Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves

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.     

Exposure of calves to aerosols of parainfluenza-3 virus and Pasteurella haemolytica.

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.     

Selenium effects on glutathione peroxidase and the immune response of stressed calves challenged with Pasteurella hemolytica

The present study was conducted to determine whether a marginal Se deficiency affects health, blood characteristics and the immune response of calves subjected to stresses associated with weaning, shipping (332 km) and Pasteurella hemolytica inoculation. Treatments were 1) -Se, 2) -Se/P. hemolytica, 3) +Se (.1 mg Se/kg feed) and 4) +Se/P. hemolytica. Previous Se intake was controlled; dams of -Se calves were fed diets marginally deficient in Se (.03 to .05 mg/kg), whereas dams of +Se calves received a s.c. injection of 30 mg Se (as sodium selenite) every 60 d. Calves were inoculated with P. hemolytica intratracheally on d 3 following weaning and transport. Inoculation with P. hemolytica increased (P less than .05) body temperatures, platelet counts, serum IgM concentrations and serum antibody titers and decreased serum albumin concentrations at 4 to 7 d postinoculation. Weight gains for the 21-d study were not affected by Se status, although whole blood and plasma glutathione peroxidase (GSH-Px) were higher (P less than .05) for +Se calves. Plasma GSH-Px increased (P less than .01) in calves showing signs of morbidity. Increases in plasma GSH-Px were correlated positively with body temperature. Serum IgM concentrations were higher (P less than .05) in +Se calves on d 17, but Se-supplemented calves had lower (P less than .05) anti-P. hemolytica titers on d 17 than -Se calves. Selenium status did not affect body temperatures, plasma creatine phosphokinase or serum IgG and albumin concentrations. These results indicate that Se status can affect IgM concentrations following stress.     

The pulmonary clearance of Pasteurella haemolytica in calves given Corynebacterium parvum and infected with parainfluenza-3 virus.

Four control calves were aerosolized with parainfluenza-3 and one week later with Pasteurella haemolytica. Three calves were given Corynebacterium parvum at a dose of 15 mg/m2 body surface area, infected with parainfluenza-3 virus one week later, and aerosolized with P. haemolytica two weeks after C. parvum injection. All calves were killed four hours after P. haemolytica exposure and the bacterial retention in the lung was determined. Parainfluenza-3 viral infection did not exert any suppressive effect on pulmonary clearance of P. haemolytica in six out of seven calves used. However, the bacterial colony counts in the lungs of control calves were higher (P less than 0.05) than those in calves given C. parvum. Hence, C. parvum appeared to enhance bacterial clearance. Despite the marked influx of neutrophils into the lungs after the bacterial inoculation, the neutrophil:macrophage ratio in lavage samples was less in calves given C. parvum than in the control calves. The alveolar macrophages in C. parvum treated calves were generally larger but did not differ significantly (P less than 0.05) from those in the controls. There was no significant (P less than 0.05) correlation between the percentages of alveolar macrophages and the bacterial clearance. In calves given C. parvum, bacterial clearance was enhanced in those calves which had larger macrophages.     

Induction of immunity against pneumonic pasteurellosis following experimental infection in calves.

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.     

The pulmonary clearance of Pasteurella hemolytica in calves infected with bovine parainfluenza-3 virus.

The purpose of this study was to determine if parainfluenza-3 virus in calves interfered with normal pulmonary bacterial clearance. Three groups (A, B and C) of four calves each were exposed to an aerosol of parainfluenza-3 virus. Three days later the four hour pulmonary clearance of Pasteurella hemolytica was determined on the first group (A), seven days later on the second (B) and 11 days later on the third (C). Group A had a mean pulmonary bacterial retention of 3.6 +/- 3.5%. Group B was 83.1 +/- 35.9% and Group C was 41.2 +/- 30.9%. The results demonstrate that parainfluenza-3 virus interfered with the pulmonary bacterial clearance of Pasteurella hemolytica particularly on day 7 and also on day 11 but not on day 3. This inhibition of pulmonary clearance caused by the virus may be a key factor in the pathogenesis of pneumonic pasteurellosis. Histological examination of the lungs did not demonstrate a correlation between pulmonary retention of bacteria and the development of pathological changes.     

