Bovine Herpesvirus-1 Challenge Research Articles

Bovine papular stomatitis virus as a vaccine vector for cattle.

Virus vectored vaccines are not available commercially for cattle even though compelling potential applications exist. Bovine papular stomatitis virus (BPSV), a highly prevalent parapoxvirus, causes self-limited oral lesions in cattle. Ability of virus to accommodate large amounts of foreign DNA, induce low level of antiviral immunity, and circulate and likely persist in cattle populations, make BPSV an attractive candidate viral vector. Here, recombinant BPSV were constructed expressing either Bovine herpesvirus 1 (BoHV-1) glycoprotein gD (BPSVgD), or gD and gB (BPSVgD/gB). Immunization of BPSV serologically-positive calves with BPSVgD or BPSVgD/gB induced BoHV-1 neutralization antibodies and provided protection for three of four animals following a high dose BoHV-1 challenge at day 70 pi. Results indicate BPSV suitability as a candidate virus vector for cattle vaccines.

Clinical status and endoscopy of the upper respiratory tract of dairy calves infected with Bovine viral diarrhea virus 2 and Bovine herpes virus 1 after vaccination and trace minerals injection

The objective was to compare clinical protection [evaluated through health scoring, endoscopy score of the upper respiratory tract (URT-ES), leukocyte count, viremia, and virus shedding in nasal secretions] following Bovine viral diarrhea virus 2 (BVDV2) and Bovine herpes virus 1 (BHV1) challenge among calves submitted to modified-live virus (MLV) booster vaccination (either intranasal or subcutaneous) concurrent with injectable trace minerals (ITM) or saline. Forty-eight dairy calves received an MLV intranasal (IN) vaccine containing BHV1, BRSV, and BPI3V and subcutaneous (SC) ITM (Se, Cu, Zn & Mn; ITM, n = 24) or saline (SAL, n = 24). Ten weeks later, calves received a second dose of ITM, or saline, according to previous groups and were randomly assigned to receive the same IN vaccine [ITM-IN (n = 12), SAL-IN (n = 12)] or a SC MLV vaccine containing BHV1, BRSV, BPI3V, BVDV1 & 2 [ITM-SC (n = 12), SAL-SC (n = 12)]. Additionally, 12 calves did not receive vaccine or treatment and served as a control group (UNVAC, n = 12). Forty-nine days after booster, calves were challenged with BVDV2; and seven days later with BHV1. Health scores indicated disease in UNVAC on days 6, 10 and 12 compared to the vaccinated groups. Unvaccinated calves had the highest URT-ES after BHV1 challenge. Calves that received SC booster had lower URT-ES after BHV1 challenge than UNVAC calves. Calves in ITM-IN had significantly lower URT-ES after BHV1 infection than SAL-IN and UNVAC calves. In conclusion, IN or SC MLV vaccination was similarly effective in protecting calves from BVDV2 + BHV1 challenges (reducing clinical and endoscopy scores, preventing leukopenia, and viremia), compared to unvaccinated calves. Endoscopic evaluation of the URT allowed visualization of the inflammation and damage at multiple depths in the URT caused by a serial BVDV2 + BHV1 challenge. Calves that received SC vaccination had significantly lower URT-ES after BHV1 challenge than the UNVAC calves. Administration of ITM concurrent with IN vaccination was associated with reduced URT inflammation after BVDV2 + BHV1 challenge.

Pre-weaning plane of nutrition and Mannheimia haemolytica dose influence inflammatory responses to a bovine herpesvirus-1 and Mannheimia haemolytica challenge in post-weaning Holstein calves

