The Cell-Mediated Immune Response against Bovine alphaherpesvirus 1 (BoHV-1) Infection and Vaccination

Buffalo Immune Competence Under Infectious and Non-Infectious Stressors

Immune competence is a critical aspect of protecting animals from the negative consequences of disease. The activation of the immune response from inflammation is part of adaptive homeostasis that serves to eliminate danger, induce tissue repair, and restore tissue homeostasis. Therefore, the main goal for the organism is to control both the induction and suppression of inflammation and resist the onset of disease. In this condition, modulators of inflammatory responses are produced, including small proteins called cytokines, which exert a pro- or anti-inflammatory action in a context-dependent manner. Indeed, the cytokine profile could be considered a useful biomarker to determine the pathophysiology of certain diseases, such as mastitis, endometritis, change-induced heat stress, and zoonoses. Recently, buffalo breeding has attracted the interest of the research communities due to their high resilience; however, little is known about the immune mechanism activated under specific stressors. This review describes the complex immune competence of the buffalo in the presence of the most common infectious and non-infectious stressors. In addition, a brief description of methods for early diagnosis of disease using cytokine quantification will be introduced.

Cytokines as potential biomarkers for the diagnosis of Mycobacterium bovis infection in Mediterranean buffaloes (Bubalus bubalis)

Mycobacterium bovis (M. bovis) is the primary agent of bovine tuberculosis (TB) in Mediterranean buffalo, which has a negative economic impact on buffalo herds. Improving TB diagnostic performance in this species represents a key step to eradicate efficiently this disease. We have recently shown the utility of the IFN-γ assay in the diagnosis of M. bovis infection in Mediterranean buffaloes (Bubalus bubalis), but other cytokines might be useful immunological biomarkers of this infection. We therefore investigated the utility of key immune cytokines as diagnostic biomarkers of M. bovis infection in this species. Thirty-six Italian Mediterranean buffaloes were used in this study: healthy animals (N = 11), infected (IFN-γ test positive, no post-mortem lesions, no M. bovis detection; N = 14), and affected (IFN-γ test positive, visible post-mortem lesions; N = 11). Heparin blood samples were stimulated with bovine purified protein derivative (PPD-B), alongside controls, and 18-24 h later plasma were collected. Levels of 14 key cytokines were measured: IFN-γ, IL-17, IL-4, IL-10, TNF, IL-1α, IL-1β, IL-6, IP-10, MIP-1α, MIP-1β, MCP-1, IL-36Ra, and VEGF-A. We observed that both infected and affected animals released higher levels of IFN-γ, IL-17, IL-10, TNF, IL-1α, IL-6, MIP-1β, in response to PPD-B compared to healthy subjects. Mycobacterium bovis infected animals released also higher levels of IL-1β and IP-10 in response to PPD-B compared to healthy subjects, whereas only tendencies were detected in affected animals. Affected animals only released MIP-1α in response to PPD-B compared to healthy subjects and in this group higher values of PPD-B specific TNF was also observed. Finally, canonical discriminant analysis (CDA) was used to generate predictive cytokine profiles by groups. Our data suggest that IL-10, TNF, IL-1α, IL-6, MIP-1β could be useful biomarkers of TB in Mediterranean Buffalo and can improve the TB diagnostic performance in this specie.

IRF7-deficient MDBK cell based on CRISPR/Cas9 technology for enhancing IBRV replication

Infectious bovine rhinotracheitis (IBR), characterized by acute respiratory lesions in cattle, is a major infectious disease caused by bovine alphaherpesvirus-1 (BoAHV-1). Control of this disease is primarily depending on vaccination. Madin-Darby bovine kidney cells (MDBK) being the main host cells and the important production platform for IBR vaccines. However, innate immune genes inhibit viral replication. Accordingly, the aim of this study was developing of IRF7 gene deleted MDBK cells to facilitate the production of high-titer vaccines. The CRISPR/Cas9 technology was used to knock out the IRF7 gene in MDBK cells and the impact on virus replication was examined using virus growth curves, CCK-8 assays, cell scratch assays, and qPCR. The knockout of the IRF7 gene in MDBK cells led to an increased replication capacity of IBRV and a significant reduction in type I interferons expression, specifically IFN-α and IFN-β. This indicates that IRF7 -/-MDBK cell lines can effectively result in production of IBRV with high-titer, which will enhance the development of inactivated or attenuated vaccines.

