ISSN:0300-5526    

DOI:10.1159/000150467

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0300-5526    

DOI:10.1159/000150468

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The Qβ gene C has been proposed as a new carrier for the exposure of foreign peptide sequences. Contrary to well-known ‘display vectors’ on the basis of coat proteins of RNA phage group I, group III phage Qβ-based vectors suggested application of the 195-amino acid extension of coat protein (CP) within the so-called Al protein for insertion of the appropriate immunological epitopes. ‘Mosaic’ capsids presenting model hepatitis B virus preSl and HIV-1 gpl20 epitopes and formed by Qβ CP together with A1-derived proteins were obtained as a result of (1) suppression of leaky UGA stop codon of the CP gene and (2) simultaneous expression of’pure’ CP and full-length A1-derived genes obtained after the changing of CP-terminating UGA to strong UAA stop codon or sense GGA codon

ISSN:0300-5526    

DOI:10.1159/000150469

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Spatial and immunochemical elucidation of hepatitis B core antigen suggested unique organization of its major immunodominant region (MIR) localized within the central part of molecule around amino acid residues 74-83. This superficial loop was recognized as the most prospective target for the insertion of foreign epitopes ensuring maximal antigenicity and immunogenicity of the latter. MIR allowed a substantial capacity of insertions up to about 40 amino acid residues without loss of the capsid-forming ability of core particles. Vector capacity as well as structural behavior and immunological fate of inserted epitopes were dependent on their primary structure. Special sets of display vectors with retained but cross-sectioned MIR as well as with uni- and bidirectionally shortened MIR have been investigated.

ISSN:0300-5526    

DOI:10.1159/000150470

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The hepatitis B virus (HBV) envelope and the subviral lipoprotein particles contain three viral surface proteins (L, M, and S) which are expressed from one open reading frame by the usage of three start codons and a common stop codon. The largest surface protein L has some unusual properties. It adopts two different transmembrane topologies due to a posttranslational switch of the folding in approximately half of the L proteins. L molecules which expose their N-terminal preSl domain on the viral particle surface are probably ligands for a putative virus receptor and determine the species specificity and liver tropism of this virus. L chains with internal preSl domains are required in virion morphogenesis and mediate the contact to the nucleocapsid like a matrix protein. Overexpression of this form of the L protein is also responsible for the inhibition of viral particle release. This short review summarizes our knowledge on the biosynthesis and maturation of the HBV surface proteins and their functions in viral particle morphogenesis with special emphasis on the L protein.

ISSN:0300-5526    

DOI:10.1159/000150471

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

A structurally highly ordered arrangement of the polyprotein precursor Pr55gag is a necessary prerequisite for assembly, budding and maturation of the human immunodeficiency virus type 1 (HIV-1). In particular, distinct regions of the matrix protein (pi7) and the capsid protein (p24) contained within Pr55gag are functionally active during these processes. In order to determine such regions we exchanged amino acid triplets within pi7 (amino acids 46-61) and p24 (amino acids 341-352) for alanine residues and deleted the whole regions. Synthetic peptides derived from these regions had been shown previously to inhibit the production of infectious virus. The effect of the mutations on the release of viral particles was investigated by using recombinant baculoviruses for the expression of mutated Pr55gag as virus-like particles and by use of the respective HI proviruses for monitoring the production of infectious particles.

ISSN:0300-5526    

DOI:10.1159/000150472

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Expression of the HIV Gag precursor in insect cells by recombinant baculoviruses results in the assembly and budding of noninfectious pseudovirions that resemble immature virus. Three strategies for packaging additional viral epitopes into pseudovirions were examined: coinfection of insect cells with individual baculoviruses encoding separate Gag and Env structural genes, inframe Gag-Env fusion proteins, and Gag-frameshift-Env fusion proteins. Electron microscopy and Western blot analysis indicated that neither the coinfection nor the inframe fusion strategies reliably produced large quantities of structurally stable chimeric pseudovirions. The frameshift fusion method utilized the retroviral Gag-Pol ribosomal frameshift mechanism for the coexpression of Gag and Gag-frameshift-Env fusion proteins. Large quantities of pseudovirions containing both the Gag and Env epitopes were produced in insect cells. Mice inoculated with the Gag-frameshift-Env pseudovirions developed cyto-toxic lymphocyte responses to both HIV Gag and Env epitopes. Vaccine and immunotherapeutic applications of chimeric pseudovirions are discussed.

