Improved detection of five closely related ruminant alphaherpesviruses by specific amplification of viral genomic sequences

[Circulation of bovine herpesvirus (Herpesviridae: Varicellovirus) and bovine viral diarrhea virus (Flaviviridae: Pestivirus) among wild artiodactyls of the Moscow region]

INTRODUCTION

Pestiviruses and viruses of the Herpesviridae family are widely distributed among different species of ungulates, but the main information about these pathogens is related to their effect on farm animals. Data on detection of bovine viral diarrhea virus (BVDV) and bovine herpes virus (BoHV) in wild ungulates reported from different countries in recent years raises the question of the role of wild animals in the epidemiology of cattle diseases.

AIM OF WORK

To study the prevalence of herpesviruses and pestiviruses in the population of wild artiodactyls of the Moscow region.

MATERIALS AND METHODS

Samples of parenchymal organs and mucosal swabs from 124 wild deer (moose and roe deer) shot during hunting seasons 20192022 in Moscow Region were examined by PCR, virological and serological methods for the presence of genetic material and antibodies to bovine infectious rhinotracheitis and viral diarrhea.

RESULTS

BVDV RNA was found in a sample from one moose, BoHV DNA was detected in samples from three roe deer and two moose shot in the Moscow region. Seropositive animals were of different sex and age, the total BoHVs and BVDV seroprevalence rates in wild artiodactyls were 46 and 29%, respectively.

CONCLUSION

Wild ruminant artiodactyls of the Moscow Region can be a natural reservoir of BoHV-1, and this must be taken into account when planning and organizing measures to control the infectious bovine rhinotracheitis. Cases of BVDV infection in wild artiodactyls are less common, so more research is needed to definitively establish their role in the epidemiology of this disease in cattle.

A Qualitative PCR Assay for the Discrimination of Bubaline Herpesvirus 1, Bovine Herpesvirus 1 and Bovine Herpesvirus 5

Bubaline herpesvirus 1 (BuHV-1), Bovine herpesvirus 1 (BoHV-1) and Bovine herpesvirus 5 (BoHV-5) are classified in the genus Varicellovirus, subfamily Alphaherpesvirinae. BoHV-1 is the causative agent of infectious bovine rhinotracheitis, BoHV-5 induces moderate disease in adult cattle while BuHV-1 has instead been associated with a decline in livestock production of water buffaloes. The aim of this study was to develop a qualitative PCR assay that allows the discrimination of BuHV-1, BoHV-1 and BoHV-5. The alignment of homologous genes identified specific nucleotide sequences of BuHV- 1, BoHV-1 and BoHV-5. The design of the primers and the optimization of the PCR assay were focused on the target sequences located on the portions of gD, gE and gG genes. This assay involved the use of three different PCR end-points: the PCR of a portion of the gD gene identified only the presence of BoHV-1; the PCR of a portion of the gE gene confirmed the presence of both BoHV-5 and BuHV-1; the PCR of a portion of the gG gene discriminated between BoHV-5 and BuHV-1, as the amplification product was observed only for BoHV-5. This qualitative PCR assay allowed the differentiation of BoHV-1 and BoHV-5 infections both in cattle and water buffaloes and heterologous BuHV-1 infections in bovine.

Molecular evidence for concurrent infection of goats by orf virus and bovine herpesvirus 1

Orf is a disease of small ruminant animals, including goats and sheep, that is caused by a parapoxvirus. Although the mortality rate is low, economic losses may occur due to the clinical signs. Bovine herpesvirus 1 (BoHV-1) infection is known to cause respiratory and reproductive disorders mainly in cattle; however, it has been found to circulate among goats and sheep as well. In contrast to orf virus (ORFV), BoHV-1 does not induce clinical disease in goats. In this study, we aimed to detect the presence of ORFV by molecular methods and to uncover eventual simultaneous herpesvirus infections masked by orf disease signs. To this end, 82 goats, housed near to a cattle herd, were tested. By polymerase chain reaction (PCR), three goats (3.7%) were found to harbour both viruses, while an additional goat was positive for ORFV only. The PCR products were sequenced and phylogenetic analyses were performed. This study revealed that ORFV and BoHV-1 may be present simultaneously in an animal causing a concurrent infection. These data should be taken into consideration when looking for secondary pathogens in diseased goats, and the prevention methods should be developed accordingly.