The objectives of this study were to determine whether plane of nutrition (PON) of milk replacer previously provided to calves, and dosage level of Mannheimia haemolytica (MH), influenced inflammatory responses to a combined viral-bacterial respiratory challenge. Holstein calves (1 d of age; n = 30) were assigned to treatments in a 2 × 3 factorial with pre-weaning PON and MH dose as main effects (n = 5 per treatment). Calves were fed either a low (LPN; n = 15) or a high PON (HPN; n = 15) from birth through weaning. Calves fed LPN were fed 436 g of dry matter (DM) per day of milk replacer until weaning, and HPN calves were fed 797 g of DM per day of milk replacer from d 1 to 10 and 1,080 g of DM per day from d 11 until weaning. Calf starter and water were offered ad libitum. Calves were step-down weaned beginning at d 54 and moved into an enclosed barn at d 70. Indwelling rectal temperature (RT) recording devices and jugular catheters were inserted at d 80. Calves were challenged with 1.5 × 108 plaque-forming units (pfu) per mL of bovine herpesvirus-1 (BHV-1) in each nostril at d 81 and with either 106, 107, or 108 cfu of MH at d 84. Blood samples were collected at varying intervals relative to BHV-1 and MH challenges. Four LPN calves either died or were euthanized soon after the 144-h observation period, whereas all HPN calves survived the entire observation period. As dosage of MH administered increased, acute and systemic inflammatory responses increased. Higher doses of MH resulted in increased leukocyte, neutrophil, and haptoglobin concentrations in infected calves. Data from the current study suggest that the highest dose, 108 cfu, triggered weaned calves' acute disease response, whereas the lower doses, 106 and 107 cfu, caused more moderate inflammation and disease. The effects of PON on inflammation responses to the disease challenge indicated that calves previously fed the LPN diet had more severe pathophysiological responses. Calves fed LPN showed higher peripheral neutrophil and leukocyte counts and serum haptoglobin concentrations following the BHV-1 challenge. Additionally, following the MH challenge, LPN calves had higher peripheral neutrophil counts, neutrophil-to-lymphocyte ratios, and serum tumor necrosis factor-α concentrations. These data demonstrate that higher doses of MH increase the acute inflammatory response and prolong inflammation, and that calves previously fed LPN responded more severely to the combined viral-bacterial respiratory challenge.

104 Administration of a DNA immunostimulant does not mitigate bovine herpesvirus-1 recrudescence in dexamethasone challenged beef cattle

Abstract The study objective was to determine the effect of a DNA immunostimulant on recrudescence of bovine herpesvirus-1 (BHV-1) after dexamethasone challenge in beef cattle. It was hypothesized that the DNA immunostimulant would mitigate stress-induced immunosuppression; thereby, reducing the incidence of BHV-1 recrudescence. Steers (n=10) and heifers (n=10; initial BW = 489 kg ± 57 kg) were stratified by pre-existing BHV-1 antibody titer, sex and initial BW and randomly assigned to treatment (n=4 pens/treatment; 2 or 3 animals/pen). All calves were administered 40 mg of dexamethasone i.v. at 0600 h from d 0 to 2, 166-d subsequent to BHV-1 challenge with 1.0 × 108 plaque-forming units per nostril. On d 1, calves were administered treatments consisting of 2 mL i.m. of DNA immunostimulant (Zelnate; ZEL) or sterile saline (CON). Once daily (0600) from d 0 to 12, a whole blood was obtained via jugular venipuncture for complete blood count (CBC) analysis and nasal swabs were collected to determine BHV-1 prevalence via virus isolation testing. A repeated measures mixed model was used to test the effect of treatment, day and their interaction for CBC variables. There was a treatment × day interaction for eosinophils (P = 0.02) and percent eosinophils (P = 0.03). Eosinophils were greater (P < 0.01) for ZEL on d 3 and 6 post-dexamethasone challenge. On d 11 and 12, eosinophils for CON rebounded such that their concentration was greater than ZEL (P < 0.01). Lymphocytes, neutrophil and monocyte concentration did not differ (P ≥ 0.44); however, a day effect (P ≤ 0.01) existed such that each variable increased transiently after dexamethasone challenge. All cattle had BHV-1 present in a nasal swab sample on at least one sample day, with prevalence of BHV-1 in nasal swab samples being greatest on d 5 (80% positive; P = 0.01). However, no treatment differences were detected for BHV-1 prevalence in this study. The DNA immunostimulant altered eosinophil concentrations but did not mitigate BHV-1 recrudesce after dexamethasone challenge

