Unveiling the Role of Bovine Herpesvirus Type 4 (BHV-4) in Dairy Cow Reproductive Disorders: Insights From a Multifaceted Study in China

Bovine herpesvirus type-4 (BHV-4) belongs to the gamma-herpesvirus subfamily, and its association with reproductive disorders in dairy cows is controversial. In this study, 386 whole blood and reproductive swab samples from dairy cows across eight provinces in China were collected. BHV-4 antibody levels in the serum were determined via ELISA, while real-time fluorescent quantitative PCR (qPCR) was employed to detect the DNA of BHV-4, BHV-1, bovine viral diarrhea virus type-I (BVDV-1), and bovine viral diarrhea virus type-II (BVDV-2) in the samples. Additionally, the DNA content of BHV-4 in various tissues of cows and stillborn fetuses was assessed via qPCR. Breeding information for the participating cows was gathered through farmer interviews, and correlation analyses were conducted between the detection results and breeding information. The findings revealed a BHV-4 antibody positive rate of 57.8% and a nucleic acid positive rate of 36.3%. Chi-square analysis revealed a correlation between BHV-4 and BHV-1 infections. Among several pathogens associated with reproductive disorders, only BHV-4 was significantly correlated, whereas BHV-1, BVDV-1, and BVDV-2 were not correlated. Furthermore, the study revealed elevated BHV-4 DNA in the reproductive tracts of cows and stillborn fetuses. Histopathological sections revealed mucosal damage in the vaginal and uterine tissues of stillborn fetuses, a phenomenon not previously reported. In summary, our study provides novel insight into the correlation between BHV-4 and reproductive disorders and presents new evidence that supports the vertical transmission of BHV-4.

Epidemiological survey of bovine gammaherpesvirus 4 (BoHV-4) infection in cattle and buffalo from Pakistan

This study was conducted to evaluate the prevalence of bovine gammaherpesvirus 4 (BoHV-4) among healthy cattle and buffaloes as well as those associated with different diseases (respiratory tract infection, mastitis and reproductive tract infection) in District Chakwal, Pakistan. Blood, swab and milk samples of cattle and buffaloes were randomly collected from different areas of Chakwal. DNA was isolated from the samples and subjected to nested PCR using thymidine kinase gene primers. Out of 300 samples (200 blood, 50 swab and 50 milk samples) from both species (cattle and buffalo), an overall prevalence of BoHV-4 of 3.33% was obtained. Samples from cattle showed a higher species-specific prevalence (4.16%) than samples from buffalo (2.78%). One sample out of 50 swab samples and 1 out of 50 milk samples were also positive for BoHV-4. DNA sequencing of a positive PCR product from cattle confirmed that the sequence was from the thymidine kinase gene of BoHV-4. Phylogenetic analysis also revealed close similarities with other BOHV-4 thymidine kinase sequences. To detect BoHV-4 antibodies, an indirect ELISA was also performed. Two hundred blood samples were also collected from the same animals in nonanticoagulant-containing tubes for the isolation of serum and were subjected to indirect ELISA. Sixteen samples (8%) were positive for BoHV-4 antibodies. This study will be useful in further diagnoses of BoHV-4 in Pakistan and in devising measures to control the spread of BoHV-4.

Effect of bovine viral diarrhea virus on subsequent infectivity of bovine gammaherpesvirus 4 in endometrial cells in primary culture: An in vitro model of viral co-infection

Bovine viral diarrhea virus (BVDV) and bovine gammaherpesvirus 4 (BoHV-4) infect the uterus of cattle, being responsible for huge economic losses. Most of the pathogenesis of BoHV-4 in the bovine reproductive tract has been elucidated by conducting tests on primary cultures. Thus, it is important to have optimal in vitro conditions, avoiding the presence of other pathogens that can alter the results. BVDV is one of the most frequent viral contaminants of cell cultures. Considering that non-cytopathic (NCP) BVDV biotype can generate persistently infected (PI) cattle, which are the major source for virus transmission in susceptible herds, it is important to check products derived from cattle that are intended to be used in research laboratories. The aim of this work was to evaluate how the natural infection of bovine endometrial cells (BEC) with a NCP BVDV strain (BEC + BVDV) affects BoHV-4 replication. We have demonstrated a delay in BoHV-4 gene expression and a decrease in viral load in the extracellular environment in BEC + BDVD cells compared to BEC (BVDV-free) cells. These results confirm that replication of BoHV-4 in BEC primary cultures is affected by previous infection with BVDV. This finding highlights the importance of ruling out BVDV infection in bovine primary cell cultures to avoid biological interference or misinterpretation of results at the time of performing in vitro studies with BoHV-4.

