Bovine Herpesvirus 1 Counteracts Immune Responses and Immune-Surveillance to Enhance Pathogenesis and Virus Transmission

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.

Tegument protein UL3 of bovine herpesvirus 1 suppresses antiviral IFN-I signaling by targeting STING for autophagic degradation

Bovine herpesvirus 1 (BoHV-1) is a highly contagious pathogen which causes infectious bovine rhinotracheitis in cattle worldwide. Although it has the ability to evade the host's antiviral innate immune response and establish persistent latent infections, the mechanisms are not fully understood, especially the function of the tegument protein to escape innate immunity and participate in viral replication. In this study, we showed that overexpression of tegument protein UL3 facilitates BoHV-1 replication and suppresses the expression of type-I interferon (IFN-I) and IFN-stimulated genes. Then, STING was identified as the target by which UL3 inhibits the IFN-I signaling pathway, and STING was degraded through the UL3-induced autophagy pathway. Furthermore, overexpression of UL3 promotes the expression of the autophagy-related protein ATG101, thereby inducing autophagy. Further study showed that UL3 enhances the interaction between ATG101 and STING, and then the degradation of STING was reversed following ATG101 silencing in UL3-overexpressing cells during BoHV-1 infection. Our research results demonstrate a novel function of UL3 in regulating host's antiviral response and provide a potential mechanism for BoHV-1 immune evasion.

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.

Bovine Herpes Virus Type 1 (BoHV-1) seroprevalence, risk factor and Bovine Viral Diarrhoea (BVD) co-infection analysis from Ireland

Surveillance of endemic pathogens is essential for disease control, providing an evidence base for policy and advice. Bovine Herpes Virus Type 1 (BoHV-1), the causative agent of Infectious Bovine Rhinotracheitis (IBR), has been found to have high seroprevalence within the Irish cattle population. The aim of the present study was to establish seroprevalence levels for culled cattle in Ireland aged < 30 months and to establish whether BVD exposure and other factors was associated with BoHV-1 exposure. We employed random effects logit models coupled with repeated bootstrap sampling to provide robust estimates. The final dataset contained results for 5273 animals tested over two study years, 2018 and 2020. The animal-level seroprevalence of BoHV-1 was 21.43% (1130/5273; 95%CI: 20.32-22.53%). Univariable analysis suggested that BoHV-1 seropositivity risk was associated with BVDV serodiagnosis status, age, sex, year sampled, herd type, herd-size, and metrics of movement into the herd. Final random-effects multivariable models suggested increased risk associated with increasing herd size of the last herd, movements made by animals during the previous year, and the year the animal was sampled. Despite BVDV status and sex being retained in the final model, repeated bootstrap sampling of the regression model to estimate biased-corrected 95%CI suggested that these associations were not robust. The overall apparent prevalence of BoHV-1 exposure for culled cattle in Ireland declined in 2020 relative to 2018 (from 23.32 to 17.61%). Herd-size and the movement of animals were found to be important factors associated with animal-level risk, but there was less statistical support for sex-based or BVDV status associations.

GARP and EARP are required for efficient BoHV-1 replication as identified by a genome wide CRISPR knockout screen

The advances in gene editing bring unprecedented opportunities in high throughput functional genomics to animal research. Here we describe a genome wide CRISPR knockout library, btCRISPRko.v1, targeting all protein coding genes in the cattle genome. Using it, we conducted genome wide screens during Bovine Herpes Virus type 1 (BoHV-1) replication and compiled a list of pro-viral and anti-viral candidates. These candidates might influence multiple aspects of BoHV-1 biology such as viral entry, genome replication and transcription, viral protein trafficking and virion maturation in the cytoplasm. Some of the most intriguing examples are VPS51, VPS52 and VPS53 that code for subunits of two membrane tethering complexes, the endosome-associated recycling protein (EARP) complex and the Golgi-associated retrograde protein (GARP) complex. These complexes mediate endosomal recycling and retrograde trafficking to the trans Golgi Network (TGN). Simultaneous loss of both complexes in MDBKs resulted in greatly reduced production of infectious BoHV-1 virions. We also found that viruses released by these deficient cells severely lack VP8, the most abundant tegument protein of BoHV-1 that are crucial for its virulence. In combination with previous reports, our data suggest vital roles GARP and EARP play during viral protein packaging and capsid re-envelopment in the cytoplasm. It also contributes to evidence that both the TGN and the recycling endosomes are recruited in this process, mediated by these complexes. The btCRISPRko.v1 library generated here has been controlled for quality and shown to be effective in host gene discovery. We hope it will facilitate efforts in the study of other pathogens and various aspects of cell biology in cattle.

Molecular detection of bovine alphaherpesvirus-1 in cases of reproductive disorders among cattle and buffaloes in Gujarat

Bovine alphaherpesvirus-1 (BoAHV-1) is an important viral pathogen that causes significant economic losses to the dairy industry. The present study aimed to determine the prevalence of BoAHV-1 in cases of bovine reproductive disorder. Clinical samples were collected from various villages in Gujarat using specialized FTA® cards and were tested using real-time PCR assay targeting the gB gene of BoAHV-1. Out of 401 animals, 18.20% (95% CI: 14.74-22.28%) tested positive for BoAHV-1 DNA. The percentage positivity of BoAHV-1 was 20.37% in abortion cases and 19.55% in retention of fetal membrane cases, while only one out of nine metritis cases screened in the study was positive for BoAHV-1 DNA. A higher percentage positivity in buffaloes (22.14%) compared to cattle (16.30%) was recorded, but this difference was not statistically significant (p = 0.169). The frequency of BoAHV-1 detection was higher among crossbreeds (16.76%) and exotics (19.61%) than among indigenous cattle (8.82%), although this difference was not statistically significant (p = 0.400). There was also no significant difference in frequency distribution among animals of varying parity, ranging from 15.20 to 33.33% (p = 0.540). This study confirms the widespread circulation of BoAHV-1 and highlights the need for its control and prevention.

Development and evaluation of recombinant gD protein based ELISA for sero-surveillance of BoHV-1 in India

Bovine herpes virus-1 (BoHV-1) is responsible for production losses through decreased milk yields, abortions, infertility, and trade restrictions in the bovine population. The disease is endemic in many countries including India. As the virus harbors a unique feature of latency animals once infected with the virus remain sero-positive for lifetime and can re-excrete the virus when exposed to stressful conditions. Hence, identification and culling of infected animals is only the means to minimize infection-associated losses. In this study, an economical indigenous assay for the detection of BoHV-1 specific antibodies was developed to cater to the huge bovine population of the country. The viral structural gD protein, expressed in the prokaryotic system was used for optimization of an indirect ELISA for bovines followed by statistical validation of the assay. The diagnostic sensitivity and specificity of the indirect ELISA were 82.9% and 91.3% respectively. Systematically collected serum samples representing organized, unorganized and breeding farms of India were tested with the indigenously developed assay for further validation.

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.

The combination of vaccines and adjuvants to prevent the occurrence of high incidence of infectious diseases in bovine

As the global population grows, the demand for beef and dairy products is also increasing. The cattle industry is facing tremendous pressures and challenges. The expanding cattle industry has led to an increased risk of disease in cattle. These diseases not only cause economic losses but also pose threats to public health and safety. Hence, ensuring the health of cattle is crucial. Vaccination is one of the most economical and effective methods of preventing bovine infectious diseases. However, there are fewer comprehensive reviews of bovine vaccines available. In addition, the variable nature of bovine infectious diseases will result in weakened or even ineffective immune protection from existing vaccines. This shows that it is crucial to improve overall awareness of bovine vaccines. Adjuvants, which are crucial constituents of vaccines, have a significant role in enhancing vaccine response. This review aims to present the latest advances in bovine vaccines mainly including types of bovine vaccines, current status of development of commonly used vaccines, and vaccine adjuvants. In addition, this review highlights the main challenges and outstanding problems of bovine vaccines and adjuvants in the field of research and applications. This review provides a theoretical and practical basis for the eradication of global bovine infectious diseases.

