Evaluation of efficacy of an inactivated vaccine against bovine respiratory syncytial virus in calves with maternal antibodies

Protection against Bovine Respiratory Syncytial Virus Afforded by Maternal Antibodies from Cows Immunized with an Inactivated Vaccine

The passive protection afforded by the colostrum from cattle that were vaccinated prepartum with an inactivated combination vaccine against the bovine respiratory syncytial virus (BRSV) was evaluated after an experimental challenge of calves. Pregnant cows without or with a low ELISA and neutralizing BRSV antibody titers were twice vaccinated or not vaccinated, the last immunization being at one month prior to calving. Vaccination was followed by a rapid increase in BRSV antibody titers after the second immunization. Twenty-eightnewborn calves were fed during the 6 h following birth, with 4 L of colostrum sourced from vaccinated cows (14 vaccine calves) or non-vaccinated cows (14 control calves) and were challenged with BRSV at 21 days of age. We showed that maternal immunity to BRSV provides a significant reduction in the clinical signs of BRSV in calves, especially for severe clinical forms. This protection was correlated with reduced BRSV detection in the lower respiratory tract but not in nasal swabs, indicating an absence of protection against BRSV nasal excretion. Finally, transcriptomic assays in bronchoalveolar lavages showed no statistical differences between groups for chemokine and cytokine mRNA transcriptions, with the exception of the overexpression of IL-9 at days 6 and 10 post-challenge, and a severe downregulation of CXCL-1 at day 3 post-challenge, in the vaccine group.

Efficacy of Bovine Respiratory Syncytial Virus Vaccines to Reduce Morbidity and Mortality in Calves Within Experimental Infection Models: A Systematic Review and Meta-Analysis

Producers and veterinarians commonly use vaccination as the main strategy to reduce the incidence of bovine respiratory syncytial virus (BRSV) infection in calves; however, supportive evidence of BRSV vaccination efficacy has been inconsistent in the literature. The objective of this meta-analysis was to evaluate data from controlled studies on the efficacy of commercially available BRSV vaccines on reducing calf morbidity and mortality after experimental infection with BRSV. A systematic review and meta-analysis was performed in BRSV experimental challenge studies that reported the efficacy of commercially available modified-live virus (MLV) and inactivated BRSV vaccines on protection against calf morbidity and mortality. The studies included in the analysis were randomized, controlled, clinical trials with clear definitions of calf morbidity and mortality. Risk ratios with 95% confidence intervals and forest plots were generated. Fourteen studies including 29 trials were selected for the analysis. Commercially available MLV BRSV vaccines reduced the risk of calf mortality after experimental infection with BRSV. Modified-live virus vaccines reduced the risk of morbidity in calves with absence of serum maternal antibodies at initial vaccination, but failed to demonstrate significant morbidity reduction when calves were vaccinated in the face of maternal immunity. Results from experimental challenge studies do not always represent the conditions of natural infection and caution should be used when making vaccine recommendations.

A Field Study Evaluating Humoral Immunity in Calves Vaccinated with Multivalent Bovine Respiratory Pathogen Vaccines

