Immunization of cattle with a BHV1 vector vaccine or a DNA vaccine both coding for the G protein of BRSV

A gE-negative bovine herpesvirus 1 (BHV1) vector vaccine carrying a gene coding for the G protein of bovine respiratory syncytial virus (BRSV) (BHV1/BRSV-G) induced the same high degree of protection in calves against BRSV infection and BHV1 infection as a multivalent commercial vaccine. A DNA plasmid vaccine, carrying the same gene as the BHV1/BRSV-G vaccine, significantly reduced BRSV shedding after BRSV infection compared with that in control calves, but less well than the BHV1/BRSV-G vaccine. Flow cytometric analysis showed a significant relative increase of gamma/delta+ T cells in peripheral blood after BRSV challenge-infection of the calves of the control group but not in the vaccinated groups. These results indicate that the G protein of BRSV can induce significant protection against BRSV infection in cattle, and that the BHV1/BRSV-G vaccine protects effectively against a subsequent BRSV and BHV1 infection.     

Virulence, immunogenicity and reactivation of bovine herpesvirus 1 mutants with a deletion in the gC, gG, gI, gE, or in both the gI and gE gene

Within the framework of developing a marker vaccine against bovine herpesvirus 1 (BHV1), several mutants with deletions in non-essential glycoprotein genes were constructed. Glycoprotein gC, gG, gI and gE single deletion mutants, a gI/gE double deletion mutant and a gE frame-shift mutant were made. The virulence and immunogenicity of these mutants were evaluated in specific-pathogen-free calves. Except for the gC deletion mutant, all mutants were significantly less virulent than the parental wild-type (wt) BHV1 strain Lam. The virulence of the gI and the gI-/gE- mutants was almost completely reduced. Upon challenge infection, the calves of the control group became severely ill, whereas all other calves remained healthy. The reduction of the virus shedding after challenge infection was related to the virulence of the strain of primary inoculation. Virus shedding was almost completely reduced in calves first inoculated with Lam-wt or with gC- and the least reduced in calves inoculated with gI- or gI-/gE-. Six weeks after challenge, all calves were treated with dexamethasone to study whether mutant or challenge virus or both could be reactivated. The gC- and the gG- mutants were reactivated, whereas none of the other mutants were reisolated. Reactivation of challenge virus was reduced in all calves inoculated with mutant viruses. The gC deletion mutant was too virulent and the gI and the gI/gE deletion mutants were the least immunogenic, but based on residual virulence and immunogenicity, both the gG and the gE deletion mutants are candidates for incorporation in live BHV1 vaccines. However, it also depends on the kinetics of the anti-gG and anti-gE antibody response after wild-type virus infection, whether these deletion mutants are really suitable to be incorporated in a marker vaccine.     

The role of glycoproteins gC, gE, gI, and gG in the induction of cell-mediated immune responses to bovine herpesvirus 1

Mutant viruses with deletions in genes encoding non-essential glycoproteins are considered as promising bovine herpesvirus 1 (BHV1) vaccine candidates. The present study compared the influence of various gene deletions (gC, gE, gI, gG) on the induction of cell-mediated immune responses against the virus. The highest BHV1 specific lymphoproliferative response was observed in the group of calves inoculated with the gC- mutant. However, in all groups of inoculated calves, limiting dilution analysis showed marked individual variability in the number of BHV1 specific T lymphocytes that were stimulated. The same animals were then challenged with wild-type BHV1. In these animals, limiting dilution analysis did not reveal gE, gI nor gG as a major T lymphocyte antigen. However, further analysis suggested the T cell antigenicity of gE in a low number of BHV1 hyperimmunized calves. Stimulation of MHC unrestricted cytotoxicity was also evaluated after inoculation with the various deletion mutants. Cytotoxicity in gC- inoculated calves was as high as in BHV1 inoculated calves. In conclusion, among the BHV1 deletion mutants that were tested, the gC- mutant stimulated the best cell-mediated immune responses.     

