The subgenus-specific C-terminal region of protein IX is located on the surface of the adenovirus capsid. (57/4982)

We have investigated the antigenicity of the C- and N-terminal halves of pIX of human adenovirus types 2 and 3 (Ad2 and Ad3) as well as their orientations in virions. We found that only the C-terminal halves of Ad2 pIX and Ad3 pIX reacted in a subgenus-specific manner by enzyme-linked immunosorbent assay and immunoblot analysis. Based on immunoelectron microscopy experiments, pIX in viral capsids appears to be positioned such that the C-terminal part of pIX constitutes the surface domain whereas the N terminus of the protein makes up the internal domain in icosahedral Ad capsids.  (+info)

Common neutralization epitope in minor capsid protein L2 of human papillomavirus types 16 and 6. (58/4982)

Studies of virus neutralization by antibody are a prerequisite for development of a prophylactic vaccine strategy against human papillomaviruses (HPVs). Using HPV16 and -6 pseudovirions capable of inducing beta-galactosidase in infected monkey COS-1 cells, we examined the neutralizing activity of mouse monoclonal antibodies (MAbs) that recognize surface epitopes in HPV16 minor capsid protein L2. Two MAbs binding to a synthetic peptide with the HPV16 L2 sequence of amino acids (aa) 108 to 120 were found to inhibit pseudoinfections with HPV16 as well as HPV6. Antisera raised by immunizing BALB/c mice with the synthetic peptide had a cross-neutralizing activity similar to that of the MAb. The data indicate that HPV16 and -6 have a common cross-neutralization epitope (located within aa 108 to 120 of L2 in HPV16), suggesting that this epitope may be shared by other genital HPVs.  (+info)

Immune responses and protection obtained by oral immunization with rotavirus VP4 and VP7 DNA vaccines encapsulated in microparticles. (59/4982)

Protective immune responses in mice were obtained after oral immunization with rotavirus DNA vaccines encapsulated in poly(lactide-co-glycolide) (PLG) microparticles. The DNA vaccines used encoded outer capsid proteins VP4 and VP7; proteins that are the basis for rotavirus serotyping and the generation of virus neutralizing antibodies. One dose of vaccine was given to BALB/c mice by oral gavage (75 microg DNA/mouse). Rotavirus-specific serum antibodies and intestinal IgA antibodies were detectable by 6 weeks postimmunization. After challenge with homologous murine rotavirus at 12 weeks postimmunization, fecal rotavirus antigen was reduced significantly in immunized mice compared with controls. Protective immunity also was generated by oral delivery of unencapsulated VP 7 DNA vaccine but to a lesser degree. These results demonstrate that the oral route is effective for generating protective immune responses with rotavirus DNA vaccines targeting neutralization antigens.  (+info)

Nucleotides 1506-1625 of bovine papillomavirus type 1 genome can enhance DNA packaging by L1/L2 capsids. (60/4982)

We have previously described a DNA-packaging assay using bovine papillomavirus type 1 (BPV-1) virus-like particles (VLPs) and have identified a region of the BPV genome that assists in packaging. In this study, we identify a specific BPV sequence involved in DNA packaging by BPV-1 VLPs. In the initial screening of BPV-1 genomic sequences essential for DNA packaging, we observed that a plasmid with deletions between nucleotides (nt) 948 and 2113 failed to be packaged into BPV-1 VLPs. However, plasmids containing nt 948 to 2113 were efficiently packaged, suggesting that this 1.2-kb fragment contains a packaging enhancement sequence (PES). Further mapping of the BPV-1 genome showed that this packaging sequence lies between nt 1506 and 1625. Furthermore, this packaging sequence is also recognized by HPV6b VLPs, suggesting that a common packaging mechanism may be used by the two papillomavirus types. Given the phylogenetic difference between these two viral types, it is likely that other papillomavirus types may also use the same packaging mechanism. Identification of the PES has allowed a minimal viral genome sequence to be used in the packaging assay, improving the usefulness of the assay in studying the process of papillomavirus DNA encapsidation.  (+info)

Sequence analysis of VP1 and VP7 genes suggests occurrence of a reassortant of G2 rotavirus responsible for an epidemic of gastroenteritis. (61/4982)