Infectious bovine rhinotracheitis: Unveiling the hidden threat to livestock productivity and global trade

An infectious disease called infectious bovine rhinotracheitis (IBR) can lead to a number of disorders affecting cattle's respiratory system. The disease is caused by bovine alphaherpesvirus type 1 (BoAHV-1). Based on antigenic and genetic characteristics, BoAHV-1 strains are divided into subtypes 1.1, 1.2a, 1.2b, and 1.3. IBR is currently widespread throughout the world, with the exception of a few nations that have achieved eradication. The most significant characteristic of this illness is that, after a clinical or subclinical infection, the virus typically establishes a latent condition that can later be reactivated in the presence of stress, immunosuppressive conditions/substances, or other diseases. Primarily, the virus spreads by direct or indirect contact between animals. It may also be transmitted via the reproductive system, causing infectious balanoposthitis or vulvovaginitis. Most virus subtypes are associated with reproductive failure, such as fetal or embryonic resorption and abortions. The virus may also be transmitted through semen, which could lead to genital transfer. Bovine herpesvirus type 1 (BoHV-1) infection produces a variety of lesions. Lesion in the mucosal surface usually consists of white necrotic material. Regular methods for diagnosing BoHV-1 infections include isolation in cell culture, enzyme linked immunosorbent assay, virus neutralisation test, and methods based on identification of nucleic acids, like PCR. The interplay of several host, pathogen, environmental, and management factors affects the spread of IBR. Through its impacts on health and fitness, IBR can lead to production losses. In order to minimize the severity of clinical signs and stop the infection from spreading, the veterinarian may advise that sick or at-risk animals be placed under immediate isolation and vaccinated (such as intranasal vaccination, including the use of both killed and live attenuated virus vaccines) as soon as an IBR diagnosis is obtained.

Transcriptomic analysis reveals bovine herpesvirus 1 infection regulates innate immune response resulted in restricted viral replication in neuronal cells

BACKGROUND

Bovine herpesvirus 1 (BoHV-1) is a major pathogen that affects the global bovine population, primarily inducing respiratory and reproductive disorders. Its ability to establish latent infections in neuronal cells and to reactivate under certain conditions poses a continual threat to uninfected hosts. In this study, we aimed to analyze the replication characteristics of BoHV-1 in neuronal cells, as well as the effects of viral replication on host cell immunity and physiology.

METHODS

Using the Neuro-2a neuronal-origin cell line as a model, we explored the dynamics of BoHV-1 replication and analyzed differential gene expression profiles post-BoHV-1 infection using high-throughput RNA sequencing.

RESULTS

BoHV-1 demonstrated restricted replication in Neuro-2a cells. BoHV-1 induced apoptotic pathways and enhanced the transcription of interferon-stimulated genes and interferon regulatory factors while suppressing the complement cascade in Neuro-2a cells.

CONCLUSIONS

Different from BoHV-1 infection in other non-highly differentiated somatic cells result in viral dominance, BoHV-1 regulated the innate immune response in neuronal cells formed a "virus-nerve cell" relative equilibrium state, which may account for the restricted replication of BoHV-1 in neuronal cells, leading to a latent infection. These findings provide a foundation for further research into the mechanism underlying BoHV-1-induced latent infection in nerve cells.

Effect of two different commercial vaccines against bovine respiratory disease on cell-mediated immunity in Holstein cattle

Background

Bovine respiratory disease (BRD) is a complex illness that impacts the respiratory system of domestic cattle, resulting in significant financial losses for the agriculture industry. Inactivated or modified live (MLV) pathogen vaccines are often used as a management tool to prevent and control BRD effectively.