Surface-based labeling of cortical anatomy using a deformable atlas

With regard to BHV1 eradication programs in cattle it is important to know whether sheep can be a reservoir of BHV1. We therefore performed an experiment that consisted of three phases. In phase 1, 10 sheep were inoculated with high doses of BHV1 and kept in close contact with 5 sheep and 5 calves. All inoculated sheep excreted BHV1 between 8 and 15 days post inoculation and seroconverted. Although BHV1 was isolated from the nasal mucosa of 3 out of 5 sentinel sheep, none of the sentinel sheep produced antibodies against BHV1. One sentinel calf excreted BHV1 through days 12-17; the remaining 4 calves excreted BHV1 between days 18 and 24 suggesting that the first calf was infected by sheep and the remaining 4 sentinel calves were infected by that calf and not by sheep. The bacic reproduction ratio (R0) of BHV1 between sheep and calves was estimated at 0.1, and among calves it was estimated at > or = 9. In phase 2, all inoculated sheep were treated with dexamethasone and kept in close contact with 5 sheep and 5 calves. All dexamethasone treated sheep re-excreted BHV1 over a 6- to 9-day period. None of the sentinel animals seroconverted. In phase 3, the sentinel sheep and calves of phase 1 were kept in two groups and were treated with dexamethasone. None of the sentinel sheep re-excreted BHV1, whereas 3 out of 5 sentinel calves did. It is concluded that while BHV1 infection in sheep is possible, BHV1 does not spread from sheep easily to cattle.     

Immunobiology of bovine respiratory syncytial virus infections

This paper describes recent findings on the immunobiology of bovine respiratory syncytial virus (BRSV) infections. The pathobiology of alveolar macrophages and BRSV, and the immunological reaction of cattle to the virus after natural or experimental infection, or vaccination, were studied. Because in severe cases BRSV infection leads to lower respiratory tract disease, replication of BRSV in alveolar macrophages was studied. Alveolar macrophages, which are important aspecific defense cells in the lower respiratory tract, exhibited a high intrinsic resistance to BRSV. Furthermore, BRSV-infected alveolar macrophages produced significantly less nitric oxide (which has a bacteriocidal effect) than uninfected macrophages. The kinetics of antibody titres against the envelope protein G were different from those of antibody titres against the envelope protein F. For example, many animals that are reinfected do not possess antibodies against the G protein. After vaccination or after natural infection, antibody titres against the F and G protein, and against epitopes on the F protein, differed markedly, and also in animals with different MHC haplotypes. These findings may be related to differences in protection. The strains of BRSV that circulate in the Netherlands belong to the subgroups A and AB. There was no evidence for differences in virulence between these subgroups. BRSV could be detected in 30% of lungs obtained from calves suffering from severe lower respiratory tract disease. Based on cross-protection studies, calves that were infected with a virus from a particular BRSV subgroup were protected against reinfection with a virus from a different subgroup. A recombinant gE-protein negative bovine herpesvirus 1 vaccine carrying a gene encoding the G protein of BRSV, and a DNA vaccine encoding the same protein afforded protection after experimental challenge of calves. This offers the possibility to develop effective multivalent (gE-negative BHV1) marker vaccines in the future.     

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.     

Podiatric casts used for surgery and trauma. Part II: Boot cast

Between April 18 and May 20, 1975, 16 cases of measles occurred in pupils in an elementary school in Baltimore County, Md., and 1 case occurred in a sibling at a junior high school. Measles was serologically confirmed in 16 of these pupils. Attack rates were determined by grade and by vaccine status. The measles attack rate was 2.1 percent for the 377 children who had been given measles vaccine at 1 year of age or later. The rates were 27.8 percent (13 times higher) for those vaccinated at less than 10 months of age and 20.0 percent (10 times higher) for those with no definite history of vaccine. The higher attack rates for children who were vaccinated only before 10 months of age supports the 1972 recommendation of the Public Health Service Advisory Committee on Immunization Practices that children vaccinated before this age need to be revaccinated with live measles virus vaccine to assure full protection. The finding that 2 of 10 children with a history of measles became ill during the outbreak suggests that such histories are not a totally reliable indicator of immunity. Containment of the outbreak was attributed to the high level of immunity in the community and prompt initiation of control measures.     

