Objective—To determine whether a combination viral
vaccine containing modified-live bovine herpesvirus-1
(BHV-1) would protect calves from infection with a
recent field isolate of BHV-1.
Design—Randomized controlled trial.
Animals—Sixty 4- to 6-month-old beef calves.
Procedure—Calves were inoculated with a placebo
42 and 20 days prior to challenge (group 1; n = 10) or
with the combination vaccine 42 and 20 days prior to
challenge (group 2; 10), 146 and 126 days prior to challenge
(group 3; 10), 117 and 96 days prior to challenge
(group 4; 10), 86 and 65 days prior to challenge (group
5; 10), or 126 days prior to challenge (group 6; 10). All
calves were challenged with BHV-1 via aerosol.
Clinical signs, immune responses, and nasal shedding
of virus were monitored for 14 days after challenge.
Results—Vaccination elicited increases in BHV-1–specific
IgG antibody titers. Challenge with BHV-1 resulted
in mild respiratory tract disease in all groups, but
vaccinated calves had less severe signs of clinical disease.
Extent and duration of nasal BHV-1 shedding following
challenge was significantly lower in vaccinated
calves than in control calves. In calves that received 2
doses of the vaccine, the degree of protection varied
with the interval between the last vaccination and
challenge, as evidenced by increases in risk of clinical
signs and extent and duration of viral shedding.
Conclusions and Clinical Relevance—Results suggest
that this combination vaccine provided protection from
infection with virulent BHV-1 and significantly reduced
nasal shedding of the virus for at least 126 days after vaccination.
(J Am Vet Med Assoc 2005;227:123–128)
Objective—To determine whether single-fraction and combination modified-live bovine respiratory syncytial virus (BRSV) vaccines commercially licensed for parenteral administration could stimulate protective immunity in calves after intranasal administration.
Design—Randomized controlled trial.
Procedures—Calves were separated from dams at birth, fed colostrum with a minimal concentration of antibodies against BRSV, and maintained in isolation. In 2 preliminary experiments, 9-week-old calves received 1 (n = 3) or 2 (3) doses of a single-component, modified-live BRSV vaccine or no vaccine (8 control calves in each experiment), and were challenged with BRSV 21 days after vaccination. In a third experiment, 2-week-old calves received combination modifiedlive virus (MLV) vaccines with or without BRSV and calves were challenged with BRSV 8 days later. Calves were euthanized, and lung lesions were measured. Immune responses, including serum and nasal antibody and nasal interferon-α concentrations, were assessed.
Results—BRSV challenge induced signs of severe clinical respiratory tract disease, including death and pulmonary lesions in unvaccinated calves and in calves that received a combination viral vaccine without BRSV. Pulmonary lesions were significantly less severe in BRSV-challenged calves that received single or combination BRSV vaccines. The proportion of calves that shed virus and the peak virus titer was decreased, compared with control calves. Protection was associated with mucosal IgA antibody responses after challenge.
Conclusions and Clinical Relevance—Single and combination BRSV vaccines administered intranasally provided clinical protection and sparing of pulmonary tissue similar to that detected in response to parenteral delivery of combination MLV and inactivated BRSV vaccines previously assessed in the same challenge model.
Objective—To determine the prevalence of antibodies against a swine-origin Helicobacter pylori–like organism (HPLO) and H pylori in conventionally reared swine.
Animals—640 conventionally reared swine of various ages from 16 high-health farms in Canada, 20 sows from Ohio, and 35 gnotobiotic swine.
Procedures—Blood was collected from the cranial vena cava. Sera were collected and tested via ELISA for antibodies against antigen prepared from a swine-origin HPLO and human H pylori strain 26695.
Results—Antibodies reactive with a swine HPLO, H pylori, or both were detected in 483 of 640 swine from all 16 farms in western Canada. Seroprevalence varied with age and was low (5.6%) in suckling (≤ 4-week-old) swine and increasingly high in swine ranging from > 4 weeks old to adulthood.
Conclusions and Clinical Relevance—Findings suggested that colonization by a swine-origin HPLO, H pylori, or both and resultant seroconversion, like that of H pylori infection in humans, were common in commercial swine operations. Furthermore, data indicated that gastric infection was acquired at an early age. The relationships to gastric colonization by HPLOs and clinical manifestations of disease such as gastritis and gastroesophageal ulceration remain to be determined.
Objective—To determine whether a combination viral vaccine containing a modified-live bovine herpesvirus-1 (BHV-1) would protect calves from infection with virulent field strains of BHV-1 for weeks or months after vaccination.
Design—Randomized controlled trial, performed in 2 replicates.
Animals—63 weaned 4- to 6-month-old crossbred beef calves seronegative for antibody against BHV-1.
Procedures—Calves were randomly allocated to 1 of 2 treatment groups. Control calves (n = 10/replicate) received a combination modified-live mixed viral vaccine without BHV-1, and treatment calves (20 and 23/replicate) received a combination modified-live mixed viral vaccine containing BHV-1. Each group was challenged via aerosol with 1 of 2 field strains of BHV-1, 30 days after vaccination in replicate 1 and 97 days after vaccination in replicate 2. After challenge, calves were commingled in 1 drylot pen. Clinical signs, immune responses, and nasal shedding of virus were monitored for 10 days after challenge, after which the calves were euthanatized and tracheal lesions were assessed.
Results—Vaccination stimulated production of BHV-1–specific IgG antibody that cross-neutralized several field and laboratory strains of BHV-1. Challenge with both field strains of BHV-1 resulted in moderate to severe respiratory tract disease in control calves. Treatment calves had significantly fewer signs of clinical disease, shed less BHV-1, had less or no weight loss after challenge, and had fewer tracheal lesions than control calves for at least 97 days after vaccination.
Conclusions and Clinical Relevance—Administration of the combination modified-live BHV-1 vaccine yielded significant disease-sparing effects in calves experimentally infected with virulent field strains of BHV-1.