G2 rotavirus was prevalent in a 1993 epidemic of acute gastroenteritis in Taiwan. In this study, the genetic relationship among G2 rotavirus strains was analysed. The VP7 genes were amplified and sequenced. Except for one strain isolated in 1981, the nucleotide sequences of the VP7 genes of most of the G2 rotaviruses were very similar (identity > 97%) and were closely related to that of a Japanese G2 reference strain, S2. The genetic relatedness of G2 rotaviruses was analysed further by RNA-RNA hybridization. The genomes of the major G2 strains of 1993 did not hybridize well with those of the G2 strains of previous seasons in RNA segments 1, 6 and 7. Partial nucleotide sequences of the VP1 gene were analysed and appeared to be similar among the major G2 strains from the same epidemic (identity > 98%), whereas the identity of the VP1 genes of the major G2 strains of the 1993 epidemic to those of previous seasons was only about 84%. Since the numbers of mutations accumulated in the VP1 and VP7 genes over a period of 10 years were comparable, the significant change in the VP1 genes of the major strains of the 1993 epidemic suggests that these G2 rotaviruses had evolved by genetic reassortment.  (+info)

Molecular determinants of adenovirus serotype 5 fibre binding to its cellular receptor CAR. (62/4982)

Adenovirus (Ad) tropism is mediated in part through the fibre protein. The common coxsackie B virus and Ad receptor (CAR) was recently identified as the major receptor for subgroup C Ad serotype 5 (Ad5) and serotype 2 (Ad2) fibres. Effects of mutations in the Ad5 fibre gene were studied to assess domains of the fibre capsomer that could alter virus tropism without altering virus assembly and replication. All mutants that accumulated as fibre monomers failed to assemble with a penton base and proved lethal for Ad5 which suggests that the absence of infectious virions resulted in part from a defect in fibre penton base assembly. Cell binding capacity of all fibre mutants was investigated in cell binding competition experiments with adenovirions using CHO-CAR cells (CHO cells that have been transfected with CAR cDNA and express functional CAR). The results suggest that the R-sheet of the Ad5 fibre knob monomer contains binding motifs for CAR and that beta-strands E and F, or a region close to them, may also be involved in receptor recognition.  (+info)

The viral protein Apoptin induces apoptosis in UV-C-irradiated cells from individuals with various hereditary cancer-prone syndromes. (63/4982)

Apoptin, a protein derived from chicken anemia virus, has previously been shown to induce apoptosis in a p53-independent and Bcl-2-stimulated manner in transformed and tumorigenic human cells but not in normal diploid human cells, suggesting that it is a potential agent for tumor therapy. Here we report that Apoptin can induce apoptosis in UV-C-irradiated diploid skin fibroblasts from individuals with various hereditary cancer-prone syndromes that are characterized by a germ-line mutation in a tumor suppressor gene. The same effect is found when these cells are irradiated with X-rays. In contrast, diploid skin fibroblasts from healthy donors or from individuals with DNA repair disorders are not responsive to Apoptin-induced apoptosis upon UV-C or X-ray irradiation. After transfection of untreated cells, Apoptin is found predominantly in the cytoplasm, whereas in UV-C-exposed Apoptin-responsive cancer-prone cells, it migrates to the nucleus, where it causes rapid apoptosis. Apoptin remains localized in the cytoplasm after UV-C treatment of diploid cells from healthy individuals. The induction of apoptosis by Apoptin in cancer-prone cells with a germ-line mutation in a tumor suppressor gene is UV dose-dependent and transient, just like many other UV-induced processes. These results suggest that Apoptin may be used as a diagnostic tool for detection of individuals with an increased risk for hereditary cancer and premalignant lesions.  (+info)

Assaying RNA chaperone activity in vivo using a novel RNA folding trap. (64/4982)

In the absence of proteins, RNAs often misfold in vitro due to alternative base pairings which result from the molecule being trapped in inactive conformations. We identify an in vivo folding trap in the T4 phage td gene, caused by nine base pairs between a sequence element in the upstream exon of the td gene and another at the 3' end of the intron. During translation, the ribosome resolves this interaction; consequently the intron folds correctly and splicing occurs. The introduction of a stop codon upstream of this base pairing prevents resolution of the inactive structure so that splicing cannot proceed. We have used this folding trap to probe for RNA binding proteins which, when overexpressed, either resolve the misfolded structure or impede its formation in vivo. We distinguish between proteins which recognize the intron structure and those which bind non-specifically and apparently ignore the intron. The first class, e.g. Neurospora crassa CYT-18, can rescue the exonic trap and intron mutants which cause a structural defect. However, known RNA chaperones such as Escherichia coli StpA and S12 and the HIV protein NCp7, only resolve the exonic trap without suppressing intron mutations. Thus, this structural trap enables detection of RNA chaperone activity in vivo.  (+info)