Gene expression and in vitro replication of bovine gammaherpesvirus type 4

In vitro cell cultures are widely used models for dissecting cellular and molecular mechanisms that lead to certain physiological conditions and diseases. The pathogenesis of BoHV-4 in the bovine reproductive tract has been studied by conducting tests on primary cultures. However, many questions remain to be answered about the role of BoHV-4 in endometrial cells. The aim of this study was to compare the replication and gene expression of BoHV-4 in cell lines and bovine reproductive tract primary cells as an in vitro model for the study of this virus. We demonstrated that BoHV-4 strains differ in their in vitro growth kinetics and gene expression but have the same cell type preference. Our results demonstrate that BoHV-4 replicates preferentially in bovine endometrial cells (BEC). However, its replication capacity extends to various cell types, since all cells that were tested were permissive to BoHV-4 infection. The highest virus titers were obtained in BEC cells. Nevertheless, virus replication efficiency could not be fully predicted from the mRNA expression profiles. This implies that there are multiple cell-type-dependent factors and strain properties that determine the level of BoHV-4 replication. The results of this study provide relevant information about the in vitro behavior of two field isolates of BoHV-4 in different cell cultures. These findings may be useful for the design of future in vitro experiments to obtain reliable results not only about the pathogenic role of BoHV-4 in the bovine female reproductive tract but also in the development of efficient antiviral strategies.

Peripartum changes in the activity and expression of neutrophils may predispose to the postpartum occurrence of metritis in dairy cows

Metritis is a postpartum uterine pathology that causes a huge economic loss due to increased culling risk and impaired milk yield and reproduction in cows. The present study was carried out to study the changes in the activity and expression of blood neutrophils in crossbred dairy cows with and without metritis. Collection of blood samples was done at -3, -2 and - 1 weeks before calving, at calving and during the first day of metritis diagnosis in metritis group (n = 8) or at day 8-10 post calving in healthy group (n = 8). Neutrophils were studied for its percentage (microscopically), respiratory burst (nitro blue tetrazolium assay), myeloperoxidase (MPO) concentrations (sandwich ELISA) and expression of CXCR1, CXCR2, TLR2, TLR4, GRα, CD11b, CD14, CD25, CD44, CD47 and CD62L (RT-PCR). Immunocytochemistry was used to investigate MPO concentration and CD14 activity, and western blotting was used for estimating MPO. Although most of these parameters changed in the cows that developed metritis one week before calving, MPO and CD14 got altered much earlier. Myeloperoxidase concentrations and expression of CD14 were considerably lower starting from -2 weeks before calving in cows that developed metritis compared to healthy cows. Further studies are warranted to study the possible use of MPO and CD14 to identify transition cows more vulnerable to develop metritis several weeks before disease occurrence.

Bull seminal plasma stimulates in vitro production of TGF-β, IL-6 and IL-8 from bovine endometrial epithelial cells, depending on dose and bull fertility

Seminal plasma (SP) regulates immune responses in the female reproductive tract through specific cytokines. It is not known whether SP from high fertility bulls (H) differs from SP from low fertility bulls (L). In this study, the cytokine response of bovine endometrial epithelial cells (bEEC) in culture was investigated after challenge with SP from two bulls of below average (L) or three bulls of above average fertility (H). The bEECs were challenged with 1% or 4% SP from l- or H-fertility bulls (L1, L4, H1, H4, respectively) or 1% or 4% PBS as control (C1, C4) for 72 h. The culture media were analysed for concentrations (pg/million cells) of transforming growth factor beta (TGF-β1, TGF-β2 and TGF-β3) by Luminex, and Interleukin 6 and 8 (IL-6, IL-8) by ELISA. Challenge significantly affected production of TGF-ß1, TGF-ß2 and IL-8 compared to controls and was affected by bull fertility (p < 0.0001), SP concentration (p < 0.0001) and their interaction (p < 0.0001). A higher production of TGF-β1, TGF-β2 and IL-8 (p < 0.0001), and also IL-6 (p < 0.01), resulted from challenge with high doses of SP, being higher for L than H (p < 0.05). For TGF-β3, fertility of bull (p < 0.05). For TGF-B3, fertility of bull (p < 0.05) and the interaction between fertility and concentration of SP were significant (p < 0.01). In conclusion, 4% SP from L bulls stimulated more TGF-β1, TGF-β2, TGF-β3, IL-6 and IL-8 production than SP from H bulls, indicating that stimulation of the endometrium is relevant for fertility. Seminal plasma from high fertility bulls seems to affect cytokine production in utero positively in inseminated cows.

