Efficacy of a temperature-sensitive modified-live bovine herpesvirus type-1 vaccine against abortion and stillbirth in pregnant heifers

OBJECTIVE: To evaluate the efficacy of a commercially available temperature-sensitive modified-live bovine herpesvirus type-1 (BHV-1) vaccine against BHV-1 challenge-induced abortion and stillbirth. DESIGN: Prospective randomized control trial. ANIMALS: 20 cycling, nonpregnant, BHV-1 seronegative heifers of various breeds and weights, 12 to 15 months old. PROCEDURE: Heifers were randomly assigned to a vaccinate (n = 10) or nonvaccinate control (n = 10) group. Seventeen to 26 days after members of the vaccinate group received a second dose of vaccine, all heifers were artificially inseminated. Heifers were challenged intravenously with Cooper strain BHV-1 between days 177 and 187 of gestation. Aborted fetuses and stillborn calves were necropsied, and tissues collected for histologic examination and virus isolation. Heifers, calves, and fetuses were tested for BHV-1 antibody throughout the study. RESULTS: The difference in number of abortions or stillbirths between vaccinated heifers (1/10) and control heifers (10/10) was significant (P < 0.003). Seven of 10 control heifers had a virus neutralization antibody titer to BHV-1 at abortion or stillbirth that declined or remained unchanged from their titer at a previous serologic evaluation (7 to 66 days earlier). CLINICAL IMPLICATIONS: Prebreeding vaccination of replacement heifers with modified-live BHV-1 vaccine provides fetal protection at 6 months of gestation (7 months after vaccination) and appears to be a reasonable precaution to control economic losses associated with BHV-1 infection. Abortions induced by BHV-1 are not necessarily associated with rising or markedly high virus neutralization antibody titers. These titers should be used cautiously when assessing the role of BHV-1 in bovine abortion and stillbirth.     

Immunopotentiation of bovine respiratory disease virus vaccines by interleukin-1 beta and interleukin-2

Three experiments, using 85 crossbred beef calves, were conducted to evaluate the adjuvanticity of single, multiple, and combined doses of recombinant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL-2), with a modified-live bovine herpesvirus-1/parainfluenza-3 (BHV-1/PI-3) virus vaccine and a killed bovine viral diarrhea (BVD) virus vaccine. Cytokines were administered intramuscularly at vaccination but at different injection sites. All cytokine treatments increased non-major histocompatibility complex (MHC)-restricted cytolytic capability of peripheral blood mononuclear cells (PBMC) against virus-infected target cells and serum neutralizing (SN) antibody titers to BHV-1 and BVD virus. Multiple, consecutive injections of rBoIL-2 generally showed the greatest adjuvant effect, and no additive effect was observed when rBoIL-1 beta and rBoIL-2 were administered together. In a challenge experiment, calves were vaccinated with a modified-live BHV-1/PI-3 vaccine and infected with BHV-1 on Day 21. Cytokine-treated calves had higher SN antibody titers to BHV-1 than did the control calves at the time of challenge. Calves that were administered rBoIL-2 on 5 consecutive days shed less BHV-1 and had the highest SN antibody titer to BHV-1 (Day 28). These data suggest that rBoIL-1 beta and rBoIL-2 may be useful immunoadjuvants for bovine respiratory disease virus vaccines.     

Attitudes of oncologists, family doctors, medical students and lawyers to euthanasia

OBJECTIVE: To evaluate clearance of the vaccine strain, immunologic responses, and potential shedding of Brucella abortus strain RB51 organisms after vaccination of bison calves. ANIMALS: Fourteen 7-month-old female bison calves. PROCEDURE: 10 bison calves were vaccinated SC with 1.22 x 10(10) colony-forming units of B abortus strain RB51. Four bison calves were vaccinated SC with 0.15M NaCl solution. Rectal, vaginal, nasal, and ocular swab specimens were obtained to evaluate potential shedding by vaccinated bison. The superficial cervical lymph node was biopsied to evaluate clearance of the vaccine strain. Lymphocyte proliferative responses to strain RB51 bacteria were evaluated in lymph node cells obtained from biopsy specimens and also in peripheral blood mononuclear cells. RESULTS: Strain RB51 was recovered from superficial cervical lymph nodes of vaccinates examined 6, 12, and 18 weeks after vaccination (4/4, 3/4, and 1/4, respectively) but not in vaccinates examined at 24 weeks (0/3) after vaccination or nonvaccinates examined at all sample collection times (n = 1 bison/sample period). Serologic, immunologic, and bacterial culture techniques failed to reveal shedding of strain RB51 by vaccinates or infection of nonvaccinated bison. Lymphocyte proliferative responses were evident in lymph node cells and blood mononuclear cells from strain RB51-vaccinated bison beginning 12 weeks after vaccination. CONCLUSION: Strain RB51 was cleared from bison by 18 to 24 weeks after vaccination. Bison vaccinated with strain RB51 did not shed the vaccine strain to nonvaccinated bison housed in close proximity. Strain RB51 did not induce antibody responses in bison that would interfere with brucellosis surveillance tests, but did stimulate cell-mediated immunity.     