Comprehensive Analysis of the Tegument Proteins Involved in Capsid Transport and Virion Morphogenesis of Alpha, Beta and Gamma Herpesviruses

Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions throughout the viral life cycle. This review provides a comprehensive and comparative analysis of the roles of specific tegument proteins in capsid transport and virion morphogenesis of selected, well-studied prototypes of each of the three subfamilies of Herpesviridae i.e., human herpesvirus-1/herpes simplex virus-1 (Alphaherpesvirinae), human herpesvirus-5/cytomegalovirus (Betaherpesvirinae) and human herpesvirus -8/Kaposi's sarcomavirus (Gammaherpesvirinae). Most of the current knowledge is based on alpha herpesviruses, in particular HSV-1. While some tegument proteins are released into the cytoplasm after virus entry, several tegument proteins remain associated with the capsid and are responsible for transport to and docking at the nucleus. After replication and capsid formation, the capsid is enveloped at the nuclear membrane, which is referred to as primary envelopment, followed by de-envelopment and release into the cytoplasm. This requires involvement of at least three tegument proteins. Subsequently, multiple interactions between tegument proteins and capsid proteins, other tegument proteins and glycoproteins are required for assembly of the virus particles and envelopment at the Golgi, with certain tegument proteins acting as the central hub for these interactions. Some redundancy in these interactions ensures appropriate morphogenesis.

Associating bovine herpesvirus 1 envelope glycoprotein gD with activated phospho-PLC-γ1(S1248)

Phospholipase C gamma 1 (PLC-γ1) may locate at distinct subcellular locations, such as cytosol, plasma membrane, and nucleus for varied biological functions. Bovine herpesvirus 1 (BoHV-1) productive infection activates PLC-γ1 signaling, as demonstrated by increased protein levels of phosphorylated-PLC-γ1 at Ser1248 [p-PLC-γ1(S1248)], which benefits virus productive infection. Here, for the first time, we reported that Golgi apparatus also contains activated p-PLC-γ1(S1248). And BoHV-1 productive infection at later stages (24 hpi) increased the accumulation of p-PLC-γ1(S1248) in the Golgi apparatus, where p-PLC-γ1(S1248) forms highlighted puncta observed via a confocal microscope. Coimmunoprecipitation studies demonstrated that the Golgi p-PLC-γ1(S1248) is specifically associated with the viral protein gD but not gC. In addition, we found that p-PLC-γ1(S1248) is consistently associated with both the plasma membrane-associated virions and the released virions. When the virus-infected cells were treated with PLC-γ1-specific inhibitor, U73122, for a short duration of 4 hours prior to the endpoint of virus infection, we found that the viral protein gD was trapped in the Golgi apparatus, suggesting that the PLC-γ1 signaling may facilitate trafficking of progeny virions out of this organelle. These findings provide a novel insight into the interplay between PLC-γ1 signaling and BoHV-1 replication. IMPORTANCE Bovine herpesvirus 1 (BoHV-1) productive infection increases protein levels of phosphorylated-phospholipase C gamma 1 at Ser1248 [p-PLC-γ1(S1248)]. However, whether it causes any variations to p-PLC-γ1(S1248) localization is not well understood. Here, for the first time, we found that partial p-PLC-γ1(S1248) is residing in the Golgi apparatus, where the accumulation is enhanced by virus infection. p-PLC-γ1(S1248) is consistently associated with virions, partially via binding to gD, in both the Golgi apparatus and cytoplasm membranes. Surprisingly, it also associates with the released virions. Of note, this is the first evidenced BoHV-1 virion-bound host protein. It seems that p-PLC-γ1(S1248) works as an escort during trafficking of progeny virions out of Golgi apparatus to the plasma membranes as well as releasing outside of the cell membranes. Furthermore, we showed that the activated p-PLC-γ1(S1248) is potentially implicated in the transport of virions out of Golgi apparatus, which may represent a novel mechanism to regulate virus productive infection.

Construction and Analysis of ceRNA Networks Reveal the Key Genes Associated with Bovine Herpesvirus Type 1 Infection

Background

Virus infection can cause the changes of lncRNA expression levels to regulate the interaction between virus and host, but the relationship between BHV-1 infection and lncRNA has not been reported.

Methods

In this study, in order to reveal the molecular mechanism of RNA in BoHV-1 infection, the Madin-Darby bovine kidney (MDBK) cells were infected with BoHV-1, transcriptome sequencing were performed by next-generation sequencing at 18 h or 24 h or 33 h of viral infection and then based on the competitive endogenous RNA (ceRNA) theory, lncRNA-miRNA-mRNA networks were constructed using these high-throughput sequencing data. The network analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed for functional annotation and exploration of ncRNA ceRNAs in BoHV-1 infection.

Results

The results showed that 48 lncRNAs, 123 mRNAs and 20 miRNAs as differentially expressed genes, and the mitogen activated protein kinase (MAPK) pathway and calcium signaling pathway were significantly enriched in the ceRNA network. Some differentially expressed lncRNA genes were randomly selected for verification by RT-qPCR, and the results showed that their expression trend was consistent with the results of transcriptome sequencing data.

Conclusion

This study revealed that BoHV-1 infection can affect the expression of RNAs in MDBK cells and the regulation of ceRNA network to carry out corresponding biological functions in the host, but further experimental studies are still necessary to prove the hub genes function in ceRNA network and the molecular mechanism in BoHV-1 infection.

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.

NFAT5 Restricts Bovine Herpesvirus 1 Productive Infection in MDBK Cell Cultures

Bovine herpesvirus 1 (BoHV-1), an important bovine viral pathogen, causes severe disease in the upper respiratory tract and reproductive system. Tonicity-responsive enhancer-binding protein (TonEBP), also known as nuclear factor of activated T cells 5 (NFAT5), is a pleiotropic stress protein involved in a range of cellular processes. In this study, we showed that the knockdown of NFAT5 by siRNA increased BoHV-1 productive infection and overexpression of NFAT5 via plasmid transfection decreased virus production in bovine kidney (MDBK) cells. Virus productive infection at later stages significantly increased transcription of NFAT5 but not appreciably alter measurable NFAT5 protein levels. Virus infection relocalized NFAT5 protein and decreased the cytosol accumulation. Importantly, we found a subset of NFAT5 resides in mitochondria, and virus infection led to the depletion of mitochondrial NFAT5. In addition to full-length NFAT5, another two isoforms with distinct molecular weights were exclusively detected in the nucleus, where the accumulation was differentially affected following virus infection. In addition, virus infection differentially altered mRNA levels of PGK1, SMIT, and BGT-1, the canonical downstream targets regulated by NFAT5. Taken together, NFAT5 is a potential host factor that restricts BoHV-1 productive infection, and virus infection hijacks NFAT5 signaling transduction by relocalization of NFAT5 molecules in cytoplasm, nucleus, and mitochondria, as well as altered expression of its downstream targets. IMPORTANCE Accumulating studies have revealed that NFAT5 regulates disease development due to infection of numerous viruses, underlying the importance of the host factor in virus pathogenesis. Here, we report that NFAT5 has capacity to restrict BoHV-1 productive infection in vitro. And virus productive infection at later stages may alter NFAT5 signaling pathway as observed by relocalization of NFAT5 protein, reduced accumulation of NFAT5 in cytosol, and differential expression of NFAT5 downstream targets. Importantly, for the first time, we found that a subset of NFAT5 resides in mitochondria, implying that NFAT5 may regulate mitochondrial functions, which will extend our knowledge on NFAT5 biological activities. Moreover, we found two NFAT5 isoforms with distinct molecular weights were exclusively detected in the nucleus, where the accumulation was differentially affected following virus infection, representing a novel regulation mechanism on NFAT5 function in response to BoHV-1infection.

Endogenous and viral microRNAs in nasal secretions of water buffaloes (Bubalus bubalis) after Bubaline alphaherpesvirus 1 (BuHV-1) challenge infection

Bubaline alphaherpesvirus 1 (BuHV-1) is a pathogen of water buffaloes responsible for economic loss worldwide. MicroRNAs (miRNAs) regulate gene expression produced by alphaherpesviruses and hosts. This study aimed at (a) unravelling the ability of BuHV-1 to produce miRNAs, including hv1-miR-B6, hv1-miR-B8, hv1-miR-B9; (b) measuring the host immune-related miRNAs associated to herpesvirus infection, including miR-210-3p, miR-490-3p, miR-17-5p, miR-148a-3p, miR-338-3p, miR-370-3p, by RT-qPCR; (c) identifying candidate markers of infection by receiver-operating characteristic (ROC) curves; (d) exploiting the biological functions by pathway enrichment analyses. Five water buffaloes BuHV-1 and Bovine alphaherpesvirus 1 (BoHV-1) free were immunized against Infectious Bovine Rhinotracheitis (IBR). Five additional water buffaloes served as negative controls. All animals were challenged with a virulent wild-type (wt) BuHV-1 via the intranasal route 120 days after the first vaccination. Nasal swabs were obtained at days (d) 0, 2, 4, 7, 10, 15, 30, and 63 post-challenge (pc). The animals of both groups shed wt BuHV-1 up to d7 pc. Results demonstrated that (a) miRNAs produced by the host and BuHV-1 could be efficiently quantified in the nasal secretion up to d63 and d15 pc, respectively; b) the levels of host and BuHV-1 miRNAs are different between vaccinated and control buffaloes; c) miR-370-3p discriminated vaccinated and control animals; d) host immune-related miRNAs may modulate genes involved in the cell adhesion pathway of the neuronal and immune system. Overall, the present study provides evidence that miRNAs can be detected in nasal secretions of water buffaloes and that their expression is modulated by BuHV-1.