Importance of Viral Disease in Dairy Cow Fertility

Many viral diseases are endemic in cattle populations worldwide. The ability of many viruses to cross the placenta and cause abortions and fetal malformations is well understood. There is also significant evidence that viral infections have additional actions in dairy cows, which are reflected in reduced conception rates. These effects are, however, highly dependent on the time at which an individual animal first contracts the disease and are less easy to quantify. This paper reviews the evidence relating to five viruses that can affect fertility, together with their potential mechanisms of action. Acute infection with non-cytopathic bovine viral diarrhea virus (BVDV) in mid-gestation increases abortion rates or causes the birth of persistently infected calves. BVDV infections closer to the time of breeding can have direct effects on the ovaries and uterine endometrium, which cause estrous cycle irregularities and early embryo mortality. Fertility may also be reduced by BVDV-induced immunosuppression, which increases the susceptibility to bacterial infections. Bovine herpesvirus (BHV)-1 is most common in pre-pubertal heifers, and can slow their growth, delay breeding, and increase the age at first calving. Previously infected animals subsequently show reduced fertility. Although this may be associated with lung damage, ovarian lesions have also been reported. Both BHV-1 and BHV-4 remain latent in the host following initial infection and may be reactivated later by stress, for example associated with calving and early lactation. While BHV-4 infection alone may not reduce fertility, it appears to act as a co-factor with established bacterial pathogens such as Escherichia coli and Trueperella pyogenes to promote the development of endometritis and delay uterine repair mechanisms after calving. Both Schmallenberg virus (SBV) and bluetongue virus (BTV) are transmitted by insect vectors and lead to increased abortion rates and congenital malformations. BTV-8 also impairs the development of hatched blastocysts; furthermore, infection around the time of breeding with either virus appears to reduce conception rates. Although the reductions in conception rates are often difficult to quantify, they are nevertheless sufficient to cause economic losses, which help to justify the benefits of vaccination and eradication schemes.

Adaptive immunity in the postpartum uterus: Potential use of vaccines to control metritis

After parturition, dairy cows rely on an effective innate immune response, through the actions of neutrophils, macrophages, and antimicrobial peptides, to clear the uterus from pathogenic bacteria, such as E. coli, Bacteroides spp, F. necrophorum and T. pyogenes. However, the role of adaptive immunity in the postpartum uterus is less understood. In this review, we explore concepts of mucosal adaptive immunity and discuss recent findings regarding the efficacy of vaccines to reduce metritis in dairy cows. Areas of lymphocytic aggregates are seen throughout the bovine reproductive tract after parturition, but it is unknown if their development is influenced by previous exposure to pathogens or other intrinsic factors. Through the actions of Treg cells and γδ T cells, the uterus is an immune-tolerant environment during pregnancy. After parturition, the dynamics in the endometrial and circulating lymphocytic populations differ among cows that develop uterine diseases and healthy counterparts. However, the functionality of those cells has not yet been determined. It has been hypothesized that cows that fail to switch their uterine environment from an anti-inflammatory state prior to parturition to a pro-inflammatory state after calving are more susceptible to uterine infections. Given the nature of metritis related pathogens and the importance of innate immunity to uterine defense mechanisms, we speculate that an adaptive immunity biased towards a Th1/Th17 cellular response will provide best protection against uterine infections. Few studies have evaluated the efficacy of immunization in reducing the incidence of metritis in dairy cows revealing inconsistent findings.