Vaccine genotype and route of administration affect pseudorabies field virus latency load after challenge

The influence of vaccine genotype and route of administration on the efficacy of pseudorabies virus (PRV) vaccines against virulent PRV challenge was evaluated in a controlled experiment using five genotypically distinct modified live vaccines (MLVs) for PRV. Several of these MLVs share deletions in specific genes, however, each has its deletion in a different locus within that gene. Pigs were vaccinated with each vaccine, either via the intramuscular or intranasal route, and subsequently challenged with a highly virulent PRV field strain. During a 2-week period following challenge with virulent PRV, each of the vaccine strains used in this study was evaluated for its effectiveness in the reduction of clinical signs, prevention of growth retardation and virulent virus shedding. One month after challenge, tissues were collected and analyzed for virulent PRV latency load by a recently developed method for the electrochemiluminescent quantitation of latent herpesvirus DNA in animal tissues after PCR amplification. It was determined that all vaccination protocols provided protection against clinical signs resulting from field virus challenge and reduced both field virus shedding and latency load after field virus challenge. Our results indicated that vaccine efficacy was significantly influenced by the modified live vaccine strain and route of administration. Compared to unvaccinated pigs, vaccination reduced field virus latency load in trigeminal ganglia, but significant differences were found between vaccines and routes of administration. We conclude that vaccine genotype plays a role in the effectiveness of PRV MLVs.     

Baculovirus expression of the fusion protein gene of bovine respiratory syncytial virus and utility of the recombinant protein in a diagnostic enzyme immunoassay

The fusion (F) protein of bovine respiratory syncytial virus (BRSV) was expressed by using a baculovirus vector. Antigenicity was tested by immunofluorescence analysis with F-specific monoclonal and polyclonal antibodies. Antibodies to recombinant F protein raised in a rabbit neutralized BRSV and human respiratory syncytial virus infectivity when tested in a plaque reduction assay. The recombinant F protein was evaluated as a source of antigen in an enzyme-linked immunosorbent assay (ELISA), and this ELISA was compared with the virus neutralization (VN) test for detecting BRSV antibodies in 10 consecutive serum samples from four calves vaccinated with a live modified BRSV vaccine and from two nonvaccinated control calves. The ELISA with the baculovirus-expressed F protein as an antigen compared favorably with the VN test and is a rapid, sensitive, and specific method for detecting serum antibodies to BRSV.     

Efficacy of a novel infectious bursal disease virus immune complex vaccine in broiler chickens

Two experiments were conducted to test the efficacy of a novel infectious bursal disease virus (IBDV) vaccine in broiler chickens with maternal IBDV immunity. The IBDV vaccine was formulated by mixing IBDV strain 2512 with bursal disease antibodies (BDA) to produce the IBDV-BDA complex vaccine. In Expt. I, 1-day-old Cobb x Cobb broiler chickens were vaccinated subcutaneously with either IBDV-BDA or commercial live intermediate IBDV vaccine (vaccine A) or were left unvaccinated. In Expt. 2, the vaccine A group was not included; instead, IBDV strain 2512 was included. Chickens were maintained in isolation houses. On day 28 (Expt. 1) and day 32 (Expt. 2) of age, chickens from each group were challenged with a standard USDA IBDV (STC strain) challenge. Challenged and unchallenged chickens were evaluated for their bursa/body weight ratios and antibody titers 3 days post-challenge. Bursae collected from Expt. 2 were examined histologically to evaluate bursal lesions and confirm gross examination. None of the unvaccinated chickens was protected against the challenge virus as evidenced by the presence of acute bursal lesions (edema/hemorrhage). All chickens receiving the IBDV-BDA complex or the IBDV strain 2512 (Expt. 2) were protected from the challenge virus as evidenced by no acute bursal lesions. Additionally, chickens receiving the IBDV-BDA complex vaccine or the IBDV strain 2512 had antibody titers to IBDV, indication the presence of an active immune response. In Expt. 1, chickens vaccinated with vaccine A and challenged had bursal lesions similar to those observed in the unvaccinated, challenged chickens. These chickens also showed no indication of active immunity against the virus. These results suggest that the 1-day-of-age-administered IBDV-BDA complex vaccine can induce active immunity and protection against a standard IBDV challenge in the face of variable levels of maternal IBDV immunity.     

