Varicellovirus UL 49.5 proteins differentially affect the function of the transporter associated with antigen processing, TAP

Cytotoxic T-lymphocytes play an important role in the protection against viral infections, which they detect through the recognition of virus-derived peptides, presented in the context of MHC class I molecules at the surface of the infected cell. The transporter associated with antigen processing (TAP) plays an essential role in MHC class I–restricted antigen presentation, as TAP imports peptides into the ER, where peptide loading of MHC class I molecules takes place. In this study, the UL49.5 proteins of the varicelloviruses bovine herpesvirus 1 (BHV-1), pseudorabies virus (PRV), and equine herpesvirus 1 and 4 (EHV-1 and EHV-4) are characterized as members of a novel class of viral immune evasion proteins. These UL49.5 proteins interfere with MHC class I antigen presentation by blocking the supply of antigenic peptides through inhibition of TAP. BHV-1, PRV, and EHV-1 recombinant viruses lacking UL49.5 no longer interfere with peptide transport. Combined with the observation that the individually expressed UL49.5 proteins block TAP as well, these data indicate that UL49.5 is the viral factor that is both necessary and sufficient to abolish TAP function during productive infection by these viruses. The mechanisms through which the UL49.5 proteins of BHV-1, PRV, EHV-1, and EHV-4 block TAP exhibit surprising diversity. BHV-1 UL49.5 targets TAP for proteasomal degradation, whereas EHV-1 and EHV-4 UL49.5 interfere with the binding of ATP to TAP. In contrast, TAP stability and ATP recruitment are not affected by PRV UL49.5, although it has the capacity to arrest the peptide transporter in a translocation-incompetent state, a property shared with the BHV-1 and EHV-1 UL49.5. Taken together, these results classify the UL49.5 gene products of BHV-1, PRV, EHV-1, and EHV-4 as members of a novel family of viral immune evasion proteins, inhibiting TAP through a variety of mechanisms

The class II membrane glycoprotein G of bovine respiratory syncytial virus, expressed from a synthetic open reading frame, is incorporated into virions of recombinant bovine herpesvirus 1

The bovine herpesvirus 1 (BHV-1) recombinants BHV-1/eG(ori) and BHV-1/eG(syn) were isolated after insertion of expression cassettes which contained either a genomic RNA-derived cDNA fragment (BHV-1/eG(ori)) or a modified, chemically synthesized open reading frame (ORF) (BHV-1/eG(syn)), which both encode the attachment glycoprotein G of bovine respiratory syncytial virus (BRSV), a class II membrane glycoprotein. Northern blot analyses and nuclear runoff transcription experiments indicated that transcripts encompassing the authentic BRSV G ORF were unstable in the nucleus of BHV-1/eG(ori)-infected cells. In contrast, high levels of BRSV G RNA were detected in BHV-1/eG(syn)-infected cells. Immunoblots showed that the BHV-1/eG(syn)-expressed BRSV G glycoprotein contains N- and O-linked carbohydrates and that it is incorporated into the membrane of infected cells and into the envelope of BHV-1/eG(syn) virions. The latter was also demonstrated by neutralization of BHV-1/eG(syn) infectivity by monoclonal antibodies or polyclonal anti-BRSV G antisera and complement. Our results show that expression of the BRSV G glycoprotein by BHV-1 was dependent on the modification of the BRSV G ORF and indicate that incorporation of class II membrane glycoproteins into BHV-1 virions does not necessarily require BHV-1-specific signals. This raises the possibility of targeting heterologous polypeptides to the viral envelope, which might enable the construction of BHV-1 recombinants with new biological properties and the development of improved BHV-1-based live and inactivated vector vaccines

Varicellovirus UL49.5 Proteins Differentially Affect the Function of the Transporter Associated with Antigen Processing, TAP

