Use of a polymerase chain reaction assay to detect bovine herpesvirus type 2 DNA in skin lesions from cattle suspected to have pseudo-lumpy skin disease

Beef cattle from a herd in north Alabama were examined because of an outbreak of nonfatal skin disease characterized by discrete circumscribed areas of inflammation that developed on the skin from the neck to the hips. Areas of inflammation, which tended to be superficial, underwent necrosis and scabbed over. The scabs eventually dropped off leaving discrete, round, whitish, hairless lesions that were 1.2 to 2.5 cm diameter. Because clinical signs were consistent with those expected with pseudo-lumpy skin disease (PLSD) caused by bovine herpesvirus type 2 (BHV-2), samples from 16 representative animals were submitted for BHV-2 testing. All 16 animals were seropositive for BHV-2, but the virus could not be isolated from skin biopsy specimens or buffy coat samples. Results of a polymerase chain reaction assay incorporating primers designed to amplify 2 DNA sequences from BHV-2 were positive for 3 of the 10 cattle, suggesting that skin lesions in these cattle were a result of PLSD. Our findings suggest that PLSD may be more common and widespread in the United States than suggested by the frequency with which BHV-2 has been isolated from cattle with PLSD-like skin lesions.

Comparison of six Australian isolates of Bovine herpes virus 2 based on UL24 gene after a passage in MDBK cells

A region of the UL24 gene of six Australian field isolates of Bovine herpesvirus 2 (BHV-2) was sequenced after a passage in Madin-Darby bovine kidney (MDBK) cells by polymerase chain reaction (PCR). While the PCR product covered the first half of the UL24 gene, a particular interest was focused on the 274-297 nucleotide (nt) region in which a two nt deletion had previously been detected in the BHM-1 strain of BHV-2. Most isolates tested did not generate any defective UL24 genes during the passage. However, a third of the UL24 genes of BHM-1 strain contained the two nts deletion, but only when a high multiplicity of infection (MOI) was used. Also in the isolate 554 at least a half of the UL24 genes were found to be altered independently of the MOT used. These UL24 genes had an insertion of four nts within the 274-297 nt region. The predicted truncation of the UL24 protein of both viruses occurred at the same stop codon. The region of the gene in which these mutations of the UL24 gene occurred is common to all herpesviruses.

An unusual outbreak of malignant catarrhal fever in a beef herd in Israel

Malignant catarrhal fever (MCF. corrizza contagiosa) is an invariably fatal communicable disease in cattle, whose causative agent is the ovine herpes virus-2, or the alcelaphine herpes virus-1. In one feed-lot family farm, 34 calves out of 100 became ill at the rate of one to four calves per week, and all of them subsequently died over a period of 4 months. Most of the initial cases were manifested clinically as the head and eye form, but most of the entire clinical spectrum of forms (the respiratory, intestinal and nervous forms) characteristic for MCF were observed as this epidemic progressed. Very few calves died without showing any specific signs of MCF. Pathological examinations revealed characteristic obliterative arteriovasculitis in the brain of calves with nervous signs, typical of MCF. Polymerase chain reaction (PCR) testing revealed 100% homology between the 238 bp hemi-nested PCR fragment and the ovine herpes virus-2 sequences. Based on the clinical signs, epidemiological data, pathological, and histopathological findings, and the PCR results, it was concluded that MCF occurred on the farm. The fact that sheep and goats were housed in close proximity on the same farm reinforced this diagnosis.

Development of a shuttle polymerase chain reaction for the detection of bovine herpesvirus 2

Three different polymerase chain reaction (PCR) protocols were evaluated for their ability to detect bovine herpesvirus 2 (BoHV-2): single-step PCR with 3 reaction stages (denaturation, annealing and extension), 2 reaction stages (denaturation and annealing/extension; shuttle PCR), and semi-nested PCR with 3 reaction stages. All the PCR protocols showed the same sensitivity (detection limit of 0.4 TCID(50)). A non-specific band sometimes appeared in mock cell DNA at annealing temperatures below 64 degrees C. The shuttle PCR was found to be superior to the other protocols under consideration because of the speed of its application. Furthermore, no non-specific band was detected in DNAs of eight other DNA viruses. Thus, the shuttle PCR seems to be an excellent diagnostic tool for BoHV-2 infections.

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.