Protection of swine by live and inactivated vaccines prepared from a leader proteinase-deficient serotype A12 foot-and-mouth disease virus

Previously, we demonstrated that a genetically engineered variant of foot-and-mouth disease virus (FMDV) serotype A12 lacking the leader proteinase-coding region (A12-LLV2) was attenuated and induced an immune response that partially protected cattle from FMD. In this study, A12-LLV2 was tested in swine as a live or chemically inactivated vaccine. Animals vaccinated with chemically inactivated A12-LLV2 or wild-type (WT) virus in oil adjuvant developed high levels of neutralizing antibodies and were protected from FMD upon challenge. Animals vaccinated with live A12-LLV2 did not exhibit signs of FMD, did not spread virus to other animals, developed a neutralizing antibody response and antibodies to nonstructural protein 3D, and were partially protected from FMD. Animals given a similar dose of chemically inactivated A12-LLV2 in the absence of adjuvant developed a poor immune response and were not protected from FMD, indicating that limited replication was responsible for the improved immune response found in animals vaccinated with live A12-LLV2. The results demonstrate the potential of A12-LLV2 as a live-attenuated vaccine as well as a safe source of antigen for chemically inactivated vaccines.     

Genoepidemiology and pathogenicity of hepatitis G virus in Japan

Danish artificial insemination (AI) centres house several boars antibody positive to porcine reproductive and respiratory syndrome virus as well as PRRSV-naive boars which may become acutely infected. The risk of transmission of PRRSV by semen may therefore constitute a serious problem to the Danish pig industry. The use of a vaccination-program may be a way to avoid or reduce the problem. This study evaluates the use of two vaccines: One live, attenuated vaccine and one inactivated vaccine. A pronounced reduction in viremia and shedding of virus in semen was demonstrated by use of the live vaccine compared to the non-vaccinated control animals. In contrast, no changes in onset, level and duration of viremia and shedding of virus in semen were observed using the inactivated vaccine. Neither viremia nor seminal shedding of virus was detected in previously PRRSV-infected, PRRSV-antibody positive boars after challenge with a Danish field strain of PRRSV.     

The insulin receptor substrate 1 associates with phosphotyrosine phosphatase SHPTP2 in liver and muscle of rats

OBJECTIVE: To determine efficacy of a vaccine containing modified-live bovine viral diarrhea virus (BVDV) type 1 for protecting pregnant cows and their fetuses against virulent heterologous BVDV type 1. DESIGN: Randomized controlled cohort study. ANIMALS: 18 yearling beef heifers seronegative for BVDV and negative when tested for BVDV by virus isolation. PROCEDURE: Cattle were randomly assigned to control (unvaccinated; n = 6) or vaccinated (12) groups. Vaccinated heifers were given a combination vaccine containing modified-live BVDV type 1 comprising a cytopathic (NADL) strain. All 18 heifers were then bred and challenge-exposed between 70 and 75 days of gestation with BVDV type 1, administered intranasally. Cattle were monitored, and infection status of offspring was determined after parturition. Antibody concentrations of vaccinated and control heifers were also monitored. RESULTS: All 6 calves from control heifers had positive results on multiple virus isolation tests and were considered persistently infected. In comparison, only 2 calves from vaccinated cows had positive results on virus isolation tests and were considered persistently infected. One vaccinated heifer aborted, but the fetus was not persistently infected, and the abortion was not attributed to BVDV infection. CLINICAL IMPLICATIONS: Analysis of these data indicated that a single dose of a modified-live NADL-derived BVDV type 1 vaccine will confer protection to dams and their fetuses against challenge-exposure to heterologous BVDV type 1 organisms.     

