No vaccine interference between bovine coronavirus and bovine herpesvirus-1 in a randomized trial when coadministrating two intranasal modified-live viral vaccines to neonatal calves.

OBJECTIVE: Compare immune responses induced by 2 commercial intranasal (IN) modified-live viral (MLV) vaccines given individually or coadministered and evaluate prevention of infection and lung pathology following bovine herpesvirus-1 (BHV-1) challenge. ANIMALS: 36 male Holstein calves (ages, 5 to 12 days). METHODS: In a randomized complete block design, each calf received an IN injection of either vaccine diluent (Placebo), an MLV vaccine containing bovine herpesvirus-1 (BHV-1; N3), bovine coronavirus vaccine (BC), or both N3 and BC (BC + N3) with a booster 4 weeks later. Nasal secretions and blood were collected weekly. Three weeks after the booster, the calves were challenged with BHV-1, sampled for virus shedding, and euthanized 10 days later to quantify lung pathology. The study period was September 7, 2020, to April 6, 2021. RESULTS: Calves were seropositive for BHV-1 and BC before vaccination. No significant difference in BC-specific serum immunoglobin G and nasal immunoglobin A antibody responses in the BC versus BC + N3 group or BHV-1-specific serum immunoglobin G and nasal immunoglobin A antibody responses in the N3 versus BC + N3 group. Cytokine responses to BHV-1 and BC did not differ among groups. BHV-1 shedding after challenge was significantly reduced in N3 groups versus Placebo and BC. There was a significant reduction in lung pathology in the N3 + BC group versus Placebo. CLINICAL RELEVANCE: This study provides evidence an MLV vaccine containing BHV-1 and an MLV BC vaccine can be coadministered to neonatal calves without significantly altering immune responses to the 2 viruses or compromising the prevention of BHV-1 respiratory disease. Calves receiving the BC + N3 vaccine had a significant reduction in lung pathology after BHV-1 aerosol challenge.

Intranasal booster vaccination of beef steers reduces clinical signs following experimental coinfection with BRSV and BHV-1 without reducing shedding of BRD-associated bacteria.

OBJECTIVE: To determine the efficacy of primary or booster intranasal vaccination of beef steers on clinical protection and pathogen detection following simultaneous challenge with bovine respiratory syncytial virus and bovine herpes virus 1. METHODS: 30 beef steers were randomly allocated to 3 different treatment groups starting at 2 months of age. Group A (n = 10) was administered a single dose of a parenteral modified-live vaccine and was moved to a separate pasture. Groups B (n = 10) and C (10) remained unvaccinated. At 6 months of age, all steers were weaned and transported. Subsequently, groups A and B received a single dose of an intranasal modified-live vaccine vaccine while group C remained unvaccinated. Group C was housed separately until challenge. Two days following vaccination, all steers were challenged with bovine respiratory syncytial virus and bovine herpes virus 1 and housed in a single pen. Clinical and antibody response outcomes and the presence of nasal pathogens were evaluated. RESULTS: The odds of clinical disease were lower in group A compared with group C on day 7 postchallenge; however, antibody responses and pathogen detection were not significantly different between groups before and following viral challenge. All calves remained negative for Histophilus somni and Mycoplasma bovis; however, significantly greater loads of Mannheimia haemolytica and Pasteurella multocida were detected on day 7 postchallenge compared with day -2 prechallenge. CLINICAL RELEVANCE: Intranasal booster vaccination of beef steers at 6 months of age reduced clinical disease early after viral challenge. Weaning, transport, and viral infection promoted increased detection rates of M haemolytica and P multocida regardless of vaccination status.

TLR activation, immune response and viral protection elicited in cattle by a commercial vaccine against Bovine Herpesvirus-1.

The innate and acquired immune response induced by a commercial inactivated vaccine against Bovine Herpesvirus-1 (BoHV-1) and protection conferred against the virus were analyzed in cattle. Vaccination induced high levels of BoHV-1 antibodies at 30, 60, and 90 days post-vaccination (dpv). IgG1 and IgG2 isotypes were detected at 90 dpv, as well as virus-neutralizing antibodies. An increase of anti-BoHV-1 IgG1 in nasal swabs was detected 6 days post-challenge in vaccinated animals. After viral challenge, lower virus excretion and lower clinical score were observed in vaccinated as compared to unvaccinated animals, as well as BoHV-1-specific proliferation of lymphocytes and production of IFNγ, TNFα, and IL-4. Downregulation of the expression of endosome Toll-like receptors 8-9 was detected after booster vaccination. This is the first thorough study of the immunity generated by a commercial vaccine against BoHV-1 in cattle.

Immune memory induced by intranasal vaccination with a modified-live viral vaccine delivered to colostrum fed neonatal calves.

