Equine Herpesvirus 1 Mutants Devoid of Glycoprotein B or M Are Apathogenic for Mice but Induce Protection against Challenge Infection

Self Cite

Key problems using viral vectors for vaccination and gene therapy are antivector immunity, low transduction efficiencies, acute toxicity, and limited capacity to package foreign genetic information. It could be demonstrated that animal and human cells were efficiently transduced with equine herpesvirus 1 (EHV-1) reconstituted from viral DNA maintained and manipulated in Escherichia coli. Between 13 and 23% of primary human CD3 ؉ , CD4 ؉ , CD8 ؉ , CD11b ؉ , and CD19 ؉ cells and more than 70% of CD4 ؉ MT4 cells or various human tumor cell lines (MeWo, Huh7, HeLa, 293T, or H1299) could be transduced with one infectious unit of EHV-1 per cell. After intranasal instillation of EHV-1 into mice, efficient transgene expression in lungs was detectable. Successful immunization using EHV-1 was shown after delivery of the human immunodeficiency virus type 1 Pr55 gag precursor by the induction of a Gag-specific CD8 ؉ immune response in mice. Because EHV-1 was not neutralized by human sera containing high titers of antibodies directed against human herpesviruses 1 to 5, it is concluded that this animal herpesvirus has enormous potential as a vaccine vector, because it is able to efficiently transduce a variety of animal and human cells, has high DNA packaging capacity, and can conveniently be maintained and manipulated in prokaryotic cells.Equine herpesvirus 1 (EHV-1), an alphaherpesvirus, causes infections in equines. Usually the disease induced by the virus is mild, and approximately 90% of equines worldwide harbor the agent, whose persistence in animals is lifelong. One of the peculiarities of EHV-1 is its tropism for blood mononuclear cells, which are the primary site for establishment of EHV-1 latency. Neuronal tissues, including the trigeminal ganglion and the brain, are only rarely infected by the agent. Neurological symptoms after infection of equines with certain EHV-1 strains are caused by infection of endothelial cells and subsequent hypoxia and neuronal degradation and are consistent with myeloencephalopathy and not myeloencephalitis (40,62).Herpesviridae enter target cells by fusion of the viral envelope with the plasma membrane at neutral pH after attachment of virions to cell surface glycosaminoglycans (47,51). Glycoproteins are crucially involved in these early stages of infection, and 11 glycoproteins in the prototype member of the Alphaherpesvirinae subfamily, Herpes simplex virus type 1 (HSV-1), have been identified. The herpesvirus glycoproteins involved in attachment, receptor binding, and fusion (i.e., gB, gC, gD, and the gH-gL complex) also appear to largely determine the mostly very restricted host tropism of Alphaherpesvirinae, i.e., the inability of animal viruses to naturally infect species other than those they have coevolved with (23). While the first contact and heparin-sensitive attachment of the studied alphaherpesviruses, including EHV-1, is mainly mediated by gC, receptor binding of HSV-1, pseudorabies virus, and bovine herpesvirus 1 (BHV-1) is via interaction of gD with cellular receptors th...

Section: Ehv-1 Efficiently Delivers a Transgene Into Cells Of Variousmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Potential of Equine Herpesvirus 1 as a Vector for Immunization

Trapp

Einem

Hofmann

et al. 2005

Self Cite

“…Absence of gB results in loss of infectivity, as observed in cell culture, and after infection of primary target cells in vivo by phenotypically complemented mutant virus, viral spread does not occur (1,31,33,37). Mutations in the cytoplasmic domain of gB resulting in a syncytial phenotype profoundly influence pathogenesis in vivo (7,10,42,45).…”

Section: Discussionmentioning

confidence: 99%

Pseudorabies Virus Expressing Bovine Herpesvirus 1 Glycoprotein B Exhibits Altered Neurotropism and Increased Neurovirulence