Monitoring of the shedding and serological dynamics of Bovine gammaherpesvirus type 4 in a dairy cattle herd

Bovine gammaherpesvirus type 4 (BoHV-4) is increasingly related with reproductive disease in cattle, but its epidemiology is not fully understood. We monitored the serological response and shedding of BoHV-4 in a positive dairy cattle farm with metritis. First, we performed an ELISA to detect BoHV-4 antibodies in all the animals (n = 104). Afterwards, ten seronegative heifers introduced in the production lot and sera samples were monthly taken for four months and then 6-10 months after introduction to detect BoHV-4 antibodies by ELISA. Moreover, a vaginal swab was taken after calving to detect BoHV-4 by PCR. Concurrently, a weekly collection of vaginal and nasal swabs and milk was performed during the first month post-partum in multiparous cows with metritis (n = 14), heifers with metritis (n = 4), heifers without metritis but positive to BoHV-4 (ELISA or PCR) (n = 2) and multiparous cows without metritis (n = 3). Seropositivity was higher in older animals and in the production lot. Three heifers which shed BoHV-4 after parturition resulted seronegative at first but eventually seroconverted. In the same vein, most heifers seroconverted after 6-10 months in the production lot (8/10). Multiparous cows shed virus by various routes: 13/14 (93 %) in vaginal secretions, 7/14 (50 %) in nasal exudates and 7/14 (50 %) in milk. However, in the other groups, shedding was only detected in vaginal swabs from the first week post-partum. Our study describes BoHV-4 shedding in field conditions. Seronegative animals may become horizontally infected when moved to a contaminated environment.

Presence of gammaherpesvirus BoHV-4 in endometrial cytology samples is not associated with subclinical endometritis diagnosed at artificial insemination in dairy cows

In the past, bovine herpesvirus 4 (BoHV-4) has been suggested to be associated with metritis and endometritis. However, not many field studies investigated the association between BoHV-4 and subclinical endometritis (SCE). In the present study, the association between the intrauterine presence of BoHV-4 and SCE diagnosed during artificial insemination (AI) was examined on two dairy farms in Belgium. An immunoperoxidase monolayer assay (IPMA) and an enzyme-linked immuno sorbent assay (ELISA) were used to screen the serum for anti-BoHV-4 antibodies. A SYBR green based one step real time qPCR was used to detect and quantify BoHV-4 (ORF20) in nasal, uterine and vaginal samples collected at AI. A reverse transcription qPCR (RT-qPCR) was used to detect mRNA (gB) as proof of a productive BoHV-4 infection. BoHV-4 was detected in 39.4% (farm A)/23.8% (farm B) of the nasal samples, 48.5% (farm A)/19.0% (farm B) of the uterine samples and 51.5% (farm A)/42.9% (farm B) of the vaginal samples. Active replication was only detected in farm A in 38.5% of the BoHV-4 positive nasal samples and in 5.9% positive cases of the vaginal samples. The prevalence of SCE diagnosed at AI was 45.5% and 42.9% in farm A and farm B, respectively. The presence of SCE was associated with a reduced pregnancy outcome at artificial insemination (AI) (P＜0.001). The occurrence of SCE at AI was not associated with the presence of latent or productive BoHV4 infections in the uterus nor in the vagina and nose (P＞0.05).

Bovine Herpesvirus-4-Based Vector Delivering Peste des Petits Ruminants Virus Hemagglutinin ORF Induces both Neutralizing Antibodies and Cytotoxic T Cell Responses

Peste des Petits Ruminants Virus (PPRV) is an extremely infective morbillivirus that primarily affects goats and sheep. In underdeveloped countries where livestock are the main economical resource, PPRV causes considerable economic losses. Protective live attenuated vaccines are currently available but they induce antibody responses similar to those produced in PPRV naturally infected animals. Effective vaccines able to distinguish between vaccinated and naturally infected animals are required to PPRV control and eradication programs. Hemagglutinin (H) is a highly immunogenic PPRV envelope glycoprotein displaying both hemagglutinin and neuraminidase activities, playing a crucial role in virus attachment and penetration. In this study, a recombinant Bovine Herpesvirus-4 (BoHV-4)-based vector delivering an optimized PPRV-Hemagglutinin expression cassette, BoHV-4-A-PPRV-H-ΔTK, was assessed in immunocompetent C57BL/6 mice. BoHV-4-A-PPRV-H-ΔTK-immunization elicited both cellular and humoral immune responses with specific T cell, cytotoxic T lymphocyte, and sero-neutralizing antibody against PPRV. These data suggest recombinant BoHV-4-A-PPRV-H-ΔTK as an effective vaccine candidate to protect against PPRV herd infection and potentially applicable for eradication programs.