Bovine respiratory disease (BRD) remains a major health problem despite extensive use of vaccines during the post-weaning period. Apparent vaccine failure is attributed, in part, to primary vaccination during the period of greatest risk for BRD, providing inadequate time for onset of protective immunity. The current study investigated whether intranasal (IN) vaccination of 3-6 week old calves with a modified-live viral (MLV) vaccine induced sufficient immune memory to prevent respiratory disease and accelerate onset of protective immunity 5 months later. Vaccine groups included naïve controls, a single IN vaccination at 3-6 weeks of age, primary IN vaccination at 6 months, and either an IN or subcutaneous (SC) booster vaccination at 6 months (n = 10/group). All calves were challenged with BHV-1 four days after vaccination at 6 months of age. Primary IN vaccination at 6 months did not significantly reduce clinical disease but significantly (P < 0.01) reduced virus shedding. A single IN vaccination at 3-6 weeks of age significantly (P < 0.05) reduced weight loss but did not reduce fever or virus shedding. Both IN and SC booster vaccinations, significantly (P < 0.01) reduced clinical disease but virus shedding was significantly (P < 0.001) reduced only by IN booster vaccination. Reduction in virus shedding was significantly (P < 0.01) greater following booster versus primary IN vaccination at 6 months. All vaccination regimes significantly (P < 0.01) reduced secondary bacterial pneumonia and altered interferon responses relative to naïve controls. Only IN booster vaccination significantly (P < 0.05) increased BHV-1 specific IgA in nasal secretions. These results confirm primary MLV IN vaccination at 3 to 6 weeks of age, when virus neutralizing maternal antibody was present, induced immune memory with a 5 month duration. This immune memory supported rapid onset of protective immunity four days after an IN booster vaccination.

Influence of a bovine respiratory disease vaccine with a temperature-sensitive modified live or killed infectious bovine rhinotracheitis component on oestrous cycle parameters and anti-Müllerian hormone concentration in nulliparous heifers.

The objective of this study was to examine the impact of a bovine respiratory disease complex (BRDC) vaccine with a temperature-sensitive modified live vaccine (MLV) infectious bovine rhinotracheitis (IBR) component on oestrous cycle parameters and the follicular pool. Twenty-four Holstein heifers (12.4 ± 0.5 months) previously calfhood vaccinated with an IBR MLV component were enrolled in two replicates (Spring; n = 10 and Fall; n = 14) and were blocked by pre-vaccination bovine viral diarrhoea (BVD) serum neutralizing (SN) titres. Upon enrolment, heifers were oestrous synchronized with sampling beginning at detected oestrus. At their second heat, heifers were vaccinated with a BRDC calfhood vaccine with a MLV (MLV; n = 12) or killed (K; n = 12) IBR component and sampled for two additional cycles. Serum samples for oestrogen (E2) and progesterone (P4) as well as ultrasound data of ovarian structures were collected every other day. Serum samples for anti-Müllerian hormone (AMH) were collected at oestrus and mid-cycle for each cycle, and serum for titres was collected prior to and following vaccination. Data were analysed with the PROC MIXED and GLM procedures of SAS. There was no difference in pre- or post-vaccination titres between MLV and K heifers (p > .5). Vaccination had no impact on P4 concentrations, P4 area under the curve, luteal tissue area, peak E2 production or oestrous cycle length (p > .05). Cycle number did impact AMH concentration (p < .05). In MLV heifers, AMH concentration was highest in cycle 1 (p < .05) while cycles 2 and 3 did not differ (p > .05). This was also true for the K heifers in the Fall replicate (p < .05). Within cycle 2, AMH concentrations were numerically lower between vaccine types (K = 308.22 ± 33.3 pg/ml, MLV = 181.13 ± 32.9 pg/ml; p > .05). Although no differences were seen in overall cycle parameters, differences in AMH concentrations may indicate a reduction of the follicular pool following vaccination and requires further investigation.

BEEF SPECIES-RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Energy and roughage levels in cattle receiving diets and impacts on health, performance, and immune responses1.

Transition of newly received feedlot cattle from a forage- to grain-based diet is challenging, and the appropriate roughage level in receiving diets is debatable. Nutritionists must consider the paradox of dietary transition and roughage level to mitigate ruminal acidosis, yet concomitantly low feed intake presents difficulty in achieving nutrient requirements when metabolic demand is increased due to inherent stress and disease challenge during the receiving period. Previous research suggests that performance is improved at the expense of increased morbidity for newly received cattle consuming diets with less roughage and greater starch concentration. The clinical signs of bovine respiratory disease (BRD) and acute acidosis are analogous; therefore, it is probable that acidotic cattle are incorrectly diagnosed with BRD in both research and production settings. Additional research efforts have attempted to elucidate alterations in microbial populations and digestion, physiological response to inflammatory challenge, and immunological response to infectious bovine rhinotracheitis virus challenge in cattle consuming diets of various roughage levels. Furthermore, our understanding of the rumen microbiome is improving rapidly with culture-independent assays, products such as direct-fed microbials are available, and increased availability and use of fibrous byproduct ingredients requires further attention. Beef cattle nutritionists and producers should consider that the health benefit of receiving diets containing greater levels of roughage and lower energy may not compensate for the reduction in performance compared with feeding receiving diets with lower roughage and greater energy.