Seroepidemiological study of bovine alphaherpesvirus 1 in the dairy cattle herds of Addis Ababa, Ethiopia

Bovine alphaherpesvirus 1(BoHV-1) causes respiratory disease, abortions, and genital disorders in cattle. Although BoHV-1 has been known to cause severe economic damage to the dairy industries, little is known about its epidemiology in dairy cattle of Addis Ababa, Ethiopia. The present study aimed to determine the seroprevalence and the risk factors associated with the occurrence of BoHV-1. A total of 369 blood samples from 115 dairy herds were collected using a proportional stratified random sampling method and examined antibodies against BoHV-1 using ELISA test. A questionnaire survey was done to gather information related to farm demographics and reproductive disorders. Univariate and multivariate mixed-effect logistic regression analyses were used. The overall seroprevalence of BoHV-1 was detected in 21 % (95%CI: 17-25%) and 32 % (95%CI: 24-42 %) at animal and herd levels, respectively. A multivariable mixed effect logistic regression model revealed that adult cattle had 14 times (OR = 14.32; 95 % CI: 2.53-81.5; P = 0.003) more likely to increase the risk of being BoHV-1 seropositive than young cattle. Purchased cattle had 4 times (OR = 4.15; 95 % CI: 1.36-12.66, P = 0.012) more likely to increase the risk of being BoHV-1 seropositive than homebred cattle. The risk of being BoHV-1 seropositive was 195 times higher in herds using bulls (OR = 195.51; 95 % CI: 3.62-1056.51; P = 0.010) than in herds using artificial insemination only for breeding. BoHV-1 seropositivity was significantly associated with cows that had a history of abortion (OR = 6.89; 95 % CI: 1.97-22.76; P = 0.002), retained placenta (OR = 3.26; 95 % CI: 1.32-8.07; P = 0.010), and repeat breeding (OR = 3.64; 95 % CI: 1.08-12.18; P = 0.036). This study demonstrated the gaps in the selection of BoHV-1 free bulls for breeding as well as limited farm biosecurity practices. Thus, awareness creation for dairy farmers on good farm biosecurity practices including vaccination should be initiated.

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

Bovine Alphaherpesvirus 1 (BoHV-1) is one of the major respiratory pathogens in cattle worldwide. Infection often leads to a compromised host immune response that contributes to the development of the polymicrobial disease known as “bovine respiratory disease”. After an initial transient phase of immunosuppression, cattle recover from the disease. This is due to the development of both innate and adaptive immune responses. With respect to adaptive immunity, both humoral and cell-mediated immunity are required to control infection. Thus, several BoHV-1 vaccines are designed to trigger both branches of the adaptive immune system. In this review, we summarize the current knowledge on cell-mediated immune responses directed against BoHV-1 infection and vaccination.

Microscopic lesions and modulation of gene expression in cervical medulla during BoAHV-1and BoAHV-5 infection: A mini-review

Bovine herpesvirus (BoAHV) types 1 and 5 are closely-related neurotropic alpha-herpesviruses. BoAHV-1 generally causes respiratory and genital disease but can occasionally cause encephalitis. BoAHV-5 is the causative agent of non suppurative meningoencephalitis in calves. During neuroinvasion, both viruses reach the central and peripheral nervous system. While brain alterations are well-described, the changes that occur in the medulla have not been fully detailed. In this work, we integrated and analyzed the virological findings, the microscopic lesions and the changes that occur in the expression of genes related to the innate immunity, cell cycle and apoptosis in the cervical medulla of calves experimentally-infected with BoAHV-1 and BoAHV-5. This will contribute to the understanding of the differential neuropathogenesis of these alpha-herpesviruses of cattle.

Whole blood transcriptome analysis in dairy calves experimentally challenged with bovine herpesvirus 1 (BoHV-1) and comparison to a bovine respiratory syncytial virus (BRSV) challenge

Bovine herpesvirus 1 (BoHV-1), is associated with several clinical syndromes in cattle, among which bovine respiratory disease (BRD) is of particular significance. Despite the importance of the disease, there is a lack of information on the molecular response to infection via experimental challenge with BoHV-1. The objective of this study was to investigate the whole-blood transcriptome of dairy calves experimentally challenged with BoHV-1. A secondary objective was to compare the gene expression results between two separate BRD pathogens using data from a similar challenge study with BRSV. Holstein-Friesian calves (mean age (SD) = 149.2 (23.8) days; mean weight (SD) = 174.6 (21.3) kg) were either administered BoHV-1 inoculate (1 × 10⁷/mL × 8.5 mL) (n = 12) or were mock challenged with sterile phosphate buffered saline (n = 6). Clinical signs were recorded daily from day (d) -1 to d 6 (post-challenge), and whole blood was collected in Tempus RNA tubes on d six post-challenge for RNA-sequencing. There were 488 differentially expressed (DE) genes (p < 0.05, False Discovery rate (FDR) < 0.10, fold change ≥2) between the two treatments. Enriched KEGG pathways (p < 0.05, FDR <0.05); included Influenza A, Cytokine-cytokine receptor interaction and NOD-like receptor signalling. Significant gene ontology terms (p < 0.05, FDR <0.05) included defence response to virus and inflammatory response. Genes that are highly DE in key pathways are potential therapeutic targets for the treatment of BoHV-1 infection. A comparison to data from a similar study with BRSV identified both similarities and differences in the immune response to differing BRD pathogens.

Phospholipase C-γ1 potentially facilitates subcellular localization of activated β-catenin, p-β-catenin(S552), during bovine herpesvirus 1 productive infection in MDBK cells

Bovine herpesvirus 1 (BoHV-1) is a significant risk factor for the bovine respiratory disease complex (BRDC), a severe disease causing great economic losses to the cattle industry worldwide. Previous studies have reported that both phospholipase C-γ1 (PLC-γ1) and β-catenin are activated during BoHV-1 infection for efficient replication. However, the interplay between PLC-γ1 and β-catenin as a consequence of virus infection remains to be elucidated. Here, we reported that PLC-γ1 interacted with β-catenin, which was enhanced following virus infection. PLC-γ1-specific inhibitor, U73122, significantly reduced the mRNA levels of β-catenin in BoHV-1-infected cells; however, the steady-state protein levels were not affected due to the virus infection. Interestingly, the treatment of virus-infected cells with U73122 reduced the accumulation of activated β-catenin [p-β-catenin(S552)] in fractions of the cytoplasmic membrane as that observed with the treatment of methyl-β-cyclodextrin (MβCD), which can disrupt cytoplasmic membrane structure via sequestering cholesterol. Nucleus accumulation of p-β-catenin(S552) was increased following U73122 treatment in virus-infected cells. In addition, the association of p-β-catenin(S552) with cytoplasmic membrane induced by the virus infection was significantly disrupted by the treatment of U73122 and MβCD. These data indicated that the PLC-γ1 signaling is potentially involved in the regulation of β-catenin signaling stimulated by BoHV-1 infection partially via affecting the subcellular localization of p-β-catenin(S552).

Prevalence of bovine herpesvirus 1 antibodies and risk factors in dairy cattle of Iran's central desert

Bovine herpesvirus type 1 (BoHV 1) is a major bovine pathogen spreading worldwide and causing extensive damage to the livestock industry. BoHV causes respiratory, genital, and neurological disorders. A cross-sectional study was performed for the first time to estimate the seroreactivity to BoHV 1 and related risk factors among Iran's central desert dairy cattle. A total of 800 blood samples was randomly collected from 76 unvaccinated herds. Samples were tested with an indirect enzyme-linked immunosorbent assay (ELISA) commercial kit to detect BoHV 1 antibodies. The logistic regression model was used to analyze the data. BoHV 1 seroreactivity at animal and herd levels was 50% and 65%, respectively. Herd size was recognized as a risk factor (OR = 2.65, CI = 1.61-4.37) for seroreactivity to BoHV using GLM (p < 0.05). The high prevalence of BoHV 1 antibodies in the study area indicates the need to implement educational programs on the importance of the disease and design methods to control and prevent virus distribution.