A new molecular method for the rapid subtyping of bovine herpesvirus 1 field isolates

Bovine herpesvirus 1 (BoHV-1) causes several clinical syndromes in cattle worldwide. There are 3 subtypes of BoHV-1: 1.1, 1.2a, and 1.2b. Several molecular methods are commonly used in the detection and characterization of BoHV-1. Among them, restriction endonuclease analysis (REA) and single-nucleotide polymorphism (SNP) analysis of the complete viral genome allow classification of BoHV-1 into different subtypes. However, developing countries need simpler and cheaper screening assays for routine testing. We designed a standard multiplex PCR followed by a REA assay allowing straightforward subclassification of all BoHV-1 isolates tested into 1.1, 1.2a, and 1.2b subtypes based on the analysis of fragment length polymorphism. Our standard multiplex PCR-REA was used to analyze 33 field strains of BoHV-1 isolated from various tissues. The assay confirmed the subtype identified previously by REA. In addition, non-polymorphic or undigested fragments were sequenced in order to confirm the mutation affecting the RE HindIII site. Our PCR-REA method is an affordable and rapid test that will subtype all BoHV-1 strains.

Abortion and Ulcerative Posthitis Associated with Caprine Herpesvirus–1 Infection in Goats in California

Three outbreaks of late-gestation abortions in does and ulcerative posthitis in bucks, associated with caprine herpes virus–1 (CHV-1), in California are described. In herd A, 10 of 17 does aborted in a 7-day period, whereas in herd B, 4 of 130 does aborted in a 45-day period and in herd C, 100 of 300 does aborted in a 3-week period. Most fetuses had multifocal pinpoint depressed foci with a zone of hyperemia on external and cut surfaces of the kidneys, liver, lungs, and adrenal glands. Histologically, scattered multifocal areas of necrosis with mild neutrophilic infiltrate were observed in kidneys, brain, liver, adrenal glands, and lungs of most fetuses of the 3 herds. Large amphophilic intranuclear inclusion bodies, which displaced the chromatin, were observed in cells within and around the necrotic foci in kidneys and adrenal glands. Particles 85–113 nm in size with morphology compatible with herpes virus were observed in the nuclei of these cells when examined by electron microscopy. Irregular, shallow, red ulcers were observed in the prepuce of 1 buck from herd C. Prepuce biopsies from this animal had necrosis of the superficial mucosal epithelium and severe submucosal lymphoplasmocytic infiltrates. Large intranuclear amphophilic inclusion bodies were observed in most cells of the stratum spinosum of the preputial epithelium, but no viral particles were observed in these cells. Caprine herpes virus–1 was isolated from tissue pools of fetuses from the 3 herds but not from prepuce biopsies. Positive results were obtained when tissues of a fetus from herd C were processed by a polymerase chain reaction technique to amplify the amino terminus of the glycoprotein C gene of CHV-1. Sera from aborted does from herds B and C and from the 3 bucks from herd C had high antibody titers to CHV-1. The results presented here support the hypothesis that the male goat is involved in the transmission of CHV-1. However, other forms of transmission cannot be ruled out.

Alpha and gamma herpesvirus detection in two herds of farmed red deer (Cervus elaphus) in New Zealand

CASE HISTORY

In September 2004 two hinds on Farm 1 were observed with epiphora and keratoconjunctivitis, and corneal scarring. A low pregnancy rate in some hinds had been recorded that year. In the same year six yearling deer were observed on Farm 2 with keratitis, uveitis and corneal scarring.