Antibody Responses to Bovine Alphaherpesvirus 1 (BoHV-1) in Passively Immunized Calves.

To date, in countries where infectious bovine rhinotracheitis (IBR) is widespread, its control is associated with deleted marker vaccines. These products lack one or more genes responsible for the synthesis of glycoproteins or enzymes. In Europe, the most widely used marker vaccine is one in which glycoprotein E (gE-) is deleted, and it is marketed in a killed or modified-live form. Using this type of immunization, it is possible to differentiate vaccinated animals (gE-) from those infected or injected with non-deleted (gE+) products using diagnostic tests specific for gE. The disadvantage of using modified-live gE-products is that they may remain latent in immunized animals and be reactivated or excreted following an immunosuppressive stimulus. For this reason, in the last few years, a new marker vaccine became commercially available containing a double deletion related to genes coding for gE and the synthesis of the thymidine-kinase (tk) enzyme, the latter being associated with the reduction of the neurotropism, latency, and reactivation of the vaccine virus. Intramuscularly and intranasally administered marker products induce a humoral immune response; however, the mother-to-calf antibody kinetics after vaccination with marker vaccines is poorly understood. This review discusses several published articles on this topic.

National surveillance plan for infectious bovine rhinotracheitis (IBR) in autochthonous Italian cattle breeds: Results of first year of activity.

Infectious bovine rhinotracheitis (IBR)/infectious pustular vulvovaginitis (IPV) caused by Bovine alphaherpesvirus 1 (BoHV-1) is a significant disease in domestic and wild cattle. In June 2015, the Ministry of Agriculture, Food and Forestry in Italy approved a national surveillance plan to control and eradicate IBR in beef cattle breeds. The objective of this study was to evaluate the results of the first year of the IBR voluntary surveillance plan in Italy. The aim of the plan is to eradicate IBR in all bovines recorded in the National Herd Book for Italian beef cattle breeds over six years. Monetary incentives are used to encourage breeders to achieve the annual seroprevalence ranges stated in the plan. A Ministerial decree states that all bovines in breeding herds and aged older than 12 months should be serologically tested. Serum samples were tested for presence of the antibody to glycoprotein E of BoHV-1 using commercially available enzyme-linked immunosorbent assays. The national herd seroprevalence was 55.49% (95% confidence interval [CI] 52.01-58.92). Of 25,121 bovines tested for antibodies against BoHV-1, 8014 were positive. The seroprevalence in animals from autochthonous Italian cattle breeds was 31.89% (95% CI 31.31-32.47). Seroprevalence was highest in Podolica cattle (55.14%; 95% CI 54.07-56.21), lowest in Maremmana cattle (9.95%; 95% CI 7.99-12.31), and intermediate in Chianina (22.01%; 95% CI 21.03-23.01), Marchigiana (24.85%; 95% CI 23.52-26.23), and Romagnola (15.60%; 95% CI 14.62-16.64) cattle. These seroprevalence rates indicate a need for intervention to decrease the inevitable severe economic losses arising from BoHV-1 infection. Although some regions in Italy have a long history of combatting BoHV-1 infection, only the province of Bolzano has eradicated IBR.

Genetic variability in the humoral immune response to bovine herpesvirus-1 infection in dairy cattle and genetic correlations with performance traits.

Bovine herpesvirus-1 (BoHV-1) is a viral pathogen of global significance that is known to instigate several diseases in cattle, the most notable of which include infectious bovine rhinotracheitis and bovine respiratory disease. The genetic variability in the humoral immune response to BoHV-1 has, to our knowledge, not ever been quantified. Therefore, the objectives of the present study were to estimate the genetic parameters for the humoral immune response to BoHV-1 in Irish female dairy cattle, as well as to investigate the genetic relationship between the humoral immune response to BoHV-1 with milk production performance, fertility performance, and animal mortality. Information on antibody response to BoHV-1 was available to the present study from 2 BoHV-1 sero-prevalence research studies conducted between the years 2010 to 2015, inclusive; after edits, BoHV-1 antibody test results were available on a total of 7,501 female cattle from 58 dairy herds. National records of milk production (i.e., 305-d milk yield, fat yield, protein yield, and somatic cell score; n = 1,211,905 milk-recorded cows), fertility performance (i.e., calving performance, pregnancy diagnosis, and insemination data; n = 2,365,657 cows) together with animal mortality data (i.e., birth, farm movement, death, slaughter, and export events; n = 12,853,257 animals) were also available. Animal linear mixed models were used to quantify variance components for BoHV-1 as well as to estimate genetic correlations among traits. The estimated genetic parameters for the humoral immune response to BoHV-1 in the present study (i.e., heritability range: 0.09 to 0.16) were similar to estimates previously reported for clinical signs of bovine respiratory disease in dairy and beef cattle (i.e., heritability range: 0.05 to 0.11). Results from the present study suggest that breeding for resistance to BoHV-1 infection could reduce the incidence of respiratory disease in cattle while having little or no effect on genetic selection for milk yield or milk constituents (i.e., genetic correlations ranged from -0.13 to 0.17). Moreover, even though standard errors were large, results also suggest that breeding for resistance to BoHV-1 infection may indirectly improve fertility performance while also reducing the incidence of mortality in older animals (i.e., animals >182 d of age). Results can be used to inform breeding programs of potential genetic gains achievable for resistance to BoHV-1 infection in cattle.

