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)

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.

The distinction of serologically related ruminant alphaherpesviruses by the polymerase chain reaction (PCR) and restriction endonuclease analysis

The amplification and analysis of a 468bp fragment from the gB gene of the serologically related ruminant alphaherpesviruses bovine herpesvirus-1.1 and 1.2 (BHV-1.1 and BHV-1.2), caprine herpesvirus-1 (CapHV-1), cervine herpesvirus-1 (CerHV-1) and rangiferine herpesvirus-1 (RanHV-1) by PCR and restriction endonuclease analysis is described. As primers, 22bp oligomers selected from the BHV-1 gB gene sequences were used for the amplification of the DNA from the five viruses. The amplification product from each virus was analysed by the restriction endonuclease enzymes BglI, HinfI, SmaI and AvaI. The specific amplification obtained demonstrate the existence of the gB gene sequences for each of the five alphaherpesviruses. However, sequences from some of the fragments were found to be different from those predicted from the gB gene following restriction endonuclease analysis. All five amplification products generated the same number of fragments after digestion with HinfI except for two additional bands evident in CapHV-1. The CerHV-1 and RanHV-1 fragments contained slightly different BglI restriction sites from those of the other three. While BHV-1.1, BHV-1.2, CapHV-1 and CerHV-1 contained SmaI and AvaI restriction sites, the RanHV-1 amplification product lacked both SmaI and AvaI restriction sites.

Herpesvirus ICP18.5 and DNA-binding protein genes are conserved in equine herpesvirus-1

The genome of equine herpesvirus-1 (EHV-1) contained three open reading frames (ORFs) in a 3.9 kbp BamHI-SmaI fragment at 0.38-0.41 map units in the long unique region. The most 5' ORF encoded the carboxy terminus of a protein with 45-55 percent amino acid homology to the DNA-binding proteins (ICP8-DBP) of four other alpha-herpesviruses. The middle ORF translated to a polypeptide of 775 residues with 43-55% homology to the ICP18.5 proteins. The most 3' ORF encoded the EHV-1 glycoprotein B (gB) gene. Three mRNAs of 4.3, 4.4-4.8, and 3.5-3.9 kb (corresponding to the three sequenced ORFs) were all transcribed from the same strand. The gene order of this group was conserved in all herpesviruses examined.

Interactions of bovine and caprine herpesviruses with the natural and the foreign hosts

Bovine herpesvirus 1 (BHV1) and caprine herpesvirus 1 (CapHV1) are useful models to study virus-host interactions, as well as pathogenicity and latency, when comparing the outcome of infection in the natural and the foreign hosts. Molecular seroepidemiological analyses revealed that cross-reacting antibodies were mainly induced by glycoprotein gI (gB analogue), by the major capsid protein and by nonstructural proteins, whereas the most virus-specific antibodies were elicited by glycoproteins gIII and gIV. These glycoproteins, especially gIII (gC analogue), might therefore play an important role in the virus-host-interactions. As a basis for further studies, we re-evaluated observations concerning experimental infections with BHV1 and CapHV1 in the natural and the foreign hosts. All parameters indicated that both viruses were able to infect either host, but that the pathogenicity was restricted to the natural host. Latent virus could be reactivated exclusively from cows infected with BHV1. It was possible neither to reactivate BHV1 from goats, nor to reactivate CapHV1 from either species. The experiments indicated that the outcome of infection in the natural and the foreign host is dependent on host and viral factors, whereby gIII is only one important virus component involved. Further investigations in the host and host cell range of BHV1 and CapHV1 will help to clarify the role of factors responsible for virus-host-interactions.

Nucleotide sequence of the gene encoding infectious laryngotracheitis virus glycoprotein B

The nucleotide sequence of the infectious laryngotracheitis virus (ILTV) gene encoding the 205K complex glycoprotein (gp205) was determined. The gene is contained within a 3-kb EcoRI restriction fragment mapping at approximately map coordinates 0.23 to 0.25 in the UL region of the ILTV genome and is transcribed from right to left. Nucleotide sequence analysis of the DNA fragment identified a single, long open reading frame capable of encoding 873 amino acids. The predicted precursor polypeptide derived from this open reading frame would have a calculated Mr of 98,895 Da and contains nine potential glycosylation sites. Hydropathic analysis indicates the presence of an amino terminal hydrophobic sequence and hydrophobic carboxyl terminal domain which may function as a signal peptide and a membrane anchor sequence, respectively. Comparison of the predicted ILTV gp205 protein sequence with those of other herpesviruses revealed a significant sequence similarity with gB-like glycoproteins. Extensive homology was observed throughout the molecule except for the amino and carboxyl termini. The high homology in predicted primary and secondary structures is consistent with the essential role of the gB family of proteins for viral infectivity and pathogenesis.