DNA Damage Response Differentially Affects BoHV-1 Gene Transcription in Cell Type-Dependent Manners

Bovine herpesvirus 1 (BoHV-1), an important pathogen of cattle, is also a promising oncolytic virus. Recent studies have demonstrated that the virus infection induces DNA damage and DNA damage response (DDR), potentially accounting for virus infection-induced cell death and oncolytic effects. However, whether the global DDR network affects BoHV-1 productive infection remains to be elucidated. In this study, we show that global DDR induced by ultraviolet (UV) irradiation prior to BoHV-1 infection differentially affected transcription of immediate early (IE) genes, such as infected cell protein 0 (bICP0) and bICP22, in a cell-type-dependent manner. In addition, UV-induced DDR may affect the stabilization of viral protein levels, such as glycoprotein C (gC) and gD, because the variation in mRNA levels of gC and gD as a consequence of UV treatment were not in line with the variation in individual protein levels. The virus productive infection also affects UV-primed DDR signaling, as demonstrated by the alteration of phosphorylated histone H2AX (γH2AX) protein levels and γH2AX formation following virus infection. Taken together, for the first time, we evidenced the interplay between UV-primed global DDR and BoHV-1 productive infection. UV-primed global DDR differentially modulates the transcription of virus genes and stabilization of virus protein. Vice versa, the virus infection may affect UV-primed DDR signaling.

Understanding the mechanisms of viral and bacterial coinfections in bovine respiratory disease: a comprehensive literature review of experimental evidence

Bovine respiratory disease (BRD) is one of the most important diseases impacting the global cattle industry, resulting in significant economic loss. Commonly referred to as shipping fever, BRD is especially concerning for young calves during transport when they are most susceptible to developing disease. Despite years of extensive study, managing BRD remains challenging as its aetiology involves complex interactions between pathogens, environmental and host factors. While at the beginning of the twentieth century, scientists believed that BRD was only caused by bacterial infections ("bovine pasteurellosis"), we now know that viruses play a key role in BRD induction. Mixtures of pathogenic bacteria and viruses are frequently isolated from respiratory secretions of animals with respiratory illness. The increased diagnostic screening data has changed our understanding of pathogens contributing to BRD development. In this review, we aim to comprehensively examine experimental evidence from all existing studies performed to understand coinfections between respiratory pathogens in cattle. Despite the fact that pneumonia has not always been successfully reproduced by in vivo calf modelling, several studies attempted to investigate the clinical significance of interactions between different pathogens. The most studied model of pneumonia induction has been reproduced by a primary viral infection followed by a secondary bacterial superinfection, with strong evidence suggesting this could potentially be one of the most common scenarios during BRD onset. Different in vitro studies indicated that viral priming may increase bacterial adherence and colonization of the respiratory tract, suggesting a possible mechanism underpinning bronchopneumonia onset in cattle. In addition, a few in vivo studies on viral coinfections and bacterial coinfections demonstrated that a primary viral infection could also increase the pathogenicity of a secondary viral infection and, similarly, dual infections with two bacterial pathogens could increase the severity of BRD lesions. Therefore, different scenarios of pathogen dynamics could be hypothesized for BRD onset which are not limited to a primary viral infection followed by a secondary bacterial superinfection.

Comparative transcriptome analysis of MDBK cells reveals that BoIFN-γ augmented host immune responses to bovine herpesvirus 1 infection

Bovine herpesvirus 1 (BoHV-1) is an alphaherpesvirus that causes infectious bovine rhinotracheitis and infectious pustular vulvovaginitis in cattle. Ιnterferon-gamma (IFN-γ) is a pleiotropic cytokine with antiviral activity that modulates the innate and adaptive immune responses. In this study, we prepared high-purity bovine interferon gamma (BoIFN-γ) dimer protein using prokaryotic expression system and affinity chromatography. We subsequently investigated the effect of BoIFN-γ on BoHV-1 infection in Madin-Darby bovine kidney (MDBK) cells. The results showed that BoIFN-γ pre-treament not only decreased the production of BoHV-1 but also reduced the cytopathic effect of the virus. Differential gene expression profiles of BoHV-1 infected MDBK cells were then analysed through high-throughput RNA sequencing. The data showed that BoIFN-γ pre-treatment reduced lipid metabolism disorder and DNA damage caused by BoHV-1 infection. Furthermore, BoIFN-γ treatment upregulated the transcription of interferon regulatory transcription factors (IRF1 and GBP5) and interferon-stimulated genes (ISGs) of MDBK cells. Additionally, BoIFN-γ promotes expression of cellular protein involved in complement activation and coagulation cascades response as well as antigen processing and presentation process, while BoHV-1 infection dramatically downregulates transcription of these immune components including C3, C1r, C1s, PLAT, ITGB2, PROCR, BoLA, CD74, B2M, PA28, BoLA-DRA, and TAPBP. Collectively, our findings revealed that BoIFN-γ pre-treatment can improve host resistance to BoHV-1 infection and regulate transcription or expression of host protein associated with cellular metabolism and innate immune response. This provides insights into the development of prophylactic agents for prevention and control of BoHV-1 infection.

Assessment of Different Infectious Bovine Rhinotracheitis Marker Vaccines in Calves

Three commercially available infectious bovine rhinotracheitis (IBR) live marker vaccines were evaluated for their ability to provide clinical protection to vaccinated calves against wild-type (wt) Bovine alphaherpesvirus-1 (BoHV-1) challenge and their possible effect on wt BoHV-1 latency reactivation following the challenge. On 35 post-vaccination days (PVDs), all animals were challenged with wt BoHV-1. Only the calves in the control group developed severe forms of IBR. The reactivation of latent BoHV-1 was induced by dexamethasone (DMS) treatment on 28 post-challenge days (PCDs). All animals showed IBR clinical signs on three post-DMS treatment days (PDTDs). On PVD 14, all vaccinated animals developed neutralizing antibodies (NAs), whereas in control animals, the NAs appeared post-challenge. The positivity for glycoprotein-B (gB) was detected using real-time polymerase chain reactions in all animals from PCDs 1 to 7. In contrast, the gB-positivity was observed in the immunized calves from PDTDs 3 to 10. Positive expression of gD and gE was observed in nasal swabs of all calves on PDTD 7. These findings suggested that the IBR marker vaccines evaluated in this study protected against wt BoHV-1-induced disease but not against wt BoHV-1-induced latency reactivation, indicating the necessity of developing new products to protect animals from wt BoHV-1-induced latency.

DDIT3 antagonizes innate immune response to promote bovine alphaherpesvirus 1 replication via the DDIT3-SQSTM1-STING pathway

DNA damage-inducible transcript 3 (DDIT3), a transcription factor, is typically involved in virus replication control. We are the first to report that DDIT3 promotes the replication of bovine viral diarrhea virus, an RNA virus, by inhibiting innate immunity. However, whether the DDIT3 gene participates in DNA virus replication by regulating innate immunity remains unclear. This study reported that DDIT3 suppressed the innate immune response caused by DNA viruses to promote bovine herpesvirus 1 (BoHV-1) replication. After BoHV-1 infection of Madin-Darby bovine kidney (MDBK) cells, upregulated expression of DDIT3 induced SQSTM1-mediated autophagy and promoted STING degradation. Overexpression of the SQSTM1 protein effectively reduced STING protein levels, whereas SQSTM1 knockdown increased STING protein levels. Coimmunoprecipitation experiments and confocal laser scanning microscopy revealed that the SQSTM1 protein interacts with and colocalizes with STING. Knockdown of SQSTM1 expression in DDIT3-overexpressing cell lines restored STING protein levels. Moreover, a dual-luciferase reporter assay revealed that DDIT3 directly binds to the bovine SQSTM1 promoter and induces SQSTM1 transcription. Overexpression of SQSTM1 promoted BoHV-1 replication by inhibiting IFN-β and IFN-stimulated genes (ISGs) production; silencing of SQSTM1 promoted the expression of IFN-β and ISGs to inhibit BoHV-1 replication. In conclusion, DDIT3 targets STING via SQSTM1-mediated autophagy to promote BoHV-1 replication. These results suggest a novel mechanism by which DDIT3 regulates DNA virus replication by targeting innate immunity. DDIT3 antagonizes the innate immune response to promote bovine alphaherpesvirus 1 replication via the DDIT3-SQSTM1-STING pathway.