Effects of dietary energy level and intake of corn by-product-based diets on newly received growing cattle: antibody production, acute phase protein response, stress, and immunocompetency of healthy and morbid animals.

Effects of dietary energy level and intake of corn by-product-based diets on antibody production, acute phase protein response, stress, and immunocompetency of healthy and morbid newly received growing cattle were evaluated. Four dietary treatments were formulated to supply 0.99, 1.10, 1.21, and 1.32 Mcal NEg/ kg DM and were offered at 100%, 95%, 90%, and 85% of ad libitum based on 0.99/100 treatment intake, respectively. Thirty-two pens were utilized with approximately 12 animals/pen. Four animals from each pen (32/dietary treatment) were randomly selected and used to serve as a subset to monitor immune function and acute phase proteins following a split-plot design. In addition, two animals were randomly and independently selected from each pen (16/dietary treatment) and used to measure fecal cortisol metabolite. Additionally, animals removed from the pen one (M1), two (M2), or three (M3) times and classified as morbid were bled in conjunction with a healthy control (H) removed at the same time and the serum analyzed for the same parameters. A quadratic response to time (P < 0.01) was detected for haptoglobin concentrations and for antibody titers for bovine viral diarrhea type 1 (BVD-I) and infectious bovine rhinotracheitis (IBR; P < 0.01). Haptoglobin was lowest on arrival, highest on day 14, and similar to baseline levels by day 27. Titer levels for BVD-I and IBR were lowest on arrival, higher on day 14, and significantly higher on day 27. Titers for bovine viral diarrhea type 2 (BVD-II) responded linearly (P < 0.05) with lower levels on arrival and highest levels on day 27. Haptoglobin was elevated in morbid animals compared to healthy pen mates (P < 0.05). Titer levels for BVD-I and IBR were also higher in healthy animals compared to animals pulled for morbidity (P < 0.01). Fecal cortisol was higher on arrival than on day 14 (P < 0.05). Dietary treatment had no effect on any of the parameters investigated. In summary, high-energy receiving diets based on fermentable fiber from by-products can be fed to newly received growing cattle without negative effects on antibody production toward vaccines, inflammation, or overall stress. In addition, haptoglobin concentrations and titer levels for BVD-I and IBR viruses are higher in healthy animals compared to sick animals.

Virus detection by PCR following vaccination of naive calves with intranasal or injectable multivalent modified-live viral vaccines.

We evaluated duration of PCR-positive results following administration of modified-live viral (MLV) vaccines to beef calves. Twenty beef calves were randomly assigned to either group 1 and vaccinated intranasally with a MLV vaccine containing bovine alphaherpesvirus 1 (BoHV-1), bovine respiratory syncytial virus (BRSV), and bovine parainfluenza virus 3 (BPIV-3), or to group 2 and vaccinated subcutaneously with a MLV vaccine containing bovine viral diarrhea virus 1 and 2 (BVDV-1, -2), BoHV-1, BRSV, and BPIV-3. Deep nasopharyngeal swabs (NPS) and transtracheal washes (TTW) were collected from all calves, and whole blood was collected from group 2 calves and tested by PCR. In group 1, the proportions of calves that tested PCR-positive to BVDV, BoHV-1, BRSV, and BPIV-3 on any sample at any time were 0%, 100%, 100%, and 10%, respectively. In group 1 calves, 100% of calves became PCR-positive for BoHV-1 by day 3 post-vaccination and 100% of calves became PCR-positive for BRSV by day 7 post-vaccination. In group 2, the proportions of calves that tested positive to BVDV, BoHV-1, BRSV, and BPIV-3 on any sample at any time were 50%, 40%, 10%, and 0%, respectively. All threshold cycle (Ct) values were >30 in group 2 calves, irrespective of virus; however, Ct values <25 were observed in group 1 calves from PCR-positive results for BoHV-1 and BRSV. All calves were PCR-negative for all viruses after day 28. Following intranasal MLV viral vaccination, PCR results and Ct values for BRSV and BoHV-1 suggest that attempts to differentiate vaccine virus from natural infection is unreliable.