Antibody responses of cattle to outer membrane proteins of Pasteurella multocida A:3

OBJECTIVE: To quantify the serum antibody responses to Pasteurella multocida A:3 outer membrane proteins (OMP) for cattle vaccinated with the homologous serogroup and to correlate those responses with the extent of experimentally induced pneumonia. ANIMALS: 29, 5- to 8-month-old beef-type calves. PROCEDURE: Calves were vaccinated SC or by aerosal exposure on days 0 and 7 with live or killed P multocida or phosphate-buffered saline solution (control) and subsequently challenge exposed with virulent P multocida. Antibody responses to P multocida A:3 outer membranes were quantified, using an ELISA. Antibody responses to individual OMP were detected by immunoblot analysis (western blot) and were quantified by densitometry. Antibody responses were compared among groups of calves and for various times after vaccination. Regression analyses were used to determine whether significant correlations existed between lesion scores and antibody responses to either whole outer membranes or to individual OMP. RESULTS: By ELISA, antibody responses to outer membranes for calves aerosol vaccinated with live P multocida were significantly (P < 0.05) greater than those for control calves or for killed P multocida vaccinates. There was a significant (P < 0.05) correlation between lesion score and antibody responses to outer membranes. By western blotting and densitometry, antibodies to 11 prominent OMP (100, 97, 90, 85, 74, 53, 46, 35, 32, 21, and 16 kd) were identified and quantified. In experiment 1, SC vaccination with live P multocida increased antibody binding to all protein bands except 85-, 74-, and 35-kd bands. Aerosol vaccination with live P multocida stimulated increases in antibody binding to all bands except 100 and 16 kd. Antibody responses to the 97-, 90-, 74-, and 35- kd bands were significantly (P < 0.05; greater for live aerosol vaccinates than for control calves. In experiment 2, antibody responses were not different between the killed P multocida vaccinates or control calves Antibody responses for live P multocida aerosol vaccinates were significantly (P < 0.05) greater than those for control calves for the 100-, 90-, 85-, 74-, 53-, 35-, and 16-kd bands. Regression analyses indicated significant correlations (P < 0.05) between lesion score and antibody responses to the 100-, 90-, 53-, 46-, 35-, and 32-kd OMP. CONCLUSIONS: Several OMP of P multocida type A:3 may be important for stimulating immunity to the organism in cattle.     

The persistence of genetic homogeneity among Trypanosoma brucei rhodesiense isolates from patients in north-west Tanzania

The decrease in titer of PRV antibodies in serum was evaluated at 10, 37, 67, 109 and 173 days of age in 16 non-vaccinated pigs and 43 pigs vaccinated at 3, 67 and 80 days of age with a modified live TK/gIII gene deleted pseudorabies virus (PRV) vaccine. Serum samples were analyzed for antibodies to PRV by the serum-virus neutralization test (SN), a commercial competitive ELISA (CELISA), and the CELISA OMNIMARK PRV differential (OMD) diagnostic kit. At 10 days of age, all pigs had SN titers > or = 1:4 and were CELISA+/OMD+, indicating circulating antibodies to field strains of PRV. At 109 days, all non-vaccinated pigs had SN titers < 1:4. Forty-five percent of vaccinated pigs had SN titers > or = 1:4, 56% were CELISA positive and most were CELISA+/OMD-, indicating antibodies due to vaccination. At 24 weeks of age, all pigs had SN titers > or = 1:4 and were CELISA+/OMD+ due to exposure to field strains. Although circulating maternal antibodies interfere with the development of active immunity, vaccination at 3 days of age resulted in detectable antibodies by 67 days of age, and a limited immune response could be measured at 109 days of age.     