CLINICAL AND PATHOLOGICAL FINDINGS

On Farm 1, conjunctival swabs and blood samples were collected from the hinds with ocular lesions, and from 24 other hinds. The two affected hinds were immunosuppressed with dexamethasone for 7 days. Conjunctival, nasal and vaginal swabs were collected daily before euthanasia and necropsy on the eighth day. Subsequently, another five non-pregnant hinds were similarly immunosuppressed and necropsied, and the reproductive tracts of 20 non-pregnant hinds were collected following slaughter. Semen samples were collected from four stags implicated with reproductive failure. On Farm 2, conjunctival swabs were collected from six hinds with ocular lesions and from 14 unaffected deer. Viral culture, consensus primer PCR and sequencing for specific herpesviruses was carried out on conjunctival swabs, buffy coat from blood samples, semen and reproductive tracts. Necropsy samples were also examined using gross pathology and histopathology. On Farm 1, a type 2 rhadinovirus (CvRhV) was detected in the conjunctiva of one hind with keratoconjunctivitis using PCR. Following immunosuppression, gross vesicular and histological vaginal lesions typical of infection with alphaherpesvirus were observed in samples of vaginal tissue from the same hind. Buffy coat, vaginal and lumbar spinal nervous tissues were also positive for cervid herpesvirus 1 (CvHV-1) using PCR. Herpesviruses were not detected in reproductive tracts, ocular or semen samples of the other deer. CvRhV was detected in buffy coats from four other hinds and in a conjunctival swab from one hind, all without ocular lesions, using PCR. On Farm 2, conjunctival swabs from two deer with keratitis were culture positive for CvHV-1. Two culture-negative conjunctival samples from deer without ocular lesions were positive for CvHV-1 by PCR. In two other affected animals, presence of CvRhV was confirmed by PCR and sequencing.

DIAGNOSIS

Infection with CvHV-1 associated with keratitis and vulvovaginitis, and CvRhV infection in deer with and without ocular lesions.

CLINICAL RELEVANCE

CvHV-1 is a likely cause of keratoconjunctivitis and possibly reproductive tract pathology in deer. Investigation of ocular lesions and reproductive failure in farmed deer should include CvRhV and CvHV-1.

Isolation and characterisation of cervine herpesvirus-1 from red deer semen

AIM

This communication describes the isolation of herpesvirus during routine export examination of semen collected from red deer stags in New Zealand.

METHODS

Virus isolation was carried out using bovine embryonic lung (BEL) cells and viruses were characterised by direct immunofluorescense, restriction-fragment-length polymorphism analysis (RFLP), polymerase chain reaction (PCR) analysis and nucleotide sequencing.

RESULTS

Herpesvirus was isolated from red deer semen on 2 different occasions from different animals. In both cases the virus was identified as cervine herpesvirus-1 (CvHV-1), based on RFLP, PCR and sequence analysis. Nucleotide sequence analysis of the glycoprotein-D gene showed 99.7% homology to the Banffshire strain of CvHV-1 and 89.5%, 89.2%, 85.3% and 79.6% homology to bovine herpesvirus 1.2 (BoHV-1.2), bovine herpesvirus 1.1 (BoHV-1.1), cervine herpesvirus-2 (CvHV-2) and caprine herpesvirus-1 (CpHV-1), respectively.

CONCLUSION

This is the first time that CvHV-1 has been isolated in New Zealand. Its inclusion in serological surveys will allow the prevalence of CvHV-1 in the red deer population to be assessed in this country. The clinical significance of CvHV1 infection in New Zealand red deer herds has yet to be determined.

Cervid herpesvirus 2 infection in reindeer: a review

Herpesviruses of the genus Varicellovirus are known to infect and cause disease in a variety of ruminant species, but the impact of cervid herpesvirus 2 (CvHV2) in reindeer (Rangifer tarandus) is mostly unknown. Reindeer is a circum-polar species with a total estimated number of more than 5 million animals. Mortality may reach high values, as in northern Norway, especially in calves (37%; 2005-2006), and disease can potentially account for some of this mortality. CvHV2 has been isolated during a natural outbreak of infectious keratoconjunctivitis, indicating an etiologal link. Serological screening has shown that CvHV2 infection is prevalent in Northern Norway and experimental infection studies have demonstrated that viremia, latency and vertical transmission occur for CvHV2. The present review aims at summarizing current knowledge on the epidemiology, pathogenesis and molecular virology of CvHV2.

