Molecular typing of a BHV-4 (bovine herpesvirus 4) field isolate

Vaccination of cattle with a virus vector vaccine against a major membrane protein of Mycobacterium avium subsp. paratuberculosis elicits CD8 cytotoxic T cells that kill intracellular bacteria

Analysis of the recall response ex vivo in cattle vaccinated with a Mycobacterium avium subsp. paratuberculosis (Map) rel deletion mutant revealed the immune response was directed toward a 35 kD major membrane protein (MMP) of Map. Antigen presenting cells (APC) primed with MMP elicited expansion of CD8 cytotoxic memory T cells (CTL) with ability to kill intracellular bacteria. Development of CTL was MHC-restricted. The gene MAP2121c, encoding MMP, was modified for expression of MMP (tPA-MMP-2mut) in a mammalian cell line to explore the potential of developing MMP as a vaccine. Ex vivo stimulation of PBMC, from Map free cattle, with APC primed with tPA-MMP-2mut expressed p35 elicited a primary CD8 CTL response comparable to the recall response elicited with PBMC from cattle vaccinated with either the Maprel deletion mutant or MMP. In the present study, the modified gene for MMP, now referred to as p35NN, was placed into a bovine herpes virus-4 (BoHV4) vector to determine the potential use of BoHV-4AΔTK-p35NN as a peptide-based vaccine. Subcutaneous vaccination of healthy cattle with BoHV-4AΔTK-p35NN elicited a CTL recall response, as detected ex vivo. The results show use of a virus vector is an effective way for delivery of MMP as a vaccine. The immunogenic activity of MMP was not lost when modified for expression in mammalian cells. The next step is to conduct a field trial to determine if presence of an immune response to MMP prevents Map from establishing an infection.

Characterization of the first bovine gammaherpesvirus 4 strain isolated from an aborted bovine fetus in Argentina

Bovine herpesvirus 4 (BoHV-4) is increasingly believed to be responsible for several disorders of the bovine reproductive tract. The first characterization of BoHV-4 in Argentina was from samples from an aborted fetus. Argentinean isolates are highly diverse and are phylogenetically grouped in three genotypes. In this study, we describe the isolation of BoHV-4 from a bovine fetus with a gestational age of 8 months and without macroscopic lesions. Genetic analyses revealed that the isolated strain belongs to genotype 2. This is the first report on the presence of infectious BoHV-4 in tissues from an aborted bovine fetus.

Comparative analysis of replicative properties of phylogenetically divergent, Argentinean BoHV-4 strains in cell lines from different origins

Bovine gammaherpesvirus 4 (BoHV4) is a member of the family Herpesviridae. In Argentina, BoHV4 was isolated and characterized in 2007 from samples of aborted cows. Argentinean isolates are highly divergent and are classified as: Genotype 1(Movar-like), Genotype 2 (DN599-like) and Genotype 3 (a novel group). The aim of this study was to comparatively evaluate the biological characteristics of six Argentinean BoHV4 field isolates in cell lines from different origins. All strains induced productive infection in the cell lines used, with different degrees of permissiveness. A direct relationship among the times of appearance of cytopathic effect, the growth kinetics, the size of the lysis plaques and the virulent-like behaviour in vitro could not be established. However, although slight, there are differences in the biological behaviour of the BoHV4 fields isolates analyzed. This variability is independent of their genetic classification but would be conditioned by the nature of the infected cells.

Whole Genome Sequencing of a Canadian Bovine Gammaherpesvirus 4 Strain and the Possible Link between the Viral Infection and Respiratory and Reproductive Clinical Manifestations in Dairy Cattle

Bovine gammaherpesvirus 4 (BoHV-4) is a herpesvirus widespread in cattle populations, and with no clear disease association. Its genome contains a long unique coding region (LUR) flanked by polyrepetitive DNA and 79 open reading frames (ORFs), with unique 17 ORFs, named Bo1 to Bo17. In 2009, a BoHV-4 strain was isolated (FMV09-1180503: BoHV-4-FMV) from cattle with respiratory disease from Quebec, Canada, and its LUR was sequenced. Despite the overall high similarity, BoHV-4-FMV had the most divergent LUR sequence compared to the two known BoHV-4 reference strain genomes; most of the divergences were in the Bo genes and in the repeat regions. Our phylogenetic analysis based on DNA polymerase and thymidine kinase genes revealed that virus isolate was BoHV-4 gammaherpesvirus and clustered it together with European BoHV-4 strains. Because BoHV-4-FMV was isolated from animals presenting respiratory signs, we have updated the BoHV-4 Canadian cattle seroprevalence data and tried to find out whether there is a link between clinical manifestation and BoHV-4 seropositivity. An indirect immunofluorescence assay (IFA) was performed with nearly 200 randomized sera of dairy cattle from two Canadian provinces, Quebec (n = 100) and Ontario (n = 91). An additional set of sera obtained from Quebec, from the healthy (n = 48) cows or from the animals experiencing respiratory or reproductive problems (n = 75), was also analyzed by IFA. BoHV-4 seroprevalence in Canadian dairy cattle was 7.9% (Quebec: 6% and Ontario: 9.9%). Among animals from the Quebec-based farms, diseased animals showed higher BoHV-4 seropositivity than healthy animals (P < 0.05), with a significant 2.494 odds ratio of being seropositive in sick compared to healthy animals. Although there is no established direct link between BoHV-4 and specific diseases, these seroprevalence data suggest the possible involvement of BoHV-4 in dairy cattle diseases.