Determining bovine viral diarrhea and infectious bovine rhinotracheitis infections in dairy cattle using precolostral blood.

The objective of this study was to determine if precolostral blood samples are useful to detect apparent fetal infections with bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses. A convenience sample of 317 sera from 50 Canadian herds was used in the study. Antibody level was measured using 2 commercial IBR and BVD ELISA kits. Precolostral status of sera was confirmed on 304 samples using serum gamma-glutamyl transferase activity. Postcolostral serum samples yielded a higher proportion of positive results to IBR (OR = 86; 95% CI: 17.8 to 415.7) and BVD (OR = 199.3; 95% CI: 41.7 to 952.3) than did precolostral samples. All positive precolostral serum samples (n = 7 of 304) originated from calves born to vaccinated cows. Postcolostral positive serum samples (n = 11 of 13) originated mostly (60%) from calves born to non-vaccinated cows. Precolostral serum sampling can detect apparent fetal infections in a herd.

Utilisation du serum précolostral pour le dépistage de la diarrhée virale bovine (BVD) et rhinotracheite infectieuse bovine (IBR) dans les troupeaux laitiers. L'objectif de cette étude était d'évaluer l'utilité du prélèvement de sérum précolostral de nouveaux nés pour détecter des infections foetales apparentes par IBR et BVD dans un troupeau. Un échantillonnage de convenance de 317 sérums, prélevés de 50 troupeaux canadiens, a été utilisé. Les niveaux d'anticorps des sérums ont été mesurés en utilisant 2 trousses ELISA (IBR et BVD). Le statut précolostral a été confirmé pour 304 échantillons par la mesure de l'activité sérique des gamma glutamyl transférases. Une plus grande proportion de résultats positifs à IBR (RC = 86; IC 95%: 17,8 à 415,7) et BVD (RC = 199,3; IC 95 %: 41,7 à 952,3) a été observée parmi les échantillons postcolostraux que parmi les précolostraux. Tous les échantillons précolostraux positifs (n = 7/304) provenaient de veaux nés de mères vaccinées. Les échantillons postcolostraux positifs (n = 11/13) étaient majoritairement (60 %) prélevés à partir de veaux nés de mères non vaccinées. Le prélèvement de sérum précolostal peut détecter des infections foetales apparentes dans les troupeaux.(Traduit par les auteurs).

Characterization of three commercial ELISA kits for detection of BOHV-1 gE specific antibodies in serum and milk samples and applicability of bulk milk for determination of herd status.

Vaccination of animals with gE-deleted vaccine strains (gE- marker vaccines) and differential detection of vaccinated vs infected animals with antibody ELISA targeting the gE or the gB proteins have been proved to be useful tools in programs for control and eradication of the bovine herpesvirus 1 (BoHV-1) responsible for infectious bovine rhinotracheitis (IBR), a major pathogen of cattle. The diagnostic sensitivity (DSe) and specificity (DSp) of three commercial gE ELISA kits from IDEXX, IDVet and CIV-HIPRA were compared for serum and milk matrices. Limiting the analysis to 198 individual with concordant ELISA results in serum (91 naïve, 37 vaccinated and 70 infected) the DSe of gE kits was estimated to 0,97 for IDEXX, 0,93 for CIV-HIPRA and 0,53 for IDVet using milk samples and the DSp to 0,95 for IDEXX, 1,00 for IDVet and CIV-HIPRA. The applicability of gE ELISA for individual or bulk milk testing as an additional tool in control programs dedicated to the certification and control of vaccinated herds was evaluated. Two of the three evaluated gE ELISA kits presented substantial to good agreement individual milk and serum samples. The bulk-tank milk also proved to be suitable for the detection of BoHV-1 in vaccinated herds provided that gE prevalence is superior to 10% as false negative results are often observed at lower gE herd prevalence. This limitation could be reduced to 8% of prevalence when a prior concentration step was applied to bulk milk samples.

Surveillance of Infectious Bovine Rhinotracheitis in marker-vaccinated dairy herds: Application of a recombinant gE ELISA on bulk milk samples.

Infectious Bovine Rhinotracheitis (IBR) occurs worldwide, requiring significant resources for eradication programs or surveillance purposes. The status of infection is usually detected by serological methods using the virus neutralization test (VNT) or enzyme-linked immunosorbent assay (ELISA) on individual sera. The gE DIVA (Differentiating Infected from Vaccinated Animals) vaccines approach, adopted in order to reduce the virus circulation and prevent clinical signs, have tightened the range of available methods for the serological diagnosis. Different gE blocking ELISA could be performed to detect specific antibodies in sera of infected or whole virus-vaccinated animals but with less sensitivity if applied to bulk milk samples, especially in marker-vaccinated herds. A new rec-gE ELISA was recently developed in Italy and applied with good performances on blood serum samples. The present paper focuses on the application of a rapid protocol for purification/concentration of immunoglobulin G (IgG) from bulk milk and on the use of the new rec-gE indirect ELISA. The study involved three different partners and 225 herds (12,800 lactating cows) with different official IBR diagnostic statuses. The diagnostic specificity of the method was demonstrated closed to 100% while the diagnostic sensitivity was strictly related to the herd-seroprevalence. Considering 2.5% as the limit of detection of within-herd seropositivity prevalence, the diagnostic sensitivity showed by the proposed method was equal to 100%. A single reactivation of a whole strain vaccine in an old cow was detected inside a group of 67 lactating cows, showing the field applicability of the method.