Cytotoxic T-lymphocytes play an important role in the protection against viral infections, which they detect through the recognition of virus-derived peptides, presented in the context of MHC class I molecules at the surface of the infected cell. The transporter associated with antigen processing (TAP) plays an essential role in MHC class I–restricted antigen presentation, as TAP imports peptides into the ER, where peptide loading of MHC class I molecules takes place. In this study, the UL49.5 proteins of the varicelloviruses bovine herpesvirus 1 (BHV-1), pseudorabies virus (PRV), and equine herpesvirus 1 and 4 (EHV-1 and EHV-4) are characterized as members of a novel class of viral immune evasion proteins. These UL49.5 proteins interfere with MHC class I antigen presentation by blocking the supply of antigenic peptides through inhibition of TAP. BHV-1, PRV, and EHV-1 recombinant viruses lacking UL49.5 no longer interfere with peptide transport. Combined with the observation that the individually expressed UL49.5 proteins block TAP as well, these data indicate that UL49.5 is the viral factor that is both necessary and sufficient to abolish TAP function during productive infection by these viruses. The mechanisms through which the UL49.5 proteins of BHV-1, PRV, EHV-1, and EHV-4 block TAP exhibit surprising diversity. BHV-1 UL49.5 targets TAP for proteasomal degradation, whereas EHV-1 and EHV-4 UL49.5 interfere with the binding of ATP to TAP. In contrast, TAP stability and ATP recruitment are not affected by PRV UL49.5, although it has the capacity to arrest the peptide transporter in a translocation-incompetent state, a property shared with the BHV-1 and EHV-1 UL49.5. Taken together, these results classify the UL49.5 gene products of BHV-1, PRV, EHV-1, and EHV-4 as members of a novel family of viral immune evasion proteins, inhibiting TAP through a variety of mechanisms

Structural and Functional Analysis of Bovine Herpesvirus 1 Minor Glycoproteins

This paper focuses on the structure and functions of bovine herpesvirus 1 minor glycoproteins gH, gE, gG and gp42. It reviews the progress which has been made in their identification and characterization, in the study of their temporal expression and processing in infected cells, and finally in the understanding of their biological activities. In addition, aspects discussed include a comparison with two other alphaherpesviruses, namely herpes simplex virus and pseudorabies virus

A Monoclonal Antibody-based Elisa Allows Discrimination Between Responses Induced By Bovine Herpesvirus Subtypes 1 (bohv-1.1) And 2 (bohv-1.2).

Bovine herpesvirus type 1 (BoHV-1) has distinct subtypes according to genomic characterization. Immune responses induced by BoHV-1 subtype 1 (BoHV-1.1) are not distinguishable from those induced by BoHV-1 subtype 2 (BoHV-1.2) through conventional serological methods. In the present report, an enzyme linked immunosorbent assay is described that allows discrimination between immune responses in cattle immunized with either subtype, based on a monoclonal antibody that recognizes specifically the amino-terminal region of glycoprotein C (gC) on BoHV-1.1 strains, thus not reacting with BoHV-1.2a. The test displayed a sensitivity of 92%, specificity of 90% and a good correlation with serum neutralization tests on samples from BoHV-1.1-immunized calves (kappa = 0.799). The test may be useful to provide new insights into the roles played by each of these two subtypes in the epidemiology of BoHV-1 infections.129191-

Binding of hematin to a new class of glutathione transferase from the blood-feeding parasitic nematode Haemonchus contortus.

The phase II detoxification system glutathione transferase (GST) is associated with the establishment of parasitic nematode infections within the gastrointestinal environment of the mammalian host. We report the functional analysis of a GST from an important worldwide parasitic nematode of small ruminants, Haemonchus contortus. This GST shows limited activity with a range of classical GST substrates but effectively binds hematin. The high-affinity binding site for hematin was not present in the GST showing the most identity, CE07055 from the free-living nematode Caenorhabditis elegans. This finding suggests that the high-affinity binding of hematin may represent a parasite adaptation to blood or tissue feeding from the host

The Capacity of UL49.5 Proteins To Inhibit TAP Is Widely Distributed among Members of the Genus Varicellovirus ▿ †