3 Administration of a DNA immunostimulant does not mitigate bovine herpesvirus-1 recrudescence in dexamethasone challenged beef cattle

Abstract The study objective was to determine the effect of a DNA immunostimulant on recrudescence of bovine herpesvirus-1 (BHV-1) after dexamethasone challenge in beef cattle. It was hypothesized that the DNA immunostimulant would mitigate stress-induced immunosuppression; thereby, reducing the incidence of BHV-1 recrudescence. Steers (n = 10) and heifers (n = 10; initial BW = 489 kg ± 57 kg) were stratified by pre-existing BHV-1 antibody titer, sex and initial BW and randomly assigned to treatment (n = 4 pens/treatment; 2 or 3 animals/pen). All calves were administered 40 mg of dexamethasone i.v. at 0600 h from d 0 to 2, 166-d subsequent to BHV-1 challenge with 1.0 × 108 plaque-forming units per nostril. On d 1, calves were administered treatments consisting of 2 mL i.m. of DNA immunostimulant (Zelnate; ZEL) or sterile saline (CON). Once daily (0600) from d 0 to 12, a whole blood was obtained via jugular venipuncture for complete blood count (CBC) analysis and nasal swabs were collected to determine BHV-1 prevalence via virus isolation testing. A repeated measures mixed model was used to test the effect of treatment, day and their interaction for CBC variables. There was a treatment × day interaction for eosinophils (P = 0.02) and percent eosinophils (P = 0.03). Eosinophils were greater (P < 0.01) for ZEL on d 3 and 6 post-dexamethasone challenge. On d 11 and 12, eosinophils for CON rebounded such that their concentration was greater than ZEL (P < 0.01). Lymphocytes, neutrophil and monocyte concentration did not differ (P ≥ 0.44); however, a day effect (P ≤ 0.01) existed such that each variable increased transiently after dexamethasone challenge. All cattle had BHV-1 present in a nasal swab sample on at least one sample day, with prevalence of BHV-1 in nasal swab samples being greatest on d 5 (80% positive; P = 0.01). However, no treatment differences were detected for BHV-1 prevalence in this study. The DNA immunostimulant altered eosinophil concentrations but did not mitigate BHV-1 recrudesce after dexamethasone challenge

Immune and metabolic responses of beef heifers supplemented with Saccharomyces cerevisiae to a combined viral-bacterial respiratory disease challenge.

Two treatments were evaluated in heifers to determine the effects of a yeast supplement on immune and metabolic responses to a combined (tandem viral-bacterial) respiratory disease challenge. Thirty-two beef heifers (325 ± 20.1 kg BW) were selected from a larger population previously assigned to one of two treatments: Control (CON), receiving no yeast supplement in the diet, or yeast (YST), CON diet plus a combination live yeast (2.5 g·heifer-1·d-1) and yeast cell wall (2.5 g·heifer-1·d-1) supplement (Phileo Lesaffre Animal Care, Milwaukee, WI). Heifers were maintained on treatments for 31 d prior to the challenge. On day -3 all heifers were fitted with an indwelling vaginal temperature recording device, received an intranasal challenge with 2 × 108 plaque-forming units of bovine herpesvirus-1 (BHV-1), and placed in outdoor pens. On day 0, all heifers were fitted with an indwelling jugular catheter, challenged intratracheally with an average dose of 3.0 × 107 colony-forming units (cfu) of Mannheimia haemolytica in 100 mL media, and were transferred into individual stanchions in an enclosed, environmentally controlled barn. Whole blood samples were collected at -72 h and at 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h (hematology) and at 0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 24, 36, 48, 60, and 72 h (serum isolation) relative to M. haemolytica challenge (0 h). Data were analyzed using the MIXED procedure of SAS specific for repeated measures with fixed effects of treatment, time, and the treatment × time interaction. Vaginal temperature and cortisol concentrations were similar between treatments (P ≥ 0.39). Although total leukocyte count following BHV-1 challenge was similar between treatments (P = 0.21), there was a tendency (P = 0.07) for CON heifers to have greater neutrophil counts than YST heifers. Serum haptoglobin concentration was similar between treatments (P = 0.13). Heifers in the YST treatment had similar serum glucose concentrations (P = 0.25) and decreased serum concentrations of urea nitrogen compared to CON (P = 0.03). Dietary treatment did not affect serum nonesterified fatty acid concentrations (P = 0.37). Nasal lesion score severity (0-4) tended (P = 0.07) to be decreased in YST compared to CON (2.5 vs. 3.19 ± 0.26), while water intake tended to be increased in YST (P = 0.06). Feeding a yeast supplement had little effect on the acute-phase response but improved metabolic outcomes in heifers during a respiratory disease challenge.

