ALBERT

Notes: Abstract. Six goats were injected transthoracically with live Pasteurella multocida A:3 to examine if an extracellular enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (n = 6) each received 1 ml of live 7.5 × 104 cfu of P. multocida mixed with polyacrylate beads transthoracically in the left lung on day 0 and 1 ml of live P. multocida (2.2 × 108 cfu) mixed with polyacrylate beads transthoracically in the left lung on day 22. Six goats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 22. Serum was obtained from all animals on days 0, 7, 14, 22, 29, and 36. Preimmune sera from all animals showed no detectable antibody to P. multocida A:3 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals demonstrated a significant antibody titer against the P. multocida A:3 neuraminidase. On day 36, serum samples from the six infected animals possessed complete enzyme-neutralizing activity. Anti-neuraminidase antibody could be detected as early as day 14 in the infected animals. These data show that neuraminidase is produced in vivo during an active P. multocida A:3 lobar infection.

Notes: Abstract. Thirteen clinical isolates of Pasteurella multocida from a variety of different animals and humans were examined for their ability to produce lipase. Lipase substrates used included Tween 20, Tween 40, Tween 80, and Tween 85. Lipase activity was detected in the filtrates of organisms grown to the exponential phase in Roswell Park Memorial Institute-1640 defined media (RPMI-1640), but activity increased in the filtrates when the cultures were allowed to proceed to the stationary phase. All strains examined (except for serotype 2) showed lipase activity against at least one of the Tweens. Tween 40 was the best substrate to demonstrate lipase activity. Pasteurella multocida serotype 8 produced the most active lipase against Tween 40 (3,561.7 units of activity/μg of protein). This activity continued to increase after P. multocida entered a stationary growth phase. P. multocida lipase activity was optimal at pH 8.0. Lipase activity of P. multocida serotype 8 was eluted from a Sepharose 2B column at several points, indicating that several lipases may be produced in vitro by this organism. These data demonstrate that clinical isolates of P. multocida produce lipase; therefore, this enzyme should be considered a potential virulence factors for this organism.

Notes: Abstract. Cross-protection studies employing three serotypes of Pasteurella haemolytica (Ph) were performed in goats, with challenge exposure by transthoracic injection. Indirect hemagglutination (IHA) serum titers showed that the herd had been naturally infected with Ph biovar A, serovar 2 (PhA2) prior to the study. Sixty-four weanling male Spanish goats were randomly allotted to 16 groups. Fifteen goats were given two transthoracic injections into the lungs 21 days apart with live Pasteurella haemolytica biovar A, serovar 1 (PhA1) in agar beads. Fifteen goats were given two transthoracic injections into the lungs 21 days apart with live PhA2 in agar beads. Sixteen goats were given two transthoracic injections into the lungs 21 days apart with live P. haemolytica biovar A, serovar 6 (PhA6) in agar beads. Eighteen control (CON) goats were given two transthoracic injections into the lungs 21 days apart with agar beads alone. Fourteen days after the second injection, goats were challenge-exposed to either live PhA1, PhA2, or PhA6 by transthoracic injection into the lung, and 4 days later, all goats were euthanatized and necropsied. Serum antibody to P. haemolytica antigens was measured throughout the experiment. Mean volumes of consolidated lung tissue for the CON goats challenged with PhA1, PhA2, and PhA6 were 28.29 cm3, 8.36 cm3, and 16.29 cm3, respectively. Mean volumes of consolidated lung tissue for the PhA1-immunized goats challenged with PhA1, PhA2, and PhA6 were 4.38 cm3, 0.25 cm3, and 1.90 cm3, respectively. Mean volumes of consolidated lung tissue for the PhA2-immunized goats challenged with PhA1, PhA2, and PhA6 were 9.68 cm3, 0.05 cm3, and 3.39 cm3, respectively. Mean volumes of consolidated lung tissue for the PhA6-immunized goats challenged with PhA1, PhA2, and PhA6 were 14.05 cm3, 1.27 cm3, and 4.53 cm3, respectively. These data demonstrate protection in immunized goats challenged with the homologous serotype of P. haemolytica. PhA1-immunized animals were protected against serotype 2 challenge as well as against serotype 6 challenge. PhA2-immunized animals were not protected against serotype 1 challenge, but were protected against transthoracic PhA6 challenge. PhA6-immunized animals were not protected against serotype 1 challenge, but were protected against transthoracic PhA2 challenge. There appears to be some cross-protection among the P. haemolytica serotypes, and this fact should be taken into consideration when developing vaccines against this organism.

Notes: Abstract A total of 721 field isolates of various Pasteurella species (haemolytica, multocida, and testudinis) from various regions of the United States were examined for extracellular neuraminidase production. All strains were grown and tested in the same way. Included were 372 P. haemolytica serotype 1 isolates, 181 P. haemolytica serotype 2 isolates, 63 P. haemolytica serotype 6 isolates, 101 Pasteurella multocida isolates, and 4 Pasteurella testudinis isolates. All Pasteurella species examined produced the enzyme. The data revealed the following: (1) Several transfers of P. haemolytica strains on blood agar medium did not cause a decrease in enzyme activity. (2) P. haemolytica serotypes 2 and 6 produce more neuraminidase than P. haemolytica serotype 1, P. multocida, and P. testudinis isolates. (3) There was no apparent change in neuraminidase production by P. haemolytica serotypes 1 and 2 obtained from the same animal taken on different days in the feedyard. (4) There was no significant change in neuraminidase production by P. haemolytica serotype 2 isolates taken from the same animal at the auction market and later at the feedyard.