Progesterone Sporadically Induces Reactivation from Latency in Female Calves but Proficiently Stimulates Bovine Herpesvirus 1 Productive Infection

Acute infection of the ocular, oral, or nasal cavity by bovine herpesvirus 1 (BoHV-1) culminates in lifelong latency in sensory neurons within trigeminal ganglia. The BoHV-1 latency reactivation cycle, including calves latently infected with commercially available modified live vaccines, can lead to reproductive complications, including abortions. Recent studies demonstrated progesterone stimulated BoHV-1 productive infection and sporadically induced reactivation from latency in male rabbits. The progesterone receptor (PR) and progesterone transactivate the immediate early transcription unit 1 (IEtu1) promoter and the infected cell protein 0 (bICP0) early promoter. These viral promoters drive expression of two viral transcriptional regulatory proteins (bICP0 and bICP4) that are crucial for productive infection. Based on these observations, we hypothesize that progesterone induces reactivation in a subset of calves latently infected with BoHV-1. These studies demonstrated progesterone was less efficient than dexamethasone at initiating reactivation from latency in female calves. Notably, heat stress correlated with enhancing the ability of progesterone to induce reactivation from latency. Previous studies demonstrated that heat stress activates the glucocorticoid receptor (GR), which suggested GR activation augments progesterone-mediated reactivation from latency. Additional studies revealed GR and PR cooperatively stimulated productive infection and synergistically transactivated the IEtu1 promoter when cultures were treated with dexamethasone. Mutating one or both GR binding sites in the IEtu1 promoter blocked transactivation. Collectively, these studies indicated that progesterone intermittently triggered reactivation from latency, and heat stress augmented reactivation from reactivation. Finally, these studies suggest progesterone enhances virus spread in tissues and cells where PR is abundantly expressed. IMPORTANCE Steroid hormone fluctuations are predicted to enhance or initiate bovine herpesvirus 1 (BoHV-1) replication and virus spread in cattle. For example, stress increases the incidence of BoHV-1 reactivation from latency in cattle, and the synthetic corticosteroid dexamethasone consistently induces reactivation from latency. The glucocorticoid receptor (GR) and dexamethasone stimulate key viral regulatory promoters and productive infection, in part because the viral genome contains numerous consensus GR-responsive elements (GREs). The progesterone receptor (PR) and GR belong to the type I nuclear hormone receptor family. PR and progesterone specifically bind to and transactivate viral promoters that contain GREs and stimulate BoHV-1 productive infection. Although progesterone did not induce reactivation from latency in female calves as efficiently as dexamethasone, heat stress enhanced progesterone-mediated reactivation from latency. Consequently, we predict that low levels of stressful stimuli can cooperate with progesterone to induce reactivation from latency or promote virus spread.

Avian Orthoavulavirus Type-1 as Vaccine Vector against Respiratory Viral Pathogens in Animal and Human

Avian orthoavulaviruses type-1 (AOaV-1) have recently transitioned from animal vaccine vector to a bona fide vaccine delivery vehicle in human. Owing to induction of robust innate and adaptive immune responses in mucus membranes in both birds and mammals, AOaVs offer an attractive vaccine against respiratory pathogens. The unique features of AOaVs include over 50 years of safety profile, stable expression of foreign genes, high infectivity rates in avian and mammalian hosts, broad host spectrum, limited possibility of recombination and lack of pre-existing immunity in humans. Additionally, AOaVs vectors allow the production of economical and high quantities of vaccine antigen in chicken embryonated eggs and several GMP-grade mammalian cell lines. In this review, we describe the biology of AOaVs and define protocols to manipulate AOaVs genomes in effectively designing vaccine vectors. We highlighted the potential and established portfolio of AOaV-based vaccines for multiple respiratory and non-respiratory viruses of veterinary and medical importance. We comment on the limitations of AOaV-based vaccines and propose mitigations strategies. The exploitation of AOaVs vectors is expanding at an exciting pace; thus, we have limited the scope to their use as vaccines against viral pathogens in both animals and humans.

Antiviral Property of the Fungal Metabolite 3-O-Methylfunicone in Bovine Herpesvirus 1 Infection

Bovine herpesvirus type-1 (BoHV-1) is a widespread pathogen that provokes infectious rhinotracheitis and polymicrobial infections in cattle, resulting in serious economic losses to the farm animal industry and trade restrictions. To date, non-toxic active drugs against BoHV-1 are not available. The exploitation of bioactive properties of microbial products is of great pharmaceutical interest. In fact, fungi are a promising source of novel drugs with a broad spectrum of activities and functions, including antiviral properties. Hence, the potential antiviral properties of 3-O-methylfunicone (OMF), a secondary metabolite produced by Talaromyces pinophilus, were evaluated on BoHV-1. In this study, during BoHV-1 infection in bovine cells (MDBK), the non-toxic concentration of 5 µM OMF considerably reduced signs of cell death and increased cell proliferation. Furthermore, OMF significantly decreased the virus titer as well as the cytopathic effect and strongly inhibited the expression of bICP0, the major regulatory protein in the BoHV-1 lytic cycle. These findings were accompanied by a considerable up-regulation in the expression of the aryl hydrocarbon receptor (AhR), a multifunctional transcription factor also linked to the host’s response to a herpesvirus infection. Overall, our results suggest that by involving AhR, OMF shows potential against a BoHV-1 infection.

Seroprevalence to common infectious abortifacient and infertility causing agents in the dairy herds of India

BACKGROUND

Information on the prevalence of infectious agents in dairy farms forms the basis for formulating a suitable control strategy; especially in endemic situations.

AIMS

A cross-sectional study was undertaken to determine the prevalence of six economically important bovine diseases, causing reproductive disorders including bovine abortion in organized dairy herds in India.

METHODS

A total of 1,075 animals (cattle and buffaloes) from 09 dairy farms were screened by ELISA tests.

RESULTS

Bovine viral diarrhoea (BVD) was the most prevalent (56.5%) disease followed by infectious bovine rhinotracheitis (IBR) (45.4%). Prevalence of Q-fever (5.4%) and neosporosis (6.1%) were less on the farms. Although 16.3% of the samples turned positive for brucellosis, the contribution of calf-hood vaccination (B. abortus S19 vaccine) to the prevalence of antibodies cannot be ruled out. The overall prevalence of bovine anaplasmosis, known to cause sporadic abortions in dairy herds, was 34.1% in the 9 farms with a prevalence of less than 20% in 5 farms. Infection of multiple abortifacient (seroprevalence to more than two pathogens) was recorded in 56.8% of animals. A very strong association was observed between BVD and brucellosis (Odds ratio 14.2; P<0.001). Further, a positive association was also seen between seroprevalence of IBR and anaplasmosis, and neosporosis and Q fever (P<0.05).

CONCLUSION

Viral diseases were found to be more common in the dairy herds than bacterial and protozoan diseases. Increased susceptibility of IBR seropositive cows to other bacterial and viral infections was observed.

Characterization of BoHV-1 gG-/tk-/gE- Mutant in Differential Protein Expression, Virulence, and Immunity

Infectious bovine rhinotracheitis (IBR), caused by bovine alphaherpesvirus 1 (BoHV-1), is an important disease affecting cattle worldwide resulting in great economic losses. Marker vaccines are effective in controlling infectious diseases including IBR, because they allow the discrimination between the natural infection and the vaccination. Therefore, a triple gene deleted strain BoHV-1 gG-/tk-/gE- was developed and evaluated in vivo and in vitro as a marker vaccine. In cell culture, this triple mutant virus showed significantly slower growth kinetics and smaller plaques when compared to wild-type (wt) BoHV-1 and double mutant BoHV-1 gG-/tk- (p < 0.01). On proteomic level, it revealed downregulation of some virulence related proteins including thymidine kinase, glycoproteins G, E, I, and K when compared to the wt. In vitro, the triple mutant virus showed a significantly lower and shorter viral shedding period (p < 0.001) in calves compared to double mutant. Moreover, the immunized calves with triple mutant virus showed protection rates of 64.2% and 68.6% against wt BoHV-1 and wt BoHV-5 challenge, respectively, without reactivation of latency after dexamethasone injection. In conclusion, BoHV-1 gG-/tk-/gE- is a safer marker vaccine against IBR although its immunogenicity in calves was decreased when compared to double mutant virus.