A triple gene mutant of BoHV-1 administered intranasally is significantly more efficacious than a BoHV-1 glycoprotein E-deleted virus against a virulent BoHV-1 challenge

Bovine herpesvirus 1 (BoHV-1) causes respiratory infections and abortions in cattle, and is an important component of bovine respiratory disease complex, which causes a considerable economic loss worldwide. Several efforts have been made to produce safer and more effective vaccines. One of these vaccines is a glycoprotein E (gE)-deleted marker vaccine which is currently mandated for use in EU countries. In the present study, we have constructed a three-gene-mutated BoHV-1 vaccine virus (UL49.5 luminal domain residues 30–32 and cytoplasmic tail residues 80–96 deleted, gE cytoplasmic tail- and entire Us9-deleted) and compared its protective vaccine efficacy in calves after intranasal vaccination with that of a gE-deleted virus. Following vaccination, both the triple mutant and gE-deleted vaccine virus replicated well in the nasal epithelium of the calves. The vaccinated calves did not show any clinical signs. Four weeks post-vaccination, the animals were challenged intranasally with a virulent BoHV-1 wild-type virus. Based on clinical signs, both the gE-deleted and triple mutant group were protected equally against the virulent BoHV-1 challenge. However, based on the quantity and duration of nasal viral shedding, virus neutralizing antibody and cellular immune responses, the triple mutant virus vaccine induced a significantly better protective immune response than the gE-deleted virus vaccine. Notably, after the virulent BoHV-1 challenge, the triple mutant virus vaccinated group cleared the challenge virus three days earlier than the BoHV-1 gE-deleted virus vaccinated group.

Comparison of pathological changes and viral antigen distribution in tissues of calves with and without preexisting bovine viral diarrhea virus infection following challenge with bovine herpesvirus-1

To compare pathological changes and viral antigen distribution in tissues of calves with and without preexisting subclinical bovine viral diarrhea virus (BVDV) infection following challenge with bovine herpesvirus-1 (BHV-1). 24 Friesian calves. 12 calves were inoculated intranasally with noncytopathic BVDV-1a; 12 days later, 10 of these calves were challenged intranasally with BHV-1 subtype 1. Two calves were euthanized before and 1, 2, 4, 7, or 14 days after BHV-1 inoculation. Another 10 calves were inoculated intranasally with BHV-1 only and euthanized 1, 2, 4, 7, or 14 days later. Two calves were inoculated intranasally with virus-free tissue culture fluid and euthanized as negative controls. Pathological changes and viral antigen distribution in various tissue samples from calves with and without BVDV infection (all of which had been experimentally inoculated with BHV-1) were compared. Following BHV-1 challenge, calves with preexisting subclinical BVDV infection had earlier development of more severe inflammatory processes and, consequently, more severe tissue lesions (limited to lymphoid tissues and respiratory and digestive tracts) and greater dissemination of BHV-1, compared with calves without preexisting BVDV infection. Moreover, coinfected calves had an intense lymphoid depletion in the Peyer patches of the ileum as well as the persistence of BVDV in target organs and the reappearance of digestive tract changes during disease progression. In calves, preexisting infection with BVDV facilitated the establishment of BHV-1 infection, just as the presence of BHV-1 favors BVDV persistence, thereby synergistically potentiating effects of both viruses and increasing the severity of the resultant clinical signs.