Aim

The purpose of this study is to assess the cell-mediated immune response (CMI) induced by two commercially available polyvalent vaccines, namely the MLV (cattle master gold FP) and the inactivated (CATTLEWIN-5K) vaccine.

Methods

A total of 20 seronegative heifers against 4 BRD viruses, bovine alphaherpisvirus-1 (BoAHV-1), bovine viral diarrhea virus (BVDV BVDV-1: Pesti virus A; BVDV-2: Pesti virus B), bovine respiratory syncytial virus (BRSV) and bovine parainfluenza virus-3 (BPIV3) were chosen for this study. The heifers were divided into three groups. The first group (n = 6) received no vaccination and was kept as a control. The second and third groups (seven heifers each) were vaccinated twice with either an MLV or inactivated vaccine. The gene expression level of interleukin-6 (IL-6) and interferon-gamma (INF-γ) was measured using real-time quantitative polymerase chain reaction on the 7th, 14th, 21st, 28th, and 60th days post-vaccination. The results were compared with the control group to study the effectiveness of the vaccines.

Results

There was an upregulation in the expression level of IL-6 and INF-γ in both MLV and inactivated vaccinated groups. The level of IL-6 mRNA expression was statistically increased from the 14th and 28th days post-vaccination in MLV and inactivated vaccine groups, respectively. The expression level of INF-γ increased significantly from the 2nd and 4th weeks post-vaccination in the MLV and inactivated vaccine groups, respectively. The mean expression level of IL-6 and INF-γ mRNAs was significantly higher in the MLV vaccine group than in the inactivated vaccine group at each examination time.

Conclusion

Both investigated vaccines are efficient in stimulating CMI, particularly with the MLV vaccine showing a higher preponderance in IL-6 and INF-γ.

Investigation of the safety and protective efficacy of an attenuated and marker M. bovis-BoHV-1 combined vaccine in bovines

Bovine respiratory disease (BRD) is one of the most common diseases in the cattle industry worldwide; it is caused by multiple bacterial or viral coinfections, of which Mycoplasma bovis (M. bovis) and bovine herpesvirus type 1 (BoHV-1) are the most notable pathogens. Although live vaccines have demonstrated better efficacy against BRD induced by both pathogens, there are no combined live and marker vaccines. Therefore, we developed an attenuated and marker M. bovis-BoHV-1 combined vaccine based on the M. bovis HB150 and BoHV-1 gG-/tk- strain previously constructed in our lab and evaluated in rabbits. This study aimed to further evaluate its safety and protective efficacy in cattle using different antigen ratios. After immunization, all vaccinated cattle had a normal rectal temperature and mental status without respiratory symptoms. CD4+, CD8+, and CD19+ cells significantly increased in immunized cattle and induced higher humoral and cellular immune responses, and the expression of key cytokines such as IL-4, IL-12, TNF-α, and IFN-γ can be promoted after vaccination. The 1.0 × 108 CFU of M. bovis HB150 and 1.0 × 106 TCID50 BoHV-1 gG-/tk- combined strain elicited the most antibodies while significantly increasing IgG and cellular immunity after challenge. In conclusion, the M. bovis HB150 and BoHV-1 gG-/tk- combined strain was clinically safe and protective in calves; the mix of 1.0 × 108 CFU of M. bovis HB150 and 1.0 × 106 TCID50 BoHV-1 gG-/tk- strain was most promising due to its low amount of shedding and highest humoral and cellular immune responses compared with others. This study introduces an M. bovis-BoHV-1 combined vaccine for application in the cattle industry.

