The family Herpesviridae: an update. The Herpesvirus Study Group of the International Committee on Taxonomy of Viruses

Neurological diseases of ruminant livestock in Australia. IV: viral infections

Most viral infections that affect the central nervous system of ruminants are exotic to Australia. As such, this review focuses on viruses of importance in Australian ruminants, including Akabane virus and the ruminant pestiviruses, bovine viral diarrhoea virus and border disease virus, as well as bluetongue virus. Each virus is discussed in terms of pathogenesis, clinical signs and diagnosis.

Human herpesvirus 6 glycoprotein complex formation is required for folding and trafficking of the gH/gL/gQ1/gQ2 complex and its cellular receptor binding

Human herpesvirus 6 (HHV-6) is a T-cell-tropic betaherpesvirus. A glycoprotein (g) complex that is unique to HHV-6, gH/gL/gQ1/gQ2, is a viral ligand for its cellular receptor, human CD46. However, whether complex formation or one component of the complex is required for CD46 binding and how the complex is transported in cells are open questions. Furthermore, in HHV-6-infected cells the gQ1 protein modified with N-linked glycans is expressed in two forms with different molecular masses: an 80-kDa form (gQ1-80K) and a 74-kDa form (gQ1-74K). Only gQ1-80K, but not gQ1-74K, forms the complex with gQ2, gH, and gL, and this four-component complex is incorporated into mature virions. Here, we characterized the molecular context leading to the maturation of gQ1 by expressing combinations of the individual gH/gL/gQ1/gQ2 components in 293T cells. Surprisingly, only when all four molecules were expressed was a substantial amount of gQ1-80K detected, indicating that all three of the other molecules (gQ2, gH, and gL) were necessary and sufficient for gQ1 maturation. We also found that only the tetrameric complex, and not its subsets, binds to CD46. Finally, a gQ2-null virus constructed in the BAC (bacterial artificial chromosome) system could not be reconstituted, indicating that gQ2 is essential for virus growth. These results show that gH, gL, gQ1, and gQ2 are all essential for the trafficking and proper folding of the gH/gL/gQ1/gQ2 complex and, thus, for HHV-6 infection.

Alphaherpesviruses and the cytoskeleton in neuronal infections

Following infection of exposed peripheral tissues, neurotropic alphaherpesviruses invade nerve endings and deposit their DNA genomes into the nuclei of neurons resident in ganglia of the peripheral nervous system. The end result of these events is the establishment of a life-long latent infection. Neuroinvasion typically requires efficient viral transmission through a polarized epithelium followed by long-distance transport through the viscous axoplasm. These events are mediated by the recruitment of the cellular microtubule motor proteins to the intracellular viral particle and by alterations to the cytoskeletal architecture. The focus of this review is the interplay between neurotropic herpesviruses and the cytoskeleton.

Comparative study on the in vitro and in vivo properties of two bovine herpesvirus-5 reference strains

BACKGROUND

Bovine herpesvirus 5 (BoHV-5) is an alphaherpesvirus responsible for meningoencephalitis in young cattle and it is antigenically and genetically related to bovine herpesvirus 1. BoHV-5 outbreaks are sporadic and restricted in their geographical distribution, being mostly detected in the Southern hemisphere. The N569 and A663 strains are prototypes of the "a" and "b" subtypes of BoHV-5, however, scarce information about their in vitro and in vivo properties is currently available.

METHODS

For the in vitro comparison between BoHV-5 A663 and N569 strains, viral growth kinetics, lysis and infection plaque size assays were performed. Additionally, an experimental infection of cattle with BoHV-5 A663 and N569 strains was carried out. Viral excretion, development of neurological signs, presence of specific antibodies in serum and nasal swabs and presence of latent BoHV-5 DNA in trigeminal ganglion, were analyzed. Histopathological examination of samples belonging to inoculated animals was also performed.

RESULTS

The lytic capacity and the cell-to-cell spread was lower for the A663 strain compared to the N569 strain, however, the production of total infectious viral particles was similar between both strains. Concerning the in vivo properties, the A663 and N569 strains are able to induce similar degrees of pathogenicity in cattle.

CONCLUSIONS

Our results show that the A663 strain used in this study is less adapted to in vitro replication in MDBK cells than the N569 strain and, although slight differences were observed, both strains are able to induce a similar degree of virulence in the natural host.

Systemic herpesvirus and morbillivirus co-infection in a striped dolphin (Stenella coeruleoalba)

During 2007 a dolphin morbillivirus epizootic affected the western Mediterranean and several striped dolphins (Stenella coeruleoalba) stranded on the Catalonian coasts. One of those animals had severe lymphoid depletion, necrosis and syncytial formation in lymph nodes and spleen, with large basophilic nuclear inclusions compatible with herpesvirus detected by immunohistochemical and ultrastructural examination. Non-suppurative encephalitis with associated morbillivirus antigen and morbillivirus antigen within alveolar macrophages were also observed. A pan-herpesvirus nested polymerase chain reaction amplified a sequence virtually identical to two cetacean herpesvirus sequences previously identified in systemic infections in an Atlantic Cuvier's beaked whale (Ziphius cavirostris) and in a Mediterranean striped dolphin. The herpesviral infection was probably secondary to the immunosuppression caused by the morbillivirus. To our knowledge, this is the first report of a cetacean co-infected by dolphin morbillivirus and herpesvirus with evidence of lesions attributable to both viruses.

Molecular identification of novel alpha- and gammaherpesviruses from cetaceans stranded on Japanese coasts

Herpesviral infections have been documented in some cetaceans; however, they have not yet been identified in species in the western North Pacific. In the present study, 178 tissue samples from 76 stranded cetacean individuals were tested for the presence of herpesviruses. Herpesvirus genomic DNA fragments surrounding the DNA polymerase gene were amplified in samples from four individuals. TA cloning and direct sequencing of these DNA fragments revealed the presence of two novel alphaherpesviruses, and two novel gammaherpesviruses in the four cetacean individuals. The alphaherpesviruses were associated with the lung tissue of a false killer whale (Pseudorca crassidens), and with the mucus of a melon-headed whale (Peponocephala electra). The gammaherpesviruses were found in the lymph tissues of a Stejneger's beaked whale (Mesoplodon stejnegeri) and a sperm whale (Physeter macrocephalus). The phylogenetic tree using amino acid sequences of the DNA polymerase gene supported the inclusion of the novel viruses identified here in a single monophyletic group containing alphaherpesviruses from other Atlantic cetacean species. Conversely, the novel gammaherpesviruses formed an independent clade distant from other known cetacean gammaherpesviruses.

Different linkages in the long and short regions of the genomes of duck enteritis virus Clone-03 and VAC strains

BACKGROUND

Duck enteritis virus (DEV) is an unassigned member in the family Herpesviridae. To demonstrate further the evolutionary position of DEV in the family Herpesviridae, we have described a 42,897-bp fragment. We demonstrated novel genomic organization at one end of the long (L) region and in the entire short (S) region in the Clone-03 strain of DEV.