Coordinated Role of Toll-Like Receptor-3 and Retinoic Acid-Inducible Gene-I in the Innate Response of Bovine Endometrial Cells to Virus

Bovine herpesvirus-4 (BoHV-4) and bovine viral diarrhea virus (BVDV) infect the uterus of cattle, often resulting in reduced fertility, or abortion of the fetus, respectively. Here, exposure of primary bovine endometrial cells to BoHV-4 or BVDV modulated the production of inflammatory mediators. Viral pathogen-associated molecular patterns (PAMPs) are detected via pattern-recognition receptors (PRRs). However, the relative contribution of specific PRRs to innate immunity, during viral infection of the uterus, is unclear. Endometrial epithelial and stromal cells constitutively express the PRR Toll-like receptor (TLR)-3, but, the status of retinoic acid-inducible gene I (RIG-I), a sensor of cytosolic nucleic acids, is unknown. Primary endometrial epithelial and stromal cells had low expression of RIG-I, which was increased in stromal cells after 12 h transfection with the TLR3 ligand Poly(I:C), a synthetic analog of double-stranded RNA. Furthermore, short interfering RNA targeting TLR3, or interferon (IFN) regulatory transcription factor 3, an inducer of type I IFN transcription, reduced Poly(I:C)-induced RIG-I protein expression and reduced inflammatory mediator secretion from stromal cells. We conclude that antiviral defense of endometrial stromal cells requires coordinated recognition of PAMPs, initially via TLR3 and later via inducible RIG-I.

Uterine infection with bovine herpesvirus type 4 in dairy cows

Diseases of the reproductive tract are a frequent problem in dairy herds. Herpesviruses are uterine pathogens also involved in other clinical diseases; for example, bovine herpesvirus type 4 BoHV-4 induces abortion, enteritis, metritis, pneumonia and vaginitis, but it can also be detected in healthy cows. The role of BoHV-4 in the development of clinical endometritis (CE) or subclinical endometritis (SE) has not clearly been described. Therefore, the objective of this study was to describe the prevalence of uterine BoHV-4 infection and its relationship with clinical, bacteriological and cytological findings in dairy cows 20-30 days after calving. The experiment was performed as a completely randomized block design, with farm (n = 10) as blocking criterion and with cow (n = 397) as the experimental unit. Logistic regression models were used to assess the effect of BoHV-4 infection on CE, SE and reproductive performance. Proportion of cows infected with BoHV-4 was 5.8% (n = 23/397). BoHV-4 was isolated in 11.0% (n = 12/109), 4.8% (n = 4/84) and 3.6% (n = 7/194) of cows diagnosed as CE, SE or healthy, respectively. A logistic model revealed that BoHV-4 infection showed a tendency to increase the risk for CE (AOR = 2.17; p = .10) but significantly reduced both, the odds for artificial insemination within 80 days post-partum (dpp) (AOR = 0.37; p = .035) and for pregnancy within 200 dpp (AOR = 0.13; p = .004). Furthermore, BoHV-4 infection increased the chance for intrauterine infection with Trueperella pyogenes (AOR = 5.55; p < .001) and vice versa (AOR = 5.79, p < .001). In conclusion, BoHV-4 infection is associated with reduced chances for insemination and pregnancy by 200 dpp and showed a trend to be associated with increased risk for CE. Furthermore, BoHV-4 and Trueperella pyogenes infections are strongly related.

BoHV-4 immediate early 1 gene is a dispensable gene and its product is not a bone marrow stromal cell antigen 2 counteracting factor

BACKGROUND

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus whose genome was cloned as Bacterial Artificial Chromosome (BAC) and exploited as a gene delivery vector for vaccine purposes. Although BoHV-4 genome has been completely sequenced and its open reading frames (ORFs) structurally defined in silico, most of them are not functionally characterized. In BoHV-4 genome two major immediate early genes (IE) are present, IE1 and IE2. IE2 is an essential gene because its removal from the viral genome renders the virus unable to replicate, whereas for IE1 no many functional information are available.