Gerdts¹,

Beyer

Lomniczi

et al. 2000

Herpesvirus glycoproteins play dominant roles in the initiation of infection of target cells in culture and thus may also influence viral tropism in vivo. Whereas the relative contribution of several nonessential glycoproteins to neurovirulence and neurotropism of Pseudorabies virus (PrV), an alphaherpesvirus which causes Aujeszky's disease in pigs, has recently been uncovered in studies using viral deletion mutants, the importance of essential glycoproteins is more difficult to assess. We isolated an infectious PrV mutant, PrV-9112C2, which lacks the gene encoding the essential PrV glycoprotein B (gB) but stably carries in its genome and expresses the homologous gene of bovine herpesvirus 1 (BHV-1) (A. Kopp and T. C. Mettenleiter, J. Virol. 66:2754-2762, 1992). Apart from exhibiting a slight delay in penetration kinetics, PrV-9112C2 was similar in its growth characteristics in cell culture to wild-type PrV. To analyze the effect of the exchange of these homologous glycoproteins in PrV's natural host, swine, 4-week-old piglets were intranasally infected with 10 6 PFU of either wild-type PrV strain Kaplan (PrV-Ka), PrV-9112C2, or PrV-9112C2R, in which the PrV gB gene was reinserted instead of the BHV-1 gB gene. Animals infected with PrV-Ka and PrV-9112C2R showed a similar course of disease, i.e., high fever, marked respiratory symptoms but minimal neurological disorders, and excretion of high amounts of virus. All animals survived the infection. In contrast, animals infected with PrV-9112C2 showed no respiratory symptoms and developed only mild fever. However, on day 5 after infection, all piglets developed severe central nervous system (CNS) symptoms leading to death within 48 to 72 h. Detailed histological analyses showed that PrV-9112C2R infected all regions of the nasal mucosa and subsequently spread to the CNS preferentially by the trigeminal route. In contrast, PrV-9112C2 primarily infected the olfactory epithelium and spread via the olfactory route. In the CNS, more viral antigen and significantly more pronounced histological changes resulting in more severe encephalitis were found after PrV-9112C2 infection. Thus, our results demonstrate that replacement of PrV gB by the homologous BHV-1 glycoprotein resulted in a dramatic increase in neurovirulence combined with an alteration in the route of neuroinvasion, indicating that the essential gB is involved in determining neurotropism and neurovirulence of PrV.Pseudorabies virus (PrV) and Bovine herpesvirus 1 (BHV-1) are related alphaherpesviruses of the genus Varicellovirus. PrV, also designated Suid herpesvirus 1, is the causative agent of Aujeszky's disease (AD), a serious illness in domestic and wild animals. PrV has a broad host range and productively infects birds and most mammals, except for horses and higher primates including humans, which are resistant to infection (reviewed in reference 25). Whereas mortality in most infected species regularly amounts to 100%, pigs can survive a productive infection and remain latently infected for life. Thus, pigs a...

“…Together, these data argue that gM almost certainly has an important role in the infectious cycle of herpesviruses and that the function of this protein may only be observable under more stringent conditions of replication such as occur in vivo. In fact, attenuation has been noted after infection of animals with viruses lacking gM and/or gN (9,26,30). The contribution of gN to the function(s) of gM is unknown.…”

mentioning

confidence: 99%

Complex Formation by Glycoproteins M and N of Human Cytomegalovirus: Structural and Functional Aspects

Mach

Kropff

Kryzaniak

et al. 2005

The genomes of herpesviruses contain a number of genes which are conserved throughout the family of Herpesviridae, indicating that the proteins may serve important functions in the replication of these viruses. Among these are several envelope glycoproteins, including glycoprotein M (gM) and gN, which form a complex that is covalently linked via disulfide bonds in some herpesviruses. However, deletion of gM and/or gN from most alphaherpesviruses has limited effects on replication of the respective viruses in vitro. In contrast, insertional inactivation of the gM gene of the betaherpesvirus human cytomegalovirus (HCMV) results in a replication-incompetent virus. We have started to analyze the structural and functional aspects of the interaction between gM and gN of HCMV. We show that large parts of gM are dispensable for the formation of a gM/gN complex that is transported to distal parts of the cellular secretory pathway. In addition, we demonstrate that the disulfide bond is between the cysteine at position 44 in gM and cysteine 90 in gN. However, disulfide linkage is not a prerequisite for modification and transport of the gM/gN complex. Moreover, mutant viruses that lack a disulfide bridge between gM and gN replicate with efficiencies similar to that of wild-type viruses.