RESULTS

A 42,897-bp fragment located downstream of the LOFR11 gene was amplified from the Clone-03 strain of DEV by using 'targeted gene walking PCR'. Twenty-two open reading frames (ORFs) were predicted and determined in the following order: 5'-LORF11-RLORF1-ORF1-ICP4-S1-S2-US1-US10-SORF3-US2-MDV091.5-like-US3-US4-US5-US6-US7-US8-ORFx-US1-S2-S1-ICP4 -3'. This was different from that of the published VAC strain, both in the linkage of the L region and S region, and in the length of the US10 and US7 proteins. The MDV091.5-like gene, ORFx gene, S1 gene and S2 gene were first observed in the DEV genome. The lengths of DEV US10 and US7 were determined to be 311 and 371 amino acids, respectively, in the Clone-03 strain of DEV, and these were different from those of other strains. The comparison of genomic organization in the fragment studied herein with those of other herpesviruses showed that DEV possesses some unique characteristics, such as the duplicated US1 at each end of the US region, and the US5, which showed no homology with those of other herpesviruses. In addition, the results of phylogenetic analysis of ORFs in the represented fragment indicated that DEV is closest to its counterparts VZV (Varicellovirus) and other avian herpesviruses.

CONCLUSION

The molecular characteristics of the 42,897-bp fragment of Clone-03 have been found to be different from those of the VAC strain. The phylogenetic analysis of genes in this region showed that DEV should be a separate member of the subfamily Alphaherpesvirinae.

Detection and differentiation of bovine herpesvirus 1 and 5 using a multiplex real-time polymerase chain reaction

A multiplex real-time PCR was developed for the detection and differentiation of two closely related bovine herpesviruses 1 (BoHV-1) and 5 (BoHV-5). The multiplex real-time PCR combines a duplex real-time PCR that targets the DNA polymerase gene of BoHV-1 and BoHV-5 and a real-time PCR targeting mitochondrial DNA, as a house-keeping gene, described previously by Cawthraw et al. (2009). The assay correctly identified 22 BoHV-1 and six BoHV-5 isolates from the Biosecurity Sciences Laboratory virus collection. BoHV-1 and BoHV-5 were also correctly identified when incorporated in spiked semen and brain tissue samples. The detection limits of the duplex assay were 10 copies of BoHV-1 and 45 copies of BoHV-5. The multiplex real-time PCR had reaction efficiencies of 1.04 for BoHV-1 and 1.08 for BoHV-5. Standard curves relating Ct value to template copy number had correlation coefficients of 0.989 for BoHV-1 and 0.978 for BoHV-5. The assay specificity was demonstrated by testing bacterial and viral DNA from pathogens commonly isolated from bovine respiratory and reproductive tracts. The validated multiplex real-time PCR was used to detect and differentiate BoHV-1 and BoHV-5 in bovine clinical samples with known histories.

First complete genome sequence of infectious laryngotracheitis virus

BACKGROUND

Infectious laryngotracheitis virus (ILTV) is an alphaherpesvirus that causes acute respiratory disease in chickens worldwide. To date, only one complete genomic sequence of ILTV has been reported. This sequence was generated by concatenating partial sequences from six different ILTV strains. Thus, the full genomic sequence of a single (individual) strain of ILTV has not been determined previously. This study aimed to use high throughput sequencing technology to determine the complete genomic sequence of a live attenuated vaccine strain of ILTV.

RESULTS

The complete genomic sequence of the Serva vaccine strain of ILTV was determined, annotated and compared to the concatenated ILTV reference sequence. The genome size of the Serva strain was 152,628 bp, with a G + C content of 48%. A total of 80 predicted open reading frames were identified. The Serva strain had 96.5% DNA sequence identity with the concatenated ILTV sequence. Notably, the concatenated ILTV sequence was found to lack four large regions of sequence, including 528 bp and 594 bp of sequence in the UL29 and UL36 genes, respectively, and two copies of a 1,563 bp sequence in the repeat regions. Considerable differences in the size of the predicted translation products of 4 other genes (UL54, UL30, UL37 and UL38) were also identified. More than 530 single-nucleotide polymorphisms (SNPs) were identified. Most SNPs were located within three genomic regions, corresponding to sequence from the SA-2 ILTV vaccine strain in the concatenated ILTV sequence.

CONCLUSIONS

This is the first complete genomic sequence of an individual ILTV strain. This sequence will facilitate future comparative genomic studies of ILTV by providing an appropriate reference sequence for the sequence analysis of other ILTV strains.

A recombinant bovine herpesvirus 5 defective in thymidine kinase and glycoprotein E is immunogenic for calves and confers protection upon homologous challenge and BoHV-1 challenge

A recombinant bovine herpesvirus 5 lacking thymidine kinase and glycoprotein E genes (BoHV-5gEΔTKΔ) was evaluated as a live experimental vaccine. In a first experiment, ten-months-old calves were vaccinated intramuscularly (n=9) or remained as controls (n=8) and 42 days later were challenged with BoHV-5 or BoHV-1 intranasally. The four control calves challenged with BoHV-5 developed severe depression and neurological signs and were euthanized in extremis at days 13 and 14 pos-infection (pi); the five vaccinated animals challenged with BoHV-5 remained healthy. The titers of virus shedding were reduced (p<0.01) from days 3 to 7 post-infection (pi) in vaccinated animals. Control and vaccinated calves challenged with BoHV-1 presented mild transient respiratory signs; yet the magnitude of virus shedding was reduced (p<0.05) in vaccinated animals (days 5, 9 and 11pi). In a second experiment, young calves (100-120 days-old) were vaccinated (n=15) or kept as controls (n=5) and subsequently challenged with a BoHV-1 isolate. Control calves developed moderate to severe rhinitis and respiratory distress; two were euthanized in extremis at days 5 and 9 pi, respectively. In contrast, vaccinated animals were protected from challenge and only a few developed mild and transient nasal signs. The duration and titers of virus shedding after challenge were reduced (p<0.05) in vaccinated animals comparing to controls. In both experiments, vaccinated animals developed antibodies to gE only after challenge. These results demonstrate homologous and heterologous protection and are promising towards the use of the recombinant BoHV-5gEΔTKΔ in vaccine formulations to control BoHV-5 and BoHV-1 infections.

Characterization of BoHV-5 field strains circulation and report of transient specific subtype of bovine herpesvirus 5 in Argentina

Background

Bovine herpesvirus 5 (BoHV-5) is a member of the subfamily Alphaherpesvirinae responsible for meningo-encephalitis in young cattle. The first case of bovine meningo-encephalitis associated with a herpesvirus infection was reported in Australia. The current geographical distribution of BoHV-5 infection is mainly restricted to South America, especially Brazil and Argentina. Outbreaks of BoHV-5 are regularly observed in Argentina suggesting the circulation of the virus in the bovine population.