Bovine Respiratory Syncytial Virus (BRSV), Bovine Parainfluenza 3 (BPI3) and Mannheimia haemolytica (Mh) are major respiratory pathogens in the bovine respiratory disease complex. It is important to optimize passive and active immunity to these pathogens early in life to reduce clinical and subclinical productivity losses. The administration of inactivated, adjuvanted and multivalent vaccines, such as Bovilis® Bovipast RSP (Bovipast), and Bovalto® Respi 3 (Bovalto) to calves, may enhance cellular and humoral immunity against BRSV, BPI3 and Mh. A field trial evaluated the immune responses to these three agents in the first year of life in 12 Bovipast and 13 Bovalto vaccinated calves, and 5 negative control calves. Calves were vaccinated starting at 2 weeks of age and revaccinated 4 weeks later (primo vaccination). A booster vaccination was given at approximately 10 months of age. Serum samples were taken at time intervals up to 6 months after primo vaccination and up to 1 month after the booster vaccination. BRSV serum titres were evaluated using a serum neutralisation assay (SN), and BRSV, BPI3 and Mh titres were evaluated using a commercial enzyme linked immunosorbent assay (ELISA) test. Serum antibodies after primo and booster vaccinations in the individual calves were evaluated by calculating the areas under the curve (AUC) of the Log2 transformed BRSV SN titres and the optic density measures of the ELISA tests for BRSV, BPI3 and Mh. Multivariate general linear models were used to evaluate the influence of the vaccination on the AUC of the serum measures within 6 months after the primo vaccination. Similarly, models evaluated the AUC of the serum measures after the booster vaccination. The Bovipast vaccinated calves had significantly higher SN and ELISA titres AUC following the primo vaccination and booster vaccinations compared to the negative control calves and the Bovalto vaccinated calves. The Bovalto vaccinated calves did not have a significantly different BRSV SN and ELISA titres AUC response after the primo or booster vaccinations compared to the negative control calves. The serum antibody responses to BPI3 and Mh in the vaccinated calves were less pronounced than the Bovipast BRSV antibody response. Bovipast and Boval- to vaccinated calves mounted a significantly higher AUC ELISA OD for both BPI3 and Mh and the highest AUC was measured in the Bovipast vaccinated calves. This study indicated that early vaccinations of calves with multivalent adjuvanted inactivated BRD vaccines, such as Bovilis® Bovipast RSP can elicit a humoral response with a cellular-mediated memory effect as indicated by the booster vaccination.

A Review of UK-Registered and Candidate Vaccines for Bovine Respiratory Disease

Vaccination is widely regarded as a cornerstone in animal or herd health and infectious disease management. Nineteen vaccines against the major pathogens implicated in bovine respiratory disease are registered for use in the UK by the Veterinary Medicines Directorate (VMD). However, despite annual prophylactic vaccination, bovine respiratory disease is still conservatively estimated to cost the UK economy approximately £80 million per annum. This review examines the vaccine types available, discusses the surrounding literature and scientific rationale of the limitations and assesses the potential of novel vaccine technologies.

Comparison of the immune response following subcutaneous versus intranasal modified-live virus booster vaccination against bovine respiratory disease in pre-weaning beef calves that had received primary vaccination by the intranasal route

This study was performed to elucidate whether the route of booster vaccination affects the immune response against respiratory vaccine viruses in pre-weaning beef calves that receive primary intranasal (IN) vaccination during the first month of life. The objective was to compare the serum neutralizing antibody (SNA) titers to BHV1, BRSV, and BPI3V, cytokine mRNA expression and mucosal BHV1- and BRSV-specific IgA in nasal secretions following administration of IN or subcutaneous (SC) modified-live virus (MLV) booster vaccines 60 days after primary IN vaccination in young beef calves. Twenty-one beef calves were administered 2 mL of an IN MLV vaccine containing BHV1, BRSV, and BPI3V (Inforce3®) between one and five weeks of age. Sixty days after primary vaccination, calves were randomly assigned to one of two groups: IN-MLV (n = 11): Calves received 2 mL of the same IN MLV vaccine used for primary vaccination and 2 mL of a SC MLV vaccine containing BVDV1 & 2 (Bovi- Shield GOLD® BVD). SC-MLV (n = 10): Calves were administered 2 mL of a MLV vaccine containing, BHV1, BRSV, BPI3V, and BVDV1 & 2 (Bovi-Shield GOLD® 5). Blood and nasal secretion samples were collected on days -61 (primary vaccination), -28, -14, 0 (booster vaccination), 14, 21, 28, 42 and 60 for determination of SNA titers, cytokine gene expression analysis and nasal virus-specific IgA concentrations. Statistical analysis was performed using a repeated measures analysis through PROC GLIMMIX of SAS®. Booster vaccination by neither IN nor SC routes induced a significant increase in SNA titers against BHV1, BRSV, and BPI3V. Subcutaneous booster vaccination induced significantly greater BRSV-specific SNA titers (on day 42) and IgA concentration in nasal secretions (on days 21 and 42) compared to calves receiving IN booster vaccination. Both IN and SC booster vaccination were able to stimulate the production of BHV1-specific IgA in nasal secretions. In summary, booster vaccination of young beef calves using either SC or IN route two months after IN MLV primary vaccination resulted in comparable SNA titers, cytokine gene expression profile and virus-specific IgA concentration in nasal secretions. Only a few differences in the systemic and mucosal immune response against BHV1 and BRSV were observed. Subcutaneous booster vaccination induced significantly greater BRSV-specific SNA and secretory IgA titers compared to IN booster vaccination.

