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PubMed1983

The cultivation of human rotavirus, strain 'Wa', to high titer in cell culture and characterization of the viral structural polypeptides.

The structural proteins of the 'Wa' (serotype 2) strain of human rotavirus have not been described previously. Single-cycle virus growth in MA-104 cells using 5 micrograms/ml of trypsin in the growth medium was rapid with maximal viral yields (approximately 10(6) PFU/ml) obtained 10-12 h post-infection. There was a continuous progression of cytopathic effect (CPE) from 6- to 5-h post-infection. Under conditions of multiple-cycle growth, a greater concentration of trypsin (40 micrograms/ml) in the growth medium was required to obtain rapid progression of CPE and production of a high titer (approximately 10(7) PFU/ml) of infectious (double-shelled) virus. Single- and double-shelled virions were separated by isopycnic centrifugation in CsCl and analyzed by SDS-PAGE. Five proteins with molecular weights of 116,000, 92,000, 88,000, 84,000 and 41,000 were identified as components of the inner shell and four proteins with molecular weights of 60,000, 38,000, 32,000 and 27,000 were located in the outer shell.

Animals↗
PubMed1984

Modification of viral structural proteins of herpesvirus sylvilagus by glycosylation and phosphorylation.

The structural proteins of herpesvirus sylvilagus, a lymphotropic gamma herpesvirus, were analyzed by sodium dodecyl sulfate and two-dimensional polyacrylamide gel electrophoreses. Modification of the proteins by glycosylation and phosphorylation was shown by the incorporation of [14C]glucosamine or 32Pi into material which comigrated with [35S]methionine-labeled proteins. One-dimensional gel electrophoresis resolved four major glycoproteins and four major phosphoproteins. By two-dimensional gel electrophoresis, 9 glycoproteins and 13 phosphoproteins were identified. Four proteins incorporated all three labels, indicating that these structural proteins may be both glycosylated and phosphorylated.

Animals↗
PubMed1999

Induction of a protective antibody response to foot and mouth disease virus in mice following oral or parenteral immunization with alfalfa transgenic plants expressing the viral structural protein VP1.

The utilization of transgenic plants expressing recombinant antigens to be used in the formulation of experimental immunogens has been recently communicated. We report here the development of transgenic plants of alfalfa expressing the structural protein VP1 of foot and mouth disease virus (FMDV). The presence of the transgenes in the plants was confirmed by PCR and their specific transcription was demonstrated by RT-PCR. Mice parenterally immunized using leaf extracts or receiving in their diet freshly harvested leaves from the transgenic plants developed a virus-specific immune response. Animals immunized by either method elicited a specific antibody response to a synthetic peptide representing amino acid residues 135-160 of VP1, to the structural protein VP1, and to intact FMDV particles. Additionally, the immunized mice were protected against experimental challenge with the virus. We believe this is the first report demonstrating the induction of a protective systemic antibody response in animals fed transgenic plants expressing a viral antigen. These results support the feasibility of producing edible vaccines in transgenic forage plants, such as alfalfa, commonly used in the diet of domestic animals even for those antigens for which a systemic immune response is required.

Administration, Oral↗
PubMed1979

Assembly of viral structural proteins in cells infected with a temperature-sensitive mutant derived from an HVJ (Sendai virus) carrier culture. Brief report.

The processing of virus polypeptides synthesized in cells infected with HVJ (haemagglutinating virus of Japan--the Sendai strain of parainfluenza 1 virus) was studied. Maturation of a temperature-sensitive (ts) mutant (HVJ-pB) derived from an HVJ carrier culture was inhibited at 38 degrees C incubation. A considerable amount of viral components were made at the restrictive temperature. They were, with the exception of the polypeptide HN, well preserved without a great loss of their function and successfully incorporated into virus particles released after lowering the incubation temperature. The membrane (M) protein seems to be essential for virus morphogenesis.

Animals↗
PubMed1980

Proteins specified by African swine fever virus. I. Analysis of viral structural proteins and antigenic properties.