Integrated Network Analysis to Identify Key Modules and Potential Hub Genes Involved in Bovine Respiratory Disease: A Systems Biology Approach

Background: Bovine respiratory disease (BRD) is the most common disease in the beef and dairy cattle industry. BRD is a multifactorial disease resulting from the interaction between environmental stressors and infectious agents. However, the molecular mechanisms underlying BRD are not fully understood yet. Therefore, this study aimed to use a systems biology approach to systematically evaluate this disorder to better understand the molecular mechanisms responsible for BRD. Methods: Previously published RNA-seq data from whole blood of 18 healthy and 25 BRD samples were downloaded from the Gene Expression Omnibus (GEO) and then analyzed. Next, two distinct methods of weighted gene coexpression network analysis (WGCNA), i.e., module-trait relationships (MTRs) and module preservation (MP) analysis were used to identify significant highly correlated modules with clinical traits of BRD and non-preserved modules between healthy and BRD samples, respectively. After identifying respective modules by the two mentioned methods of WGCNA, functional enrichment analysis was performed to extract the modules that are biologically related to BRD. Gene coexpression networks based on the hub genes from the candidate modules were then integrated with protein-protein interaction (PPI) networks to identify hub-hub genes and potential transcription factors (TFs). Results: Four significant highly correlated modules with clinical traits of BRD as well as 29 non-preserved modules were identified by MTRs and MP methods, respectively. Among them, two significant highly correlated modules (identified by MTRs) and six nonpreserved modules (identified by MP) were biologically associated with immune response, pulmonary inflammation, and pathogenesis of BRD. After aggregation of gene coexpression networks based on the hub genes with PPI networks, a total of 307 hub-hub genes were identified in the eight candidate modules. Interestingly, most of these hub-hub genes were reported to play an important role in the immune response and BRD pathogenesis. Among the eight candidate modules, the turquoise (identified by MTRs) and purple (identified by MP) modules were highly biologically enriched in BRD. Moreover, STAT1, STAT2, STAT3, IRF7, and IRF9 TFs were suggested to play an important role in the immune system during BRD by regulating the coexpressed genes of these modules. Additionally, a gene set containing several hub-hub genes was identified in the eight candidate modules, such as TLR2, TLR4, IL10, SOCS3, GZMB, ANXA1, ANXA5, PTEN, SGK1, IFI6, ISG15, MX1, MX2, OAS2, IFIH1, DDX58, DHX58, RSAD2, IFI44, IFI44L, EIF2AK2, ISG20, IFIT5, IFITM3, OAS1Y, HERC5, and PRF1, which are potentially critical during infection with agents of bovine respiratory disease complex (BRDC). Conclusion: This study not only helps us to better understand the molecular mechanisms responsible for BRD but also suggested eight candidate modules along with several promising hub-hub genes as diagnosis biomarkers and therapeutic targets for BRD.

EVALUATION OF IMMUNE FUNCTION IN TWO POPULATIONS OF GREEN SEA TURTLES (CHELONIA MYDAS) IN A DEGRADED VERSUS A NONDEGRADED HABITAT

There is a strong correlation between degraded marine habitats and the prevalence of diseases such as green turtle fibropapillomatosis (GTFP) in coastal populations. In GTFP, small to large tumors grow on the turtle's soft tissues and shell, while internal nodules may also occur. The disease primarily affects juvenile green sea turtles (Chelonia mydas) that reside in nearshore waters. As a link has been shown between environmental pollution and immune suppression in a variety of animals, the objective of our research was to compare innate and adaptive immune responsiveness in green sea turtles from a severely degraded and a more pristine habitat, which differ greatly in rates of GTFP. We quantified phagocytosis by flow cytometry and performed in vitro stimulation analysis to measure activity of both the innate and adaptive immune systems in wild-caught Florida green turtles. Sea turtles from the degraded environment, both with and without visible cutaneous tumors, exhibited significantly reduced phagocytosis and stimulation indices than did those from the less polluted environment. Our results suggest that environmental factors may contribute to the development of GTFP and thus can impact the health of sea turtle populations.

A Pioneer Transcription Factor and Type I Nuclear Hormone Receptors Synergistically Activate the Bovine Herpesvirus 1 Infected Cell Protein 0 (ICP0) Early Promoter

Following bovine herpesvirus 1 (BoHV-1) acute infection of ocular, oral, or nasal cavities, sensory neurons within trigeminal ganglia are an important site for latency. Stress, as mimicked by the synthetic corticosteroid dexamethasone, consistently induces reactivation from latency. Expression of two key viral transcriptional regulatory proteins, BoHV-1 infected cell protein 0 (bICP0) and bICP4, are regulated by sequences within the immediate early promoter (IEtu1). A separate early promoter also drives bICP0 expression, presumably to ensure sufficient levels of this important transcriptional regulatory protein. Productive infection and bICP0 early promoter activity are cooperatively transactivated by Krüppel-like factor 4 (KLF4) and a type I nuclear hormone receptor (NHR), androgen receptor, glucocorticoid receptor, or progesterone receptor. The bICP0 early promoter contains three separate transcriptional enhancers that mediate cooperative transactivation. In contrast to the IEtu1 promoter, the bICP0 early promoter lacks consensus type I NHR binding sites. Consequently, we hypothesized that KLF4 and Sp1 binding sites are essential for type I NHR and KLF4 to transactivate the bICP0 promoter. Mutating KLF4 and Sp1 binding sites in each enhancer domain significantly reduced transactivation by KLF4 and a type I NHR. Chromatin immunoprecipitation (ChIP) studies demonstrated that occupancy of bICP0 early promoter sequences by KLF4 and type I NHR is significantly reduced when KLF4 and/or Sp1 binding sites are mutated. These studies suggest that cooperative transactivation of the bICP0 E promoter by type I NHRs and a stress-induced pioneer transcription factor (KLF4) promote viral replication and spread in neurons or nonneural cells in reproductive tissue. IMPORTANCE Understanding how stressful stimuli and changes in the cellular milieu mediate viral replication and gene expression in the natural host is important for developing therapeutic strategies that impair virus transmission and disease. For example, bovine herpesvirus 1 (BoHV-1) reactivation from latency is consistently induced by the synthetic corticosteroid dexamethasone, which mimics the effects of stress. Furthermore, BoHV-1 infection increases the incidence of abortion in pregnant cows, suggesting that sex hormones stimulate viral growth in certain tissues. Previous studies revealed that type I nuclear hormone receptors (NHRs) (androgen, glucocorticoid, or progesterone) and a pioneer transcription factor, Krüppel-like factor 4 (KLF4), cooperatively transactivate the BoHV-1 infected cell protein 0 (bICP0) early promoter. Transactivation was mediated by Sp1 and/or KLF4 consensus binding sites within the three transcriptional enhancers. These studies underscore the complexity by which BoHV-1 exploits type I NHR fluctuations to enhance viral gene expression, replication, and transmission in the natural host.

VP8, the Major Tegument Protein of Bovine Herpesvirus-1, Is Partially Packaged during Early Tegument Formation in a VP22-Dependent Manner

Bovine herpesvirus-1 (BoHV-1) is a major cause of rhinotracheitis and vulvovaginitis in cattle. VP8, the major tegument protein of BoHV-1, is essential for viral replication in the host. VP8 is phosphorylated by the viral kinase US3, mediating its translocation to the cytoplasm. VP8 remains nuclear when not phosphorylated. Interestingly, VP8 has a significant presence in mature BoHV-1YmVP8, in which the VP8 phosphorylation sites are mutated. This suggests that VP8 might be packaged during primary envelopment of BoHV-1. This was investigated by mass spectrometry and Western blotting, which showed VP8, as well as VP22, to be constituents of the primary enveloped virions. VP8 and VP22 were shown to interact via co-immunoprecipitation experiments, in both BoHV-1-infected and VP8-transfected cells. VP8 and VP22 also co-localised with one another and with nuclear lamin-associated protein 2 in BoHV-1-infected cells, suggesting an interaction between VP8 and VP22 in the perinuclear region. In cells infected with VP22-deleted BoHV-1 (BoHV-1ΔUL49), VP8 was absent from the primary enveloped virions, implying that VP22 might be critical for the early packaging of VP8. In conclusion, a novel VP22-dependent mechanism for packaging of VP8 was identified, which may be responsible for a significant amount of VP8 in the viral particle.