Evaluation of reproductive protection against bovine viral diarrhea virus and bovine herpesvirus-1 afforded by annual revaccination with modified-live viral or combination modified-live/killed viral vaccines after primary vaccination with modified-live viral vaccine.

The objective of this study was to compare reproductive protection in cattle against bovine viral diarrhea virus (BVDV) and bovine herpesvirus 1 (BoHV-1) provided by annual revaccination with multivalent modified-live viral (MLV) vaccine or multivalent combination viral (CV) vaccine containing temperature-sensitive modified-live BoHV-1 and killed BVDV when MLV vaccines were given pre-breeding to nulliparous heifers. Seventy-five beef heifers were allocated into treatment groups A (n=30; two MLV doses pre-breeding, annual revaccination with MLV vaccine), B (n=30; two MLV doses pre-breeding, annual revaccination with CV vaccine) and C (n=15; saline in lieu of vaccine). Heifers were administered treatments on days 0 (weaning), 183 (pre-breeding), 366 (first gestation), and 738 (second gestation). After first calving, primiparous cows were bred, with pregnancy assessment on day 715. At that time, 24 group A heifers (23 pregnancies), 23 group B heifers (22 pregnancies), and 15 group C heifers (15 pregnancies) were commingled with six persistently infected (PI) cattle for 16days. Ninety-nine days after PI removal, cows were intravenously inoculated with BoHV-1. All fetuses and live offspring were assessed for BVDV and BoHV-1. Abortions occurred in 3/23 group A cows, 1/22 group B cows, and 11/15 group C cows. Fetal infection with BVDV or BoHV-1 occurred in 4/23 group A offspring, 0/22 group B offspring, and 15/15 group C offspring. This research demonstrates efficacy of administering two pre-breeding doses of MLV vaccine with annual revaccination using CV vaccine to prevent fetal loss due to exposure to BVDV and BoHV-1.

Bovine herpesvirus-1: Genetic diversity of field strains from cattle with respiratory disease, genital, fetal disease and systemic neonatal disease and their relationship to vaccine strains.

Bovine herpesvirus-1 (BoHV-1) causes disease in cattle with varied clinical forms. In the U.S. there are two BoHV1 subtypes, BoHV-1.1 and BoHV-1.2b. Control programs in North America incorporate modified live (MLV) or killed (KV) viral vaccines. However, BoHV-1 strains continue to be isolated from diseased animals or fetuses after vaccination. It is possible to differentiate BoHV-1 wild-type from MLV vaccine strains by determining their single nucleotide polymorphism (SNP) patterns through either whole-genome sequencing or PCR sequencing of genomic regions containing vaccine-defining SNPs. To determine the BoHV-1 subtype in clinical isolates and their relationship to MLV strains, 8 isolates from varied clinical disease at three different laboratories in the U.S. were sequenced and phylogenetically analyzed. Five samples were isolated within the past 5 years from New York and 3 were archived samples recovered 35 years prior from Oklahoma and Louisiana. Based on phylogenetic analysis, four of the cases appeared to be due to an MLV vaccine: 3 cases of aborted fetuses and one neonate with systemic BoHV-1 disease. One aborted fetus was from a herd with no reported history of MLV vaccination in two years. The remaining four isolates did not group with any MLV vaccines: two were associated with bovine respiratory disease, one with vulvovaginitis, and a fourth was determined to be a BoHV-1.2b respiratory isolate. Recovery of BoHV-1.1 that is very closely related to an MLV vaccine virus from a herd not receiving vaccines in an extended period prior to its isolation suggests that MLV viruses may remain latent or circulate within herds for long periods.

Short-term energy restriction during late gestation of beef cows decreases postweaning calf humoral immune response to vaccination.