Attenuation of bovine herpesvirus type 1 by deletion of its glycoprotein G and tk genes and protection against virulent viral challenge

To develop a novel vaccine against infectious bovine rhinotracheitis (IBR), a bovine herpesvirus-1 (BoHV-1) mutant was constructed by deleting the genes for glycoprotein G (gG) and thymidine kinase (tk) through homologous recombination. The resulting sequences for both genes were shown to be correct and a gG expression defect was also confirmed. A parallel study of the BoHV-1 gG(-)/tk(-), gE(-)/tk(-) mutants and wild type (wt) in 31 calves was performed at three different doses, 4×10(5)PFU, 4×10(6)PFU and 4×10(7)PFU. Compared to wt BoHV-1, inoculation of BoHV-1 gG(-)/tk(-) and gE(-)/tk(-) produced no clinical signs and the virus was not reactivated by dexamethasone (dex). Inoculation of BoHV-1 gG(-)/tk(-) at the doses of 4×10(6) and 4×10(7)PFU provided full clinical protection for the cattle against wt BoHV-1 challenge at 4×10(7)PFU/calf. Although the mutants were associated with significantly lower levels of serum neutralizing antibody, interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) than wt BoHV-1 on days 3, 5 and 7 after immunization, stimulation of IFN-β by BoHV-1 gG(-)/tk(-) was significantly higher than that of wt BoHV-1 and gE(-)/tk(-) on days 3 and 5. We conclude that BoHV-1 gG(-)/tk(-) was attenuated adequately and that it maintains the ability to stimulate immune protection. Therefore, it may be a promising candidate for a marker vaccine against IBR.

Recombinant MVA Expressing Secreted Glycoprotein D of BoHV-1 Induces Systemic and Mucosal Immunity in Animal Models

Bovine herpesvirus-1 (BoHV-1) infection is distributed worldwide and the development of new tools to fight against this pathogen has become extremely important. In this work a recombinant modified vaccinia virus Ankara (MVA) vector expressing the secreted version of glycoprotein D, MVA-gDs, was obtained and evaluated as a candidate vaccine. First, the correct expression, antigenicity, and N-glycosylation of glycoprotein D were confirmed by molecular techniques. Then MVA-gDs was used as parenteral immunogen in BALB/C mice in which a specific anti-gD humoral immune response was induced and maintained for 7 mo. Two doses of MVA-gDs supplemented with cholera toxin delivered by intranasal immunization induced IgA anti-gD humoral immune responses in nasal and bronchopulmonary washes, as well as IgG anti-gD antibodies in serum samples. In order to evaluate the protection conferred by MVA-gDs immunization, a rabbit BoHV-1 challenge assay was performed. A shorter viral excretion period and a reduction in the number of animals shedding BoHV-1 was observed in the group immunized with recombinant MVA-gDs. In conclusion our data encourage further studies to evaluate MVA-gDs, alone or combined with other immunogens, as a candidate vaccine for BoHV-1.

Evaluation of the onset of protective immunity from administration of a modified-live, non-adjuvanted vaccine prior to intranasal challenge with bovine herpesvirus-1