Development and evaluation of a time-resolved fluorescence labelled immunochromatographic strip assay for rapid and quantitative detection of bovine herpesvirus 1

Bovine herpes virus 1 (BoHV-1) causes a wide variety of diseases in wild and domestic cattle. The most widely used method for viral identification is real-time PCR, which can only be performed in laboratories using sophisticated instruments by expert personnel. Herein, we developed an ultrasensitive time-resolved fluorescence lateral flow immunochromatographic strip (ICS) assay for detecting BoHV-1 in bovine samples using a monoclonal antibody against BoHV-1 labelled with fluorescent microspheres, which can be applied in any setting. The intact process from sample collection to final result can be achieved in 15 min. The limit of detection of the assay for BoHV-1 was 102 TCID50/100 μL. The coincidence rate of the ICS method and real-time PCR recommended by the World Organization for Animal Health (WOAH) was 100% for negative, 92.30% for positive, and 95.42% for total, as evaluated by the detection of 131 clinical samples. This detection method was specifically targeted to BoHV-1, not exhibiting cross-reactivity with other bovine pathogens including BoHV-5. We developed an ICS assay equipped with a portable instrument that offers a sensitive and specific platform for the rapid and reliable detection of BoHV-1 in the field. The Point-of-Care test of BoHV-1 is suitable for the screening and surveillance of BoHV-1 in dairy herds.

Assessment of BoAHV-1 Seronegative Latent Carrier by the Administration of Two Infectious Bovine Rhinotracheitis Live Marker Vaccines in Calves

Seronegative latent carriers (SNLCs) are animals that carry the virus without detectable antibodies and pose a risk for disease transmission and diagnostic challenges, suggesting the importance of consideration of marker vaccines in managing them. Therefore, in this study, we evaluated two modified live infectious bovine rhinotracheitis (IBR) marker vaccines (single and double deletions) for their ability to generate SNLC calves. These vaccines were administered to four groups (n = 3 in each group) of three-month-old calves in the presence or absence of passive immunity. Three hundred days after the first vaccination and after confirming the IBR seronegativity of all animals, dexamethasone was administered intravenously for five consecutive days. Only animals immunized with the modified live IBR marker vaccine (single deletion) in the absence of passive immunity exhibited a more enduring immune response than those vaccinated in the presence of passive immunity. Moreover, the administration of a modified live IBR marker vaccine (double deletion) to calves with passive immunity generated SNLC. These findings underscore the potential of live IBR marker vaccine (double-deletions) to aid serological diagnostic tools and develop vaccination protocols in achieving the desired immune response, particularly in the context of latent carrier status, offering valuable insights into optimizing vaccination strategies for effective IBR control.

Genomic Characterization of a Wild-Type Bovine alphaherpesvirus 1 (BoAHV-1) Strain Isolated in an Outbreak in Central Italy

Bovine alphaherpesvirus-1 (BoAHV-1) infection is common in cattle worldwide. However, information on the spread of BoAHV-1-circulating strains in Italy remains limited. In this study, we investigated an outbreak characterized by severe respiratory symptoms in a cattle herd (n = 30) located in Central Italy. BoAHV-1 was isolated from three cattle in a cell culture, which confirmed viral infection. Next, we characterized one (16453/07 TN) of the three isolates of BoAHV-1 using whole-genome sequencing. BLASTn and phylogenetic analysis revealed a nucleotide identity >99% with all BoAHV-1 strains belonging to subtype 1.1, highlighting the genetic stability of the virus. This study reports the first full genomic characterization of a BoAHV-1 isolate in Italy, enriching our understanding of the genetic characteristics of the circulating BoAHV-1 strain in Italy.

Fosfomycin modifies the replication kinetics of bovine alphaherpesvirus-1 and reduces the timing of its protein expression on bovine (MDBK) and human (SH-SY5Y) cell lines

Bovine alphaherpesvirus 1 (BoAHV-1) predisposes cattle to respiratory secondary bacterial infections, which can be treated with the broad-spectrum antibiotic fosfomycin. This drug also suppresses NF-kB activity and pro-inflammatory responses. Therefore, cattle may be exposed to an interaction between the virus and the antibiotic which may have effects on it. The aim of this study was to determine the effect of calcium fosfomycin (580 µg/mL) on BoAHV-1 (moi = 0.1) replication. Two cell lines (MDBK and SH-SY5Y) were used in this study. Our results show that fosfomycin has novel properties. By MTT assay we have shown that it is non-cytotoxic for any of the cell lines. Extracellular and intracellular viral titers demonstrated that fosfomycin has a cell-type and time-dependent effect on BoAHV-1 replication. By direct immunofluorescence it was shown that it reduces the timing of BoAHV-1 protein expression, and by qPCR, we found that its effect on NF-kB mRNA expression depends on the cell type.