Review of Infections With Bovine Herpesvirus 1 in Slovenia

In the 1950s, infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IBR/IPV) disease was clinically detected and documented in cattle for the first time in Slovenia. The bovine herpes virus 1 (BoHV-1) was confirmed several times from infected herds by virus isolation on cell cultures. To keep the IC virus-free, high biosecurity measures were introduced. Before entering the IC, all calves are serologically tested and quarantined. Bulls in Slovenian insemination centres (IC) have been negative for IBR /IPV infection since 1979. From 1985 to 1991, few large-scale studies of the prevalence of IBR/IPV were carried out. In 1985, a high percentage (56.9%) of serologically positive animals were found in large state farms with Holstein Friesian cattle. Epidemiological studies in farm with bulls' mother herds were also carried out in the farms with Simmental and Brown cows. Antibodies against BoHV-1 were detected in the serum of 2.3% of Brown cattle and 3.5% of Simmental cattle. In the year 2000, 3.4% of bulk tank milk samples from 13,349 dairy farms were detected BoHV-1 antibodies positive. The highest percentage of positive animals was found in regions with an intensive grazing system (6.2% positive) and the lowest percentage in the east part of Slovenia (0.9% positive) on farms with mostly Simmental cattle. In 2006, a total 204,662 sera of cattle older than 24 months were tested for the presence of BoHV-1 antibodies and positive cattle were detected in 3.6% of tested farms. These farms kept 34,537 animals that were potential carriers of the BoHV-1. Most of the positive farms kept Holstein Friesian cattle, descendants from the state-owned farms, which were privatised or closed after 1990. In 2015, the Administration of the Republic of Slovenia for Food Safety, Veterinary and Plant Protection issued a rule that describes the conditions for granting and maintaining the status of BoHV-1 free holdings. The rule provides a voluntary control programme for breeders who want to obtain BoHV-1 free status and are willing to cover all the cost of acquiring and maintaining that status. There has been very little response from breeders.

MG-132 interferes with iron cellular homeostasis and alters virulence of bovine herpesvirus 1

Bovine herpesvirus 1 (BoHV-1) requires an iron-replete cell host to replicate efficiently. BoHV-1 infection provokes an increase in ferritin levels and a decrease of transferrin receptor 1 (TfR-1) expression, ultimately lowering iron pool extent. Thus, cells try to limit iron availability for virus spread. It has been demonstrated that MG-132, a proteasome inhibitor, reduces BoHV-1 release. Since ferritin, the major iron storage protein in mammalian cells, undergoes proteasome-mediated degradation, herein, the influence of MG-132 on iron metabolism during BoHV-1 infection was examined. Following infection in bovine cells (MDBK), MG-132 reduced cell death and viral yield. Western blot analysis showed a significant ferritin accumulation, likely due to the inhibition of its proteasome-mediated degradation pathway. In addition, the concomitant down-regulation of TfR-1 expression, observed during infection, was counteracted by proteasome inhibitor. This trend may be explained by enhanced acidic vesicular organelles, detected by acridine orange staining, determining a reduction of intracellular pH, that promotes new synthesis of TfR-1 degraded in a recycling pathway. In addition, MG-132 influences cellular iron distribution during BoHV-1 infection, as revealed by Perls' Prussian blue staining. However, cellular iron content, evaluated by Atomic Absorption Spectrophotometry, resulted essentially unaltered. These findings reveal that MG-132 may contribute to limit cellular iron availability for virus replication thereby enhancing cell survival.

Diet and gut microbiome enterotype are associated at the population level in African buffalo

Studies in humans and laboratory animals link stable gut microbiome “enterotypes” with long-term diet and host health. Understanding how this paradigm manifests in wild herbivores could provide a mechanistic explanation of the relationships between microbiome dynamics, changes in dietary resources, and outcomes for host health. We identify two putative enterotypes in the African buffalo gut microbiome. The enterotype prevalent under resource-abundant dietary regimes, regardless of environmental conditions, has high richness, low between- and within-host beta diversity, and enrichment of genus Ruminococcaceae-UCG-005. The second enterotype, prevalent under restricted dietary conditions, has reduced richness, elevated beta diversity, and enrichment of genus Solibacillus. Population-level gamma diversity is maintained during resource restriction by increased beta diversity between individuals, suggesting a mechanism for population-level microbiome resilience. We identify three pathogens associated with microbiome variation depending on host diet, indicating that nutritional background may impact microbiome-pathogen dynamics. Overall, this study reveals diet-driven enterotype plasticity, illustrates ecological processes that maintain microbiome diversity, and identifies potential associations between diet, enterotype, and disease.

There are stable relationships between diet and microbiome in humans and lab animals. A study on African buffalo finds that diet influences microbiome variation and enterotype formation. Three pathogens may associate with microbiome depending on host diet, suggesting nutrition impacts relationships between gut microbiome and host health.

The Bacterial and Viral Agents of BRDC: Immune Evasion and Vaccine Developments

Bovine respiratory disease complex (BRDC) is a multifactorial disease of cattle which presents as bacterial and viral pneumonia. The causative agents of BRDC work in synergy to suppress the host immune response and increase the colonisation of the lower respiratory tracts by pathogenic bacteria. Environmental stress and/or viral infection predispose cattle to secondary bacterial infections via suppression of key innate and adaptive immune mechanisms. This allows bacteria to descend the respiratory tract unchallenged. BRDC is the costliest disease among feedlot cattle, and whilst vaccines exist for individual pathogens, there is still a lack of evidence for the efficacy of these vaccines and uncertainty surrounding the optimum timing of delivery. This review outlines the immunosuppressive actions of the individual pathogens involved in BRDC and highlights the key issues in the development of vaccinations against them.

Antisense Transcripts and Antisense Protein: A New Perspective on Human Immunodeficiency Virus Type 1

It was first predicted in 1988 that there may be an Open Reading Frame (ORF) on the negative strand of the Human Immunodeficiency Virus type 1 (HIV-1) genome that could encode a protein named AntiSense Protein (ASP). In spite of some controversy, reports began to emerge some years later describing the detection of HIV-1 antisense transcripts, the presence of ASP in transfected and infected cells, and the existence of an immune response targeting ASP. Recently, it was established that the asp gene is exclusively conserved within the pandemic group M of HIV-1. In this review, we summarize the latest findings on HIV-1 antisense transcripts and ASP, and we discuss their potential functions in HIV-1 infection together with the role played by antisense transcripts and ASPs in some other viruses. Finally, we suggest pathways raised by the study of antisense transcripts and ASPs that may warrant exploration in the future.

A plasmid encoding the extracellular domain of CD40 ligand and Montanide™ GEL01 as adjuvants enhance the immunogenicity and the protection induced by a DNA vaccine against BoHV-1

DNA vaccines are capable of inducing humoral and cellular immunity, and are important to control bovine herpesvirus 1 (BoHV-1), an agent of the bovine respiratory disease complex. In previous work, a DNA plasmid that encodes a secreted form of BoHV-1 glycoprotein D (pCIgD) together with commercial adjuvants provided partial protection against viral challenge of bovines. In this work, we evaluate new molecules that could potentiate the DNA vaccine. We show that a plasmid encoding a soluble CD40 ligand (CD40L) and the adjuvant Montanide™ GEL01 (GEL01) activate in vitro bovine afferent lymph dendritic cells (ALDCs). CD40L is a co-stimulating molecule, expressed transiently on activated CD4+ T cells and, to a lesser extent, on activated B cells and platelets. The interaction with its receptor, CD40, exerts effects on the presenting cells, triggering responses in the immune system. GEL01 was designed to improve transfection of DNA vaccines. We vaccinated cattle with: pCIgD; pCIgD-GEL01; pCIgD with GEL01 and CD40L plasmid (named pCIgD-CD40L-GEL01) or with pCIneo vaccines. The results show that CD40L plasmid with GEL01 improved the pCIgD DNA vaccine, increasing anti-BoHV-1 total IgGs, IgG1, IgG2 subclasses, and neutralizing antibodies in serum. After viral challenge, bovines vaccinated with pCIgD-GEL01-CD40L showed a significant decrease in viral excretion and clinical score. On the other hand, 80% of animals in group pCIgD-GEL01-CD40L presented specific anti-BoHV-1 IgG1 antibodies in nasal swabs. In addition, PBMCs from pCIgD-CD40L-GEL01 had the highest percentage of animals with a positive lymphoproliferative response against the virus and significant differences in the secretion of IFNγ and IL-4 by mononuclear cells, indicating the stimulation of the cellular immune response. Overall, the results demonstrate that a plasmid expressing CD40L associated with the adjuvant GEL01 improves the efficacy of a DNA vaccine against BoHV-1.