Bovine Respiratory Disease Vaccination Against Viral Pathogens: Modified-Live Versus Inactivated Antigen Vaccines, Intranasal Versus Parenteral, What Is the Evidence?

Vaccination of cattle against viral respiratory pathogens to minimize losses associated with bovine respiratory disease (BRD) is a common practice among producers and veterinarians. Three different calf populations in which BRD is most prevalent (recently weaned beef calves, preweaning beef calves, and young dairy calves) are the principal focus of morbidity and mortality prevention through vaccination; however, the evidence of vaccination efficacy is inconsistent in the literature. This review addresses the evidence of efficacy of vaccination in the prevention or reduction of naturally occurring and experimentally induced BRD in each calf group.

The Differential Expression of Mitochondrial Function-Associated Proteins and Antioxidant Enzymes during Bovine Herpesvirus 1 Infection: A Potential Mechanism for Virus Infection-Induced Oxidative Mitochondrial Dysfunction

Reactive oxidative species (ROS) are important inflammatory mediators. Electrons escaping from the mitochondrial electron transport chain (ETC) during oxidative phosphorylation (OXPHOS) in the mitochondrial respiratory chain (RC) complexes contribute to ROS production. The cellular antioxidant enzymes are important for maintaining ROS release at the physiological levels. It has been reported that BoHV-1 infection induces overproduction of ROS and oxidative mitochondrial dysfunction in cell cultures. In this study, we found that chemical interruption of RC complexes by TTFA (an inhibitor of RC complex II), NaN₃ (an inhibitor of RC complex IV), and oligomycin A (an inhibitor of ATP synthase) consistently decreased virus productive infection, suggesting that the integral processes of RC complexes are important for the virus replication. The virus infection significantly increased the expression of subunit SDHB (succinate dehydrogenase) and MTCO1 (cytochrome c oxidase subunit I), critical components of RC complexes II and IV, respectively. The expression of antioxidant enzymes including superoxide dismutase 1 (SOD1), SOD2, catalase (CAT), and glutathione peroxidase 4 (GPX4) was differentially affected following the virus infection. The protein TFAM (transcription factor A, mitochondrial) stimulated by either nuclear respiratory factor 1 (NRF1) or NRF2 is a key regulator of mitochondrial biogenesis. Interestingly, the virus infection at the late stage (at 16 h after infection) stimulated TFAM expression but decreased the levels of both NRF1 and NRF2, indicating that virus infection activated TFAM signaling independent of either NRF1 or NRF2. Overall, this study provided evidence that BoHV-1 infection altered the expression of molecules associated with RC complexes, antioxidant enzymes, and mitochondrial biogenesis-related signaling NRF1/NRF2/TFAM, which correlated with the previous report that virus infection induces ROS overproduction and mitochondrial dysfunction.

Risk factors associated with exposure to bovine respiratory disease pathogens during the peri-weaning period in dairy bull calves

Background

Bovine respiratory disease (BRD) remains among the leading causes of death of cattle internationally. The objective of this study was to identify risk factors associated with exposure to BRD pathogens during the peri-weaning period (day (d)-14 to d 14 relative to weaning at 0) in dairy bull calves using serological responses to these pathogens as surrogate markers of exposure.

Clinically normal Holstein-Friesian and Jersey breed bull calves (n = 72) were group housed in 4 pens using a factorial design with calves of different breeds and planes of nutrition in each pen. Intrinsic, management and clinical data were collected during the pre-weaning (d − 56 to d − 14) period. Calves were gradually weaned over 14 days (d − 14 to d 0). Serological analysis for antibodies against key BRD pathogens (BRSV, BPI3V, BHV-1, BHV-4, BCoV, BVDV and H. somni) was undertaken at d − 14 and d 14. Linear regression models (for BVDV, BPI3V, BHV-1, BHV-4, BCoV and H. somni) and a single mixed effect random variable model (for BRSV) were used to identify risk factors for changes in antibody levels to these pathogens.