RESULTS

In this work, IE1 contribution in initiating and maintaining BoHV-4 lytic replication was assessed generating a recombinant BoHV-4 genome lacking of IE1 gene, BoHV-4ΔIE1. In contrast to BoHV-4IE2 deleted mutant, BoHV-4ΔIE1 infectious replicating viral particles (IRVPs) could be reconstituted following viral DNA electroporation in permissive cells. However the titer of BoHV-4ΔIE1 IRVPs produced into the cell supernatant and BoHV-4ΔIE1 plaques size were reduced respect to BoHV-4 undeleted control. Further the impaired BoHV-4ΔIE1 IRVPs produced into the cell supernatant could be rescued by expressing IE1 gene product in trans, confirming the implication of IE1 in BoHV-4 lytic replication. Next, the possible role of BoHV-4IE1 as bone marrow stromal cell antigen 2 (BST-2) counteracting factor, as hypothesized by IE1 amino-terminal gene product homology with Kaposi Sarcoma Associated Herpesvirus (KSHV) K5, was excluded too.

CONCLUSIONS

Although the real function of BoHV-4IE1 is still elusive, a new BoHV-4 genome gene locus as a target site for the insertion of foreign DNA and resulting in the attenuation of the virus has been revealed. These data can be considered of relevance to improve BoHV-4 gene delivery properties.

BoHV-4-Based Vector Single Heterologous Antigen Delivery Protects STAT1(-/-) Mice from Monkeypoxvirus Lethal Challenge

Monkeypox virus (MPXV) is the etiological agent of human (MPX). It is an emerging orthopoxvirus zoonosis in the tropical rain forest of Africa and is endemic in the Congo-basin and sporadic in West Africa; it remains a tropical neglected disease of persons in impoverished rural areas. Interaction of the human population with wildlife increases human infection with MPX virus (MPXV), and infection from human to human is possible. Smallpox vaccination provides good cross-protection against MPX; however, the vaccination campaign ended in Africa in 1980, meaning that a large proportion of the population is currently unprotected against MPXV infection. Disease control hinges on deterring zoonotic exposure to the virus and, barring that, interrupting person-to-person spread. However, there are no FDA-approved therapies against MPX, and current vaccines are limited due to safety concerns. For this reason, new studies on pathogenesis, prophylaxis and therapeutics are still of great interest, not only for the scientific community but also for the governments concerned that MPXV could be used as a bioterror agent. In the present study, a new vaccination strategy approach based on three recombinant bovine herpesvirus 4 (BoHV-4) vectors, each expressing different MPXV glycoproteins, A29L, M1R and B6R were investigated in terms of protection from a lethal MPXV challenge in STAT1 knockout mice. BoHV-4-A-CMV-A29LgD106ΔTK, BoHV-4-A-EF1α-M1RgD106ΔTK and BoHV-4-A-EF1α-B6RgD106ΔTK were successfully constructed by recombineering, and their capacity to express their transgene was demonstrated. A small challenge study was performed, and all three recombinant BoHV-4 appeared safe (no weight-loss or obvious adverse events) following intraperitoneal administration. Further, BoHV-4-A-EF1α-M1RgD106ΔTK alone or in combination with BoHV-4-A-CMV-A29LgD106ΔTK and BoHV-4-A-EF1α-B6RgD106ΔTK, was shown to be able to protect, 100% alone and 80% in combination, STAT1(-/-) mice against mortality and morbidity. This work demonstrated the efficacy of BoHV-4 based vectors and the use of BoHV-4 as a vaccine-vector platform.

[Bovine herpesvirus 4 (BoHV-4): general aspects of the biology and status in Argentina]

Bovine herpesvirus 4 (BoHV-4) has been isolated from cattle with respiratory infections, vulvovaginitis, mastitis, abortions, endometritis and from apparently healthy animals throughout the world. Although it has not yet been established as causal agent of a specific disease entity, it is primarily associated with reproductive disorders of cattle. This virus can infect a wide range of species, either in vivo or in vitro. Two groups of prototype strains were originated from the first isolates: the DN599-type strains (American group) and the Movar-type strains (European group). In Argentina, BoHV-4 was isolated and characterized in 2007 from vaginal discharge samples taken from cows that had aborted. So far, more than 40 isolates, mainly associated with aborting bovine females have been registered in our country.