Herpesviruses and the Type III Interferon System

Type III interferons (IFNs) represent the most recently discovered group of IFNs. Together with type I IFNs (e.g. IFN-α/β), type III IFNs (IFN-λ) are produced as part of the innate immune response to virus infection, and elicit an anti-viral state by inducing expression of interferon stimulated genes (ISGs). It was initially thought that type I IFNs and type III IFNs perform largely redundant functions. However, it has become evident that type III IFNs particularly play a major role in antiviral protection of mucosal epithelial barriers, thereby serving an important role in the first-line defense against virus infection and invasion at contact areas with the outside world, versus the generally more broad, potent and systemic antiviral effects of type I IFNs. Herpesviruseses are large DNA viruses, which enter their host via mucosal surfaces and establish lifelong, latent infections. Despite the importance of mucosal epithelial cells in the pathogenesis of herpesviruses, our current knowledge on the interaction of herpesviruses with type III IFN is limited and largely restricted to studies on the alphaherpesvirus herpes simplex virus (HSV). This review summarizes the current understanding about the role of IFN-λ in the immune response against herpesvirus infections.

Dewormer drug fenbendazole has antiviral effects on BoHV-1 productive infection in cell cultures

BACKGROUND

Fenbendazole, a dewormer drug, is used widely in the clinical treatment of parasite infections in animals. Recent studies have shown that fenbendazole has substantial effects on tumor growth, immune responses, and inflammatory responses, suggesting that fenbendazole is a pluripotent drug. Nevertheless, the antiviral effects have not been reported. Fenbendazole can disrupt microtubules, which are essential for multiple viruses infections, suggesting that fenbendazole might have antiviral effects.

OBJECTIVES

This study examined whether fenbendazole could inhibit bovine herpesvirus 1 (BoHV-1) productive infection in cell cultures.

METHODS

The effects of fenbendazole on viral production, transcription of the immediate early (IE) genes, viron-associated protein expression, and the cellular signaling PLC-γ1/Akt pathway were assessed using distinct methods.

RESULTS

Fenbendazole could inhibit BoHV-1 productive infections significantly in MDBK cells in a dose-dependent manner. A time-of-addition assay indicated that fenbendazole affected both the early and late stages in the virus replication cycles. The transcription of IE genes, including BoHV-1 infected cell protein 0 (bICP0), bCP4, and bICP22, as well as the synthesis of viron-associated proteins, were disrupted differentially by the fenbendazole treatment. The treatment did not affect the cellular signaling pathway of PLC-γ1/Akt, a known cascade playing important roles in virus infection.

CONCLUSIONS

Overall, fenbendazole has antiviral effects on BoHV-1 replication.

Diphtheric aspergillosis tracheitis with gastrointestinal dissemination secondary to viral infections in a dairy calf

Diphtheric aspergillosis tracheitis is an uncommon syndrome described in human pathology, usually associated with immunosuppression in the affected individuals. Interestingly, no comparative/equivalent cases were found in domestic animals. This report describes the pathological and mycological findings associated with diphtheric aspergillosis tracheitis in an immunocompromised calf. The main pathological findings were diphtheric tracheitis and rhinitis, and necrotizing ruminitis associated with intralesional septate, acute branching fungal hyphae consistent with Aspergillus spp. Mycological culture and isolation confirmed the fungal hyphae as A. fumigatus due to characteristic features. Immunohistochemistry (IHC) assays identified intralesional antigens of bovine viral diarrhea virus (BVDV) and malignant catarrhal fever virus (MCFV) at the trachea and small intestine; IHC detected intralesional antigens of bovine alphaherpesvirus 1 (BoHV-1) only at the trachea. These findings confirmed the simultaneous occurrence of A. fumigatus with concomitant infections due to BVDV, MCFV, and BoHV-1 in this calf. Since ovine gammaherpesvirus-2 (OvHV-2) is the cause of MCF in Brail, it is likely that the intralesional MCFV antigens identified were those of OvHV-2. In this case, disseminated aspergillosis was probably associated with the undeveloped immunological status of the calf that was further impaired due to the combined immunodepressive effects of BVDV and BoHV-1 infections. Although BVDV and BoHV-1 are infectious disease pathogens frequently associated with the development of bovine respiratory disease (BRD) in feedlot and dairy cattle, the identification of intralesional OvHV-2-like antigens in several parts of the lungs suggest that this MCFV also played a role in the BRD-associated lesions identified in this calf.

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An unusual presentation of fungal diphtheric tracheitis associated with Aspergillus fumigatus is described in a dairy calf.

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A Malignant Catarrhal Fever Virus, most likely, OvHV-2, was associated with the development of pneumonia in this calf.

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Simultaneous infections in dairy calves may be more frequent than previously reported.

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OvHV-2 should be considered as a possible disease pathogen associated with the development of bovine respiratory disease.

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The immunodepressive effects of BVDV and BoHV-1 were fundamental for the development of the fungal disease observed in this calf.

The Role of Epidermal Growth Factor Receptor Signaling Pathway during Bovine Herpesvirus 1 Productive Infection in Cell Culture

Accumulating studies have shown that the epidermal growth factor receptor (EGFR) signaling pathway plays an essential role in mediating cellular entry of numerous viruses. In this study, we report that bovine herpesvirus 1 (BoHV-1) productive infection in both the human lung carcinoma cell line A549 and bovine kidney (MDBK) cells leads to activation of EGFR, as demonstrated by the increased phosphorylation of EGFR at Tyr1068 (Y1068), which in turn plays important roles in virus infection. A time-of-addition assay supported that virus replication at post-entry stages was affected by the EGFR specific inhibitor Gefitinib. Interestingly, both phospholipase C-γ1 (PLC-γ1) and Akt, canonical downstream effectors of EGFR, were activated following virus infection in A549 cells, while Gefitinib could inhibit the activation of PLC-γ1 but not Akt. In addition, virus titers in A549 cells was inhibited by chemical inhibition of PLC-γ1, but not by the inhibition of Akt. However, the Akt specific inhibitor Ly294002 could significantly reduce the virus titer in MDBK cells. Taken together, our data suggest that PLC-γ1 is stimulated in part through EGFR for efficient replication in A549 cells, whereas Akt can be stimulated by virus infection independent of EGFR, and is not essential for virus productive infection, indicating that Akt modulates BoHV-1 replication in a cell type-dependent manner. This study provides novel insights on how BoHV-1 infection activates EGFR signaling transduction to facilitate virus replication.

Shedding of bovine alphaherpesvirus-1 in bovine extended frozen semen in Indian semen stations: A longitudinal analysis

Infectious bovine rhinotracheitis (IBR) caused by bovine alphaherpesvirus 1 (BoHV-1) is an economically important disease of cattle and buffaloes. Following acute infection, the virus usually attains latency in the sensory neurons. Stress-induced reactivation of latency can cause the infected animals to intermittently shed the virus in body secretions including semen. A longitudinal analysis was carried out to study BoHV-1 shedding in the semen of IBR seropositive cattle and buffaloes. The study involved data generated from the screening of 119,850 extended frozen semen (EFS) batches, collected from 1,229 IBR seropositive bulls, over a period of four years (April 2015 to March 2019). A TaqMan based real-time PCR assay was employed to detect the gB gene BoHV-1 DNA in the EFS batch samples. Each sample was tested in duplicate and amplification in any of the replicates at or below the threshold cycle (Ct ≤ 40) was considered positive. The overall positivity of BoHV-1 in EFS batches was 1.18%. About 41% of the bulls (509 of 1,229) were found to have excreted the virus in semen at least once during the study period. The frequency of viral shedding in buffaloes (0.96%) was significantly lower than that of cattle (1.3%) (p < 0.001). No significant difference was noted in the rate of shedding between the first and the second ejaculates collected on the same day (p = 0.607). The rate of shedding also did not vary among various breeds of cattle (p = 0.454) or with the age of the bulls (p = 0.054). No significant variation in the shedding rate was observed in cattle across different seasons (p = 0.101); while in buffaloes, the rate was higher in autumn (1.2%) than in winter (0.7%) (p = 0.037). The difference in positivity among semen stations was statistically significant (p < 0.001). Analysis of data revealed that ≥100 EFS batch samples/bull were screened from 361 of the 1,229 bulls included in the study. None of the EFS batches screened from 39 of these 361 bulls were found positive during the four years, suggesting they were non-shedders. Further research is warranted to delineate the underlying features of the seropositive non-shedders; following which an adequate risk assessment may be made for the maintenance of infected but non-shedding bulls in semen production.