Study objectives were to determine if subcutaneous administration of a modified-live, non-adjuvanted vaccine containing bovine herpesvirus-1 (BHV-1) at five, three, or two days pre-challenge, would reduce clinical signs, rectal temperatures, and viral shedding, and enhance serological response to BETV-1. Colostrum-deprived, neonatal calves (n=48) were randomly assigned to six treatment groups, each containing eight calves. Treatment groups were based on administration of vaccine (VAC) or saline controls (CON) and day of administration (day-5, -3 or -2) relative to intranasal BHV-1 challenge (day 0). Following challenge, calves were monitored for clinical signs, rectal temperature, seroconversion, and quantity of BHV-1 recovered by virus isolation from nasal swabs. Data for the evaluation period (days 4-14) were analyzed using multivariable statistics. Day-5 and -3 VAC groups had fewer (P less than 0.05) days of clinical illness compared to CON. Rectal temperatures were lower (P less than 0.05) during days 4-8 for each of the VAC groups as compared to combined CON groups. CON calves shed BHV-1 for more days than calves vaccinated on day-5 (P less than 0.01), day-3 (P=0.06), or day-2 (P=0.06). Mean concentrations of nasal BHV-1 also differed (P less than 0.05) between combined CON groups and each of the VAC groups during at least one study day. Calves in the VAC groups (median=10 days) seroconverted to BHV-1 (P less than 0.01) sooner than CON calves (median=14 days). This study demonstrated that the use of a non-adjuvanted MLV vaccine in neonatal calves can reduce the effects of BETV-1 challenge soon after vaccination.

Strategies for induction of protective immunity to bovine herpesvirus-1 in newborn calves with maternal antibodies

The objective of this study was to evaluate Th1 promoting strategies for vaccination of neonates against bovine herpesvirus-1 (BHV-1). A plasmid encoding a secreted truncated version of glycoprotein D (tgD) and tgD protein formulated with CpG oligodeoxynucleotide (ODN) effectively primed the immune system of newborn lambs, whereas without CpG ODN the tgD protein was less effective. Furthermore, a heterologous DNA prime-protein/CpG boost induced stronger and more balanced immune responses than either the DNA vaccine or a protein/CpG prime-DNA boost. Three of these strategies were compared as an approach to induce protective immunity in newborn calves with BHV-1-specific maternal antibodies. Whereas the DNA vaccine induced minimal protection, the DNA prime-protein boost resulted in reduced temperature response, weight loss and virus shedding in comparison to the placebo group. Close to complete protection against BHV-1 challenge was elicited in the calves immunized with the protein/CpG formulation, as these animals lost very little weight, had only slightly elevated temperatures and shed almost no virus.

Induction of antigen-specific T-cell subset activation to bovine respiratory disease viruses by a modified-live virus vaccine

To determine the efficacy of a modified-live virus vaccine containing bovine herpes virus 1 (BHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza virus 3, and bovine viral diarrhea virus (BVDV) types 1 and 2 to induce neutralizing antibodies and cell-mediated immunity in naïve cattle and protect against BHV-1 challenge. 17 calves. 8 calves were mock-vaccinated with saline (0.9% NaCl) solution (control calves), and 9 calves were vaccinated at 15 to 16 weeks of age. All calves were challenged with BHV-1 25 weeks after vaccination. Neutralizing antibodies and T-cell responsiveness were tested on the day of vaccination and periodically after vaccination and BHV-1 challenge. Specific T-cell responses were evaluated by comparing CD25 upregulation and intracellular interferon-gamma expression by 5-color flow cytometry. Titration of BHV-1 in nasal secretions was performed daily after challenge. Results-Vaccinated calves seroconverted by week 4 after vaccination. Antigen-specific cell-mediated immune responses, by CD25 expression index, were significantly higher in vaccinated calves than control calves. Compared with control calves, antigen-specific interferon-gamma expression was significantly higher in calves during weeks 4 to 8 after vaccination, declining by week 24. After BHV-1 challenge, both neutralizing antibodies and T-cell responses of vaccinated calves had anamnestic responses to BHV-1. Vaccinated calves shed virus in nasal secretions at significantly lower titers for a shorter period and had significantly lower rectal temperatures than control calves. A single dose of vaccine effectively induced humoral and cellular immune responses against BHV-1, BRSV, and BVDV types 1 and 2 and protected calves after BHV-1 challenge for 6 months after vaccination.