Our objectives were to evaluate the pre- and postweaning growth and measurements of innate and humoral immune response of beef calves born to cows fed 70 or 100% of NEm requirements during the last 40 d of gestation. On d 0 (approximately 40 d before calving), 30 multiparous Angus cows pregnant to embryo transfer (BW = 631 ± 15 kg; age = 5.2 ± 0.98 yr; BCS = 6.3 ± 0.12) were randomly allocated into 1 of 10 drylot pens (3 cows/pen). Treatments were randomly assigned to pens (5 pens/treatment) and consisted of cows limit-fed (d 0 to calving) isonitrogenous, total-mixed diets formulated to provide 100 (CTRL) or 70% (REST) of daily NEm requirements of a 630-kg beef cow at 8 mo of gestation. Immediately after calving, all cow-calf pairs were combined into a single management group and rotationally grazed on tall fescue pastures (6 pastures; 22 ha/pasture) until weaning (d 266). All calves were assigned to a 40-d preconditioning period in a drylot from d 266 to 306 and vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea virus (BVDV), , and spp. on d 273 and 287. Blood samples from jugular vein were collected from cows on d 0, 17, and 35 and from calves within 12 h of birth and on d 266, 273, 274, 276, 279, and 287. By design, REST cows consumed less ( ≤ 0.002) total DMI, TDN, and NEm but had similar CP intake ( = 0.67), which tended ( = 0.06) to increase BW loss from d 0 to calving, than CTRL cows (-1.09 vs. -0.70 ± 0.14 kg/d, respectively). However, gestational NEm intake did not affect ( ≥ 0.30) plasma concentrations of cortisol, insulin, and glucose during gestation and BCS at calving as well as postcalving pregnancy rate, BW, and BCS change of cows. Calf serum IgG concentrations and plasma concentrations of haptoglobin and cortisol at birth as well as calf pre- and postweaning BW and ADG did not differ ( ≥ 0.15) between calves born to REST and CTRL cows. However, calf postweaning overall plasma concentrations of cortisol; plasma haptoglobin concentrations on d 274, 276, and 279; and serum BVDV-1a titers on d 306 were less for REST calves than for CTRL calves ( ≤ 0.05). Hence, a NEm restriction to 70% of daily requirements during the last 40 d of gestation had minimal effects on cow precalving growth and did not affect postcalving cow growth and reproductive performance. However, it decreased postweaning vaccination-induced humoral immunity, inflammatory, and physiological stress responses of calves.

Distribution of bovine alpha-herpesviruses and expression of toll-like receptors in the respiratory system of experimentally infected calves.

This study provides an initial analysis of the toll-like receptors (TLRs) that might be implicated in alpha-herpesvirus infection of the bovine respiratory system. A significant variation in the expression of TLR3 and TLRs 7-9 during bovine herpesvirus type 1 (BoHV-1) and 5 (BoHV-5) acute infections and particularly an up-regulation during viral reactivation in respiratory tissues has been demonstrated. Furthermore, viral distribution in the respiratory tract of BoHV-1- and BoHV-5-infected calves at different stages of the infectious cycle was analysed. The wide distribution of BoHV DNA in the respiratory tract during acute infection was restricted during latent infection and the subsequent reactivation of BoHV-1 and BoHV-5. Overall, the findings presented here contribute to the knowledge on the replication and dissemination of bovine alpha-herpesviruses. Furthermore, some of the immune factors triggered in the host that determine the different outcomes of infection by two closely related pathogens of cattle have been elucidated.

Identification of an epitope within the Bovine herpesvirus 1 glycoprotein E cytoplasmic tail and use of a monoclonal antibody directed against the epitope for the differentiation between vaccinated and infected animals.

We constructed a recombinant bovine herpesvirus type 1 triple mutant virus (BoHV-1 tmv) that lacks UL49.5 residues 30-32 and 80-96, gE cytoplasmic tail (gE CT) residues 452-575 and the entire 435 bp long Us9 ORF. To develop a gE CT-specific blocking ELISA test that is necessary to distinguish the BoHV-1 tmv vaccinated calves from the wild-type (wt) virus-infected calves, a mouse monoclonal antibody (mAb) 2H8F3 was generated by using the Escherichia coli expressed gE CT residues 452-575. Further, by performing a PEPSCAN analysis of 12 mer overlapping peptides spanning the entire gE CT, the epitope sequence recognized by the mAb2H8F3 was mapped within the gE CT residues 499SDDDGPASN507. A blocking ELISA test was then developed for detecting antibodies in wild-type BoHV-1 infected calves against the gE CT epitope specified by 499SDDDGPASN507. The assay is based on the use of HRP conjugated mAb2H8F3 and the E. coli expressed gE CT protein as an indicator antibody and a coating antigen, respectively. In this assay, serum from entire gE-deleted and BoHV-1 tmv-infected calves scored negative, whereas serum from calves infected with BoHV-1 wt scored positive. Therefore, the gE CT-ELISA, based on the mAb2H8F3 and E. coli expressed gE CT protein, is suitable for differentiating the wt virus-infected and BoHV-1 tmv-vaccinated cattle.

Bovine herpesvirus 1: within-herd seroprevalence and antibody levels in bulk-tank milk.