Colonization of the nasal passages of calves with Pasteurella haemolytica serotype 1 and regeneration of colonization after experimentally induced viral infection of the respiratory tract

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.     

Serum complement-fixing antibody to Pasteurella haemolytica A1 and its effect on experimentally induced pneumonic pasteurellosis in calves

Ninety-three calves comprising 16 experimental groups were exposed to viral (bovine herpesvirus-1 or parainfluenza-3 virus) and Pasteurella haemolytica aerosols. Serum samples from these calves were tested before and after exposure for antibodies to P haemolytica by a modified direct complement-fixation test. At slaughter of the calves, the extent of pneumonia produced was estimated for each calf and compared with the results of the modified direct complement-fixation tests. The extent of pneumonia was not related (P greater than 0.05) to the amount of anti-P haemolytica antibody produced by either naturally occurring or experimentally induced infection.     

Immunologic and physiologic responses of calves inoculated with potassium thiocyanate extract of Pasteurella multocida type A

Inoculation of calves with potassium thiocyanate (KSCN) extract of Pasteurella multocida type A in saline-tris buffer or in Freund's incomplete adjuvant or modified Freund's incomplete adjuvant resulted in the elicitation of agglutinating, hemagglutinating, bactericidal and homocytotropic antibodies. The antibody response was significantly (P = 0.05) higher in calves inoculated with the KSCN extract in either adjuvant than in those inoculated with the extract in saline-tris buffer. Hemagglutination also was observed if the KSCN extract of P hemolytica was used for sensitizing the tanned sheep red blood cells. Further, calf anti-P multocida extract antisera also was bactericidal to P hemolytica. The KSCN extract of P multocida was found to be nontoxic to calves at 2 doses tested, as judged by an evaluation of total and differential leukocyte counts, body temperature, and pulse rates at various intervals after inoculation.     

Preliminary Observations on the Effect of Specific Immunity on Nasal Bacterial Flora

This investigation has shown that Pasteurella hemolytica could actively colonize the nasal cavity of calves in the presence of indirect hemagglutinating IHA antibody against that particular strain. It was not determined if the level of nasal IHA antibody to Past. hemolytica had an effect on colonization of the nasal passage by Past. hemolytica. Specific immunity to Past. hemolytica would appear to be important in respiratory disease induced by this organism.     

Production of cattle immunotolerant to bovine viral diarrhea virus.

Inoculation of bovine virus diarrhea virus into 58 to 125 day old fetuses of bovine virus diarrhea virus seropositive pregnant cows, or inoculation of bovine virus diarrhea virus into seronegative cows 42 to 114 days pregnant, may produce clinically normal calves which are persistently infected with the specific isolate of bovine virus diarrhea virus yet seronegative to the homologous and heterologous isolates. Reinoculation of these persistently infected cattle with their homologous isolate produced no neutralizing antibody response to bovine virus diarrhea virus. These persistently infected cattle were immunocompetent as they developed neutralizing serotiters to infectious bovine rhinotracheitis, parainfluenza-3 viruses and agglutinating serotiters to Pasteurella hemolytica .     

Respiratory disease in calves produced with aerosols of parainfluenza-3 virus and Pasteurella haemolytica.

In four experiments, 22 calves were exposed to aerosols of parainfluenza-3 virus, followed by Pasteurella haemolytica at intervals of three to 13 days. The purpose of each experiment was to study viral-bacterial interactions in the respiratory tracts. Two experiments, in which the viral aerosols were diluted by the addition of air, produced sporadic temperature elevations while two experiments with undiluted viral aerosols produced consistent temperature elevations. Diluted viral aerosols produced lobular sized lesions in the lungs and hemagglutinating inhibition antibodies in sera, whilst undiluted aerosols produced a synergistic effect in the form of purulent pneumonia in ten of 14 calves when the interval between viral and bacterial aerosols was from three to ten days. Histopathological changes attributable to the virus only were seen in all experiments, and the histopathological changes due to mixed infection of parainfluenza-3 virus and P. haemolytica are described in detail. This is the first report of extensive purulent pneumonia in calves after parainfluenza-3 virus and P. haemolytica exposure. This was achieved using much smaller inocula than in experiments previously reported.     