Results

Seventeen field strains of BoHV-5 isolated from 1984 to now were confirmed by differential PCR and subjected to restriction endonuclease analysis (REA). Viral DNA was cleaved with BstEII which allows the differentiation among subtypes a, b and non a, non b. According to the REA with BstEII, only one field strain showed a pattern similar to the Argentinean A663 strain (prototype of BoHV-5b). All other isolates showed a clear pattern similar to the Australian N569 strain (prototype of BoHV-5a) consistent with the subtypes observed in Brazil, the other South-American country where BoHV-5 is known to be prevalent. The genomic region of subtype b responsible for the distinct pattern was determined and amplified by PCR; specifically a point mutation was identified in glycoprotein B gene, on the BstEII restriction site, which generates the profile specific of BoHV-5b.

Conclusions

This is the first report of circulation of BoHV-5a in Argentina as the prevailing subtype. Therefore the circulation of BoHV-5b was restricted to a few years in Argentina, speculating that this subtype was not able to be maintained in the bovine population. The mutation in the gB gene is associated with the difference in the restriction patterns between subtypes "a" and "b".

Characterization of the betaherpesviral pUL69 protein family reveals binding of the cellular mRNA export factor UAP56 as a prerequisite for stimulation of nuclear mRNA export and for efficient viral replication

UL69 of human cytomegalovirus (HCMV) encodes a pleiotropic transactivator protein and has a counterpart in every member of the Herpesviridae family thus far sequenced. However, little is known about the conservation of the functions of the nuclear phosphoprotein pUL69 in the homologous proteins of other betaherpesviruses. Therefore, eukaryotic expression vectors were constructed for pC69 of chimpanzee cytomegalovirus, pRh69 of rhesus cytomegalovirus, pM69 of murine cytomegalovirus, pU42 of human herpesvirus 6, and pU42 of elephant endotheliotropic herpesvirus. Indirect immunofluorescence experiments showed that all pUL69 homologs expressed by these vectors were localized to the cell nucleus. Coimmunoprecipitation experiments identified homodimerization as a conserved feature of all homologs, whereas heterodimerization with pUL69 was restricted to its closer relatives. Further analyses demonstrated that pC69 and pRh69 were the only two homologs that functioned, like pUL69, as viral-mRNA export factors. As we had reported recently that nucleocytoplasmic shuttling and interaction with the cellular DExD/H-box helicases UAP56 and URH49 were prerequisites for the nuclear-mRNA export activity of pUL69, the homologs were characterized with regard to these properties. Heterokaryon assays demonstrated nucleocytoplasmic shuttling for all homologs, and coimmunoprecipitation and mRNA export assays revealed that the interaction of UAP56 and/or URH49 with pC69 or pRh69 was required for mRNA export activity. Moreover, characterization of HCMV recombinants harboring mutations within the N-terminal sequence of pUL69 revealed a strong replication defect of viruses expressing pUL69 variants that were deficient in UAP56 binding. In summary, homodimerization and nucleocytoplasmic shuttling activity were identified as conserved features of betaherpesviral pUL69 homologs. UAP56 binding was shown to represent a unique characteristic of members of the genus Cytomegalovirus that is required for efficient replication of HCMV.

Equine herpesvirus 4: recent advances using BAC technology

The equine herpesviruses are major infectious pathogens that threaten equine health. Equine herpesvirus 4 (EHV-4) is an important equine pathogen that causes respiratory tract disease, known as rhinopneumonitis, among horses worldwide. EHV-4 genome manipulation with subsequent understanding of the viral gene functions has always been difficult due to the limited number of susceptible cell lines and the absence of small-animal models of the infection. Efficient generation of mutants of EHV-4 would significantly contribute to the rapid and accurate characterization of the viral genes. This problem has been solved recently by the cloning of the genome of EHV-4 as a stable and infectious bacterial artificial chromosome (BAC) without any deletions of the viral genes. Very low copy BAC vectors are the mainstay of present genomic research because of the high stability of inserted clones and the possibility of mutating any gene target in a relatively short time. Manipulation of EHV-4 genome is now feasible using the power of BAC technology, and should aid greatly in assessing the role of viral genes in the virus-host interaction.

A recombinant bovine herpesvirus 5 defective in thymidine kinase and glycoprotein E is attenuated and immunogenic for calves

Bovine herpesvirus 5 (BoHV-5) is an important pathogen of cattle in South America and efforts have been made to produce safer and more effective vaccines. In addition to afford protection, herpesvirus vaccines should allow serological differentiation of vaccinated from naturally, latently infected animals. We previously reported the construction and characterization in vitro of a double mutant BoHV-5 (BoHV-5gE/TK Δ) lacking the genes encoding thymidine kinase (tk) for attenuation, and glycoprotein E (gE) as the antigenic marker, as a vaccine candidate strain (Brum et al. 2010a). The present article reports an investigation on the attenuation and immunogenicity of this recombinant in calves. In a first experiment, 80 to 90-day-old seronegative calves (n=6) inoculated intranasally with the recombinant (titer of 10(7.5)TCID50) shed virus in low to moderate titers in nasal secretions for up to 6 days, yet did not develop any respiratory, systemic or neurological signs of infection. At day 30 post-infection (pi) all calves had BoHV-5 specific neutralizing (VN) antibodies in titers of 4 to 8 and were negative for anti-gE antibodies in a commercial ELISA test. Administration of dexamethasone (0.1mg/kg/day during 5 days) to four of these calves at day 42 pi did not result in virus shedding or increase in VN titers, indicating lack of viral reactivation. Secondly, a group of 8-month-old calves (n=9) vaccinated intramuscularly (IM) with the recombinant virus (10(7.5)TCID50/animal) did not shed virus in nasal secretions, remained healthy and developed VN titers from 2 to 8 at day 42 post-vaccination (pv), remaining negative for gE antibodies. Lastly, 21 calves (around 10 months old) maintained under field conditions were vaccinated IM with the recombinant virus (titer of 10(7.3)TCID50). All vaccinated animals developed VN titers from 2 to 16 at day 30 pv. A boost vaccination performed at day 240 pv resulted in a rapid and strong anamnestic antibody response, with VN titers reaching from 16 to 256 at day 14 post-booster. Again, serum samples remained negative for gE antibodies. Selected serum samples from vaccinated animals showed a broad VN activity against nine BoHV-5 and eight BoHV-1 field isolates. These results show that the recombinant virus is attenuated, immunogenic for calves and induces an antibody response differentiable from that induced by natural infection. Thus, the recombinant BoHV-5gE/TKΔ is an adequate candidate strain for a modified live vaccine.

The possible role of bovine herpesvirus type-4 infection in cow infertility

Experimental and field studies have proven that the bovine herpesvirus type-4 (BHV-4) infection leads to various reproductive system problems. In this study, the role of BHV-4 infection in repeat breeding was investigated serologically. Eighty-four samples were obtained from repeat-breeding diagnosed cows in two organized dairy herds; an equal number of healthy cows were sampled from the same farms. The rest of the samples (105) were obtained from reproductively normal cows that were breeding in 18 small enterprises as a control group. The seropositivity proportion in repeat-breeding diagnosed cows was found to be significantly higher (69% (58/84)) than other cows (44% (37/84)) on the same farms. The lowest antibody positivity value for BHV-4 was detected as 24.7% (26/105) in the samples from family-type small farms. The odds ratio (OR) value was calculated as 2.834 in repeat-breeding diagnosed and healthy cows on the same farms, while 6.778 was determined in cows with and without reproductive problems on organized farms compared to small farms. As a result, the BHV-4 infection can be considered one of the reasons for repeat breeding besides other reproductive disorders.