Studies on calf salmonellosis. 3. Preclinical evaluation of a Smd. Salmonella dublin live vaccine

Results of preclinical assay, preparation and conservation of a S.-dublin live vaccine based on streptomycin dependent mutants and for oral application are demonstrated and discussed in detail. The used oral vaccine is very good tolerated by calves and results in stable immunity after administration of a daily dose of 5 x 10(10) bis 1 x 10(11) living Smd.-mutants for 10 consecutive days. Complete immunity developes in calves within a period of two weeks after the last antigen administration and persists up to the age of 5 to 6 months. Conserving the vaccine at low temperatures (-15 degrees C) the number of living organism is far-reaching preserved in the first 5 months after preparation. After thawing the vaccine is to be used within a period of 3 days. With respect to the preparation of the live vaccine on semisynthetic nutritiv media some informations are given concerning the improvement of bacterial yield.     

Pathogenesis of wild-type and leaderless foot-and-mouth disease virus in cattle

Four calves were experimentally infected via aerosol with foot-and-mouth disease virus. Two were infected with a wild-type virus derived from a full-length infectious clone (A12-IC), and two were infected with a clone-derived virus lacking the leader gene (A12-LLV2), with euthanasia and tissue collection at 24 and 72 h postexposure (hpe). Clinical disease was apparent only in the animal given A12-IC and euthanized at 72 hpe. In situ hybridization revealed that the animal infected with A12-IC and euthanized at 24 hpe had abundant viral nucleic acid in the lung, present in clusters of positive cells in the respiratory bronchiolar epithelium and associated subepithelial regions. At 72 hpe in the A12-IC-infected calf, viral nucleic acid in the lung was present in interstitial areas, and in addition, viral nucleic acid was detectable in epithelial tissues around histologically apparent vesicles. In animals infected with A12-LLV2, viral nucleic acid was detectable in the lung at both 24 and 72 hpe, but staining revealed a more localized distribution with less nucleic acid than was found in animals given A12-IC. Therefore, it appears that after aerosol exposure to A12-IC, early replication is in the region of the lung, with subsequent dissemination to distal sites. In comparison, the A12-LLV2 virus is much less widely disseminated in the lung at 24 hpe, with no lesions or virus detectable in secondary sites at 72 hpe. The greatly reduced pathogenicity of A12-LLV2 may make it an excellent candidate for a modified live viral vaccine.     

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.     

Cell-mediated and humoral immunity in bulls infected with IBR/IPV virus (BHV 1)

Time-related changes in specific cell-mediated immunity (CMI) and in humoral immunity were monitored in 20 bulls, aging 12 to 16 months, in four groups, each consisting of 5 animals. Group I was experimentally and group III-naturally infected with BHV 1 virus, groups II and IV serving as control animals. Tests for CMI included delayed type hypersensitivity (DTH), leukocyte migration inhibitory factor (LMIF) and granulocyte migration inhibitor factor (GMIF-LIF-buffy coat leukocyte migration inhibitory factor) in the presence of BHV I antigen while humoral immunity was tested by serum induced neutralization of the virus (SN) and by estimation of serum IgG, IgG1, IgG2, IgM and IgA levels. Immunologic, virologic and clinical studies were performed two days before infection and 17 timed within 91 days after the infection in bulls of group I and II and 7 times within 42 days after developing the disease in bulls of groups III and IV. The results showed that positive CMI reactions appeared 3 to 4 weeks earlier than positive antibody titers in SN test. The antibodies belonged most probably to IgG1 and IgG2 subclasses.     

Therapeutic periocular vaccination with a subunit vaccine induces higher levels of herpes simplex virus-specific tear secretory immunoglobulin A than systemic vaccination and provides protection against recurrent spontaneous ocular shedding of virus in latently infected rabbits