Stimulus specific adaptation in inferior temporal and medial temporal cortex of the monkey

We studied the early immunity induced by a live glycoprotein E (gE) negative bovine herpesvirus 1 (BHV1) marker vaccine. Three groups of specific-pathogen-free calves were either not vaccinated, or vaccinated two days or two hours before the introduction of a calf that was intranasally infected with wild-type BHV1 the day before. We quantified the shedding of gE-negative vaccine virus and of wild-type virus, using a double-staining immunoassay. In calves vaccinated two hours before the introduction of the infected calf, the shedding of wild-type virus was reduced, compared with that of the unvaccinated control calves. The shedding of wild-type virus was most significantly reduced in the calves that were vaccinated two days before: only very small amounts of wild-type virus were isolated. Wild-type virus was not detected at all in the samples from one of the five calves of that group. Furthermore, this calf was the only one in which we did not detect antibodies against gE. Hence, intranasal vaccination with a live gE-negative vaccine induced early immunity against a BHV1 contact infection. This suggests that this vaccine can be used efficaciously in the early stages of a BHV1 outbreak.     

Effect of three sustained-release devices on parasitic bronchitis in first year calves

The effect of three intraruminal sustained-release devices (SRD) against Dictyocaulus viviparus infection was tested in five groups of six calves. Group 1 served as untreated controls, and groups 2, 3 and 4 were dosed with a levamisole SRD, a fenbendazole SRD, and an ivermectin SRD, respectively. Group 5 was vaccinated against lungworm and received a levamisole SRD. The calves were turned out on May 28 and the devices given seven days later. All the calves received trickle infections with a total of 200 lungworm larvae between 9 and 34 days after turnout. They were housed on October 28, challenged with 5000 lungworm larvae and slaughtered three weeks later. No clinical signs of parasitic bronchitis were observed during the study. The treated groups gained significantly more weight (P < 0.05) than the controls, but did not differ among themselves. Larvae were first detected in the faeces of the control group between 25 and 32 days after the first infection, and had a group mean of 21 larvae per gram (lpg) after 60 to 80 days, after which the lpg gradually decreased. In group 2, larvae were detected near the end of the grazing season and never exceeded a group mean of 1.5 lpg. In group 3, a very low larval output was observed after housing (group mean 0.1 lpg). Groups 4 and 5 never became patent. The results of an ELISA followed the pattern of larval output; optical densities above the cut-off value were recorded in groups 1, 2 and 3. On the basis of worm recoveries after challenge, group 1 was immune. Group 4 had significantly more lungworms than group 2. There were no significant differences in worm numbers between groups 2, 3 and 5, but the worms in group 5 were retarded in growth (P < 0.05).     

Rise in erythropoietin concentrations in experimental Trypanosoma congolense infection of calves

A bioassay was used to measure erythropoietin (EPO) concentrations in calves with haemorrhagic anaemia due to blood loss and in calves with anaemia due to Trypanosoma congolense infection. The bioactivity of EPO was measured in the assay by its stimulatory effect on 125I-deoxyuridine incorporation in spleen cells from phenylhydrazine-treated mice. Erythropoietin concentrations in blood-volume-depleted calves were elevated 6 h after blood loss, maximal (1225 mU/ml) at 33 h and below detection limits at 72 h. Reticulocytes (0.05 +/- 0.1%) appeared in blood by 72 h, peaked at 120 h and disappeared from the circulation by 7 days after bleeding. The packed cell volume (PCV) started increasing at 120 h and reached near pre-bleeding values by 14 days. In T. congolense-infected calves, parasites were first detected in the peripheral blood 12 days post-infection (dpi). Parasitaemia peaked (5 x 10(5) trypanosomes/ml of blood) at 15-18 dpi and, thereafter, several waves of parasitaemia were observed, but the peaks gradually diminished. Undiluted plasma from T. congolense-infected calves suppressed 125I-deoxyuridine incorporation into spleen cells from 13 dpi onwards. The suppressive effect of plasma was partly negated by five-fold dilution, which made possible the detection of increased EPO concentrations during the acute and chronic stages of the anaemia. The highest EPO peaks, reaching 2300 mU/ml in one calf, were detected during the chronic stage of the infection. At 15-39 dpi, there was a transient bone-marrow erythropoietic response characterized by an increase in mean corpuscular volume and a decrease in mean corpuscular haemoglobin concentration but with few reticulocytes (0.4%). However, from 76 dpi onwards, this response waned despite low PCV and elevated EPO concentrations. These results suggest that there is an ineffective erythroid response in the face of elevated EPO concentrations during bovine trypanosomiasis. The negative effect of plasma and serum from trypanosome-infected calves on the in-vitro bioactivity of EPO suggests the presence of inhibitory factors.     