Transcriptional profiling of host gene expression in chicken embryo lung cells infected with laryngotracheitis virus

Background

Infection by infectious laryngotracheitis virus (ILTV; gallid herpesvirus 1) causes acute respiratory diseases in chickens often with high mortality. To better understand host-ILTV interactions at the host transcriptional level, a microarray analysis was performed using 4 × 44 K Agilent chicken custom oligo microarrays.

Results

Microarrays were hybridized using the two color hybridization method with total RNA extracted from ILTV infected chicken embryo lung cells at 0, 1, 3, 5, and 7 days post infection (dpi). Results showed that 789 genes were differentially expressed in response to ILTV infection that include genes involved in the immune system (cytokines, chemokines, MHC, and NF-κB), cell cycle regulation (cyclin B2, CDK1, and CKI3), matrix metalloproteinases (MMPs) and cellular metabolism. Differential expression for 20 out of 789 genes were confirmed by quantitative reverse transcription-PCR (qRT-PCR). A bioinformatics tool (Ingenuity Pathway Analysis) used to analyze biological functions and pathways on the group of 789 differentially expressed genes revealed that 21 possible gene networks with intermolecular connections among 275 functionally identified genes. These 275 genes were classified into a number of functional groups that included cancer, genetic disorder, cellular growth and proliferation, and cell death.

Conclusion

The results of this study provide comprehensive knowledge on global gene expression, and biological functionalities of differentially expressed genes in chicken embryo lung cells in response to ILTV infections.

Herpesvirus systematics

This paper is about the taxonomy and genomics of herpesviruses. Each theme is presented as a digest of current information flanked by commentaries on past activities and future directions. The International Committee on Taxonomy of Viruses recently instituted a major update of herpesvirus classification. The former family Herpesviridae was elevated to a new order, the Herpesvirales, which now accommodates 3 families, 3 subfamilies, 17 genera and 90 species. Future developments will include revisiting the herpesvirus species definition and the criteria used for taxonomic assignment, particularly in regard to the possibilities of classifying the large number of herpesviruses detected only as DNA sequences by polymerase chain reaction. Nucleotide sequence accessions in primary databases, such as GenBank, consist of the sequences plus annotations of the genetic features. The quality of these accessions is important because they provide a knowledge base that is used widely by the research community. However, updating the accessions to take account of improved knowledge is essentially reserved to the original depositors, and this activity is rarely undertaken. Thus, the primary databases are likely to become antiquated. In contrast, secondary databases are open to curation by experts other than the original depositors, thus increasing the likelihood that they will remain up to date. One of the most promising secondary databases is RefSeq, which aims to furnish the best available annotations for complete genome sequences. Progress in regard to improving the RefSeq herpesvirus accessions is discussed, and insights into particular aspects of herpesvirus genomics arising from this work are reported.

Presence of herpesvirus in striped dolphins stranded during the cetacean morbillivirus epizootic along the Mediterranean Spanish coast in 2007

A screening for herpesvirus (HV) was carried out using a tissue bank obtained from the cetacean morbillivirus (CeMV) mortality episode that occurred along the Mediterranean Spanish coast in 2007. A total of 14 cetaceans, including six long-finned pilot whales and eight striped dolphins, were studied using histopathology and molecular analysis to detect HV and CeMV. In five of the eight dolphins (62.5%) infected with CeMV, eight novel HV sequences were also detected. No HV lesions were found in any of the coinfected dolphins, which may indicate that HV did not contribute to the mortality in the CeMV outbreak. This is the first report of HV infection in any cetacean from the Mediterranean Sea.

Selection and characterization of brivudin resistant bovine herpesvirus type 5

Bovine herpesvirus type 5 (BoHV-5) is the agent of meningoencephalitis, an important disease of cattle in South America. The neuropathogenesis of BoHV-5 infection is poorly understood and most previous research focused on the role of envelope glicoproteins in neurovirulence. Thymidine kinase (TK) is a viral enzyme necessary for virus replication in neurons and, therefore, represents a potential target for virus attenuation. The selection and characterization of BoHV-5 variants resistant to the nucleoside analog brivudin (BVDU), which selects TK-defective viruses is here described. Several BVDU-resistant clones were obtained after multiple passages in tissue culture in the presence of BVDU and one clone (BoHV-5/R-27) was further characterized. The selected clone replicated to similar titers and produced plaques with similar size and morphology to those of wild-type virus (SV507/99). The genetic stability of the resistant virus was demonstrated after ten passages in cell culture in the absence of the drug. Moreover, the drug-resistant virus showed reduced virulence in a rabbit model: virus inoculation in four rabbits did not result in disease, in contrast with 75% morbidity (3/4) and 50% mortality (2/2) among rabbits inoculated with the parental virus. These results demonstrate that BoHV-5 is sensitive to BVDU and that drug-resistant mutants can be readily selected upon BVDU treatment. BVDU-resistant mutants, likely defective in TK, retained their ability to replicate in tissue culture yet were attenuated for rabbits. This strategy to obtain TK-defective BoHV-5 may be useful to study the role of TK in BoHV-5 neuropathogenesis and for vaccine development.

Acute and latent infection by bovine herpesvirus type 2 in a guinea pig model

Bovine herpetic mammillits is a self-limiting cutaneous disease of the udder and teats of cows associated with bovine herpesvirus 2 (BoHV-2) whose pathogenesis is poorly understood. This article describes the use of guinea pigs (Cavia porcellus) to study the pathogenesis of BoHV-2 infection. Twelve weanling female guinea pigs inoculated subcutaneously with BoHV-2 in the genitalia and teats developed local hyperemia, edema, vesicles, ulcers and scabs. Infectious virus was recovered between days 3 and 7 post-infection (pi) from the genital area (9/12) and teats (1/12); and all inoculated animals seroconverted (virus-neutralizing titers of 16-128). Histological examination of lesions revealed lymphoplasmacytic perivascular infiltrates and intranuclear inclusion bodies in keratinocytes. PCR examination of tissues collected at day 35 pi detected latent viral DNA predominantly in lumbosacral spinal segments. In another experiment, eight females inoculated with BoHV-2 in the genitalia and treated with dexamethasone (Dx) at day 35 pi developed mild to moderate local signs, yet no virus could be recovered from lesions. PCR examination of spinal segments from these animals confirmed the presence of latent viral DNA. These results demonstrate that guinea pigs are susceptible to BoHV-2 infection and therefore may be used to study selected aspects of BoHV-2 biology.

