significantly (P less than 0.05) greater than from the nostrils of other healthy calves that had been exposed by instilling the culture into the ventral nasal meatus of both nostrils in a previous study. The concentration of antibodies (IgG, IgA, and IgM) to P haemolytica increased significantly (P less than 0.05) in serum and nasal secretions after exposure. Four weeks after initial P haemolytica exposure, calves were exposed to infectious bovine rhinotracheitis virus and became clinically ill. Four calves were induced to shed P haemolytica from both nostrils by the virus infection; thus, they were harboring the bacterium and were susceptible to active recolonization. Four calves were not induced to shed P haemolytica. The apparent reason was not that they were resistant to active colonization, but that they were no longer harboring the bacterium, because they became active shedders after they were reinfected with P haemolytica.  相似文献   

16.
Four healthy calves were inoculated with Pasteurella haemolytica serotype 1 by instillation of a broth culture into the middle nasal meatus of the left nostril. Four weeks later, calves were exposed to infectious bovine rhinotracheitis virus by aerosol into both nostrils. All calves became ill, from approximately day 3 through day 10 after virus exposure, and shed increased amounts of nasal mucus. Two calves were induced to shed P haemolytica by the virus infection, and 2 calves required reinoculation with P haemolytica for nasal passages to become actively colonized. Elastase activity in nasal mucus increased about 15-fold within 3 days and peaked about 60-fold over baseline by 7 days after virus exposure. Activity of N-acetyl-beta-D-glucosaminidase, a measure of cell damage and serum leakage, increased slightly by day 3 and reached plateau on day 5, almost threefold over baseline activity. Protein and carbohydrate content increased at a rate similar to that of N-acetyl-beta-D-glucosaminidase activity with about 12-fold and sixfold increases, respectively. None of the variables returned to baseline by 19 days after virus exposure. Increased elastase activity preceded colonization by P haemolytica and decreasing elastase activity preceded decreasing P haemolytica concentration in the nasal secretions. A causal relation between elastase activity and P haemolytica colonization could be mediated by cleavage of epithelial cell surface fibronectin and exposure of receptors.  相似文献   

17.
Acute lung injury was induced in 24 calves by intratracheal inoculation with Pasteurella haemolytica. Calves in groups 1 and 2 were neutrophil depleted, using hydroxyurea given IV. Group 1 calves (n = 7) were inoculated intratracheally with saline solution, and group 2 calves (n = 7) were inoculated with P haemolytica. Group 3 calves (n = 7) had normal numbers of neutrophils and were inoculated with P haemolytica. Group 4 calves (n = 3) were treated acutely with hydroxyurea IV, had normal numbers of neutrophils, and were inoculated with P haemolytica. After inoculation, calves with normal numbers of neutrophils (groups 3 and 4) became hypoxemic 2 hours after inoculation, and hypoxemia persisted until necropsy (6 hours after inoculation). These calves also developed tachypnea, bradycardia, neutropenia, and lymphopenia. Lung lesions consisted of necrosis of the alveolar walls, intra-alveolar hemorrhage, and a severe exudative and necrotizing bronchopneumonia, with accumulation of proteinaceous fluid in alveoli and lymphatics. In neutrophil-depleted calves (groups 1 and 2), blood gas values, heart and respiratory rates, and numbers of circulating leukocytes did not change after inoculation with saline solution or with P haemolytica. At necropsy, the lungs of neutrophil-depleted calves were grossly normal. Therefore, neutrophils were required for the acute lung injury induced by P haemolytica. The protective effect of neutrophil depletion was a specific effect of hydroxyurea because calves with high circulating concentrations of hydroxyurea and calves with normal numbers of neutrophils (group 4) developed lung injury.  相似文献   

18.
牛病毒性腹泻病毒BVDV-JL株的分离与鉴定   总被引：3，自引：0，他引：3  
本研究从吉林某牛场表现严重腹泻症状濒死牛的胸腺病料样品中分离一株病毒,该病毒在MDBK细胞中盲传4代无细胞病变产生,而通过RT-PCR和间接免疫荧光试验、微量血清中和试验检测表明该分离病毒株为牛病毒性腹泻病毒(BVDV),并命名为BVDV-JL.将BVDV-JL株F4代细胞培养液(10<'7.13>TCID<,50>/...  相似文献   

19.
Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenza-3 virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, nonstressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.  相似文献   

20.
A study was designed to develop and define a sc tissue chamber as a suitable device for establishing a soft-tissue infection model in cattle and to use this model to study the interaction between Pasteurella haemolytica, sulfadiazine/trimethoprim, and bovine viral diarrhea virus (BVDV). Thermoplastic tissue chambers were implanted in the paralumbar fossae of 20 calves. At 35 days after implantation, calves were allotted to 4 groups of equal size and the calves in 2 groups were inoculated intratracheally with a New York-1 strain of BVDV. At 45 days after implantation, all chambers were inoculated with a 6-hour culture of P haemolytica serotype 1. Starting 36 hours after bacterial inoculation, sulfadiazine/trimethoprim was administered IV once a day to half of the virus-inoculated calves and to half of those calves that had not been exposed to virus. Inoculation of P haemolytica into tissue chambers resulted in the establishment of a localized soft-tissue infection, characteristic of pneumonic pasteurellosis. Despite the maintenance of chamber antimicrobial concentrations that exceeded minimal bactericidal concentrations established in vitro, the infections were not sterilized. This lack of efficacy was associated with decreased pH and increased protein concentrations in chamber fluids after inoculation. Infection with BVDV, which is thought to depress host defenses, had no effect on the response of P haemolytica to sulfadiazine/trimethoprim administration. Observation of responsive antibody titers, bacterial phagocytosis, and high leukocyte viability within P haemolytica-infected chambers documented functional host defenses within tissue chambers.  相似文献   

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