Antiviral activity of Taurisolo® during bovine alphaherpesvirus 1 infection

Bovine alphaherpesvirus 1 (BoAHV-1), the pathogen causing Infectious Bovine Rhinotracheitis (IBR) and predisposing to polymicrobial infections in cattle, provokes farm economic losses and trading restrictions in the world. However, nontoxic antiviral agents for BoAHV-1 infection are still unavailable, but plant extracts, such as flavonoid derivatives possess activity against BoAHV-1. Taurisolo®, a nutraceutical produced by Aglianico grape pomace, has recently shown promising antiviral activity. Herein, the potential activity of Taurisolo® during BoAHV-1 infection in Madin Darby bovine kidney (MDBK) cells was tested. Taurisolo® enhanced cell viability and reduced morphological death signs in BoAHV-1-infected cells. Moreover, Taurisolo® influenced the expression of bICP0, the key regulatory protein of BoAHV-1, and it strongly diminished virus yield. These effects were associated with an up-regulation of aryl hydrocarbon receptor (AhR), a transcription factor involved in microbial metabolism and immune response. In conclusion, our findings indicate that Taurisolo® may represent a potential antiviral agent against BoAHV-1 infection. Noteworthy, AhR could be involved in the observed effects and become a new target in antiviral therapy.

Evaluation of Hematological Profiles and Monocyte Subpopulations in Water Buffalo Calves after Immunization with Two Different IBR Marker Vaccines and Subsequent Infection with Bubaline alphaherpesvirus-1

Bubaline alphaherpesvirus-1 (BuAHV-1) and Bovine alphaherpesvirus-1 (BoAHV-1) are respiratory viruses that can cause an infection known as "Infectious Bovine Rhinotracheitis" (IBR) in both water buffalo and bovine species. As the main disease control strategy, vaccination can protect animals from clinical disease through the development of specific humoral and cell-mediated immune responses. In the present study, the time-related circulatory kinetics of hematological profile and bubaline monocyte subsets have been investigated in vaccinated buffalo calves after challenge infections with BuAHV-1. Thirteen buffalo calves were selected and grouped into the VAX-1 group, which received an IBR-live-attenuated gE-/tk-deleted marker vaccine; the VAX-2 group, which received an IBR-inactivated gE-deleted marker vaccine; the CNT group, which remained an unvaccinated control. Fifty-five days after the first vaccination, the animals were infected with 5 × 105.00 TCID50/mL of wild-type BuAHV-1 strain via the intranasal route. Whole blood samples were collected at 0, 2, 4, 7, 10, 15, 30, and 63 days post-challenge (PCDs) for the analysis of hematological profiles and the enumeration of monocyte subsets via flow cytometry. The analysis of leukocyte compositions revealed that neutrophils were the main leukocyte population, with a relative increase during the acute infection. On the other hand, a general decrease in the proportion of lymphocytes was observed early in the post-infection, both for the VAX-1 and VAX-2 groups, while in the CNT group, the decrease was observed later at +30 and +63 PCDs. An overall infection-induced increase in blood total monocytes was observed in all groups. The rise was especially marked in the animals vaccinated with an IBR-live-attenuated gE-/tK-deleted marker vaccine (VAX-1 group). A multicolor flow cytometry panel was used to identify the bubaline monocyte subpopulations (classical = cM; intermediate = intM; and non-classical = ncM) and to investigate their variations during BuAHV-1 infection. Our results showed an early increase in cMs followed by a second wave of intMs. This increase was observed mainly after stimulation with live-attenuated viruses in the VAX-1 group compared with the animals vaccinated with the inactivated vaccine or the non-vaccinated animal group. In summary, the present study characterized, for the first time, the hematological profile and distribution of blood monocyte subsets in vaccinated and non-vaccinated water buffalo in response to experimental infection with BuAHV-1. Although not experimentally proven, our results support the hypothesis of a linear developmental relationship between monocyte subsets.