Serologic and reproductive findings after a herpesvirus-1 abortion storm in goats

CASE DESCRIPTION

An abortion storm occurred in a goat herd, resulting in 75 aborted kids and 1 neonatal death from December 2004 to February 2005.

CLINICAL FINDINGS

Aborted fetuses ranged from being premature to past term. Laboratory findings in 4 of 5 aborted fetuses were consistent with herpesvirus abortion. A virus that yielded positive results with a fluorescent antibody test for bovine herpesvirus-1 was isolated and identified as caprine herpesvirus-1 (CpHV-1) via DNA sequence analysis.

TREATMENT AND OUTCOME

Many does that aborted were rebred for kidding in late summer. Most of the young wethers born in 2005 were sold; however, all of the young does were kept for breeding in fall. In November 2005, all 241 goats in the herd were tested for antibodies against CpHV-1 to identify goats that had seroconverted during the outbreak. No complications attributable to CpHV-1 were identified during kidding in 2006.

CLINICAL RELEVANCE

On the basis of serologic findings, infection with CpHV-1 was not associated with reduced reproductive success in the subsequent breeding.

Clinical protection against caprine herpesvirus 1 genital infection by intranasal administration of a live attenuated glycoprotein E negative bovine herpesvirus 1 vaccine

Background

Caprine herpesvirus 1 (CpHV-1) is responsible of systemic diseases in kids and genital diseases leading to abortions in goats. CpHV-1 is widespread and especially in Mediterranean countries as Greece, Italy and Spain. CpHV-1 is antigenically and genetically closely related to bovine herpesvirus 1 (BoHV-1). Taking into account the biological properties shared by these two viruses, we decided in the current study to assess the protection of a live attenuated glycoprotein E (gE) negative BoHV-1 vaccine against a genital CpHV-1 infection in goats.

Results

The vaccine was inoculated intranasally twice three weeks apart followed by a subsequent CpHV-1 intravaginal challenge which is the natural route of infection in three goats. To analyse the safety and the efficacy of this marker vaccine, two groups of three goats served as controls: one immunised with a virulent CpHV-1 and one uninoculated until the challenge. Goats were clinically monitored and all sampling procedures were carried out in a blind manner. The vaccine did not induce any undesirable local or systemic reaction and goats did not excrete gE-negative BoHV-1. After challenge, a significant reduction in disease severity was observed in immunised goats. Moreover, goats immunised with either gE-negative BoHV-1 or CpHV-1 exhibited a significant reduction in the length and the peak of viral excretion. Antibodies neutralising both BoHV-1 and CpHV-1 were raised in immunised goats.

Conclusion

Intranasal application of a live attenuated gE-negative BoHV-1 vaccine is able to afford a clinical protection and a reduction of virus excretion in goats challenged by a CpHV-1 genital infection.

Characterization of caprine herpesvirus 1 glycoprotein D gene and its translation product

Caprine herpesvirus 1 (CpHV-1) is responsible of systemic infection in neonatal kids as well as abortion and fertility disorders in adult goats. This virus is closely related to bovine herpesvirus 1 (BoHV-1) which causes infectious bovine rhinotracheitis. Glycoprotein D (gD) mediates important functions in alphaherpesviruses and is also a main immunogen. The sequence of CpHV-1 gD gene and the biochemical properties of its translation product were analyzed and compared to those of BoHV-1 and other alphaherpesviruses. A relatively high homology was found between CpHV-1 and BoHV-1 glycoproteins D amino acid sequences (similarity of 68.8%). Moreover, six cysteine residues are conserved by CpHV-1 gD and the other studied alphaherpesviruses. CpHV-1 gD has a molecular mass similar to BoHV-1 gD and contains complex N-linked oligosaccharides. In contrast to the BoHV-1 gD, CpHV-1 gD is expressed as a late protein. In spite of the observed differences which could influence its biological functions, CpHV-1 gD shares most characteristics with other alphaherpesviruses and especially BoHV-1.