Immunological relationship between feline herpesvirus type 1 (FHV-1) and canine herpesvirus (CHV) as revealed by polyvalent and monoclonal antibodies

Polyvalent and monoclonal antibodies were used to demonstrate serological and antigenic relationships between feline herpesvirus type 1 (FHV-1) and canine herpesvirus (CHV). Using virus neutralization tests, enzyme-linked immunosorbent and indirect immunofluorescence assays, and immunoblotting analysis, reciprocal cross-reactivities to the heterologous virus were observed with some polyvalent and monoclonal antibodies. One monoclonal antibody against CHV neutralized FHV-1 infectivity and one monoclonal antibody against FHV-1 inhibited the hemagglutination activity of CHV as well as FHV-1-infected mouse serum. The major cross-reacting proteins were identified as the 143/108 kDa and 60 kDa glycoproteins of FHV-1 and the 145/112 kDa and 41 kDa glycoproteins of CHV. Previously, we have identified the 60 kDa and 41 kDa glycoproteins as the hemagglutinins of FHV-1 and CHV, respectively. The present results indicated the presence of shared antigenic determinants among these proteins.

Conserved epitopes of simian herpesvirus SA 8 and bovine herpesvirus type 2

Some major structural components of simian herpesvirus SA 8 were analyzed and the relationship of SA 8 with HSV-1 and especially with BHV-2 was further characterized using a panel of SA 8- and BHV-2-specific monoclonal antibodies directed against gB, gD, gE, and ICP 8. It could be shown that SA 8 and BHV-2 expressed gB-1 equivalents, which differ in electrophoretic mobility, but share common epitopes with HSV-1. The antigenic determinants were detectable in the cytoplasm, on the surface of infected cells and on the virus envelope. Monoclonal antibodies reactive with epitopes of gB-SA 8 and gB-BHV-2 neutralized the homologous virus and cross-neutralized only HSV-1 and HSV-2, suggesting differences in accessibility of the corresponding epitope on SA 8 and BHV-2, respectively. A second protein with conserved epitopes on SA 8, BHV-2, and HSV-1 was identified as ICP 8. This nucleus associated protein was additionally detected on the envelope of SA 8 and HSV-1. The results imply that ICP 8 might have a function not only in virus replication, but also in virus assembly. We could furthermore define type-specific epitopes on two SA 8 envelope proteins which are analogous to gD-1 and gE-1, respectively. The gD-specific epitope induced a type-specific neutralizing antibody, making it interesting for differentiation of closely related herpesviruses.

Compartment-specific immunolocalization of conserved epitopes of the glycoprotein gB of herpes simplex virus type 1 and bovine herpes virus type 2 in infected cells

Monoclonal antibodies directed against a surface glycoprotein of the bovine herpes virus type 2 (BHV-2, bovine herpes mammillitis virus) recognize also determinants of the major glycoprotein gB of the human herpes simplex virus type 1 (HSV-1). Cross-reacting antigens of the virions and in infected cells were localized with immunocytochemical methods, immunofluorescence as well as pre-embedding and cryoultramicrotomy immune electron microscopy. All antibodies stain to different degrees cell free BHV-2 and HSV-1 virions. In the cell two predominant staining patterns could be observed indicating that expression of epitopes is dependent upon the cell compartment: (i) staining of cytoplasmic membranes and enveloped particles within membrane systems and (ii) staining of intranuclear antigens. Antibodies tagging intranuclear antigens react with moderately dense material or with the periphery of nucleocapsids. This unexpected result is interpreted in terms of two hypotheses: (1) presence of common epitopes on two entirely different herpesvirus proteins conserved in HSV-1 and BHV-2 and (2) transport of gB or its precursor into the nucleus.