Metabolism of the carcinogen N-hydroxy-N-2-fluorenylacetamide by rat peritoneal neutrophils

A thymidine kinase (TK), inverted repeat, glycoprotein I (gI) and glycoprotein X (gpX) gene-deleted modified live virus pseudorabies vaccine was evaluated for safety in swine and for efficacy in protecting swine against challenge with pseudorabies virus (PRV). Safety was evaluated by inoculating pregnant gilts intravenously and 3-day-old pigs intracerebrally with the vaccine. Efficacy was evaluated by 1) vaccinating 3-day-old pigs with a minimal protective dose intranasally and then challenging with PRV 3 weeks postvaccination or 2) vaccinating weaned pigs with a standard field dose intramuscularly and then challenging with PRV 4 weeks postvaccination. The pigs vaccinated intranasally remained clinically normal following vaccination and challenge with PRV. The pigs vaccinated intramuscularly remained clinically normal following vaccination, but mild respiratory signs were seen in some of the vaccinated pigs following challenge with PRV. Humoral immune response was evaluated with enzyme-linked immunosorbent assays (ELISAs) and a serum virus neutralization test. All of the intramuscularly vaccinated pigs became gI and gpX positive on differential ELISAs following challenge. All of the intranasally vaccinated pigs were seropositive on the indirect gI ELISA following challenge, but not all of the pigs were seropositive on the blocking gI ELISA or the gpX ELISA 3 weeks postchallenge.     

Effects of B vitamin injections on plasma B vitamin concentrations of feed-restricted beef calves infected with bovine herpesvirus-1

For nonruminants, stress and disease greatly increase requirements for vitamin B6, folic acid, pantothenic acid, and ascorbate. The effects of feed restriction, virus infection, and vitamin injections on plasma concentrations of B vitamins critical to the immune response were evaluated. Twelve beef steer calves, 6 to 8 mo of age, were fed below maintenance for 17 d and deprived of food for 3 d during a 20-d period after weaning. They then were inoculated intranasally with live attenuated bovine herpesvirus-1 (BHV-1). Six calves received saline injections and six received injections of a B vitamin mixture and ascorbate every 48 h for 14 d before and 14 d after inoculation. A mild respiratory infection developed in all calves 4 to 5 d after inoculation. In control calves, restricted intake and food deprivation decreased plasma vitamin B6 and pantothenate and increased vitamin B12 but did not affect folic acid and ascorbate concentrations. Vitamin injections increased plasma concentrations of vitamin B6, folic acid, vitamin B12, pantothenic acid, and ascorbate (P < .002). Plasma concentrations of vitamin B6, vitamin B12, pantothenic acid, and ascorbate, but not folic acid, were markedly reduced in all calves during the BHV-1 infection (P = .001). The vitamin B6, pantothenic acid, vitamin B12, and ascorbate status of stressed calves may affect their immune response to vaccination or infection.     

Evaluation of serological tests for the detection of pseudorabies gE antibodies during early infection