Association of IL8 -105G/A with mastitis somatic cell score in Chinese Holstein dairy cows

The single nucleotide polymorphisms (SNPs) in the 5' upstream of bovine IL8 gene were investigated in 810 Chinese Holstein cows from 35 bull families in a dairy farm in Shanghai using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique. The Real-time PCR and Western blot were used to detect the mRNA and protein levels of genotype Chinese Holstein dairy cows. The results showed that one SNP -105G>A was detected, designating three genotypes (GG, GA and AA) with respective frequencies of 0.38, 0.46, and 0.16. The significant association of the SNP -105G>A with somatic cell score (SCS) was identified. Genotype GG had a significantly lower SCS than genotype GA or AA (P < 0.01), and the relative mRNA expression and protein level of GG was found to be the highest. These results suggest that the genotype GG may be a useful genetic marker for mastitis resistance selection and breeding in Chinese Holstein dairy cows.

Characterization of buffalo interleukin 8 (IL-8) and its expression in endometritis

River buffalo (Bubalus bubalis bubalis) with a population over 135 million heads is an important livestock. Interleukin 8 (IL-8) is a member of the chemokine family and is an important chemoattractant for neutrophils associated with a wide variety of inflammatory diseases such as endometritis. Tissue samples from the mammary gland, uterus and ovary were obtained from river buffalo (Mediterranean type) with and without endometritis. Bacteriological examination showed the presence of both gram positive and negative in all buffalo with endometritis. RNA extraction and complementary DNA (cDNA) synthesis were conducted from all tissues. Specific primer for IL8 full coding regions was designed using known cDNA sequences of Bubalus bubalis, Genbank accession number AY952930.1. IL-8 gene expression was investigated in buffalo tissues. Expression of IL-8 in buffalo with endometritis was found to increase significantly over buffalo without endometritis only in the uterus (P = 0.0159). PCR products from uterus tissues (target organs) of buffalo with and without endometritis, were purified and sequenced. No polymorphic sites were detected in the investigated samples. IL-8 cDNA nucleotide sequences of buffalo with and without endometritis were 100% identical (accession number JX413057). Buffalo IL8 cDNAs were compared with corresponding sequences of member of subfamily Bovinae (buffalo and cattle) and subfamily Caprinae (sheep and goat). IL-8 species specific differences were identified.

Enzyme linked immunosorbent assay for quantification of bovine interleukin-8 to study infection and immunity in the female genital tract

PROBLEM

The chemokine IL-8 recruits neutrophils to sites of infection, including the endometrium of the bovine uterus. However, quantification of bovine IL-8 often yields lower concentrations than for other species, which may reflect impaired innate immune responses by bovine cells or inaccurate measurement of IL-8 using the current human IL-8 ELISA method.

METHOD OF STUDY

An ELISA was developed and validated for detection of bovine IL-8. Utility of the assay was tested by measuring the response of bovine endometrium and cells to bacteria and pathogen-associated molecular patterns.

RESULTS

The developed ELISA detected 62.5-2000 pg/mL IL-8, with minimal cross-reactivity to other inflammatory mediators. Concentrations of bovine IL-8 were measured more accurately by the bovine than human IL-8 ELISA. Bovine endometrial IL-8 responses to pathogen-associated molecules were quantitatively similar to other species.

CONCLUSION

A bovine-specific IL-8 ELISA was developed, which accurately measured IL-8 secretion from endometrial cells.

Enlightened Mannhemia haemolytica lung inflammation in bovinized mice

Polymorphonuclear cells diapedesis has an important contribution to the induced Mannhemia haemolytica (M. haemolytica) infection lung inflammation and IL-8 is the primary polymorphonuclear chemoattractant. Using a bovine IL-8/luciferase transiently transgenized mouse model, the orchestration among M. haemolytica, IL-8 promoter activation and neutrophilia was followed in real time by in vivo image analysis.

Impact of Bovine Herpesvirus 4 (BoHV-4) on Reproduction

Bovine herpesvirus 4 (BoHV-4) is increasingly considered as responsible for various reproductive troubles. This virus infects blood mononuclear cells and displays a specific tropism for vascular endothelia, mammary tissue, endometrium and foetal tissues. Viral multiplication can be reactivated by corticosteroids or stress, both factors present at calving. BoHV-4 has been isolated in a large variety of clinical cases, primarily metritis, vaginitis and mastitis, but also endometritis, abortion and orchitis. Its impact on reproductive performance has been suggested by several epidemiological studies: seroprevalence against BoHV-4 is higher in aborted females and in repeat breeders. Nevertheless, its intrinsic pathogenic power seems low, symptoms developing only when BoHV-4 cooperates with bacteria: within the uterus or mammary gland. BoHV-4 is rather currently considered as a cofactor for the development of an inflammatory reaction initiated by bacteria.