Rapid detection and differentiation of bovine herpesvirus 1 and 5 glycoprotein C gene in clinical specimens by multiplex-PCR

A multiplex polymerase chain reaction (multiplex-PCR) to detect and differentiate bovine herpesvirus 1 (BoHV-1) and 5 (BoHV-5) was developed using primers for the gene sequence that encodes the glycoprotein C. The technique was assessed against the BoHV-1 and BoHV-5 cell culture adapted strains, and clinical samples collected from animals with clinical signs of BoHV-1 (n = 10) or BoHV-5 (n = 7) infection and with diagnosis confirmed by virus isolation in cell culture and semi-nested PCR. Fifteen clinical samples from asymptomatic animals were included as control group. For the evaluation of the amplifiability of the extracted nucleic acid from clinical specimens was included a bovine internal control that amplified a 626 bp fragment of the ND5 gene present in the bovine mitochondrial DNA. For DNA extraction, a combination of the phenol/chloroform/isoamyl alcohol and silica/guanidine isothiocyanate methods was used. The specificity of the BoHV-1 and BoHV-5 amplicons from standard strains were confirmed by sequence analysis. All the positive clinical samples for BoHV included in this study were characterized as BoHV-1 or BoHV-5 by the difference in length of the amplified product visualized in a agarose gel (354 bp size for BoHV-1, and 159 bp for BoHV-5). The internal control was amplified in all clinical specimens. Non-specific reactions were not observed when the multiplex-PCR was assessed with other viruses (bovine viral diarrhea virus and rabies virus) and BoHV-negative clinical samples from fetuses and adult cattle obtained from a slaughterhouse.

Improved antigenic methods for differential diagnosis of bovine, caprine, and cervine alphaherpesviruses related to bovine herpesvirus 1

The control of infectious bovine rhinotracheitis induced by bovine herpesvirus 1 (BoHV-1) requires sensitive and specific diagnostic assays. As BoHV-1 is antigenically and genetically related to four other alphaherpesviruses of ruminants-namely, BoHV-5, caprine herpesvirus 1 (CpHV-1), cervine herpesvirus 1 (CvHV-1) and CvHV-2-diagnostic tests able to discriminate BoHV-1 from these related viruses are needed to avoid misdiagnosis, especially because some of these viruses are able to cross the species barrier. In this study, murine monoclonal antibodies (MAbs) specific for BoHV-1, BoHV-5, CpHV-1, CvHV-1, and CvHV-2 were produced with the aim of setting up an immunofluorescence assay able to discriminate between these related herpesviruses. Produced MAbs were selected for their viral specificity by enzyme-linked immunosorbent assay and indirect immunofluorescence staining of virus-infected cells. Radioimmunoprecipitation characterization of the selected MAbs revealed that four of them are directed against glycoprotein C (gC) and one of them is directed against gD of these related viruses. The obtained results demonstrate that the antibodies produced allow an unambiguous discrimination of each of the four alphaherpesviruses related to BoHV-1.

Development of a polymerase chain reaction and restriction typing assay for the diagnosis of bovine herpesvirus 1, bovine herpesvirus 2, and bovine herpesvirus 4 infections

A multiplex polymerase chain reaction (PCR) method coupled with a restriction analysis of PCR products (PCR with restriction fragment length polymorphism) was developed for the simultaneous detection of bovine herpesvirus 1, bovine herpesvirus 2, and bovine herpesvirus 4 infections. The specificity, sensitivity, and practical diagnostic applicability of this method were evaluated. This assay may be also adapted to the diagnosis of suid herpesvirus 1 and equine herpesviruses 1 and 3 and could become a powerful diagnostic tool.