Neurological and epidemiological aspects of a BoHV-5 meningoencephalitis outbreak

Bovine herpesvirus 5 is a DNA virus that has been associated with meningoencephalitis in young cattle. While its clinical diagnosis is obscured by other major diseases that also produce similar neurological disease in cattle, the use of conventional virological techniques is hampered by the establishment of a lifelong latent infection in the host and the difficulty in differentiating BoHV-1 and BoHV-5. The aim of the current report is to describe the clinical and epidemiological aspects observed in a natural outbreak of BoHV-5 meningoencephalitis in a dairy cattle herd from Brazil. In the outbreak, the affected animals consisted of nine calves, which presented three possible forms of the neurological disease, subjectively classified as peracute, acute, and subacute/chronic. In contrast to conventional herpetic meningoencephalitis, characterized mainly by progressive multifocal brain dysfunctions, BoHV-5 infection resulted in focal non-progressive caudal brainstem dysfunction (pontomedullary syndrome) in an animal presented with subacute/chronic BoHV-5 meningoencephalitis. The evaluation of CNS tissue of affected calves through both histological examination and multiplex-PCR was able to confirm BoHV-5 infection. Additionally, the analysis of CSF samples through PCR allowed ante-mortem BoHV-5 diagnosis during the outbreak, which enabled the implementation of several measures of control for the disease.

Cervid herpesvirus 2 experimentally reactivated in reindeer can produce generalized viremia and abortion

Cervid herpesvirus 2 (CvHV2) has never been isolated from reindeer in Norway, but serological data and investigations by PCR indicate that the virus is endemic in the country, with horizontal and vertical transmission, systemic spread, and latency in the trigeminal ganglion. In this study two seropositive reindeer, one of which was pregnant, were administered dexamethasone, to reactivate CvHV2 latent infection. One control animal received sterile water. All animals including the control reactivated, as shown by amplification of CvHV2 DNA from nasal swabs. The pregnant animal showed lesions in the lip mucosa 10 days after the first dexamethasone injection and CvHV2 was visualized by electron microscopy and isolated from those lesions, as well as from nasal and vaginal swabs. On day 13 she aborted and CvHV2 was isolated from both the aborted calf and the mother. CvHV2 was isolated from the other animal administered dexamethasone. Despite amplification of viral DNA in the control animal, it was never possible to isolate the virus. Molecular characterization of the new isolates confirmed these to be CvHV2, and similar to the previous known strain Salla82. Present results represent the first isolation of CvHV2 in Norway and reconfirm that this virus can cause systemic infections in reindeer even after reactivation episodes, and infect the fetus in utero despite a prompt immune response. While it is not possible to atribute the abortion to CvHV2 alone, present data together with previous reports of vertical transmission of CvHV2 and neonatal death, point to an abortogenic potential, which should be further investigated.

Cloning and expression of a truncated form of envelope glycoprotein D of Bovine herpesvirus type 5 in methylotrophic yeast Pichia pastoris

Meningoencephalitis caused by Bovine herpesvirus type 5 (BoHV-5) is responsible for heavy economic losses in the cattle industry. As in other Alphaherpesviruses, the envelope glycoprotein IV (gD), which mediates penetration into host cells, is one of the major candidate antigens for a recombinant vaccine, since it induces a strong and persistent immune response. The DNA coding for a truncated form of BoHV-5 gD (tgD) has been cloned into the Pichia pastoris expression vector pPICZalphaB to allow protein secretion into the medium. After induction with methanol, a approximately 55kDa protein was obtained. Enzyme deglycosylation with Endo H showed a smaller size band in SDS-PGAE, with approximately 50kDa, suggesting that tgD has N-linked oligosaccharides and that it is not hyperglycosylated. The approximately 55kDa protein was recognized by several polyclonal antibodies, including polyclonal antibody anti-tgD and polyclonal antibodies of different animal species immunized with BoHV-5 and BoHV-1. This is the first report of BoHV-5 gD expression in yeast. It was shown that the recombinant truncated form of BoHV-5 gD has antigenic and immunogenic properties similar to the native BoHV-5 gD. Expression of tgD as a secreted protein allows simple and inexpensive purification methods that can be used for further studies to evaluate its immunogenicity in cattle.

Biology of bovine herpesvirus 5

Bovine herpesvirus 5 (BoHV-5) is an alphaherpesvirus responsible for meningoencephalitis in young cattle and is closely antigenically and genetically related to bovine herpesvirus 1 (BoHV-1). Both viruses have common aspects in their pathogenesis: (1) they infect epithelial cells at the portal of entry and (2) they establish a latent infection in the sensory nerve ganglia, i.e., the trigeminal ganglia. However, they have different neuroinvasion and neurovirulence capacities. Only in rare cases can BoHV-1 reach the brain of infected cattle. BoHV-5 infection induces different degrees of severity of neurological disease depending on both viral and host factors. Although a case of BoHV-5 associated disease in Europe and some outbreaks in USA and Australia have been reported, the current geographical distribution of BoHV-5 infection is mainly restricted to South America, especially Brazil and Argentina. This review focuses on the genomic characteristics, pathobiology and epidemiology of BoHV-5, in order to provide information on the possible basis of alphaherpesvirus neuropathogenesis.

A four year longitudinal sero-epidemiological study of bovine herpesvirus type-1 (BHV-1) in adult cattle in 107 unvaccinated herds in south west England

Background

Bovine herpesvirus type-1 (BHV-1) is an important pathogen of cattle that presents with a variety of clinical signs, including the upper respiratory tract infection infectious bovine rhinotracheitis (IBR). A seroepidemiological study of BHV-1 antibodies was conducted in England from 2002 – 2004: 29,782 blood samples were taken from 15,736 cattle from 114 herds which were visited on up to three occasions. Antibody concentration was measured using a commercial ELISA. Farm management information was collected using an interview questionnaire, and herd size and cattle movements were obtained from the cattle tuberculosis testing database and the British Cattle Movement Service. Hierarchical statistical models were used to investigate associations between cattle and herd variables and the continuous outcome percentage positive (PP) values from the ELISA test in unvaccinated herds.

Results

There were 7 vaccinated herds, all with at least one seropositive bovine. In unvaccinated herds 83.2% had at least one BHV-1 seropositive bovine, and the mean cattle and herd BHV-1 seroprevalence were 42.5% and 43.1% respectively. There were positive associations between PP value, age, herd size, presence of dairy cattle. Adult cattle in herds with grower cattle had lower PP values than those in herds without grower cattle. Purchased cattle had significantly lower PP values than homebred cattle, whereas cattle in herds that were totally restocked after the foot-and-mouth epidemic in 2001 had significantly higher PP values than those in continuously stocked herds. Samples taken in spring and summer had significantly lower PP values than those taken in winter, whereas those taken in autumn had significantly higher PP values than those taken in winter. The risks estimated from a logistic regression model with a binary outcome (seropositive yes/no) were similar.

Conclusion

The prevalence of BHV-1 seropositivity in cattle and herds has increased since the 1970s. Although the study population prevalence of BHV-1 was temporally stable during study period, the associations between serological status and cattle age, herd size, herd type, presence of young stock and restocked versus continuously stocked herds indicate that there is heterogeneity between herds and so potential for further spread of BHV-1 within and between herds.