Two enzyme-linked immunosorbent assays (ELISAs) and a particle concentration fluorescence immunoassay (PCFIA) were compared for their ability to detect antibodies against pseudorabies virus (Aujeszky's disease virus) glycoprotein E (gE) in the early stages of infection in pigs previously vaccinated with gE-deleted pseudorabies vaccines. Seventy pigs were included in the study. Five groups of 6 pigs each were vaccinated with one of 5 different pseudorabies virus (PRV) gE-deleted vaccines, and subsequently infected intranasally with 10(5.6) TCID50 of the Iowa 4892 pneumotropic strain of PRV. This entire procedure was repeated using 10(4.6) TCID50 of the Rice strain of PRV. Five unvaccinated control pigs were also challenged with each virus strain. Three control pigs died before seroconverting, leaving 67 pigs for comparison. Blood samples were drawn from experimentally inoculated pigs on the day of vaccination, the day of challenge, and on 4-10, 14, and 21 days postchallenge (DPC). Serology test sensitivity estimates and comparisons among tests were made for each sampling day. Results of this study demonstrated differences among the tests in the time from inoculation to initial antibody detection, and the time to detect 50% and 75% of the infected pigs. The average time until first detection of pigs as seropositive for gE antibodies by PCFIA was 7.5 DPC. The blocking ELISA detected pigs as seropositive an average of 8.8 DPC, and the indirect ELISA first detected gE antibodies by 9.3 DPC. Fifty percent of the pigs were detected as seropositive by days 7, 8, and 9 for the PCFIA, blocking ELISA, and indirect ELISA, respectively. Similarly, 75% of the pigs were detected as seropositive by days 8, 9, and 10 for the PCFIA, blocking ELISA, and indirect ELISA, respectively. All pigs were detected as seropositive by 14 DPC for all 3 tests.     

Detection of virus infection-associated antigen and 3D antibodies in cattle vaccinated against foot and mouth disease

The analysis of sera obtained from animals vaccinated or revaccinated with inactivated vaccines against foot and mouth disease (FMD) virus showed that these vaccines induced antibodies against the virus infection-associated (VIA) antigen, detectable by agar gel immunodiffusion (AGID). The present study evaluates the antibody response to protein 3D and the VIA antigen (VIAA) of FMD virus induced by different vaccines in a group of 51 calves. This response was detected using AGID and a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for anti-3D antibodies (ELISA-3D). No anti-VIAA or anti-3D antibodies were detected after the initial vaccination. Following revaccination, animals giving positive results were detected by both methods. This immune response disappeared 60-120 days post-revaccination (dprv) according to the AGID method, and 90-180 dprv when ELISA-3D was used. Samples of oesophageal-pharyngeal fluid obtained from animals that remained positive for anti-VIAA antibodies at 90-120 dprv gave negative results for viral isolation, indicating that the transitional antibody response induced by the vaccine was due to the presence of non-structural antigens in the vaccine and not to viral infection. These results indicate that the ELISA-3D method could be used as a complementary method for sero-epidemiological studies as an indirect indicator of viral activity, as long as the age and vaccination status of the animals being sampled are taken into consideration.     

Serologic responses of young colostrum fed dairy calves to antigens of Pasteurella haemolytica A1

The potential and limitations of early calfhood vaccination to induce active immunity to Pasteurella haemolytica A1 in conventional colostrum fed calves were investigated. Holstein dairy calves (n = 29) were vaccinated at 2 and 4 weeks of age, or at 6 and 8 weeks of age with a commercial culture supernatant vaccine (Presponse, Langford Inc., Guelph, Ont., Canada), or remained unvaccinated as controls. Serum antibody titres were measured using an indirect bacterial agglutination assay, a leukotoxin neutralization assay, and enzyme immunoassays for antibodies of the IgM, IgG1, and IgG2 isotypes binding purified capsular polysaccharide of P. haemolytica A1. Seroconversion (fourfold or greater increase in serum antibody titre) rates were compared using Fisher's exact test. The effects of passive antibody titres and age on response to vaccination were assessed by linear modelling. Vaccination at 2 and 4 weeks of age was associated with 40%, and 0% of calves seroconverting on the basis of agglutinating antibody titres, and leukotoxin neutralizing titres respectively, and 50%, 0%, and 0% seroconverting on the basis of IgM, IgG1 and IgG2 antibodies to capsular polysaccharide, respectively. Agglutinating antibody responses were not related to prevaccination antibody titres, or to age at vaccination. Higher responses (p = 0.08) to leukotoxin were observed in older calves (after taking differences in prevaccination titres into account). Statistical analyses of responses to capsular polysaccharide among calves with comparable prevaccination IgG1 antibody titres revealed significantly higher IgM, IgG1 and IgG2 responses in older calves. Rising titres of IgM antibodies in nonvaccinated calves after 5 weeks of age suggest natural exposure to P. haemolytica A1 or antigens which result in serologic cross-reactions as a means of priming immune responses.     