Results

BRSV was the only pathogen which demonstrated clustering by pen. Jersey calves experienced significantly lower changes in BVDV S/P than Holstein-Friesian calves. Animals with a high maximum respiratory score (≥8) recorded significant increases in H. somni S/P during the peri-weaning period when compared to those with respiratory scores of ≤3.

Haptoglobin levels of between 1.32 and 1.60 mg/ml at d − 14 were significantly associated with decreases in BHV-1 S/N during the peri-weaning period. Higher BVDV S/P ratios at d − 14 were significantly correlated with increased changes in serological responses to BHV-4 over the peri-weaning period.

Conclusions

Haptoglobin may have potential as a predictor of exposure to BHV-1. BRSV would appear to play a more significant role at the ‘group’ rather than ‘individual animal’ level. The significant associations between the pre-weaning levels of antibodies to certain BRD pathogens and changes in the levels of antibodies to the various pathogens during the peri-weaning period may reflect a cohort of possibly genetically linked ‘better responders’ among the study population.

Effect of suckler cow vaccination against glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) on passive immunity and physiological response to subsequent bovine respiratory disease vaccination of their progeny

The study objectives were: 1) to characterise the development of immunocompetence in beef suckler calves from birth to three months of age, and 2) to trace glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) antibodies from dam to calf and subsequent vaccination against pneumonia. Thirty multiparous beef suckler, spring-calving cows, consisting of two genotypes were involved; Limousin × Friesian (LF) and Charolais × Limousin (CL). Cows were immunised against the inactivated antigen strain of BoHV-1 (gE- (IBR marker vaccine) at day − 84 and received a booster at day − 56 relative to the expected calving date (d 0). Calves were immunised at 14 and 42 days of age against PI-3 virus, BRSV and Mannheimia (Pasteurella) haemolytica serotype A1 using a commercial vaccine administered subcutaneously. Additionally, calves were immunised against BoHV-1 at 42 days of age, using 1 dose of a live commercial vaccine administered intranasally. Blood samples were collected from all calves (n = 30) via jugular venipuncture at birth, prior to colostrum feeding (0 h), at 12 h (h), 24 h, 72 h and 168 h after the initial feeding of colostrum, and at d 7, 14, 28, 42, 56 and 84 post birth. The mean ratio of gE negative antibodies circulating in the blood of LF and CL dams pre-partum scored negative to gE ab (S/N ≥ 0.70). Antibody levels of BoHV-1 (wild type (wt)) peaked at 12 h post-birth in calves and declined thereafter, as the maternal antibodies decayed. There was no difference in BoHV-1 and BRSV antibody levels in calves post vaccination.

•

Greater decrease in cow serum IgG concentration in LF cows than CL cows pre-partum.

•

Progeny of LF cows have a greater pre-weaning ADG than the progeny of CL cows.

•

Maternally derived antibodies affects response to vaccination in suckled beef calves.

Vaccination of calves against common respiratory viruses in the face of maternally derived antibodies(IFOMA)

Vaccination of calves in the face of maternal antibodies (IFOMA) often does not result in seroconversion as maternally derived immunity interferes with the activation of adequate antibody responses to vaccination; however, it can prime T and B cell memory responses that protect calves against clinical disease when maternal immunity has decayed. The activation of B and T cell memory responses in calves vaccinated IFOMA varies and is affected by several factors, including age, level of maternal immunity, type of vaccine, and route of administration. These factors influence the adequate priming of humoral and cell mediated immune responses and the outcome of vaccination. The failure to adequately prime immune memory after vaccination IFOMA could result in lack of clinical protection and increased risk of viremia and/or virus shedding.

Bovine respiratory syncytial virus ISCOMs-Immunity, protection and safety in young conventional calves