Distribution of latent bovine herpesvirus 2 DNA in tissues of experimentally infected sheep

The biology of latent infection by bovine herpesvirus 2 (BoHV-2), the agent of mammillitis in cows, remains largely unknown. We herein report attempts to reactivate the latent infection and investigated the sites of BoHV-2 latency in experimentally infected sheep. Ewes inoculated with BoHV-2 in the udder's skin shed virus for up to five days, developed mammillitis and seroconverted. However, attempts to reactivate latent infection by dexamethasone administration at day 40 pi failed. Nevertheless, viral DNA--and not infectious virus--was detected by PCR in several nerve ganglia and/or regional lymph nodes (LNs) of all animals at day 40 post-reactivation. Likewise, lambs previously inoculated with BoHV-2 in the nose harbored latent viral DNA in trigeminal ganglia, tonsils and regional LNs. These results demonstrate that BoHV-2 establishes latent infection in nerve ganglia and in regional lymphoid tissues, yet virus reactivation is not easily achieved by standard protocols used.

The order Herpesvirales

The taxonomy of herpesviruses has been updated by the International Committee on Taxonomy of Viruses (ICTV). The former family Herpesviridae has been split into three families, which have been incorporated into the new order Herpesvirales. The revised family Herpesviridae retains the mammal, bird and reptile viruses, the new family Alloherpesviridae incorporates the fish and frog viruses, and the new family Malacoherpesviridae contains a bivalve virus. Three new genera have been created in the family Herpesviridae, namely Proboscivirus in the subfamily Betaherpesvirinae and Macavirus and Percavirus in the subfamily Gammaherpesvirinae. These genera have been formed by the transfer of species from established genera and the erection of new species, and other new species have been added to some of the established genera. In addition, the names of some nonhuman primate virus species have been changed. The family Alloherpesviridae has been populated by transfer of the genus Ictalurivirus and addition of the new species Cyprinid herpesvirus 3. The family Malacoherpesviridae incorporates the new genus Ostreavirus containing the new species Ostreid herpesvirus 1.

Evolution of the G+C Content Frontier in the Rat Cytomegalovirus Genome

Within the 230138 bp of the rat cytomegalovirus (RCMV) genome, the G+C content changes abruptly at position 142644, constituting a G+C content frontier. To the left of this point, overall G+C content is 69.2%, and to the right it is only 47.6%. A region of extremely low G+C content (33.8%) is found in the 5 kb immediately to the right of the frontier, in which there are no predicted coding sequences. To the right of position 147501, the G+C content rises and predicted coding sequences reappear. However, these genes are much shorter (average 848 bp, 50% G+C) than those in the left two-thirds of the genome (average 1462 bp, 70% G+C). Whole genome alignment of several viruses indicates that the initial ultra-low G+C region appeared in the common ancestor of the genera Cytomegalovirus and Muromegalovirus, and that the lowering of G+C in the right third has been a subsequent process in the lineage leading to RCMV. The left two-thirds of RCMV has stop codon occurrences at 67.5% of their expected level, based on a modified Markov chain model of stop codon distribution, and the corresponding figure for the right third is 78%. Therefore, despite heavy mutation pressure, selective constraint has operated in the right third of the RCMV genome to maintain a degree of gene length unusual for such low G+C sequences.

Neurological Disease in Cattle in Southern Brazil Associated with Bovine Herpesvirus Infection

The occurrence of neurological disease in cattle caused by Bovine herpesvirus in 11 farms from southern Brazil between 1987 and 2007 is described. Twenty-two animals were necropsied. Major clinical signs included excessive salivation, nasal and ocular discharge, circling, recumbency, depression, incoordination, grinding of teeth, and paddling movements. Necropsy findings in 10 of 22 cattle included hyperemia and softening of the rostral portions of the telencephalic cortex, with flattening of gyri, and malacia. Cattle in 10 cases did not show any gross lesions. Histological examination in most cases revealed nonsuppurative and necrotizing meningoencephalitis with acute neuronal necrosis, edema, eosinophilic intranuclear inclusion bodies in astrocytes and neurons, and infiltration of gitter cells. No histologic lesions could be detected in 4 cases. The initial diagnosis was based upon the clinical, epidemiological, and pathological findings. The diagnosis was confirmed by virus isolation in cell culture followed by virus identification by a glycoprotein C–based polymerase chain reaction. Seven isolates were identified as Bovine herpesvirus 5, and 4 were identified as Bovine herpesvirus 1.

Herpes virus antibodies seroprevalence in children with autoimmune thyroid disease

BACKGROUND

Elevated titers of antibodies against different herpes virus antigens have been reported in some immunodeficient and systemic autoimmune disorders.

OBJECTIVE

To examine if Herpes Simplex Virus (HSV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV) IgG and IgM antibodies are detected more frequently in children with autoimmune thyroid disease (AITD) compared to controls.

SUBJECTS AND METHODS

Thirty-four children with AITD, aged 9.62 +/- 2.35 years, and 31 matched controls, aged 9.24 +/- 2.98 years, were studied.

RESULTS

The percentage of EBV IgG+ children with AITD was statistically higher than the percentage of EBV IgG+ controls (82.35% versus 51.61%, P = 0.008). The percentage of EBV IgG+ children with AITD and hypothyroidism was statistically higher than the percentage of EBV IgG+ children with AITD, without hypothyroidism (100% versus 70%, P = 0.024). No other statistically significant differences were observed in HSV-1+2, and CMV IgG or IgM antibodies between the subgroups of children studied.

CONCLUSIONS

EBV seroprevalence is higher in children with AITD compared to controls and the underlying pathology remains to be elucidated.

The presence of a deletion sequence in the BHV-1 UL49 homolog in a live attenuated vaccine for infectious bovine rhinotracheitis (IBR)

The difference between the attenuated live vaccine strain 758-43 and its parent virulent strain 758 was investigated genetically. These viruses were propagated in Madin-Darby bovine kidney cells, and viral DNA was obtained from the culture supernatants of the infected cells. Based on a previous report, a large deleted region would seem to exist in the Hind III J fragment located between nucleotide numbers 2439 and 11,270. Three pairs of primers were designed based on the complete BHV-1 DNA sequence. With one pair of primers used, the PCR products derived from strains 758 and LA resulted in fragment sizes of 1850 bp, whereas that from the vaccine strain was smaller than those from the virulent strains. The attenuated live vaccine strain, 758-43, lacked 652 bp in the PCR product region, accounting for approximately 84% of the coding region of the UL49 homolog gene of BHV-1. The present results provide a new and important information to distinguish the vaccine strain 758-43 clearly from wild-type BHV-1 isolates in Japan. The UL49 homolog gene seems to participate in pathogenicity in herpesvirus infections.