Clinical and immunologic responses of calves with colostrally acquired maternal antibody against parainfluenza-3 virus to homologous viral infection.

Exposure of colostrum-deprived calves and calves with colostrally acquired maternal antibody to aerosols of parainfluenza-3 (PI-3) virus resulted in signs of infection, leukopenia, and shedding of virus from the nasal passages. However, infection was not as severe in calves with colostrally acquired maternal antibody as it was in colostrum-deprived calves which did not have antibody to PI-3 virus before they were exposed. All calves responded immunologically to PI-3 virus, as indicated by resistance to challenge exposure and subsequent development of virus-neutralizing antibody. However, levels of serum and nasal secretion (NS) antibody at 30 days after viral exposure were lower in calves with colostrally acquired maternal antibody than in colostrum-deprived calves, and a serum antibody response in the former was primarily indicated by an anamnestic response after challenge exposure. After calves were challenge exposed to PI-3 virus, serum and NS antibodies were increased in all calves, but antibody titers were generally lower for calves that had colostrally acquired maternal antibody before their exposure than for those that acquired antibody only after PI-3 viral infection.     

Preliminary studies with a live streptomycin-dependent Pasteurella multocida and Pasteurella haemolytica vaccine for the prevention of bovine pneumonic pasteurellosis.

Twelve Pasteurella-free Holstein-Friesian calves were used in a study to test the efficacy of a live streptomycin-dependent Pasteurella multocida A:3 and streptomycin-dependent Pasteurella haemolytica A1 vaccine. The calves were inoculated intramuscularly twice at 14-day intervals with either the streptomycin-dependent vaccine, containing 1 X 10(6) colony forming units/mL P. multocida and 4 X 10(8) colony forming units/mL P. haemolytica, commercial bacterin, or phosphate buffered saline. Two weeks following the second vaccination, all calves were challenged by intranasal inoculation of 10(8) TCID50/4.0 mL infectious bovine rhinotracheitis virus followed three days later by intratracheal injection with 2.3 X 10(7) colony forming units/mL of a 16 hour culture of P. multocida A:3 and 2.6 X 10(8) colony forming units/mL of an 8 hour culture of P. haemolytica A1. Seven days after challenge with Pasteurella, calves were killed for collection of tissues at necropsy. Each calf was given a score based on macroscopic and microscopic lesions. The scores for the calves receiving live vaccines were significantly lower (p less than 0.025) than those for the controls. Also, the calves receiving live vaccines had a significant (p less than 0.05) increase in the level of serum antibody to P. haemolytica. The results of this preliminary study showed that the streptomycin-dependent vaccine offered better protection than the commercial bacterin against a virulent homologous challenge.     

Some observations on the use of the morantel sustained-release bolus in first season-grazing calves on a Belgian dairy cattle farm

The efficacy of the morantel sustained-release bolus (MSRB) in controlling gastrointestinal parasites in first-season grazing calves was evaluated on a dairy cattle farm in Belgium. The calves grazed a pasture which had been used by bolus-treated animals in the three previous years. The effect of bolus administration was determined with respect to live weight gain, faecal egg shedding, herbage larval counts, serum pepsinogen levels and ELISA antibody titres. In spite of an incomplete reduction of faecal egg shedding during the first months of the grazing season, bolus administration resulted in the prevention of parasitic gastro-enteritis in the calves. A weight gain advantage of 35,2 kg of the bolus-treated animals over the controls was noted already at two months after turnout. This weight gain advantage was maintained until housing. The usefulness of serum pepsinogen values and ELISA antibody titres as parameters in prevention experiments is stressed. Both serological parameters gave more information concerning infection level than did the faecal egg output and the herbage larval counts.     