Bovine respiratory syncytial virus (BRSV) is a major cause of bronchiolitis and pneumonia in cattle and causes yearly outbreaks with high morbidity in Europe. Commercial vaccines against this virus needs improvement of efficacy, especially in calves with BRSV-specific maternally derived antibodies (MDA). We previously reported that an experimental BRSV-ISCOM vaccine, but not a commercial vaccine, induced strong clinical and virological protection in calves with MDA, immunized at 7–15 weeks of age. The aim of the present study was to characterize the immune responses, as well as to investigate the efficacy and safety in younger animals, representing the target population for vaccination. Four groups of five 3–8 week old calves with variable levels of BRSV-specific MDA were immunized s.c. twice at a 3 weeks interval with (i) BRSV immunostimulating complexes (BRSV-ISCOMs), (ii) BRSV-protein, (iii) adjuvant, or (iv) PBS. All calves were challenged with virulent BRSV by aerosol 2 weeks later and euthanized on day 6 after infection. The cellular and humoral responses were monitored as well as the clinical signs, the viral excretion and the pathology following challenge. Despite presence of MDA at the time of the immunization, only a minimum of clinical signs were observed in the BRSV-ISCOM group after challenge. In contrast, in all control groups, clinical signs of disease were observed in most of the animals (respiratory rates up to 76 min⁻¹ and rectal temperatures up to 41 °C). The clinical protection was associated to a highly significant reduction of virus replication in the upper and lower respiratory tract of calves, rapid systemic and local antibody responses and T helper cell responses dominated by IFNγ production. Animals that did not shed virus detectable by PCR or cell culture following challenge possessed particularly high levels of pulmonary IgA. The protective immunological responses to BRSV proteins and the ability to overcome the inhibiting effect of MDA were dependent on ISCOM borne antigen presentation.

Bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is a major cause of respiratory disease and a major contributor to the bovine respiratory disease (BRD) complex. BRSV infects the upper and lower respiratory tract and is shed in nasal secretions. The close relatedness of BRSV to human respiratory syncytial virus (HRSV) has allowed researchers to use BRSV and HRSV to elucidate the mechanisms by which these viruses induce disease. Attempted vaccine production using formalin-inactivated vaccine resulted in exacerbated disease when infants became exposed to HRSV. Cattle vaccinated with formalin-inactivated virus had enhanced disease when inoculated with BRSV. This article discusses various aspects of BRSV, its epidemiology, pathogenesis, diagnostic tests, immunity, and vaccination.

A field study evaluating health, performance, and behavior differences in crossbred beef calves administered different vaccine-parasiticide product combinations

Bovine respiratory disease complex (BRDC) is the most important health issue in beef feeder calves. Our study was a randomized, blinded field trial to evaluate potential differences in health, production and behavior in feeder calves administered two different preventive health programs. Calves in two replicates (n=308 and n=305) were allocated to pens and then pens were randomly assigned a preventive health program. One program (Prog1) consisted of 1 injectable clostridial vaccine, 1 intranasal modified live respiratory vaccine, 1 topical and 1 oral parasiticide. The other program (Prog2) consisted of 1 injectable clostridial vaccine, 1 modified live respiratory vaccine and 1 injectable parasiticide. A greater percentage of calves in Prog1 (59.7%) experienced BRDC morbidity compared to the Prog2 program (47.8%). There were no differences between programs in mortality, case fatality, 1st treatment success or chronicity risks. The average daily gain over the entire study period for the Prog2 calves (1.23 kg) was greater than the Prog1 calves (1.16 kg). Calves administered Prog1 on average took more steps each day during the first 28 days of the study. Additionally, Prog1 calves spent more time lying down on certain days during the last 14 days of the study. During initial program administration, fewer Prog1 calves (39.8%) vocalized compared to Prog2 calves (47.8%). In this study, calves administered a program with fewer injections indicated less aversion to program administration than those administered more injections, but experienced greater morbidity and poorer performance.

Comparison of humoral and cellular immune responses to a pentavalent modified live virus vaccine in three age groups of calves with maternal antibodies, before and after BVDV type 2 challenge

The aim of this study was to evaluate the ability of a pentavalent (BVDV types 1 and 2, BHV-1, BRSV, and PI-3) modified live virus (MLV) vaccine given to 1-2-, 4-5-, and 7-8-week-old calves with maternal antibodies to induce humoral and cellular immune responses and protect calves from virulent BVDV type 2. Eight calves in each age group were vaccinated and four served as controls. All calves were challenged intranasally with BVDV type 2, 12 weeks after vaccination. SVN titers to all five viruses declined in all groups after vaccination (except 4-5-week-old calves to BVDV type 1). After challenge, the SVN titers for both types of BVDV showed anamnestic responses in calves vaccinated at 4-5 and 7-8 weeks, but not at 1-2 weeks of age. In all groups, T cell subsets responded specifically to BVDV types 1 and 2 but not to BHV-1, BRSV, or PI-3 after vaccination by increasing their expression of activation markers (CD25, IFN-gamma and IL-4). All vaccinated calves were significantly protected from BVDV type 2 challenge.