The lifelong infection by varicelloviruses is characterized by a fine balance between the host immune response and immune evasion strategies used by these viruses. Virus-derived peptides are presented to cytotoxic T lymphocytes by major histocompatibility complex (MHC) class I molecules. The transporter associated with antigen processing (TAP) transports the peptides from the cytosol into the endoplasmic reticulum, where the loading of MHC-I molecules occurs. The varicelloviruses bovine herpesvirus 1 (BoHV-1), pseudorabies virus, and equid herpesviruses 1 and 4 have been found to encode a UL49.5 protein that inhibits TAP-mediated peptide transport. To investigate to what extent UL49.5-mediated TAP inhibition is conserved within the family of Alphaherpesvirinae, the homologs of another five varicelloviruses, one mardivirus, and one iltovirus were studied. The UL49.5 proteins of BoHV-5, bubaline herpesvirus 1, cervid herpesvirus 1, and felid herpesvirus 1 were identified as potent TAP inhibitors. The varicella-zoster virus and simian varicellovirus UL49.5 proteins fail to block TAP; this is not due to the absence of viral cofactors that might assist in this process, since cells infected with these viruses did not show reduced TAP function either. The UL49.5 homologs of the mardivirus Marek's disease virus 1 and the iltovirus infectious laryngotracheitis virus did not block TAP, suggesting that the capacity to inhibit TAP via UL49.5 has been acquired by varicelloviruses only. A phylogenetic analysis of viruses that inhibit TAP through their UL49.5 proteins reveals an interesting hereditary pattern, pointing toward the presence of this capacity in defined clades within the genus Varicellovirus

Caracterização antigênica e molecular de oito amostras do vírus da doença de Aujeszky isoladas no estado do Rio Grande do Sul em 2003 Antigenic and molecular characterization of eight samples of Aujeszky's disease virus isolated in the state of Rio Grande do Sul, Brazil, in 2003

A doença de Aujeszky ou pseudoraiva (DA), causada pelo vírus da pseudoraiva (PRV) é a maior preocupação na produção de suínos. No estado do Rio Grande do Sul, Brasil, a DA foi somente detectada em 1954, em bovino. Em 2003, ocorreram dois surtos de encefalite em granjas na região norte do estado, fronteira com o estado de Santa Catarina. O vírus da doença de Aujeszky (VDA) foi isolado a partir de animais coletados em oito granjas distintas da região e submetido a análises antigênicas e moleculares. As amostras de VDA isoladas foram comparadas com as amostras padrão NIA-3 e NP. A caracterização antigênica dos mesmos foi realizada com testes de imunoperoxidase frente a um painel de anticorpos mono-clonais (Mabs) preparado contra epitopos de glicoproteinas virais (gB, gC, gD e gE). A caracterização genômica foi realizada através da análise restrição enzimática (REA) sobre o genoma total das amostras, com a enzima de restrição (REA) Bam HI. O perfil antigênico das oito amostras isoladas no Rio Grande do Sul, bem como os apresentados pelas amostras padrão NIA-3 e NP, foram similares. A REA revelou que todos as oito amostras do Rio Grande do Sul apresentaram um arranjo genômico do tipo II, genótipo frequentemente encontrado em surtos prévios de DA em outros estados do Brasil. Os resultados aqui obtidos indicam que as oito amostras isoladas no Rio Grande do Sul são similares.<br>Pseudorabies or Aujeszky's disease (AD), caused by pseudorabies virus (PRV) is a major concern in swine production. In the state of Rio Grande do Sul, Brazil, AD was only detected in 1954, in cattle. In 2003 two outbreaks of encephalitis occurred on the northern region of the state, close to the border with the state of Santa Catarina. Pseudorabies virus (PRV) was isolated from distinct farms within the region and subjected to antigenic and genomic analyses. These isolates were compared with prototype strains NIA-3 and NP. Antigenic characterization with a panel of monoclonal antibodies (Mabs) directed to viral glycoproteins (gB, gC, gD and gE,) was performed by an imunoperoxidase monolayer assay (IPMA) on infected cell monolayers. Genomic characterization was carried out by restriction enzyme analysis (REA) of the whole DNA viral genome with Bam HI. The antigenic profile of the eight isolates from Rio Grande do Sul as well as strains NIA-3 and NP were similar. REA analysis revealed that all isolates from Rio Grande do Sul displayed a genomic type II arrangement, a genotype often found in other outbreaks of AD previously reported in other Brazilian states. The results obtained suggest that the eight isolates examined here were similar