Notes: Abstract. Positive control 1 (PC1) (n = 9) goats were injected transthoracically into the left lung with live Pasteurella haemolytica biovar A, serovar 1 (PhA1) in polyacrylate (PA) beads on days 0 and 21. Positive control 2 (PC2) (n = 6) goats were nebulized with live PhA1 and PA beads on days 0 and 21. Negative control (NC) goats (n = 6) were each injected transthoracically into the left lung with PA beads alone on days 0 and 21. Four groups (n = 6) were administered PA beads mixed with ultraviolet (UV) killed PhA1 on days 0 and 21. The treatment doses of bacteria for these groups were principal group 1 (PR1) injected into the left lung (7.7 × 1010 cfu); PR2, 7.7 × 1010 UV-killed PhA1 injected subcutaneously (SC); PR3, 7.7 × 1010 UV-killed PhA1 injected SC only on day 21; PR4, nebulized with PA beads mixed with 5.6 × 1010 cfu of UV-killed PhA1; and PR5, nebulized with PA beads mixed with 5 × 108 cfu of UV-killed PhA1. All goats were challenged transthoracically in the right lung with 1 × 108 cfu of live PhA1 on day 42 and necropsied on day 46. The sizes of consolidated lung lesions at the challenge site were used as a measure of immunity. The data show that the introduction of live PhA1 into the lungs of goats, either by injection or aerosolization, offers excellent protection against a subsequent homologous challenge. The data also demonstrate that two transthoracic injections (21 days apart) of UV-killed PhA1 (PR1), and subcutaneous injection of UV-killed PhA1(PR2) also offer excellent protection against a subsequent homologous live PhA1 challenge. One SC injection of UV-killed PhA1 (PR3) appears to offer only partial protection against a subsequent homologous live PhA1 challenge. Inhalation of UV-killed PhA1 mixed with PA beads (PR4 and PR5) induced no protection in goats against a subsequent live PhA1 transthoracic challenge.

Notes: Abstract. Ninety-one isolates of Pasteurella multocida (Pm) and 124 of Pasteurella haemolytica (Ph) were recovered from the lungs of calves that died of bovine respiratory tract disease (BRTD). Nine Pm enzyme profiles (A through I) and 9 Ph enzyme profiles (J through R) were determined for the Pasteurella isolates. The Pm isolates were relatively evenly divided among the enzyme profiles, with one exception, profile I. The Ph isolates were not evenly distributed among the profiles. Fifty of the 91 Pm isolates were serotyped. Forty-two Pm isolates were positive for capsule type A, and 8 were untypable. Five somatic type antigen profiles (3; 3,4; 3,7; 3,4,7; and 4) were identified among the 50 serotyped Pm isolates; one isolate was untypable. The Ph isolates were further divided through serotyping and grouped as follows: 74 (60%) Pasteurella haemolytica A1 (PhA1), 12 (10%) PhA2, 4 (3%) PhA5, and 34 (27%) PhA6. Eighty-one percent of the Ph serotypes were clustered in the M and N enzyme profile. The P enzyme profile was almost unique to PhA2 (8 of 12, 67% of PhA2 isolates). Results of this study indicate a need to collect more data on Ph serotypes at the state veterinary diagnostic laboratories.

Notes: Abstract. Pasteurella haemolytica (Ph) is the most important cause of the bovine acute fibrinohemorrhagic pneumonia that occurs in market stressed calves after shipment to feedyards. Recent characterization of neuraminidase production by these organisms has shown that all 16 serotypes produce an immunologically similar form of the enzyme. Anti-neuraminidase antibody against PhA1 and PhA6 was determined in 101 2- to 5-month-old calves, on their farms of origin, at the order buyer barn (OBB), and through 28 days in the feedyard. Half of the calves were vaccinated with a killed Ph serotype-A1 (PhA1) product. Nasal secretion and tonsil wash specimens were cultured for Ph and Pasteurella multocida (Pm). Serum antibody against PhA1 and PhA6 was measured by indirect hemagglutination (IHA), and anti-neuraminidase antibody was determined by the neutralization assay. At the feedyard, 73 calves had respiratory tract disease. IHA values ranged between 1:2 and 1:1024 for PhA1 and between 1:2 and 1:512 for Ph serotype A6 (PhA6). Forty-two, 24, and 28% of the calves were infected with PhA1, PhA6, and Pm, respectively. Ninety-six percent of the calves experienced an increase in anti-PhA1 neuraminidase antibody when sera drawn on feedyard day 28 were compared with sera drawn on the farm. These data demonstrate that the enzyme neuraminidase is produced in vivo in market stressed cattle after a natural Ph infection.