Nylon membrane-immobilized PCR for detection of bovine viruses

Bridge Technology is an amplification technique in which pairs of primers are immobilized on a solid support, allowing amplification only at the location of the primer pair spot. The technique has diagnostic potential since an array of primer pairs, each specific for a different pathogen, can be used with a diagnostic sample without inter-pair interactions that plague the development of multiplex PCRs. As a result, one assay should be able to determine which of multiple pathogens are present and which are absent in each sample. As test material, we examined the specificity of detection of the RNA-containing bovine viral diarrhea virus (BVDV) and two DNA-containing bovine herpesviruses 1 and 2 (BHV-1 and BHV-2). Nylon membranes with two spots of UV-immobilized primer pairs--one for BVDV and one for BHV--were used in amplification with both corresponding templates, with each template singly and with no template. When amplification was assayed by chemiluminescent detection of incorporated DIG-nucleotides, the expected amplification patterns were obtained.

Bovine herpesvirus type 2 is closely related to the primate alphaherpesviruses

Bovine herpesvirus type 2 (BoHV-2), also known as bovine mammillitis virus, is classified in the Family Herpesviridae, Subfamily Alphaherpesvirinae, and Genus Simplexvirus along with herpes simplex viruses type 1 and 2 (HSV-1 and HSV-2) and other primate simplexviruses on the basis of similarities in 4 genes within the 15 kb U(L) 23-29 cluster. This could be explained either by a global similarity or a recombination event that brought primate herpesviral sequences into a bovine virus. Our sequences for DNA polymerase (U(L)30), a large gene adjacent to the previously identified conserved cluster, and glycoprotein G (U(S)4), a gene as distant from the cluster as possible on the circularized genome, confirm the close relationship between BoHV-2 and the primate simplexviruses, and argue for a global similarity and probably a close evolutionary relationship. Thus one can speculate that BoHV-2 may represent a greater hazard to humans than has been appreciated previously.

Loss of thymidine kinase activity due to a base deletion in a candidate vaccine strain of bovine herpesvirus 2

The nucleotide (nt) sequence of the thymidine kinase (TK) gene (a 918 nt long coding region) of two TK-deficient (TK) strains of bovine herpesvirus 2 (BHV-2) was determined. The candidate vaccine strain C290BU5, which was no longer able to cause disease, was found to have an A deletion after nt 887 of the TK gene with a predicted change of His 296 to Pro, altering the last 10 amino acids (aa) and extending the gene by another 34 aa. The strain which still caused disease, C290BU3, had a T insertion after nt 16 causing a predicted chain termination after only 16 aa.

Glycoprotein E of bovine herpesvirus type 1 is involved in virus transmission by direct cell-to-cell spread

In order to identify the role of the bovine herpesvirus type 1 (BHV-1) glycoprotein E (gE) in the viral infection cycle, we have constructed a BHV-1 gE deletion mutant strain (BHV-1 gE-). This strain was assayed in vitro by comparing its growth kinetics with the wild type strain used as a host of the deletion. Our results indicate that those conditions which prevent the infection by direct adsorption to the cells (presence of a semi-solid medium or presence of neutralizing antibodies in the medium) selectively inhibit the growth of the gE- strain, suggesting that gE plays a central role in the BHV-1 spread by direct cell-to-cell transmission, a major mechanism of the BHV-1 in vivo virulence.

Efficacy of a deletion mutant bovine herpesvirus-1 (BHV-1) vaccine that allows serologic differentiation of vaccinated from naturally infected animals

Fifteen bovine herpesvirus-1 (BHV-1)-negative calves were vaccinated intramuscularly with 10(7.4) plaque-forming units of a double-deletion BHV-1 mutant (IBRV(NG)dltkdlgIII), and 6 remained as nonvaccinated controls. Thirty days after vaccination, the animals were challenged by nasal instillation of 10(8.2) CCID50 of a virulent BHV-1 strain (Cooper). The vaccinated calves were protected against wildtype virus challenge as demonstrated by clinical evaluation. Most of the vaccinates developed only a mild rhinitis (lasting an average of 6.5 days) with almost no systemic symptoms, whereas the controls developed a serious illness characterized by rhinitis (mean = 11.5 days), conjunctivitis, hyperthermia, apathy, loss of appetite, and dyspnea. The vaccinates also shed significantly less virus and for a shorter period of time (mean = 5.5 days) than the controls (mean = 9 days). Thirty days after vaccination, the vaccinates were negative in an anti-gIII specific blocking enzyme-linked immunosorbent assay (ELISA), despite the fact that most of them had developed neutralizing antibodies (serum neutralization titers ranging from 1:2 to 1:16). Seroconversion to gIII was detected as early as 7 days postinfection (dpi). Fourteen days after the challenge, all the animals exposed to wildtype BHV-1 had developed anti-gIII antibodies and were positive in this differential serologic test. Six controls plus 8 vaccinates kept in isolation were still positive to gIII when tested at 75 dpi. The use of the IBRV(NG)dltkdlgIII strain in conjunction with an anti-gIII specific blocking ELISA kit represents a powerful tool for BHV-1 control/eradication programs.

