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Effects of delivery method on serological responses of bighorn sheep to a multivalent Pasteurella haemolytica supernatant vaccine

by McNeil, Heather Joan

Abstract (Summary)
The eficacy and safety of a multivalent Pasreurella haemolyrica (serotypes A2 and TI0) supernatant vaccine using diflerent delivery systerns were examined in captive Roc- Mountain bighom sheep (Ovis canadenris canadensis). Thirty bighorn sheep were grouped according to baseline leukotoxin neutralizing antibody titres (52 or >Z log,-') and vaccination history @reviouslyvaccinated or unvaccinatrd). Within these grooupps. animals were randomly assigned to one of three delivery treatments: hand-injection (controi), biobullet implantation, or oral alginate microsphere suspension. Al1 30 treated bighorns received a single dose h m the same lot of vaccine (n =iO/treatrnent); to monitor potential changes in baseline titres. four additional anirnals were injected intramuscularly with 0.9% saline. Mild. transient larneness in most bighoms one day after receiving vaccine either by hand-injection or biobullet implantation was the only adverse effect observed. Sem neutralizing antibody titres to P. hoemolylica leukotoxin differed arnong delivery treatments (P = 0.009) and arnong baseline titre/vaccination history groups (P = 0.013). Neuualizing titres were highest among hand-injected bighorns; no sem antibody response was detscted mong bighorns vaccinated orally. Although neutralizing titres were lower arnong implanted bighorns than hand-injected controls for 2 2 weeks after vaccination (P < 0.02 l), seroconversion rates in response to implantation (6110) and hand injection (WO) did not differ (P = 0.303). Agglutinating antibody titres to Tl0 were high and did not vary ovsr time or between delivery treatments. Between 2 and 4 weeks post-vaccination, hand-injected controls had higher agglutinating antibody titers to A2 than those animals vaccinated orally (P < 0.026). Agglutkating antibody titres to A2 in the hand-injected controls were not different (P = 0.07) from those in bighorm vaccinated by biobullet implantation. These data demonstrate that although hand-injection elicits higher absolute titres than either biobullet implantation or oral vaccination, biobuilet implantation may also stimulate effective antibody responses to P. haemoiytica supernatant vaccine. Whether lack of serum antibody responses to oral vaccination tmly reflects failure to stimulate immunity remains undetermined. No attempt was made in this study to assess mucosal responses. Furthcr evaluation of biobullet vaccination against pneumonie pasteurellosis in populations of wild bighom sheep is warranted.
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Source Type:Master's Thesis

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Date of Publication:01/01/1999

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