Rabbits latently infected with herpes simplex virus type 1 (HSV-1) were vaccinated either periocularly or systemically with a subunit vaccine (gB2 + gD2) plus adjuvant or adjuvant alone. Tear films were collected daily to measure recurrent infectious HSV-1 shedding. After systemic vaccination, the latently infected rabbits were not protected against recurrent ocular viral shedding (HSV-1-positive tear film cultures/total cultures) compared with either the systemic or periocular adjuvant controls (systemic vaccination = 49 of 972, 5.0%; systemic control = 46 of 972, 4.7%; periocular control = 43 of 930, 4.6%; P > 0.8). In contrast, latently infected rabbits vaccinated periocularly with the same vaccine had significantly reduced recurrent shedding (20 of 1026, 2.0%) compared with controls (P < 0.001) or systemic vaccination (P = 0.0002). Thus, recurrent HSV-1 shedding was significantly reduced by therapeutic local periocular subunit vaccination but not by therapeutic systemic subunit vaccination. Neutralizing antibody titers in the serum of systemically and ocularly vaccinated rabbits was similar. In contrast, HSV-specific tear secretory immunoglobulin A was significantly higher in the ocularly vaccinated group (P < 0.01). These results strongly suggest that in the rabbit, and presumably in humans, the local ocular (mucosal) immune response is much more important than the systemic immune response for therapeutic protection against recurrent ocular HSV-1. Thus development of a therapeutic vaccine against recurrent ocular HSV-1 should be directed at enhancing the local ocular (mucosal) immune response.     

The dynamics of an infectious disease in a population with birth pulses

In December 1996, a questionnaire about farm management and parasite control measures in calves was sent to 956 randomly chosen dairy cattle farmers in The Netherlands. Another 150 farmers in the vicinity of Deventer who had vaccinated their calves in 1995 against lungworm were approached with the same questions. Our object was to investigate the consequences on worm control of the withdrawal of the lungworm vaccine from the market for reasons of possible BSE contamination of the vaccine. OF the returned questionnaires, 411 (43%) of the 'at random' group and 89 (59.3%) of the 'Deventer' group were valid. The most important data with regard to the farms of the 'at random' group (41) were: mean area 31.6 ha, mean number of calves 23, heifers 23 and milking cows 53. Sheep (mean 37) were present on 18.3% of the farms. With regard to management: 74.5% of the farmers turned the calves in their first year onto pasture, 25.5% kept them indoors. The average time on pasture was ca. 5 months. Rational grazing was practise on 81.4% of the farms, on 18.6% calves were set stocked. The first pasture of the calves was mown before turn-out on 72.9% of the farms. On 48.2% of these farms, calves were always moved to mown pastures. With regard to treatments: 33.8% of the farmers vaccinated their calves against lungworm in the years 1993, 1994 and 1995. Despite the withdrawal of the vaccine from the market in 1996, 7.2% of the farmers vaccinated their calves as recommended, with two doses, and 13.1% with a single dose. At turn-out, 41.5% of the farmers gave the calves a preventive anthelmintic treatment. Of these treatments, 66.9% were sustained of pulse release long acting device. During the grazing season, 36.6% of the farmers treated their calves. After housing 50.3% of the farmers gave a treatment. Signs of lungworm infection were noticed on 18.6% of the farms. Of the 'Deventer' group (89 farmers), 96.6% turned the calves out, Of these farmers, 86.0% had used the lungworm vaccine in 1995. In 1996, 52.7% of the farmers had vaccinated the calves:36.5% with a single dose and 16.2% with the double dose. Of the 35 farmers who did not vaccinate in 1996, 62.9% gave a preventive treatment at turn-out. Clinical signs of lungworm infection were not observed on the 12 farms which vaccinated the calves twice. On 11% of the farms which vaccinated once and on 14% of the farms which did not vaccinate, signs of lungworm infection were observed. It is concluded that more than 80% of Dutch dairy cattle farmers take appropriate measures to control gastrointestinal nematode and lungworm infections in calves in their first grazing season by grazing on aftermath, rotational grazing on mown pastures combined or not with preventive anthelmintic treatments. However, combinations of aftermath grazing and preventive treatment occurred on 30% of the farms. This may be overprotective and may prevent sufficient build up of immunity, causing worm problems at a later age. The withdrawal of the lungworm vaccine from the market did not cause a rise in lungworm problems. Some farmers did vaccinate, despite the withdrawal. The majority used other preventive treatment measures, mainly the application of long acting boli.     

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.