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Title: Immune responses of calves after vaccination with a live attenuated derivative of Pasteurella multocida B:2
Author: Kachooei, Saeed Ataei
ISNI:       0000 0001 3593 7504
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2007
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The primary aim of this research was to investigate safety and potency of an aroA mutant of Pasteurella multocida serotype B:2 (JRMT12) as a live vaccine candidate in cattle against experimental haemorrhagic septicaemia (HS). To do this, three different experiments were set up to study the responses of calves to vaccination with the aroA strain and their response to challenge with the parent wild type 85020 strain one week after vaccination: 1) Different routes of vaccination, intranasal (IN) and intramuscular (IM) using two doses of 109 CPU of the aroA strain with a 4-week interval; 2) Different doses (107, 108 and 109 CFU) injected twice IM; 3) A single IM vaccination with 108 CPU. Safety of JRMT12 was assessed by determination of clinical responses (rectal temperature and demeanour) and changes in serum amyloid A (SAA) and haptoblobin (Hp), taken as indicators of the progress and severity of infection. IN injection of calves with c.109 CFU of the mutant did not cause any clinical signs of HS. IM injection of c. 109 CPU of the mutant caused some typical clinical signs of the disease such as dullness and there was a clinical response manifested by a rise in rectal temperature and SAA levels. IM injection of calves with lower doses (c.108 and c.107 CFU) of JRMT12 did not cause disease symptoms but significantly increased the concentrations of SAA levels at 3 hours after both the primary and booster IM vaccinations. Our results showed that the mutant could be safely administered to calves. Potency was assessed by measurement of serum antibodies (IgG and IgM) to P. multocida B:2 and by survival rate after subcutaneous challenge with the wild type strain. Vaccination with JRMT12 was able to induce a strong antibody response only after a second IM dose. Lower IgG titres were detected after the second vaccination with 108 or 107 CFU. A similar pattern of response was seen with IgM titres. IN-vaccinated calves showed no detectable antibody response to one or two doses of vaccine. All of the animals vaccinated twice IM with JRMT12 at doses of 109, 108 and 107 CPU were solidly immune to challenge with 107 CPU of P. multocida B:2 wild type. A single IM vaccination of calves with 108 CPU of JRMT12 did not confer protection against challenge. IM vaccination twice with 108 CFU was considered an optimum dose that fully protected calves but showed no obvious reactogenicity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available