摘要:

Isolates of herpesvirus type 2 from different geographic areas were examined for antigenic differences using the kinetics of neutralization and 51Cr release tests. Though differences in the kinetics of neutralization between strains were observed, the 51Cr release test appeared to provide better discrimination of strains. The results of 51Cr release assays using adsorbed sera suggest that 2 subsets of type 2 strains may exist which were tentatively called α and β. Members of subset α appear to have an antigen exposed on the surface of infected cells which is qualitatively or quantitatively expressed to a lesser degree on cells infected with subset β viruses. In the limited number of strains tested, hamster cells transformed by subset α viruses were oncogenic when injected into hamsters while cells transformed by subset β viruses wer

ISSN:0300-5526    

DOI:10.1159/000149738

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Activation of the transcriptase in purified reovirus by chymotrypsin requires facilitating conditions in the digestion mix. In the presence of facilitation the virions are uncoated to cores. Without facilitation, uncoating is blocked at an intermediate stage, with transcriptase latent. Two independent types of facilitation have been discovered. The first type is mediated by K+, Rb+ or Cs+ ions. A second type, described here, is mediated by suitably high concentrations of virus in the digestion mix and requires collisions between intermediate subviral particles for its occurrence. The virus-concentration-mediated process is reversibly inhibited by high levels of active chymotrypsin.

ISSN:0300-5526    

DOI:10.1159/000149739

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Under certain conditions two temperature-sensitive mutants of reovirus type 3 (strain Dearing) yield particles that lack either one or two of the ten genome RNA segments. They resemble the wild type strain in this respect, but there are significant differences. (i) When passaged at low multiplicity neither wild type virus nor the group F mutant ts 556 yields significant numbers of defective particles, but the group C mutant ts 447 yields progeny that consists of roughly equal amounts of nondefective particles and particles that lack genome RNA segment L3. (ii) When passaged three to four times at high multiplicity (more than 500 virus particles, equivalent to 5 to 10 PFU per cell), yields of ts 556 decrease precipitously and consist of roughly equal numbers of particles that lack RNA segment LI and particles that lack both segments L1 andL3. Only a small proportion of the yield consists of nondefective particles, (iii) Yields of wild type virus only begin to decline and contain defective particles after about eight passages at high multiplicity; progeny then consists of about one-quarter of nondefective particles and three-quarters of particles that lack segment L1. Yields of ts 447 also begin to contain particles that lack LI at this stage. All defective particles contain the normal complement of capsid polypeptides and possess full transcriptase activity. Ts 447 and ts 556 may be useful in studies on the mechanism that is responsible for selecting unique sets of single-stranded RNA molecules for encapsidation in progeny virions.

ISSN:0300-5526    

DOI:10.1159/000149740

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The molecular sizes of the capsid polypeptides of different serotypes of bluetongue virus (BTV) have been compared to those of serotype 10A, after electrophoretic fractionation on SDS-containing polyacrylamide gels. Computer-programmed dis criminant analyses of the polypeptides’ migration distances indicated significant differences between serotypes. The results obtained are in agreement with those of molecular hybridization studies of the viral genome segments, suggesting that the main determinants of its serological specificity reside in the two polypeptides forming the outer coat of the viru

ISSN:0300-5526    

DOI:10.1159/000149741

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Cells productively infected with simian adenovirus 1 (SA7) were extracted by the Hirt procedure and the supernatant and pellet fractions assayed for infectious DNA. Infectivity was detected, with the bulk of the activity localized in the supernatant fraction. The activity was sensitive to DNase, phenol and proteolytic enzymes, but resistant to RNase and SA7-specific antiserum. DEAE-dextran was required in order to detect the infectivity.

ISSN:0300-5526    

DOI:10.1159/000149742

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Some rifamycin antibiotics which do not inhibit the viral DNA polymerase activity of oncornaviruses can nevertheless inhibit formation of foci of transformed cells in human and mouse cell cultures by transforming oncornaviruses through a blockade of an early step in virus infection.

ISSN:0300-5526    

DOI:10.1159/000149743

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Rifamycin SV and several of its derivatives were examined for their ability to inhibit the replication of Gross murine leukemia virus in intact Swiss mouse embryo cells growing in culture. Antiviral activity was observed with rifamycin SV, 3-formyl rifamycin SV: dipropylhydrazone and benzyl dimethyl rifampicin, when the compounds were tested against this RNA tumor virus by means of the UV-XC plaque-reduction procedure. However, several of the rifamycin derivatives which strongly inhibited the viral RNA-directed DNA polymerase reaction in cell-free systems failed to inhibit virus replication in intact cells at noncytotoxic concentrations.

ISSN:0300-5526    

DOI:10.1159/000149744

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

A comparison of the proteins of ‘R’ and ‘T’ strains of mosquito iridescent virus (M1V) was made using PAGE and amino acid analysis. The banding patterns of RMIV and TM1V were similar, each showing 9 proteins. None of the proteins reacted with Schiff’s reagent. When the proteins of RMIV and TMIV were S-carboxymethylated, PAGE showed only 4 proteins for both strains compared with the 9 bands detected in control preparations. Amino acid analyses and tryptic peptide analyses indicated that the proteins of the two strains were ver

ISSN:0300-5526    

DOI:10.1159/000149745

出版商:S. Karger AG    

年代:1974

数据来源: Karger

ISSN:0300-5526    

DOI:10.1159/000149746

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Structural changes in the cells of a continuous cell line of hamster origin infected with A/NWS (HoNi) influenza virus were studied by electron microscopy. From the sixth hour on, inelusions consisting of fibrillar structures 35–45 Å in diameter were observed in the cell nucleoli. These inclusions gradually dispersed over the nuclear area and then penetrated into the cytoplasm through the pores of the nuclear membrane. In the cytoplasm they presented new morphological aspects: the fibrils were more regularly oriented, and the inclusions were surrounded by ribosom

ISSN:0300-5526    

DOI:10.1159/000149747

出版商:S. Karger AG    

年代:1974

数据来源: Karger