Effects of vaccination with a Moraxella bovis bacterin on the subsequent development of signs of corneal disease and infection with M bovis in calves under natural environmental conditions

A vaccination study was conducted for infectious bovine keratoconjunctivitis (IBK) in 440 purebred Hereford cattle (cows and their newborn calves) of the USDA Meat Animal Research Center cattle herd at Clay Center, Ne. The cattle were allotted to 4 groups: 60 calves were vaccinated with an autogenous Moraxella bovis bacterin (group 1); 60 calves that were matched with group 1 calves were designated nonvaccinated matched controls (group 2); 99 calves were peer group nonvaccinated controls (group 3); and 219 cows, the dams of the calves, were nonvaccinated consorts (group 4). The infection rates in cattle groups 1, 2, 3, and 4 during the summer were 96.6, 98.3, 100, and 79.1%, respectively, and the disease rates were 90, 93, 85, and 20%. The infection and the disease rates were significantly (P less than 0.01) different between claves and cows. The disease rate was also significantly different between older and younger cows. A larger percentage of the affected calves and cows had mild or moderate (61%) signs of IBK rather than severe (39%) signs. The rate of body weight gain was reduced in calves with severe signs of IBK. The results seemed to indicate that little would be gained by vaccinating cattle against IBK under the conditions of study.     

An experimental study of a concurrent primary infection with bovine respiratory syncytial virus (BRSV) and bovine viral diarrhoea virus (BVDV) in calves

Experimental infections with bovine respiratory syncytial virus (BRSV) and bovine viral diarrhoea virus (BVDV) were performed to study the effect of concurrent BRSV and BVDV infections. Twelve seronegative calves, in 3 groups, were inoculated on a single occasion with pure BRSV (group A), BRSV and noncytopathogenic BVDV (group B) or mock infected (group C). Mild respiratory symptoms were recorded 4 to 5 days post inoculation (dpi) in group A and group B calves. One calf in group A was severely affected and required medical treatment. In group B, fever (40.7-41.4 degrees C) was prominent 7 to 8 dpi. Only calves in group B were BVDV positive in purified lymphocytes at 2 to 14 dpi and showed increased serum interferon levels, with a peak at 4 dpi, indicating BVDV to be responsible for inducing the rise. BRSV was detected in lung lavage fluids up to 7 dpi for group A calves, compared to 11 dpi for group B and calves in this group also seroconverted later displaying lower BRSV titers. The time lag before an antibody response and the titers recorded in group B, indicated that the duration of BVDV infection in lymphocytes negatively influenced the capacity to mount a BRSV antibody response.     

Experimental coryza in broiler chickens. I. Effects of vaccination with Haemophilus gallinarum bacterin and its components on weight gains and resistance to infection

Effects of a Haemophilus gallinarum bacterin and its components were studied in young broiler chickens. When the bacterin was administered subcutaneously in the dorsal neck region at 2 weeks of age, no significant differences in weight gains of vaccinated and control birds were detected at eight weeks of age. In four groups vaccinated at 1, 2, 3, or 4 weeks of age and challenged with virulent haemophilus organisms 3 weeks later, the incidence of clinical signs was 30% in the vaccinates and 60% in controls. The bacterin was equally protective at the four ages of administration. Caseous plugs were found at the vaccination sites in all birds which had received adjuvant either alone or in the complete bacterin. Signs of depression lasting about 24 hours were observed in the youngest birds injected with the bacterin, but overall weight gains were normal.     

A bovine model of vaccine enhanced respiratory syncytial virus pathophysiology

A critical issue has been the observation that vaccination of children with a formalin-inactivated respiratory syncytial virus (RSV) vaccine is associated with disease enhancement. We have taken advantage of bovine RSV and our experience with this disease in calves to develop a natural model that parallels human disease. Using formalin-inactivated bovine RSV vaccine calves were either sham-vaccinated/infected, vaccinated/infected, or vaccinated/sham-infected and their clinical signs, pulmonary function, and histological lung lesions quantitatively scored. Interestingly there was significantly greater disease in vaccinated/infected calves and histological lesions in calves were similar to those of affected children. Finally, we note that vaccination did not induce neutralizing antibodies, but IgG antibodies were detected by ELISA. Our model of RSV enhanced disease is important because it provides quantifiable evidence of disease severity that can be applied to evaluate the mechanisms of immunopathology and the safety of candidate RSV vaccines.     