Effects of diet for early-weaned crossbred beef steers on metabolic profiles and febrile response to an infectious bovine herpesvirus-1 challenge

Thirty-three early-weaned steers (average age at weaning = 132 days) were used to evaluate effects of protein supplementation of forage diets vs. a 70% concentrate diet fed during a backgrounding phase (84 d) on metabolic profiles and febrile response to an infectious bovine herpesvirus-1 (BHV-1) challenge during a receiving phase (27 d). Backgrounding treatments included a bermudagrass hay diet (CTRL); CTRL plus soybean meal (SBM) fed at 0.175% of BW (as-fed); CTRL plus SBM at 0.35% of BW; or a 70% concentrate (CONC) diet. During the receiving phase, all steers were fed CONC and intranasally challenged on d 85 with an infectious dose of BHV-1. Unexpectedly, 3 d after the BHV-1 challenge, serum IgG was greater ( P < 0.05) for steers fed forage diets vs. CONC. Three and 4 d after the BHV-1 challenge, rectal temperatures were greater ( P < 0.01) for protein-supplemented steers vs. CTRL. We conclude that a higher quality diet fed to early-weaned steers during a backgrounding phase enhances average daily gain and gain to feed ratio, and increases febrile response (measured by rectal temperature) to an infectious BHV-1 respiratory challenge.

Bovine Herpesvirus 1 VP22 Enhances the Efficacy of a DNA Vaccine in Cattle

For this study, the intercellular trafficking ability of bovine herpesvirus 1 (BHV-1) VP22 was applied to improve the efficacy of a DNA vaccine in calves. A plasmid encoding a truncated version of glycoprotein D (tgD) fused to VP22 was constructed. The plasmid encoding tgD-VP22 elicited significantly enhanced and more balanced immune responses than those induced by a plasmid encoding tgD. Furthermore, protection against a BHV-1 challenge was obtained in calves immunized with the plasmid encoding tgD-VP22, as shown by significant reductions in viral excretion. However, less significant protection was observed for animals vaccinated with the tgD-expressing plasmid, correlating with the lower level of immunity observed prechallenge. This is the first report of the use of VP22 as a transport molecule in the context of a DNA vaccine for a large animal species.

Relative efficacy of inactivated bovine herpesvirus-1 (BHV-1) vaccines

The relative efficacy of four commercially available inactivated bovine herpesvirus-1 (BHV-1) vaccines was directly assessed in controlled studies in 5–6-month-old, BHV-1 naïve calves. The sero-response due to the basic course of two intramuscular vaccinations was closely similar for three of four vaccines whereas one vaccine did not induce seroconversion in five of six calves. At the level of challenge virus shedding in nasal mucus, all four vaccines were significantly protective but to a markedly variable degree. Clinically, however, the relative protection ranking of the vaccines was different to that observed for challenge virus shedding. There was no obvious correlation observed between pre-challenge circulating virus neutralising antibody titre and vaccine-induced protection against virus shedding or clinical signs following the intranasal BHV-1 challenge. Present comparative findings suggest that commercially available BHV-1 vaccines are likely to be of variable potency in the natural host.

Single Subcutaneous Dose of a Combination Vaccine Containing Bovine Herpes Virus- 1 (BHV-1) Provides Protection Against an Intranasal BHV-1 Challenge 72 Hours Later

Bovine herpesvirus 1 (BHV-1) is associated with several disease syndromes in cattle. The BHV-1 respiratory infections can result in several clinical manifestations that range from inapparent to severe respiratory disease, infectious bovine rhinotracheitis (IBR). Signs include pyrexia, anorexia, conjunctivitis with lacrimal discharge, dyspnea and nasal discharge. BHV-1 respiratory infection in calves and feedlot cattle can lead to the bovine respiratory disease complex (BRDC), with secondary bacterial infections that cause significant economic losses to the livestock industry.&#x0D; Vaccination programs are a routine practice in US feedlot operations to protect cattle against BHV-1 associated disease. Unfortunately, many calves are not vaccinated prior to weaning or commingling into backgrounding lots, feedlots or pasture operations. These animals are at increased risk of BHV-1 infection and are predisposed to secondary bacterial pneumonia. The time from vaccination to onset of protection can play an important role in subsequent management of newly arrived cattle against IBR.&#x0D; An experiment was conducted to determine the onset of protection against an intranasal BHV-1 challenge following a subcutaneous injection of a commercial modified-live virus (MLV) vaccine containing attenuated BHV-1.