Encephalomyelitis associated with akabane virus infection in adult cows

Between August and September 2000, five 2-7-year-old cows in Korea exhibited neurologic signs and were diagnosed as infected with Akabane virus based on the results of histopathology, immunohistochemistry, serology, and reverse transcription polymerase chain reaction (RT-PCR) analysis. Immunohistochemistry and RT-PCR were equally effective and sensitive for diagnosing Akabane virus infection during the early stage of infection. Typical lymphohistiocytic inflammation characterized by perivascular mononuclear cell infiltration, gliosis, neuronophagia, and neuronal loss was noted in the brain and the ventral horn gray matter of the spinal cord. The lesions in the brain were most prominent in the pons and medulla oblongata. Akabane virus antigen was detected in the brain and spinal cord, mainly in degenerating neurons and glial cells. RT-PCR analysis revealed a target band of expected size in four cows. This is the first report on an outbreak of natural Akabane virus infection in adult cattle.

Development of a multiplex polymerase chain reaction for the differentiation of bovine herpesvirus-1 and -5

Bovine herpesvirus-1 (BHV-1) and bovine herpesvirus-5 (BHV-5) are closely related viruses which exhibit some important differences at the genetic and immunogenic levels which may explain the differences in their pathogenicity and epidemiological characteristics. A multiplex polymerase chain reaction (M-PCR) was developed to detect and differentiate between BHV-1 and BHV-5. In this M-PCR two pairs of primers (TK1, TK2 and GD1, GD2) were used in the same reaction mix to amplify a thymidine kinase genomic region (183 bp) of BHV-1 and one genomic region of the gLycoprotein D (564 bp) of BHV-5. The specificity of the M-PCR was demonstrated when using both primers pairs simultaneously with BHV-1 and BHV-5 templates. The two expected bands were amplified without the apparition of non-specific products. However, when other herpesvirus strains were used, there was no amplification. To evaluate the sensitivity of the assay, dilutions of purified viral DNA were made for M-PCR amplification. The detection limit was 7 pg for BHV-1 and 22 pg for BHV-5. It was also determined by comparing the M-PCR with viral isolation. M-PCR was able to detect one log10 more than viral isolation for BHV-1 and for BHV-5 was two logarithms lower. The applicability of M-PCR was demonstrated on different specimens. Twenty isolates from field samples (11 BHV-1 and nine BHV-5) were positive by M-PCR, and the results were completely coincident with previous characterization using the immunoperoxidase assay. M-PCR could detect viral DNA in organ samples from natural infections, such as semen and brain. In addition, M-PCR detected more positive samples than observation of the citophatic effect in cell culture of nasal swabs from experimentally infected animals in two different assays. Owing to the difference in size of the M-PCR products which allows easy identification in an electrophoretic run, it is not necessary to use extra blotting and hybridization steps or a second round of amplification to differentiate clearly between BHV-1 and BHV-5.

Pathogenesis of primary respiratory disease induced by isolates from a new genetic cluster of bovine viral diarrhea virus type I

The pathogenesis of infection induced by cytopathogenic isolates from the newly identified genetic cluster Id of bovine viral diarrhea virus (BVDV) type I was studied in two experimental infections of previously seronegative, immunocompetent calves. Experiment 1 focused on the evaluation of clinical patterns, viremia, and serological responses. All infected calves in this experiment developed respiratory symptoms and seroconverted to BVDV positivity. Contact calves also contracted a respiratory tract infection following exposure to infected animals. Viremia was demonstrated between postinfection days 2 and 17, and the virus was detected in organ specimens of all but one each of the infected and contact calves. In experiment 2, the distribution of BVDV in various tissues of calves euthanized at defined days postinfection was studied. In two of these calves recurrent shedding of BVDV in nasal secretions was shown. BVDV was detected in various tissues of all infected calves throughout the experiment and also following seroconversion and the clearance of BVDV from the circulatory system. Despite the widespread distribution of the virus in various organs, significant tissue damage was found mainly in respiratory tract and lymphoid tissues. These experiments revealed that viruses from cluster Id of BVDV are able to induce primary respiratory disease in previously seronegative, immunocompetent calves. Contact transmission and virus recurrence, contrary to observations from acute experimental infections with noncytopathogenic BVDV, are likely to reflect differences in biological features of these cytopathogenic isolates. Virus shedding and its presence in tissues following peripheral clearance and in the presence of antibodies may have implications in the diagnosis, pathogenesis, and epidemiology of BVDV-induced syndromes in cattle.