Location and characterization of the bovine herpesvirus type 2 thymidine kinase gene

The precise genomic location and the nucleotide sequence of the bovine herpesvirus type 2 (bovine herpes mammillitis virus) thymidine kinase (TK) gene have been determined. The genomic location of the TK gene was found to be in a similar position to that of herpes simplex virus. The coding region consists of 918 bases, which is slightly smaller in length than other reported herpesvirus TK genes. However with an Mr of 38,108 the individual protein is similar in size to other herpesvirus TK enzymes. Despite there being only limited overall sequence homology with the TK genes of other herpesviruses, there are several regions of extensive homology at the amino acid level.

Conservation of a gene cluster including glycoprotein B in bovine herpesvirus type 2 (BHV-2) and herpes simplex virus type 1 (HSV-1)

A library of subgenomic fragments of bovine herpesvirus type 2 (BHV-2) DNA was constructed in the expression cloning vector lambda gt11 and screened with monoclonal antibodies to the glycoprotein gb BHV-2, which is homologous to glycoprotein gB (gB-1) of herpes simplex virus type 1 (HSV-1). Lambda gt11 clones containing gB BHV-2-specific sequences were used to identify lambda EMBL3 vectors with DNA inserts which contained the complete gB BHV-2 gene. Nucleotide sequencing revealed that the gB BHV-2 gene is highly conserved compared to gB-1. The amino acid sequences and the predicted secondary structures of both glycoproteins are very similar. Two further open reading frames (ORF) in close vicinity to the gene encoding gB BHV-2 showed considerable homology to HSV-1 genes. They code for the major DNA-binding protein (dbp) of BHV-2 and a putative 72-kDa polypeptide. The gene of the latter protein corresponding to ICP18.5 of HSV-1 is interspersed between the ORFs of gB BHV-2 and the dbp of BHV-2. All three genes map in the unique long region of the genome. Their homology and the colinear arrangement compared to HSV-1 indicate a close relationship between the two viruses.

Common epitopes of glycoprotein B map within the major DNA-binding proteins of bovine herpesvirus type 2 (BHV-2) and herpes simplex virus type 1 (HSV-1)

Bovine herpesvirus 2 (BHV-2) specifies a glycoprotein of 130 kDa (gB BHV-2) which shows extensive homology to glycoprotein B (gB-1) of herpes simplex virus 1 (HSV-1). The BHV-2-specific 130-kDa glycoprotein is able to induce cross-reacting antibodies, some of which even cross-neutralize HSV-1. In order to determine the genome localization of gB BHV-2 and in order to identify conserved antigenic domains in both glycoproteins, we established libraries of subgenic fragments of BHV-2 and HSV-1 DNA in the prokaryotic expression vector lambda gt11 and screened them with cross-reacting monoclonal antibodies which allowed us to identify recombinant lambda gt11 clones expressing gB fusion protein. Nucleotide sequencing of inserted DNA fragments within these recombinant lambda gt11 clones revealed that they originated from the carboxy-terminal part of the major DNA-binding proteins (dbp) of BHV-2 (dbp BHV-2) and its counterpart ICP8 in HSV-1. Antisera raised against the beta-galactosidase fusion protein of recombinant phage lambda-113/2 coding for an 84 amino acid (aa) polypeptide originating from dbp BHV-2 neutralized infectivity of BHV-2 and HSV-1 in the presence of complement and precipitated [3H] glucosamine-labeled gB BHV-2 and gB-1. This antiserum also reacts with ICP8 and presumably with dbp BHV-2. Two hypotheses are discussed to explain this unexpected result: (i) epitopes in the carboxy-terminal part of gB BHV-2 and gB-1 are similar to antigenic determinants in the amino-terminal region of the gBs, thus providing cross-reacting antibody-binding sites; (iii) during gene expression a carboxy-terminal part of dbp BHV-2 and ICP8 genes might be spliced to the amino-terminal region of the glycoproteins gB BHV-2 and gB-1.