Bovine Herpesvirus 4 in Parana State, Brazil: case report, viral isolation, and molecular identification

Bovine Herpesvirus 4 (BoHV-4) is a member of Gammaherpesvirinae sub-family and belongs to genus Rhadinovirus . This virus has been associated with different clinical manifestations and research activity has put forward a strong correlation among virus infection, postpartum metritis, and abortion. The goal of this work was to characterize a virus strain isolate from a cow’s uterine outflow. From swabs drawn of uterine secretion, a virus strain was isolated and characterized by its cytopathology, morphology, and molecular biology approaches. In culture there was CPE development, characterized mainly by long strands with several small balloons along them, radiated from infected cells. Electron microscopy analysis revealed virus particles that had icosahedrical capsid symmetry surrounded by a loose envelope, typical of a herpesvirus. A 2,571 bp PCR product after Hind III digestion generated four fragments, whose base pair composition were 403, 420, 535, and 1,125 bp. Restriction enzymes Hind III and Bam HI generated the expected diagnostic bands as well as a 2,350 bp hypermolar fragment as a result of Bam HI treatment to demonstrate that agent was a bovine herpesvirus 4, appertaining to DN-599 group.

[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.

Isolation and characterization of bovine herpesvirus 4 (BoHV-4) from a cow affected by post partum metritis and cloning of the genome as a bacterial artificial chromosome

BACKGROUND

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus with a Worldwide distribution in cattle and is often isolated from the uterus of animals with postpartum metritis or pelvic inflammatory disease. Virus strain adaptation to an organ, tissue or cell type is an important issue for the pathogenesis of disease. To explore the mechanistic role of viral strain variation for uterine disease, the present study aimed to develop a tool enabling precise genetic discrimination between strains of BoHV-4 and to easily manipulate the viral genome.

METHODS

A strain of BoHV-4 was isolated from the uterus of a persistently infected cow and designated BoHV-4-U. The authenticity of the isolate was confirmed by RFLP-PCR and sequencing using the TK and IE2 loci as genetic marker regions for the BoHV-4 genome. The isolated genome was cloned as a Bacterial Artificial Chromosome (BAC) and manipulated through recombineering technology

RESULTS

The BoHV-4-U genome was successfully cloned as a BAC, and the stability of the pBAC-BoHV-4-U clone was confirmed over twenty passages, with viral growth similar to the wild type virus. The feasibility of using BoHV-4-U for mutagenesis was demonstrated using the BAC recombineering system.

CONCLUSION

The analysis of genome strain variation is a key method for investigating genes associated with disease. A resource for dissection of the interactions between BoHV-4 and host endometrial cells was generated by cloning the genome of BoHV-4 as a BAC.

Double immunization strategy with a BoHV-4-vectorialized secreted chimeric peptide BVDV-E2/BoHV-1-gD

A bovine herpesvirus 4 was isolated from the milk cell fraction of a healthy cow and his full genome cloned as a bacterial artificial chromosome. So cloned viral genome was used as a vector platform to deliver in vitro and in vivo an optimized secreted chimeric peptide obtained by the fusion of the bovine viral diarrhoea virus glycoprotein E2 ectodomain with the bovine herpesvirus 1 glycoprotein D ectodomain. Recombinant virus infected cells robustly expressed and secreted the chimeric peptide into the culture medium and inoculated animals with the recombinant virus successfully responded toward antigens, gE2 and gD. Thus, this work has implications for the development of safe and effective polyvalent vaccines.

Exploiting persistent infection for selection of bovine herpesvirus 4 recombinants

Bovine herpesvirus 4 (BoHV-4) is a gamma-herpesvirus with no clear disease association, and due to its biological characteristics, has been suggested as a gene delivery vector. It was demonstrated previously that recombinant BoHV-4 carrying a neomycin-resistance gene was able to infect a human rhabdomyosarcoma cell line (RD-4), resulting in no detectable cytopathic effect (CPE) and allowing selection of G418-resistant persistently-infected cells containing circular episomal viral DNA [Donofrio, G., Cavirani, S., van Santen, V.L., 2000a. Establishment of a cell line persistently infected with recombinant BoHV-4. J. Gen. Virol. 81, 1807-1814.]. Those cells produce infectious virus and infection is predominantly non-permissive and non-cytopathic. Starting from these results, the ability of RD-4 cells to sustain persistent infection was combined with positive selection activity conferred by the neomycin-expression cassette insert, as an easier way to select recombinants of BoHV-4 following homologous recombination in permissive cells. A tool for selecting BoHV-4 recombinants was developed by drug positive selection.