Modulation of immune responses to bovine herpesvirus‐1 in cattle by immunization with a DNA vaccine encoding glycoprotein D as a fusion protein with bovine CD154

The objective of this study was to determine whether a DNA vaccine encoding bovine CD154 linked to a truncated version of bovine herpesvirus-1 (BHV-1) glycoprotein D (tgD-CD154) induces enhanced tgD-specific immune responses in cattle. In vitro characterization demonstrated that tgD and tgD-CD154 both bind to cultured bovine B cells, whereas only tgD-CD154 induces interleukin-4-dependent proliferation, suggesting that tgD-CD154 specifically binds the CD40 receptor and induces receptor signalling. Calves were immunized with plasmid encoding either tgD or tgD-CD154 by intradermal injection with a needle-free device. After two immunizations, tgD-specific immune responses were observed in both vaccinated groups and after challenge with BHV-1 these responses further increased. Animals immunized with plasmid encoding tgD-CD154 had significantly higher tgD-specific serum titres of immunoglobulins G and A but significantly lower numbers of tgD-specific interferon-gamma-secreting cells than animals immunized with plasmid encoding tgD after BHV-1 challenge. This suggests that the expression of an antigen as a chimeric protein with CD154 can qualitatively alter immune responses in cattle. Since we previously showed that plasmid encoding tgD-CD154 induces significantly enhanced secondary tgD-specific antibody responses in sheep, there appear to be interspecies differences in the immune responses induced by tgD-CD154, which suggests that both proteins in the chimeric molecule may influence protein targeting and the induction of an immune response.

Glycol chitosan improves the efficacy of intranasally administrated replication defective human adenovirus type 5 expressing glycoprotein D of bovine herpesvirus 1

The ability of two soluble formulations, namely chitosan and glycol chitosan, when used as an intranasal adjuvant, to improve the immunogenicity of an intranasal human adenovirus type 5 replication defective expressing bovine herpesvirus 1 (BoHV-1) glycoprotein D based vaccine, was investigated in cattle. Their adjuvant effects on immune response by increasing clinical and especially virological protection against an intranasal BoHV-1 challenge were then evaluated. The best virological protection was obtained in calves immunized with the vaccine vector adjuvanted with glycol chitosan which decreased the challenge BoHV-1 virus excretion titres by 0.5–1.5 log when compared to those obtained in calves immunized with the vaccine vector alone or adjuvanted with chitosan. A slight difference in clinical scores was observed in calves immunized with the adjuvanted vaccine vector compared to calves immunized with the vaccine vector alone. The obtained data suggest that the tested soluble formulation of glycol chitosan has promising potential use as an intranasal adjuvant for recombinant viral vector vaccines in cattle.

The immunogenicity and protective efficacy of bovine herpesvirus 1 glycoprotein D plus Emulsigen are increased by formulation with CpG oligodeoxynucleotides.

The immunogenicity and protective efficacy of a bovine herpesvirus 1 (BHV-1) subunit vaccine formulated with Emulsigen (Em) and a synthetic oligodeoxynucleotide containing unmethylated CpG dinucleotides (CpG ODN) was determined in cattle. A truncated, secreted version of BHV-1 glycoprotein D (tgD) formulated with Em and CpG ODN at concentrations of 25, 2.5, or 0.25 mg/dose produced a more balanced immune response, higher levels of virus neutralizing antibodies, and greater protection after BHV-1 challenge compared to tgD adjuvanted with either Em or CpG ODN alone. In contrast, tgD formulated with Em and either 25 mg of a non-CpG ODN or another immunostimulatory compound, dimethyl dioctadecyl ammonium bromide, induced similar immunity and protection compared to tgD formulated with Em alone, a finding which confirms the immunostimulatory effect of ODN to be CpG motif mediated. Our results demonstrate the ability of CpG ODN to induce a strong and balanced immune response in a target species.