Experimentally induced infections bovine keratoconjunctivitis: effectiveness of a pilus vaccine against exposure to homologous strains of Moraxella bovis

A study was conducted to determine whether vaccination with sonicated pili of Moraxella bovis would protect cattle from subsequent infection and disease when experimentally challenged by exposure to homologous cultures of M bovis. Some calves were intramuscularly inoculated 2 times with pili of M bovis suspended in water, and others were subcutaneously inoculated 2 times with pili of M bovis suspended in oil; 21 days were allowed between inculations. Controls were nonvaccinated calves. Fourteen days after the last inculation, all calves were exposed to virulent homologous cultures of M bovis. The results indicated that vaccination with sonicated pili of M bovis may induce protective immunity against homologous strain challenge exposure. Vaccines in oil that were injected subcutaneously protected to a greater extent than did vaccines in water that were injected intramuscularly. The development of inflammatory nodules at the site of inoculation was associated with resistance to infection and disease. Only 1 of the vaccinated calves that resisted disease lacked precipitating antibodies against sonicated pili at the time of the challenge exposure. This calf had antibodies 2 weeks later.     

Clinical and immunologic responses of vaccinated and unvaccinated calves to infection with a virulent type-II isolate of bovine viral diarrhea virus

OBJECTIVE: To determine efficacy of a modified-live type-I isolate of bovine viral diarrhea virus (BVDV) vaccine in protecting calves from infection with a virulent type-II isolate, and to determine which type of immune response (i.e., humoral or cellular) correlates with protection. DESIGN: Prospective study. ANIMALS: 28 neonatal Holstein and Holstein-cross calves. PROCEDURE: Within 18 hours of birth, calves received maternal colostrum or were fed pooled colostrum. On days 7 to 10 after birth, calves were determined to be seropositive (n = 16) or seronegative (12) for antibodies to BVDV on the basis of ELISA and virus neutralization test results. Seropositive and seronegative 10- to 14-day-old calves were then given a combined vaccine that contained a modified-live type-I isolate of BVDV or a similar vaccine that lacked protection against bovine viral diarrhea. All calves were inoculated intranasally approximately 21 days after vaccination with a virulent type-II isolate of BVDV. Clinical and immunologic variables, including clinical scores, rectal temperatures, results of CBC with lymphocyte subset analysis, antibody responses, and cell-mediated immune responses, were monitored for 14 days after inoculation. RESULTS: Seronegative-unvaccinated calves developed severe disease and required euthanasia. Vaccination of seronegative calves with a modified-live type-I isolate had a disease-sparing effect as did passive transfer of colostral antibodies to BVDV. Clinical scores were not significantly different between seropositive-vaccinated and seropositive-unvaccinated calves after viral inoculation. CLINICAL IMPLICATIONS: A single dose of a modified-live type-I isolate of BVDV vaccine protects young calves from clinical signs of disease associated with type-II isolates.     

Effects of copper deficiency and copper deficiency coupled with high dietary iron or molybdenum on phagocytic cell function and response of calves to a respiratory disease challenge

A study was conducted to determine the effects of supplementing a diet marginally deficient in copper (Cu) with iron (Fe), molybdenum (Mo), or Cu on phagocytic cell function and disease resistance of calves. Thirty-one calves were born to heifers fed a corn silage-based diet containing 4.5 mg of Cu/kg. Treatments consisted of 1) control (CON; no supplemental Cu, Fe, or Mo), 2) 600 mg of Fe added/kg (FE), 3) 5 mg of Mo added/kg (MO), or 4) 10 mg of Cu added/kg of DM (CU). Activity of superoxide dismutase was lower (P < .06) in neutrophils from MO vs CON or CU calves at 170 d of age. bactericidal activity of neutrophils from MO calves tended (P = .15) to be lower compared with those from CU calves at 70 d of age. Calves were inoculated intranasally with live infectious bovine rhinotracheitis virus (IBRV) 2 d after weaning, followed by intratracheal administration of Pasteurella hemolytica 5 d later. Iron- and Cu-supplemented calves exhibited higher (P < .01) body temperatures and lower (P < .06) feed intakes following IBRV inoculation compared with CON and MO calves. Copper-supplemented calves had higher levels of plasma tumor necrosis factor (TNF) than MO calves at weaning (P < .05) and tended to have higher plasma TNF (P = .11) than FE and MO calves 5 d after IBRV inoculation. These data indicate that dietary levels of Mo and Cu can affect body temperature and feed intake responses to disease by affecting TNF and perhaps other cytokines.