Antibody titers to Pasteurella haemolytica A1 in Ontario beef cattle.

Indirect bacterial agglutination titers to Pasteurella haemolytica A1 were determined in serum, thoracic, pericardial, or peritoneal fluid from cattle necropsied as part of the Bruce County Beef Project in 1979-80 and 1980-81. Antibody titers were also assayed in serum from 84 calves on entry to feedlots in the fall of 1979. Titers on entry were low compared to antibody levels at necropsy. Cattle which died with pneumonia, in particular those dying of fibrinous pneumonia (shipping fever), had lower levels of antibody to P. haemolytica than did those dying of other causes.     

Effect of supplemental chromium on antibody responses of newly arrived feeder calves to vaccines and ovalbumin.

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.     

Effects of experimentally induced Pasteurella haemolytica pneumonia on the pharmacokinetics of erythromycin in the calf

Pneumonic pasteurellosis was produced experimentally in 3- to 4-month-old Holstein bull calves by bilateral intrapulmonary administration of 5 X 10(7) to 10(9) colony-forming units of Pasteurella haemolytica. Of 8 calves, 4 developed minor pulmonary changes, 1 died of an apparent bacteremia within 24 hours, and 3 developed extensive pneumonic changes. At 1 week before (1 dose) and at 48, 60, and 72 hours (3 doses) after Pasteurella administration, the calves were given erythromycin at a dosage of 15 mg/kg, and the pharmacokinetic values were determined. There were statistically (P less than or equal to 0.05) significant increases in the distribution and elimination rates associated with pneumonia. The elimination half life decreased from 132.7 +/- 9.6 minutes in prepneumonic calves to 111.1 +/- 13.8 minutes and 99.7 +/- 2.6 minutes in calves with minor and with moderate pneumonic changes, respectively. There also was a decrease in apparent volume of distribution with pneumonia. Erythromycin tissue concentrations were determined 2 hours after the last dose was given to the calves with pneumonia. Tissue concentrations in the pneumonic lung areas were as high or higher than those in nonaffected lung tissues in the same animals. Because of the increased rate of elimination from serum in pneumonic calves, it may be advisable to use shorter dosage intervals in calves with severe respiratory tract disease.     

Colonization of the tonsils of calves with Pasteurella haemolytica.

Tonsils of 10 calves were inoculated with Pasteurella haemolytica (PH) and the degree of colonization was followed by collecting sequential tonsil. wash specimens. Tonsils were colonized for at least 3 weeks after instillation of PH into the tonsillar sinus. Calves with colonized tonsils responded with serum and nasal secretion antibody responses to PH and to leukotoxin. Pasteurella haemolytica was detected in nasal mucus specimens of 2 calves during the week after inoculation of the tonsils, but all other specimens were culture-negative. Infectious bovine rhinotracheitis virus-induced respiratory tract disease 25 days later did not elicit a population increase of PH in the tonsils, and did not elicit shedding of PH in nasal mucus.     

Isolation of Pasteurella haemolytica and correlation with serum antibody response in clinically normal beef calves

Bacteria from the nasal cavity and trachea were cultured, and serum antibody titers determined for Pasteurella haemolytica serotype 1 in 164 beef calves obtained from a closed herd on range pasture. At the first sampling, P. haemolytica serotype 1 was cultured from 16.4% of the calves. Antibody titers were determined by a quantitative fluorimetric method and the mean titer was 9.5 +/- 5.8. Fifty-seven randomly selected calves were used to study the correlation of serum antibody response and positive culture of P. haemolytica under natural conditions. Clinical signs of respiratory disease were not observed in those calves. During the observation periods, there was a two-fold increase in the percentage of calves that were culture positive. There was no significant difference between mean serum antibody titers or frequency distribution of antibody titers from the two samplings. Comparisons between serum antibody titers, rise in titers, and P. haemolytica isolation failed to reveal any significant correlation. Of the 9 calves that had a decline in antibody titer to P. haemolytica, none was culture positive. Seroconversion to respiratory viruses did not correlate with P. haemolytica related variables.