At least 28 polypeptides have been identified in intracellular virus, with molecular weights ranging from 11,500 to 243,000 daltons. By treatment with Nonidet P-40 and 2-mercaptoethanol it is possible to obtain subviral particles that have lost some proteins and have a density in CsCl of 1.31 g/cm3 which is higher than that of the complete virus (1.23 g/cm3). After addition of NaCL the virus loses its major protein VP73 which indicates that it is localized in the viral envelope. Cores obtained after this treatment are made up of at least 14 proteins. Incorporation of 3H-fucose and 3H-glucosamine in intracellular virus occurs in three minor components. The protein VP42 is possibly the cell actin and appears to be strongly associated with the virus. It is not possible to eliminate it under conditions where the viral envelopes disappear morphologically. At least the proteins VP172, VP162, VP146 and VP73 act as antigens in the natural infection.

African Swine Fever Virus↗
PubMed1996

[A study on the pathogenetic role of the viral structural proteins of hemorrhagic fever with renal syndrome].

In order to clarify the pathogenesis of hemorrhagic fever with renal syndrome (HFRS), we detected HFRS virus structural proteins expressed in perepheral blood mononuclear cells (PBMC) by using immunohistochemical technique. Meanwhile we also determined plasma endothelin (ET), substance P (SP) and some sensitive markers of renal function with radioimmunoassay. The result showed that in HFRS patients, from the day of admission up to the thirteenth day of illness, the antigens of HFRS virus membrane protein (MP) and nucleocapsid (NP) could simultaneously be found in PBMC, though their expressive degree gradually decreased when the condition of the patients became better. Based on the external appearance and nucleus pattern of PBMC we recognized the MP and NP positive cells were mainly monocytes among which only a few presented faint IgM and C3 stain. On admission there was difference in expressive intensity between MP and NP. The MP expressive intensity was in parallel with plasma ET/SP ratio, the general condition and the severity of renal damage. These data suggest that HFRS virus can invade PBMC, replicate in them, and express their structural proteins. MP may be related with the pathogenesis of HFRS virus and the increase of plasma ET/SP ratio may be an important factor aggravating kidney injury.

Adult↗
PubMed1978

Effects of inhibitors of lipid synthesis on the replication of Rous sarcoma virus. A specific effect of cerulenin on the processing of major non-glycosylated viral structural proteins.

The effects of two inhibitors of lipid biosynthesis on the replication of Rous sarcoma virus Prague C strain in chick embryo fibroblasts have been examined in media containing delipidated serum. 25-Hydroxycholestetate into sterols, had no effect on the formation of infectious virions or on the synthesis and processing of intracellular virion proteins. Cerulenin strongly inhibited [1(-14C)]acetate incorporation into fatty acids and partially inhibited its incorporation into sterols in chick embryo cells. Rous sarcoma virus production as measured by focus formation and by the production of [35S]methionine-labeled virions was strongly inhibited within 5 h after cerulenin addition to infected cultures. Examinatin of extracts of these cells revealed the accumulation of the 76 000 dalton precursor (Pr76) of the major non-glycosylated virion structural proteins, p27, p19, p15 and p12. The failure to process the 76 000 dalton precursor was coincident in time with the decrease in viron production. Neither whole serum nor mixtures of fatty acids plus cholesterol were able to reverse the effects of cerulenin.

Acetates↗
PubMed1993

Differences between cell membrane fusion activities of two dengue type-1 isolates reflect modifications of viral structure.

The genetic diversity of dengue (DEN) virus was explored using two South American DEN-1 virus strains isolated from viremic human sera. DEN-1 virus strains BR/90 and FGA/89 were selected on the basis of their membrane fusion properties in mosquito cell cultures. Infection of mosquito cell lines with BR/90 virus strain induced a cytopathic effect characterized by syncytium formation whereas no cytopathic changes were observed with FGA/89. Cell-to-cell fusion experiments indicated that the fusogenic activity of FGA/89 required a lower pH than BR/90. Immunoreactivity analysis of the DEN-1 envelope (E) protein with monoclonal antibodies revealed a minor difference between the antigenic structures of FGA/89 and BR/90 virions. FGA/89 was less neurovirulent than BR/90 for newborn mouse. To determine the genetic origin of these modifications, the amino acid sequences of the structural proteins from these virus strains were compared. One amino acid difference was found within the carboxy-terminal domain of protein C. Five amino acid substitutions were found in the E proteins at positions 96, 180, 297, 379, and 473. Changes at positions 96, 297, and 379 map within two overlapping antigenic domains of protein E. These limited amino acid differences in the E protein could affect the biological properties and the antigenicity of the DEN virion.