Immunoprophylaxis against important virus disease of horses, farm animals and birds

Since the refinement of tissue culture techniques for virus isolation and propagation from the mid 1960s onwards, veterinary virology has received much academic and industrial interest, and has now become a major global industry largely centred on vaccine development against economically important virus diseases of food animals. Bio-tech approaches have been widely used for improved vaccines development. While many viral diseases are controlled through vaccination, many still lack safe and efficacious vaccines. Additional challenges faced by academia, industry and governments are likely to come from viruses jumping species and also from the emergence of virulent variants of established viruses due to natural mutations. Also viral ecology is changing as the respective vectors adapt to new habitats as has been shown in the recent incursion by bluetongue virus into Europe. In this paper the current vaccines for livestock, horses and birds are described in a species by species order. The new promising bio-tech approaches using reverse genetics, non-replicating viral vectors, alpha virus vectors and genetic vaccines in conjunction with better adjuvants and better ways of vaccine delivery are discussed as well

Vaccination of calves using the BRSV nucleocapsid protein in a DNA prime-protein boost strategy stimulates cell-mediated immunity and protects the lungs against BRSV replication and pathology

Respiratory syncytial virus (RSV) is a major cause of respiratory disease in both cattle and young children. Despite the development of vaccines against bovine (B)RSV, incomplete protection and exacerbation of subsequent RSV disease have occurred. In order to circumvent these problems, calves were vaccinated with the nucleocapsid protein, known to be a major target of CD8⁺ T cells in cattle. This was performed according to a DNA prime–protein boost strategy. The results showed that DNA vaccination primed a specific T-cell-mediated response, as indicated by both a lymphoproliferative response and IFN-γ production. These responses were enhanced after protein boost. After challenge, mock-vaccinated calves displayed gross pneumonic lesions and viral replication in the lungs. In contrast, calves vaccinated by successive administrations of plasmid DNA and protein exhibited protection against the development of pneumonic lesions and the viral replication in the BAL fluids and the lungs. The protection correlated to the cell-mediated immunity and not to the antibody response.

Immunization strategies for the prevention of pneumovirus infections

Pneumoviruses, which are viruses of the family Paramyxoviridae, subfamily Pneumovirinae, are pathogens that infect the respiratory tract of their host species. The human pneumovirus pathogen, human respiratory syncytial virus (RSV), has counterparts that infect cows (bovine RSV), sheep (ovine RSV), goats (caprine RSV) and rodents (pneumonia virus of mice). Each pneumovirus is host specific and results in a spectrum of disease, ranging from mild upper-respiratory illness to severe bronchiolitis and pneumonia with significant morbidity and mortality. Given the public health burden caused by human RSV and the concomitant agricultural impact of bovine RSV, these two viruses are considered as prime targets for the development of safe and effective vaccines. In this review, we describe the strategies used to develop vaccines against human and bovine RSV and introduce the pneumonia virus mouse model as a novel and invaluable tool for preclinical studies and new vaccine strategies.

Quantitative evaluation of genetic and environmental parameters determining antibody response induced by vaccination against bovine respiratory syncytial virus

The parameters controlling IgG antibody responses induced by vaccination against bovine respiratory syncytial virus (BRSV) were investigated in 463 Holstein-Charolais crossbred cattle. Pre- and post-vaccination sera were tested by enzyme linked immunosorbent assays (ELISA) for BRSV-specific IgG and IgG2. Year-of-birth, age, sex and pre-existing antibody were significant sources of variation for IgG responses. Pre-vaccination, progeny with a higher proportion of Holstein genes had higher total BRSV-IgG. By Day 35 post-vaccination, heritabilities peaked at 0.26 for total BRSV-IgG and 0.36 for BRSV-IgG1. There was no evidence for interbreed differences between Holstein and Charolais calves, post-vaccination. These results suggest that calf-sire has a major heritable influence on serum IgG levels following BRSV immunisation.