Seroprevalence and comparison of isolates of endometriotropic bovine herpesvirus-4

Sixty-eight cases of suppurative, ulcerative endometritis associated with Bovine Herpesvirus-4 (BHV-4) in postparturient dairy cows (62 Holsteins and 6 Jerseys, mean age 4.2 years) were confirmed by a combination of histopathology, fluorescent antibody assays, electron microscopic evaluation of uterus, and polymerase chain reaction (PCR). All cases occurred in the 3- to 28-day postpartum period, and histologic lesions among various cows were consistent when compared with postpartum interval. The endometrial lining epithelium was necrotic and ulcerated from 3 to 7 days postpartum, with only mild inflammation in the lamina propria and submucosa. From 1 to 4 weeks postpartum, the ulcers were confluent to diffuse. Epithelium was replaced by fibrinonecrotic, suppurative mats, resulting in severe bacterial pyometra by day 24. Seroprevalence to BHV-4 in one dairy with a history of 18 mortality cases was 36% (107 of 296). In a random sample of 8 cows from this herd, none had serologic titers in blood sampled 2 weeks prepartum, but 3 of 8 seroconverted with significant titers of 1:8 to 1:16 at 2 weeks postpartum. By 10 weeks postpartum, all 8 cows returned to negative serologic status. Two of 6 cats from the premises also had positive titers. Random serum samples taken from 480 dairy cattle at sale barns indicated 76 (16%) were positive by serum neutralization. Clinical signs, postparturient timing, and histologic lesions were very similar to those previously reported in Belgium with BHV-4. But sequence analysis of PCR products of the glycoprotein B region of 4 separate field isolates of endometriotropic BHV-4 suggests these field isolates were more closely related to the North American nonvirulent strain DN-599 than to the endometriotropic European strain V.

Potential of bovine herpesvirus 4 as a gene delivery vector

A cloning system was developed for construction of BHV-4 recombinants and recombinant virus BHV-4EGFPDeltaTK containing an enhanced green fluorescent protein (EGFP) gene was constructed. The host range of BHV-4EGFPDeltaTK was characterized in vitro. When cell lines from various species and tissues were infected, most of the non-bovine cell lines exhibited neither cytopathic effect (CPE) nor supported viral replication, but EGFP expression was clearly observed. Next, embryonic stem cells were infected and induced to either non-specific or neural differentiation to determine whether they could survive and differentiate after BHV-4EGFPDeltaTK infection. Embryonic stem cells were infected successfully, as indicated by EGFP expression prior to differentiation, and EGFP expression could be detected in many differentiated cells. No CPE was noted. Therefore, BHV-4EGFPDeltaTK infection caused neither cell death nor interfered with non-specific or neural differentiation of embryonic stem cells. Finally, to assess the capability of BHV-4EGFPDeltaTK to infect post-mitotic neurons, cultures from brains of 2-weeks old mice were infected. No death of neuronal cells due to infection was observed and EGFP expression persisted for at least 15 days. Several biological characteristics of BHV-4 demonstrated previously make it a good candidate for a gene delivery vector. These include: little or no pathogenicity, unlikely oncogenicity, ability to establish persistent infection, and capability of herpesviruses to accommodate large amounts of foreign genetic material. These findings add the ability to infect several cell types coming from different animal species, usually without CPE, lack of interference with differentiation, and ability to maintain transgene expression in both undifferentiated and differentiated cells.

Endometritis in postparturient cattle associated with bovine herpesvirus-4 infection: 15 cases

Suppurative, ulcerative endometritis associated with bovine herpesvirus-4 (BHV-4) infection was identified in 15 postparturient dairy cows from 5 separate dairies. Characteristic eosinophilic to amphophilic intranuclear viral inclusion bodies were identified within degenerate endometrial lining epithelium and endothelial cells. Bovine herpesvirus-4 was confirmed as the etiology by a combination of fluorescent antibody assays, viral isolation, heminested PCR, ultrastructural examination of the uterus and inoculated tissue culture cells, and negative-stain electron microscopy of tissue culture supernatant. Viral particles measuring 70-95 nm were demonstrated in uterine epithelial and endothelial cells by electron microscopy. Bacteria including Arcanobacterium pyogenes, Escherichia coli, and an alpha-Streptococcus isolate were isolated from all uteri. Bovine herpesvirus-4-associated endometritis has been previously reported in sporadic cases in Europe but has not been previously reported in the United States. Endometritis associated with BHV-4 appears to be an emerging syndrome in Georgia dairy herds.