Genomic location of bovid herpesvirus type 2 nucleotide sequences homologous to five herpes simplex virus type 1 genes

The location of nucleotide sequences within the bovid herpesvirus 1 (BHV-2) genome homologous to herpes simplex virus 1 (HSV-1) DNA were investigated. BHV-2 DNA was digested with restriction endonucleases and blotted to nitrocellulose paper. The blots were then probed with plasmids containing HSV-1 genes for thymidine kinase (TK), the major DNA binding protein (ICP8), the major capsid protein (VP5) and genes for HSV-1 glycoproteins gB, gD, and gC. Except for HSV-1 gC, each HSV-1 gene tested hybridized to BHV-2 nucleotide sequences that were located either on both sides of a restriction endonuclease cleavage site, within a small restriction endonuclease fragment, or to an area common to two overlapping restriction fragments. Thus, we were able to localize BHV-2 nucleotide sequences homologous to the HSV-1 ICP8 gene between 0.38 and 0.41 map units (m.u.), and BHV-2 nucleotide sequences homologous to the HSV-1 VP5 gene between 0.24 and 0.27 m.u. In addition, BHV-2 nucleotide sequences homologous to HSV-1 genes for TK, gB and gD were found to lie on both sides of restriction endonuclease cleavage sites at 0.30, 0.35, and 0.94 m.u., respectively.

Studies of the major DNA binding proteins of two bovine herpes mammillitis virus isolates

Antigenic cross-reaction of the DNA-binding protein between herpes simplex virus type 2 (HSV-2) and two bovine herpes mammillitis virus (BHMV) isolates (BHM-1 and BHMV CSIRO 290) was demonstrated by indirect immunofluorescence. Southern blot analysis showed a region of homology between HSV-2 BglII O DNA (coding for the HSV-2 major DNA-binding protein) and BHMV XbaI DNA fragment N, suggesting a similar gene map unit position on both genomes.

The genome of bovine herpesvirus 1 (BHV-1) strains exhibiting a neuropathogenic potential compared to known BHV-1 strains by restriction site mapping and cross-hybridization

Bovine herpesvirus 1 (BHV-1) strains can be differentiated by their DNA and polypeptide patterns, and by antigenic properties as demonstrated by monoclonal antibodies. We classified the BHV-1 strains according to these data as BHV-1.1, BHV-1.2 (a/b) and BHV-1.3 (a/b). BHV-1.1 and BHV-1.2 correspond to the well known 'common' BHV-1 strains, whereas BHV-1.3 has only recently been recognized and exhibits a neuropathogenic potential. In the present paper we describe the structural genome characteristics of BHV-1.3 compared to those of the other BHV-1 strains, examined by means of restriction site mapping, electron microscopy and cross-hybridization. Our results also confirm and complete data concerning BHV-1.1 and BHV-1.2 published by other authors. The following main conclusions can be drawn from our investigations: BHV-1.1 and BHV-1.2 differences are restricted to distinct genomic regions, characterized by loss or gain of restriction sites. BHV-1.3, however, differs from the other BHV-1 strains in restriction site alterations throughout the whole genome. Electron microscopy showed the typical BHV-1 DNA structure for BHV-1.3. Genetic homology between BHV-1.1 and BHV-1.2, reported to be about 95%, was confirmed by cross-hybridization, and a similar high base sequence homology for BHV-1.3 could be shown.

Anatomy of bovine mammillitis DNA. I Restriction endonuclease maps of four populations of molecules that differ in the relative orientation of their long and short components

In this paper, we report that the DNA of bovine mammillitis virus (BMV) consists of two covalently linked components that are 71.5 x 10(6) and 15.7 x 10(6) in molecular weight and designated L and S, respectively. We further report that the BMV DNA consists of four equimolar populations differing only in the orientation of the L and S components relative to each other. This conclusion is based on the following: (i) The sum molecular weight of fragments generated by digestion of BMV DNA with Hsu I, Hpa I, Bgl II, or Xba I significantly exceeds the established molecular weight of the intact DNA. (ii) In each digest, the fragments form three groups differing in molar concentration. In reference to the molar concentration of intact DNA, each enzyme digest contained a set of four fragments 0.25 M in concentration, a set of four fragments 0.5 M in concentration, and a variable size set, unique for each enzyme digest, 1.0 M in concentration. (iii) Experiments involving digestion of intact DNA by lambda exonuclease followed by restriction endonuclease digestion established that each of four 0.5 M fragments were positioned at the termini of the BMV DNA. (iv) Complete maps for the fragments generated by each enzyme established that the 0.25 M fragments arise by fusion of the sequences of the terminal fragments when these are juxtaposed as a consequence of the inversion of L and S components. The maps also established the dimensions of the L and S components. We conclude that the structure of BMV DNA is similar to that of HSV DNA previously shown to consist of two unequal size components that invert relative to each other.