Immunity and inflammation in the uterus

Microbes often infect the uterus and particularly the endometrium of animals. Infections are most commonly associated with natural service, pregnancy and the post-partum period, leading to inflammation with the elaboration of cytokines, chemokines and prostaglandins. Clinical diseases such as metritis, endometritis and abortion are important causes of infertility. The adaptive immune response to infection has been characterized previously, so the present review aims to highlight the emerging role for innate immunity in the endometrium. The detection of microbes and the innate immune response depends on the detection of pathogen-associated molecular patterns by pattern recognition receptors. The main families of pattern recognition receptors are Toll-like receptors (TLRs), nucleotide oligomerization domain-like receptors, retinoic acid-inducible gene I-like receptors and C-type lectin receptors. These receptors are most often expressed by hematopoietic cells, but the epithelial and stromal cells of the endometrium also possess functional receptors. For example, endometrial cells express TLR4 for recognition of the lipopolysaccharide endotoxin of Gram-negative bacteria, leading to secretion of IL-6, IL-8 and prostaglandin E(2) . It is likely that the epithelial and stromal cells provide a first line of defence in the endometrium to alert hematopoietic cells to the presence of microbes within the uterus.

In vivo imaging of transiently transgenized mice with a bovine interleukin 8 (CXCL8) promoter/luciferase reporter construct

One of the most remarkable properties of interleukin 8 (CXCL8/IL-8), a chemokine with known additional functions also in angiogenesis and tissue remodeling, is the variation of its expression levels. In healthy tissues, IL-8 is barely detectable, but it is rapidly induced by several folds in response to proinflammatory cytokines, bacterial or viral products, and cellular stress. Although mouse cells do not bear a clear homologous IL-8 gene, the murine transcriptional apparatus may well be capable of activating or repressing a heterologous IL-8 gene promoter driving a reporter gene. In order to induce a transient transgenic expression, mice were systemically injected with a bovine IL-8 promoter–luciferase construct. Subsequently mice were monitored for luciferase expression in the lung by in vivo bioluminescent image analysis over an extended period of time (up to 60 days). We demonstrate that the bovine IL-8 promoter–luciferase construct is transiently and robustly activated 3–5 hours after LPS and TNF-α instillation into the lung, peaking at 35 days after construct delivery. Bovine IL-8 promoter–luciferase activation correlates with white blood cell and neutrophil infiltration into the lung. This study demonstrates that a small experimental rodent model can be utilized for non-invasively monitoring, through a reporter gene system, the activation of an IL-8 promoter region derived from a larger size animal (bovine). This proof of principle study has the potential to be utilized also for studying primate IL-8 promoter regions.

Functional characterisation of bovine interleukin 8 promoter haplotypes in vitro

Interleukin 8 (IL-8) is a major mediator of the innate immune response and polymorphisms in this gene are associated with susceptibility to inflammatory disease in humans. The aim of this study was to characterise the promoter region of the bovine IL8 gene towards understanding its regulation and the effect of promoter polymorphisms on gene expression levels. Twenty-nine polymorphic sites were identified across a 2.1kb upstream promoter region of the IL8 gene including two insertion/deletion polymorphisms. Sequence analysis and SNP genotyping identified two distinct promoter haplotypes (IL8-h1 and IL8-h2), which were present at significantly different frequencies in two divergently selected cattle breeds - Holstein-Friesian and Norwegian Red (IL8-h1 at 48% and 80% respectively). IL8-h1 was functionally less responsive in unstimulated mammary epithelial cells and in response to stimulation with LPS or bovine TNF. Serial deletion analysis and in silico transcription-factor binding site analysis indicated that allele specific binding of the transcriptional repressor Oct-1 may account for the reduced sensitivity of IL8-h1. Our finding of genetic variation in the bovine IL8 promoter that differentially regulates its expression has significant functional implications for IL8 expression in vitro and which may impact on susceptibility to bovine infectious disease and inflammation.