Adult↗
PubMed1983

Papillomavirus infection of the cervix. II. Relationship to intraepithelial neoplasia based on the presence of specific viral structural proteins.

Three hundred twenty-two cases of cervical dysplasia (mild, moderate, and severe) and carcinoma in situ (CIS) were examined for the presence of papillomavirus structural antigens with a peroxidase-antiperoxidase method on formalin-fixed, paraffin-embedded tissue. The primary antiserum, prepared from purified, detergent-disrupted bovine papillomavirus type 1 virions, is broadly reactive against the genus-specific (common) antigen(s) of the papillomaviruses. Using the peroxidase-antiperoxidase technique on cervical tissue obtained from biopsy, conization and hysterectomy specimens, papillomavirus structural proteins were identified in association with mild dysplasia in 65 of 152 (43%) cases, with moderate dysplasia in 12 of 82 (15%) cases, with severe dysplasia in eight of 47 (17%) cases, and with CIS in four of 41 (10%) cases. Papillomavirus antigens were found directly within the lesion in all the cases of mild and moderate dysplasia but in only two instances of severe dysplasia and in none of the examples of CIS. In the remaining 10 cases of severe dysplasia and CIS associated with the presence of papillomavirus antigens, cells containing papillomavirus structural proteins were present in areas of moderate dysplasia immediately adjacent to the high-grade lesions in seven instances and in areas of mild or moderate dysplasia not directly in contact with the high-grade lesions in three. Among the 12 high-grade lesions associated with the presence of papillomavirus antigens, a morphologic transition from areas of moderate dysplasia containing papillomavirus antigens to the areas of severe dysplasia and CIS was present in five instances. The results of this study, therefore, provide direct evidence demonstrating the relationship of papillomavirus to intraepithelial cervical neoplasia ranging from mild dysplasia to severe dysplasia and CIS.

Animals↗
PubMed1985

Cross-reactions of immunoglobulin M and G antibodies with enterovirus-specific viral structural proteins.

We analysed the reactivity of enterovirus-specific human IgM and IgG antibodies with the structural proteins of different enteroviruses by the immunoblot technique. In general, all immunoglobulin G antibodies of the tested sera reacted with capsid polypeptide VP 1 of the viruses tested (echoviruses 9 and 11, coxsackievirus B3 and poliovirus 2). In contrast, enterovirus specific immunoglobulin M antibodies of adults reacted with capsid polypeptides VP 1, VP 2, and/or VP 3 of the viruses mentioned above. The reactions with VP 2 and/or VP 3 were often stronger than with VP 1. IgM antibodies from sera of newborns infected by echovirus 11 reacted with VP 1 and VP 2/3 of echovirus 11 and also with VP 2 and VP 3 of poliovirus 2. Preabsorption experiments indicate that cross-reactive IgG antibodies react with epitopes of VP 1 not present on the surface of intact virus particles. The results from the immunoblot technique were compared to data from microneutralization tests and M-antibody capture radioimmunoassays.

Adult↗
PubMed1977

Solubilized TSTA and the major viral structural proteins, gp70 and p30, in the immune response to murine leukemias induced by Friend and Rauscher virus.

Antigens present in gp70 and p30 purified from Rauscher virus, were tested for immunogenicity in various assays measuring the anti-tumor immune response against lymphocytic leukemias of Friend (FBL-3) or Rauscher (RBL-5) virus origin. p30 had no effect on in vitro cytotoxicity against tumor cell targets mediated by either an anti RBL-5 serum or lymphocytes from animals immunized with FBL-3 cells. gp70 had had no effect on serum-mediated cytotoxicity but used at high concentrations it inhibited cell-mediated cytotoxicity. When used to immunize mice directly against subsequent challenge with the RBL-5 and FBL-3 leukemias, p30 had no discernible effect, while gp70 afforded partial protection against RBL-5 but only at high concentrations. Cell-free preparations of tumor membranes containing negligible amounts of gp70 were antigenically superior to gp70 in both the in vitro and in vivo assays. It is concluded that antigens on these purified proteins that are also expressed on tumor cells are not major targets of the anti-tumor immune response in this system.

