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Abstract

OBJECTIVE To evaluate changes in systemic and ocular antibody responses of steers following intranasal vaccination with precipitated or partially solubilized recombinant Moraxella bovis cytotoxin (MbxA).

ANIMALS 13 Angus steers with ages ranging from 318 to 389 days and weights ranging from 352 to 437 kg.

PROCEDURES Steers were assigned to receive 500 μg of a precipitated (MbxA-P; n = 5) or partially solubilized (MbxA-S; 5) recombinant MbxA subunit adjuvanted with polyacrylic acid. A control group (n = 3) received the adjuvant alone. Each steer received the assigned treatment (1 mL/nostril) on days 0 and 28. Serum and tear samples were collected on days 0 (before vaccination), 14, 28, 42, and 55. Changes in MbxA-neutralizing antibody titers and MbxA-specific IgG concentrations in serum and tears and changes in MbxA-specific IgA concentrations in tears were measured.

RESULTS Mean fold changes in MbxA-specific IgG concentration in serum and tears and MbxA-neutralizing antibody titer in tears for the MbxA-P group were significantly greater than those for the MbxA-S and control groups. Mean serum MbxA-neutralizing antibody titer did not differ among the 3 groups. Although the mean fold change in tear MbxA-specific IgA concentration differed significantly among the groups in the overall analysis, post hoc comparisons failed to identify any significant pairwise differences.

CONCLUSIONS AND CLINICAL RELEVANCE Systemic and ocular immune responses induced by intranasal administration of the MbxA-P vaccine were superior to those induced by the MbxA-S vaccine. Additional research is necessary to determine whether the MbxA-P vaccine can prevent naturally occurring infectious bovine keratoconjunctivitis.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals.

Animals—12 healthy weanling foals.

Procedures—Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical observation and ultrasonographic evaluation of the small intestine were performed, and body weight, serum concentration of total solids, fecal excretion of L intracellularis, and seroconversion were measured for each foal until day 56. Diseased foals were treated with antimicrobials and supportive care.

Results—None of the 4 vaccinated foals developed clinical disease following challenge with virulent L intracellularis. Three of 4 nonvaccinated foals developed moderate to severe clinical signs compatible with proliferative enteropathy, hypoproteinemia, and thickened small intestinal loops. Vaccinated foals had significantly less fecal shedding of L intracellularis than nonvaccinated foals. Serologic responses between vaccinated and nonvaccinated foals after challenge were similar. Control foals remained clinically unaffected with no evidence of fecal shedding and seroconversion.

Conclusions and Clinical Relevance—Intrarectal administration of a commercial avirulent porcine vaccine against L intracellularis resulted in complete protection against proliferative enteropathy in the foals in this study and may also reduce environmental contamination with the organism on endemic farms.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate efficacy of a recombinant Moraxella bovis pilin-cytotoxin-Moraxella bovoculi cytotoxin subunit vaccine to prevent naturally occurring infectious bovine keratoconjunctivitis (IBK).

Animals—107 beef steers.

Procedures—2 groups of calves were inoculated SC with an immunostimulating complex (ISCOM) matrix adjuvant (control group; n = 54) or a recombinant M bovis pilin-cytotoxin–M bovoculi cytotoxin subunit antigen with the ISCOM matrix adjuvant (vaccine group; 53); calves received booster injections 21 days later. Calves were examined once weekly for 16 weeks. Investigators and herd managers were not aware of the inoculum administered to each calf throughout the trial. Primary outcome of interest was the cumulative proportion of calves that developed IBK. Serum samples were obtained before inoculation (day 0) and on days 42 and 112. Serum hemolysin-neutralizing titers against native M bovis and M bovoculi cytotoxin were determined.

Results—No difference was detected between groups for the cumulative proportion of calves that developed IBK at weeks 8 and 16 after inoculation. Non–IBK-affected calves in the vaccine group had a significantly higher fold change in serum hemolysin-neutralizing titer against native M bovoculi cytotoxin from day 0 to 42 compared to control calves.

Conclusions and Clinical Relevance—The M bovis pilin-cytotoxin-M bovoculi cytotoxin subunit vaccine with the ISCOM matrix adjuvant was not effective at preventing naturally occurring IBK. It is likely that the incorporation of additional protective antigens in a recombinant Moraxella spp subunit vaccine will be required to yield a product that can be used for effective immunization of cattle against IBK.

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in American Journal of Veterinary Research

. 10.1016/S0167-5877(01)00181-7 5. USDA APHIS Veterinary Services Centers for Epidemiology and Animal Health . Persistent infection of calves with bovine viral diarrhea virus on U.S. beef cow-calf operations . No. 551.0609. Fort Collins, Colo

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in American Journal of Veterinary Research

.1.3 13. Gay JR . Epidemiology concepts for disease in animal groups . Available at: www.vetmed.wsu.edu/courses-jmgay/EpiMod2.htm . Accessed May, 21, 2008 . 14. House JK Ontiveros MM Blackmer NM , et al. Evaluation of an autogenous

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in American Journal of Veterinary Research

), in Proceedings . 2nd Int Vet Vaccines Diagn Conf 2000;36. h. Daly JM, Newton JR, Park A. Current epidemiology and evolution of influenza A H3N8 strains (abstr), in Proceedings . 9th Cong World Equine Vet Assoc 2006;4–9. References 1

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in American Journal of Veterinary Research

. Dairy 2007, part II: changes in the US dairy cattle industry, 1991–2007. No. N481.0308 . Fort Collins, Colo : USDA APHIS Veterinary Services Center for Epidemiology and Animal Health , 2008 . 2. Kaneene JB , Hurd S . The national animal health

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in American Journal of Veterinary Research