ISSN:0300-5526    

DOI:10.1159/000150473

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Papillomavirus-like particles can be obtained by expression of the major capsid protein LI alone or by coexpression with the minor capsid protein L2 in various systems. Virus-like particles (VPLs) and virions have very similar capsid structures. Immunization with VLPs yields antibodies neutralizing virions in vitro. Vaccination of animals with VLPs has been shown to protect against viral challenge. VLPs of human papillomavirus (HPV) are therefore the most promising vaccine candidate to prevent infections with HPVs associated with cervical cancer, the most frequent carcinoma in women worldwide.

ISSN:0300-5526    

DOI:10.1159/000150474

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Genital infection with high-risk human papillomaviruses (HPV) has been etiologically linked with the development of cervical and other anogenital cancers. There is therefore a need for an effective HPV vaccine with the potential to significantly reduce the burden of more than half a million new cervical cancer cases in women worldwide each year. The LI major capsid protein of papillomaviruses expressed in eukaryotic cells self-assembles into virus-like particles (VLP). VLP are attractive subunit vaccine candidates since they lack potentially oncogenic papillomavirus DNA and express the conformationally dependent epitopes necessary to induce high-titer neutralizing antibodies. Prophylactic VLP vaccination has achieved a high degree of protection in animal studies. Thus VLP are now considered the immunogen of choice for human vaccine trials to prevent genital HPV infection. VLP of different HPV have been developed to study the serologic relationship between HPV types. VLP-based ELISA are able to detect antibodies in human sera and are now widely used in epidemiologic studies of the natural history of HPV infection and the associated risk of developing neoplasia.

ISSN:0300-5526    

DOI:10.1159/000150475

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The Orbivirus genus within the family Reoviridae consists of nonenveloped architecturally complex viruses. The icosahedral viruses are 810 A diameter in size and are comprised of two protein shells containing seven proteins (VP1–VP7), surrounding a genome often double-stranded RNA segments. The prototype virus, bluetongue virus (BTV), is the etiological agent of a disease that can reach epidemic proportions among sheep and cattle. To develop highly protective virus-like particles, we have developed novel baculovirus multigene expression vector systems which have allowed us to coexpress three, four or five BTV genes from single recombinant vectors. The resultant particulate structures resemble BTV virus-like and subvirus-like particles which are structurally and immunologically indistinguishable from the BTV, and preliminary clinical trials have verified this vaccines safety and efficacy. Unlike live virus vaccines, VLPs are noninfectious and lack virus (or other) DNA/RNA required for replication. VLPs do not replicate in host cells. However, sheep trials have shown that VLPs are more immunogenic than subunit vaccines (viral proteins), or viruses killed by chemical inactivation. In addition, they are effective at eliciting humoral, cell-mediated and mucosal immunities. Virus-like particles (VLPs) are safe to produce and handle. The baculovirus vector and host cells used to make VLPs do not come from mammalian sources (hence they do not contain mammalian-derived pathogens). The multicomponent VLPs have also been utilized as vaccine delivery systems for multiple immunogens including B and T cell epitopes. The expression system described here is a tool which may have a range of applications in industries employing biotechnology to produce vaccines, insecticides, diagnostic and protein reagent

ISSN:0300-5526    

DOI:10.1159/000150476

出版商:S. Karger AG    

年代:1996

数据来源: Karger