Caracterização clinicopatológica da mamilite aguda em ovelhas lactantes infectadas experimentalmente com o herpesvírus bovino 2

A mamilite causada pelo herpesvírus bovino tipo 2 (BoHV-2) possui importante repercussão sanitária em gado leiteiro de alguns países, mas a sua patogenia permanece pouco conhecida. Este trabalho descreve a reprodução e caracterização da mamilite aguda em ovelhas lactantes inoculadas com o BoHV-2 na pele do úbere e dos tetos. Cinco de oito ovelhas inoculadas desenvolveram extensas placas com necrose focal, pequenas vesículas e formação de crostas nos locais de inoculação. As lesões foram inicialmente observadas no 4º dia pós-inoculação (pi), progrediram em extensão e gravidade até os dias 7-8pi e posteriormente regrediram. O vírus foi isolado das lesões entre os dias 7 e 8 pi. Antígenos virais e partículas típicas de herpesvírus foram demonstrados por microscopia eletrônica em biópsias de lesões coletadas nos dias 5, 6 e 10pi. Os achados histológicos foram caracterizados por necrose epitelial, erosões e úlceras, com formação de células sinciciais e infiltrado inflamatório linfoplasmocitário na derme. Associadas a essas lesões observaram-se inclusões eosinofílicas intranucleares em células epiteliais, sinciciais e inflamatórias. Em um segundo experimento, 7 de 10 cordeiros inoculados na mucosa nasal desenvolveram hiperemia e descarga nasal, bem como vesículas e erosões no focinho. O vírus foi isolado das secreções nasais por até três dias e todos os cordeiros soroconverteram ao BoHV-2. Tentativas de reativar a infecção latente pela administração de dexametasona no 40º dia pi foram infrutíferas, pois não foram observados re-excreção viral, recrudescência clínica ou soroconversão. Esses resultados demonstram que ovelhas são susceptíveis à infecção experimental pelo BoHV-2 e desenvolvem lesões semelhantes às observadas em casos naturais de mamilite herpética. Além disso, esses resultados sugerem o uso dessa espécie animal como modelo para o estudo de vários aspectos da biologia da infecção pelo BoHV-2.

Phylogenetic comparison of the carboxy-terminal region of glycoprotein C (gC) of bovine herpesviruses (BoHV) 1.1, 1.2 and 5 from South America (SA)

Different types and subtypes of bovine herpesvirus 1 and 5 (BoHV-1 and BoHV-5) have been associated to different clinical conditions of cattle, in such a way that type/subtype differentiation has become an essential tool for understanding the pathogenesis and epidemiology of BoHV infections. In search for a genomic region that would allow a clear distinction between BoHV-1 and BoHV-5, the carboxy-terminal portion of glycoprotein C (gC), corresponding to residues 321-450 (BoHV-1) and 301-429 (BoHV-5) of 23 South American (SA) isolates (Brazil mostly) was amplified and sequenced. The nucleotide sequence alignments revealed levels of genomic similarity ranging from 98.7 to 99.8% among BoHV-1 isolates, 88.3 to 92% between BoHV-1/BoHV-5 and 96 to 99.7% among BoHV-5 isolates. At the amino acid level, sequence similarity varied ranging from 97.5 to 99.5% among BoHV-1, 77.5 to 84.4% between BoHV-1/BoHV-5 and 92.1 to 99.5% (BoHV-5/BoHV-5). The isolates could be clearly separated into BoHV-1.1, BoHV-1.2 and BoHV-5 after phylogenetic analysis. The results suggest that the phylogenetic analysis performed here can be used as a potential molecular epidemiological tool for herpesviruses.

Identificação e diferenciação de herpesvírus bovino tipos 1 e 5 isolados de amostras clínicas no Centro-Sul do Brasil, Argentina e Uruguai (1987-2006)

Os herpesvírus bovino tipos 1 e 5 (BoHV-1; BoHV-5) são genética e antigenicamente muito semelhantes e por isso são indistinguíveis pela maioria dos testes diagnósticos. Como o BoHV-1 tem sido classicamente associado com doença respiratória e genital, os herpesvírus isolados dessas enfermidades têm sido provisoriamente - e às vezes definitivamente - identificados como BoHV-1. Da mesma forma, os casos de infecção neurológica por herpesvírus em bovinos têm sido atribuídos em sua totalidade ao BoHV-5. Este trabalho relata a identificação de 40 amostras de herpesvírus isoladas de diferentes casos clínicos na região Centro-Sul do Brasil, Argentina e Uruguai entre 1987 e 2006, pelo uso de um PCR capaz de diferenciar esses vírus. As amostras identificadas como BoHV-1 (n=16) foram isoladas de doença respiratória (n=3), balanopostite e/ou vulvovaginite (n=3), do sêmen de touros saudáveis (n=5) e de casos doença neurológica (n=5). As amostras virais identificadas como BoHV-5 (n=24) foram em sua maioria isoladas de doença neurológica (n=21), mas também do sêmen de touros saudáveis (n=2) e do baço de um bezerro com doença sistêmica (n=1). Esses resultados demonstram que tanto o BoHV-1 como o BoHV-5 não estão estritamente associados às suas respectivas síndromes clínicas e que podem estar freqüentemente envolvidos em casos clínicos classicamente atribuídos ao outro vírus. Esses achados também reforçam a necessidade de se identificar corretamente os isolados de herpesvírus para um melhor conhecimento da sua patogenia e epidemiologia.

Molecular and antigenic characterization of Brazilian bovine herpesvirus type 1 isolates recovered from the brain of cattle with neurological disease

Bovine herpesviruses type 1 and 5 (BoHV-1 and BoHV-5) are closely related yet differ markedly in their neuropathogenic potential. BoHV-1 isolates have been associated with respiratory and genital disease whereas BoHV-5 has been consistently isolated from neurological infection. We report the characterization of five Brazilian BoHV-1 isolates associated with neurological disease, an unusual finding. All five viruses were isolated from the brain of cattle presenting neurological disease, yet prominent histological encephalitis was not observed in three cases. The isolated viruses were identified as BoHV-1 by a glycoprotein C gene-based PCR able to differentiate BoHV-1 from BoHV-5. The identity of the isolates was confirmed by nucleotide sequencing of the amplicons and by restriction analysis of PCR products from another gC region. Monoclonal antibody binding and cross-neutralization assays with BoHV-1 and BoHV-5 antisera showed a typical BoHV-1 antigenic profile. Lastly, inoculation of rabbits with these five BoHV-1 isolates did not result in neurological disease, contrasting with fatal meningoencephalitis produced by BoHV-5. Thus, the involvement of BoHV-1 in neurological disease of cattle is more frequent than previously reported, indicating the need for fast and precise means of differentiating it from BoHV-5. Likewise, the potential role of BoHV-1 in neurological infection in cattle should be further investigated.

Comparison of two methods used for monitoring low-copy cytomegalovirus infection in a patient with chronic myeloid leukemia after unrelated umbilical cord blood transplantation

Introduction:

Detection of human cytomegalovirus (CMV, HHV-5) DNA in clinical specimens is considered a cornerstone in the diagnosis of HHV-5 disease. The present study compared two quantitative methods used for diagnosing cytomegalovirus infection in a 21-year-old woman with chronic myeloid leukemia after an unrelated umbilical cord blood transplantation.