The aim of the present study was to establish a relationship between the results obtained with the enzyme-linked immunosorbent assay (ELISA) technique for antibodies (against bovine herpesvirus 1) in serum and those in milk at the herd level. For this purpose, 275 samples of bulk-tank milk were analysed with glycoprotein E (gE) antibody ELISA and 207 more were analysed with glycoprotein B (gB) antibody ELISA (482 in total). All of these samples came from dairy herds whose seroprevalence was also evaluated. The results of this study were then used to analyse the sensitivity of the bulk-tankmilk test in detecting herds with a high risk of active infection (>60% seroprevalence) and its specificity in detecting those with few (<20%) or no seropositive animals. In regard to the reference test (results in blood serum), the sensitivity of the bulk-tankmilk test in detecting herds with >60% seropositive animals was 100% for both gE and gB ELISAs. The specificity figures, for gE and gB ELISAs, respectively, were 88.4% and 99.1% for infection-free herds and 72.6% and 96% for herds with <20% seroprevalence. In a quantitative approach, Pearson's correlation coefficients, reported as a measure of linear association between herd seroprevalences and transformed optical density values recorded in bulk-tank milk, were -0.63 for gE ELISA and 0.67 for gB ELISA.

Les auteurs présentent une étude visant à faire ressortir la corrélation entre les résultats obtenus à l'échelle du troupeau au moyen d'une épreuve immunoenzymatique (ELISA) pour la détection d'anticorps dirigés contre l'herpèsvirus bovin de type 1 dans des échantillons de sérum et ceux obtenus dans le lait. À cet effet, 275 échantillons de lait de citerne ont été soumis à un test ELISA visant à déceler la présence d'anticorps dirigés contre la glycoprotéine E (gE) du virus, et 207 autres ont été analysés au moyen d'un test ELISA visant à déceler la présence d'anticorps dirigés contre la glycoprotéine B (gB) (482 échantillons analysés au total). La totalité des échantillons provenait d'élevages laitiers dans lesquels la séroprévalence a également été evaluée. Les résultats de l'étude ont ensuite permis d'analyser la sensibilité du test sur le lait de citerne, c'est-àdire la capacité de ce test à détecter les troupeaux présentant un risque élevé d'infection active (séroprévalence > 60 %), ainsi que sa spécificité, c'est-à-dire sa capacité à détecter les troupeaux dans lesquels le pourcentage d'animaux séropositifs était faible (moins de 20 %) ou nul (0 %). Comparativement au test de référence (analyse des échantillons de sérum), la sensibilité des tests ELISA sur le lait de citerne était de 100 % (détection de tous les troupeaux dotés d'au moins 60 % d'animaux possédant des anticorps dirigés contre la glycoprotéine E ou B). En termes de spécificité des tests ELISA anti-gE et anti-gB, les valeurs étaient, respectivement, de 88,4 % et 99,1 % dans les troupeaux indemnes et de 72,6 % et 96 % dans les troupeaux accusant une séroprévalence inférieure à 20 %. Les coefficients de corrélation de Pearson obtenus par une méthode quantitative pour exprimer la relation linéaire entre les prévalences sérologiques et les valeurs de densité optique modifiées dans le lait de citerne étaient respectivement de ­0,63 pour l'ELISA gE et de 0,67 pour l'ELISA gB.

Los autores describen un estudio encaminado a determinar si existe una relación, y de ser así cuál, entre los resultados del ensayo inmunoenzimático (ELISA) de detección de anticuerpos (contra el herpesvirus bovino 1) en suero y los resultados obtenidos al analizar la leche de rebaños enteros. Para ello se sometieron 275 muestras de leche de tanque a la prueba ELISA de detección de anticuerpos contra la glicoproteína E (gE) y otras 207 muestras a la prueba ELISA de detección de anticuerpos contra la glicoproteína B (gB) (esto es, un total de 482 muestras). Todas esas muestras procedían de rebaños lecheros cuya prevalencia serológica también se calculó. A partir de los resultados del estudio se determinó la sensibilidad de la prueba practicada en la leche de tanque para detectar rebaños con un elevado riesgo de infección activa (más del 60% de animales seropositivos) y su especificidad para detectar aquellos rebaños con pocos (menos del 20%) animales seropositivos o ninguno (0%). En comparación con la prueba de referencia (resultados del análisis sérico), la sensibilidad del análisis de la leche de tanque para detectar rebaños con más de un 60% de animales seropositivos fue del 100% en el caso de ambas pruebas ELISA (gE y gB). En cuanto a la especificidad, las técnicas ELISA para la gE y la gB permitieron detectar respectivamente un 88,4% y un 99,1% de los rebaños libres de infección y un 72,6% y un 96% de los rebaños con menos de un 20% de animales seropositivos. El análisis cuantitativo de los resultados deparó coeficientes de correlación de Pearson, utilizados como medida de la relación lineal entre las seroprevalencias de rebaño y los valores transformados de densidad óptica obtenidos en la leche de tanque, de ­0,63 para el ELISA gE y de 0,67 para el ELISA gB.