Animals↗
PubMed1981

High yield growth and purification of human parainfluenza type 3 virus and initial analysis of viral structural proteins.

Structural proteins from a large-plaque variant (LPV) of human parainfluenza type 3 virus were analysed by electrophoresis on Laemmli-type polyacrylamide gels. High virus concentrations were obtained by growth in BS-C-1 cells cultivated on microcarrier beads. Purification of the virus in composite equilibrium gradients of potassium tartrate:glycerol resulted in 25% recovery of input infectivity and a preparation containing less than 0.08% of input host cell protein and RNA. Parainfluenza type 3 virus equilibrated at a density of 1.20 g/ml in these gradients. Analysis by polyacrylamide gel electrophoresis of 3H-glucosamine-labelled virus taken from peak gradient fractions revealed 8 or 9 major virion peptides, ranging in mol. wt. from 17 x 10(3) to 125 x 10(3) (17K to 125K), two of which were glycoproteins. The sum of the estimated mol. wt. of these peptides, 501.5K to 570.5K, does not exceed the estimated genomic potential of other paramyxoviruses.

Electrophoresis, Polyacrylamide Gel↗
PubMed2001

The gene encoding the major viral structural protein stimulates recombination in polyomavirus DNA.

RmI is a chimeric DNA molecule consisting of a polyoma genome in which a partly duplicated VP1-coding region brackets an insert of murine DNA (Ins); when transfected into mouse cells, RmI recombines intramolecularly to yield infectious, unit-length, polyoma DNA. We report here that RmI encodes a polypeptide of 337 amino acids (designated VmP1) which includes the N-terminal 328 amino acids of VP1 and 9 amino acids specified by Ins. Mutating the VmP1-coding sequence strongly reduces the ability of RmI to yield polyoma DNA. In contrast, mutating the portion of the VP1-coding sequence which is not part of the VmP1-coding sequence has little or no impact on the ability of RmI to yield polyoma DNA, even though it renders such DNA noninfectious. Thus, release of polyoma DNA from RmI involves a function of VP1 distinct from that ensuring virus assembly and propagation; since VP1 can arise only after recombination has occurred, VmP1, but not VP1, could carry such a function. We suggest that VmP1 acts in concert with VP2, which we have already reported to stimulate recombination in RmI.

Amino Acid Sequence↗
PubMed1995

Self-potentiation of ligand-toxin conjugates containing ricin A chain fused with viral structures.

A chimeric protein was obtained by fusing together the ricin toxin A chain (RTA) gene and a DNA fragment encoding the N terminus of protein G of the vesicular stomatitis virus. Chimeric RTA (cRTA) retained full enzymic activity in a cell-free assay, but was 10-fold less toxic against human leukemic cells than either native RTA (nRTA) or unmodified recombinant RTA (rRTA). However, conjugates made with cRTA and human transferrin (Tfn) showed 10-20-fold greater cell killing efficacy than Tfn-nRTA or Tfn-rRTA conjugates despite equivalent binding of the three conjugates to target tumor cells. As a consequence, by fusion of the KFT25 peptide to the RTA sequence, the specificity factor (i.e. the ratio between nonspecific and specific cytotoxicity) of Tfn-cRTA was increased 90-240 times with respect to those of Tfn-nRTA and Tfn-rRTA. cRTA interacted with phospholipid vesicles with 15-fold faster kinetics than nRTA at acidic pH. Taken together, our results suggest that the ability of vesicular stomatitis virus protein G to interact with cell membranes can be transferred to RTA to facilitate its translocation to the cell cytosol. Our strategy may serve as a general approach for potentiating the cytotoxic efficacy of antitumor immunotoxins.

Amino Acid Sequence↗