Materials and Methods:

Blood samples were tested for the presence of HHV-5 DNA using the LightCycler PCR, the quantitative Eclipse^® CMV DNA Detection Kit, and a qualitative in-house PCR assay using primers that amplify part of the HHV-5 MIE gene.

Results:

Results from samples containing a low cytomegalovirus load were more accurate with the LightCycler test than those obtained with the Eclipse^® test, which underestimated the viral load of samples containing low DNA copy numbers.

Conclusions:

These findings underline the value of novel PCR methods used in current therapeutic procedures and in monitoring antiviral therapy with nucleoside analogs. The high level of sensitivity, specificity, accuracy, and rapidity provided by the LightCycler instrument are favorable for the use of this system in the detection of HHV-5 DNA in clinical specimens.

Cytopathic herpesvirus infection in a green iguana (Iguana iguana)

A juvenile male green iguana (Iguana iguana) died 5 days following movement to a room 3-5 degrees C cooler than its previous housing. Gross necropsy lesions were limited to thin body condition. Histologically the animal had multifocal, random, moderate to severe, acute hepatocellular necrosis with intranuclear inclusion bodies at the periphery of the necrotic areas. Electron microscopy of the liver revealed icosahedral viral particles approximately 110 nm in diameter, consistent with a herpesvirus infection. Characteristics of the herpesvirus are similar to those described for iguanid herpesvirus 1.

Detection of respiratory herpesviruses in foals and adult horses determined by nested multiplex PCR

A nested multiplex PCR was developed as a rapid (<12h), sensitive test for the simultaneous identification of equine herpesviruses (EHV1, EHV4, EHV2 and EHV5) in clinical samples from horses. Peripheral blood and nasal swab (NS) samples from 205 weanling Thoroughbred foals on 6 different studs over 3 consecutive seasons and from 92 adult horses without clinical signs of respiratory disease were examined using direct multiplex PCR of clinical samples (direct PCR) and conventional cell culture with differentiation of EHV in cell cultures by multiplex PCR. Multiplex PCR proved a sensitive and specific technique for the detection of EHV in cell culture and clinical samples. The technique described appeared equally sensitive as one using a single set of primers for individual EHV but reduced labour and reagent costs. Cell cultures showing cytopathic effect (CPE) were always positive for EHV on PCR. EHV were also detected by multiplex PCR in 11 samples which failed to show CPE. By a combination of multiplex PCR and cell culture or direct multiplex PCR, the presence of up to three EHV in the same sample was detected. Overall, EHV5 was detected by direct multiplex PCR of peripheral blood mononuclear cells (PBMC) and/or NS samples from 78% of foals and 47% of adult horses. Repeated sampling or cell culture in combination with multiplex PCR and with the incorporation of IL-2 in culture medium increased the sensitivity for detection of EHV in PBMC and demonstrated that EHV5 DNA could be identified in PBMC from 89% of foals and 100% of adult horses. EHV2 was identified from approximately 30% of foals, but was more frequently identified in samples from 17 foals with mild respiratory disease and was isolated infrequently from adult horses. EHV1 and EHV4 were identified uncommonly in any population in the current study.

Presence of herpesviruses in middle ear fluid of children with otitis media with effusion

BACKGROUND

Otitis media with effusion (OME) is a disease that frequently occurs in children. Etiopathogenesis of the diseases has not been completely elucidated. There are limited numbers of studies on the presence of herpesviruses in otitis media cases with OME. The present study was undertaken to determine the rate of some herpesviruses in OME cases of children.

METHODS

A total of 92-middle ear fluids were collected from 51 children. The samples were analyzed using polymerase chain reaction (PCR) for detection of herpesviruses including Herpes simplex virus (HSV), cytomegalovirus (CMV), Varicella zoster virus (VZV), and Epstein-Barr virus (EBV).

RESULTS

PCR analysis of the 92 samples showed that genomes of EBV in 12 (13.04%), HSV in seven (7.60%), CMV in five (5.43%), and VZV in three (3.26%) were present. Two of these samples were positive for both HSV and EBV genomes. Therefore, 25 (27.17%) of the samples were determined to be infected with any of the herpesviruses tested.

CONCLUSIONS

In the present study, herpesviruses were determined at a high rate in middle ear fluids of children with OME. However, the present study is a preliminary study and more extensive studies, especially experimental studies, are required to elucidate the role of herpesviruses in pathogenesis of OME and whether there is a relation between rate of herpesviruses in OME cases, and the reactivation of latent infections.

Epidemiology and eradication of infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IBR/IPV) virus in Finland

Background

Infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IBR/IPV) is a significant disease among domestic and wild cattle. The BHV-1 infection was first detected in Finland in 1970; presumably it was imported in 1968. The infection reappeared in the large-scale bulk-tank milk surveillances which started in 1990, and was eradicated in 1994. Our aim is to describe the epidemiology of this infection in Finland, and its eradication.

Materials and methods

The official sources of pertinent information, the legal basis for the disease control and the serological methods for the detection of the infection are described.

Results and conclusion

Ten AI bulls were found to be seropositive in 1970–1971. The total number of herds with BHV-1 antibody positive animals in the large-scale surveillance in 1990 and subsequent epidemiological investigations in 1991 was five, and the total number of seropositive animals was 90. The five herds formed three epidemiological units; semen of at least one bull seropositive in 1971 had been used in each unit. This remained the only plausible route of infection in each of the three units. Using the 'test and slaughter' approach and total stamping out in one herd the infection was eradicated in 1994.

Acute and latent infection by bovine herpesvirus type 5 in experimentally infected goats

The ability of alphaherpesviruses to infect different ruminant species may have important implications for control/eradication efforts. Serological data indicate that goats may be naturally infected with bovine herpesviruses. To investigate the susceptibility of goats to bovine herpesvirus-5 (BoHV-5), 3-4-month-old kids were inoculated intranasally with each of three Brazilian BoHV-5 isolates (G1, n=8; G2, n=5; G3, n=5). The acute infection was characterized by virus shedding in nasal secretions for up to 14 days (titers up to 10(5.97)TCID(50)/mL), mild respiratory signs and conjunctivitis. All animals seroconverted to BoHV-5, developing virus neutralizing (VN) titers from 4 to 32 to the homologous viruses. At day 60 post inoculation (pi), two animals from each group were euthanized for tissue collection and the remaining goats were submitted to dexamethasone administration (0.4 mg kg(-1) for 5 days). Dexamethasone treatment resulted in virus reactivation in 9 out of 12 animals, as ascertained by virus shedding and/or by increase in VN titers. Virus shedding was detected in 8/12 animals and lasted from 1 to 9 days. Latent viral DNA was detected by PCR in the olfactory bulb and/or trigeminal ganglia of 6/6 goats euthanized at day 60 pi and in 12/12 animals euthanized 40 days post-dexamethasone. These results show that young goats are susceptible to BoHV-5 and may shed virus upon reactivation of latent infection. Thus, it is reasonable to expect that goats raised in close contact with cattle in areas where BoHV-5 is endemic may be infected and therefore should be considered potential reservoirs of the virus.