摘要:

Poliovirus replication in HeLa cells is significantly inhibited by a 30-min pulse of infected cells with 4,5’,8-trimethylρsoralen plus long wavelength ultraviolet light. When infected cells are exposed to psoralen plus light during peak viral RNA synthesis, formation of virus-specific RNAs is inhibited. Viral RNA species, formed in vivo in the presence of, or treated in vitro with, psoralen plus light, appear to have become degraded when analyzed by sedimentation in sucrose-dimethyl sulfoxide gradients. Treatment with psoralen plus light in vitro results in the loss of infectivity of single-stranded viral R

ISSN:0300-5526    

DOI:10.1159/000148924

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

A designated strain of plaque-purified Trichoplusia ni nuclear polyhedrosis virus (NPV) was used to initiate a serial passage series in vivo. The virulence of polyhedra inclusion bodies (PIB) and the distribution of MP (many PIB) and FP (few PIB) strains in hemolymph were monitored. When virus was passaged per os as PIB, there was no major change in virulence after 15 passes in insects. Plaque analysis of hemolymph from the infected insects indicated that there was no selection for the FP strain of virus. There was little overall change in the infectivity of nonoccluded virus (NOV) after 16 passes by injection into T. ni larvae; however, plaque analysis of the hemolymph from the infected insects indicated progressive selection of FP virus. It is postulated that when PIB are the vehicles of virus transmission, there is no progressive accumulation of noninfectious FP PIB; however, when NOV are the vehicles of virus transmission, FP NOV production displaces MP virus synthesis. This may result from a growth advantage of the FP NOV over the MP NOV as shown in vitro and from the noninfectious nature of FP PIB.

ISSN:0300-5526    

DOI:10.1159/000148925

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The kinetics of the appearance of Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) and early antigen (EA) in different EBV-infected target cell systems was studied. In addition, attention was given to the effect of pokeweed mitogen (PWM) and phosphonoacetic acid (PAA) (an inhibitor of herpesvirus DNA replication in infected cells) on the expression of EBNA and EA in EBV genome-negative target cells. The results obtained show that both of the EBV strains used (B95–8 and P3HR-1) induce EBNA at different time periods in the EBV genome-negative BJA-B cells and that P3HR-1 EBV is unable to induce either EBNA or EA in human umbilical cord blood lymphocytes (CBL) even after prestimulating these cells with PWM. Thus, our data present additional evidence for biological differences between B95–8 and P3HR-1 strains of EBV. EBNA is indeed the very first EBV-induced intracellular antigen to appear in an EBV-infected cell, and it is possible that the blast state may play an important role in the early induction of EBNA in CBL (as compared to BJA-B cells). Our data also suggest that the resident EBV genome in Raji cells may contribute, through an unknown mechanism, to the early expression of EA following superinfection with P3HR-1 EBV. Furthermore, our results also indicate that PAA does not inhibit the expression of EBNA or EA in BJA-B cells. The importance of these findings in relation to EBV-lymphocyte interaction and particularly in relation to cell transformation by EBV is discus

ISSN:0300-5526    

DOI:10.1159/000148926

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

A hemagglutinin has been prepared from Nebraska calf diarrhea virus (NCDV) propagated in BS-C-1 cell line. After cesium chloride centrifugation, the hemagglutinin of the bovine rotavirus was found to be associated with intact virions (density 1.355 g/ml) but not with virions lacking an outer capsid layer (density 1.375 g/ml). In hemagglutination-inhibition (HAI) tests, the hemagglutinin reacted specifically with NCDV serum, and HAI seroconversions were detected in some sera tested. Cross-reactions were observed in complement fixation tests between the human and bovine rotaviruses but were not demonstrated by HAI, suggesting that the hemagglutinin detects a specific rather than a group antibody response.

ISSN:0300-5526    

DOI:10.1159/000148927

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Three cytopathic strains of subacute sclerosing panencephalitis (SSPE) virus were isolated from brain biopsies of three patients. These strains were isolated and maintained by cocultivation of infected brain cells with fresh Vero cells. The biological characteristics of two strains were studied. It was found that these strains remain cell-associated after repeated cocultivations with Vero cells and produce plaques under fluid medium or traga-canth overlay. The correlation with measles virus was demonstrated by the plaque reduction test as well as by the immunofluorescence test. Large numbers of nucleocapsids were observed in the cytoplasm of infected cells but none in nuclei. Intracerebral inoculation of monkeys, adult guinea pigs, newborn and adult hamsters or mice was followed by acute encephalitis and death.

ISSN:0300-5526    

DOI:10.1159/000148928

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In a synchronous infection of cowpea chlorotic mottle virus in cowpea leaves, the three largest viral RNA components were synthesized throughout the infection at relatively constant ratios of two molecules of component 3 to one each of components 1 and 2. Component 4 (the coat protein message) was produced minimally during the initial stages of the infection, and as the infection progressed the proportion of component 4 continuously increased. The replicative forms of components 1, 2, and 3 were produced with kinetics similar to those of the corresponding single-stranded molecules.

ISSN:0300-5526    

DOI:10.1159/000148929

出版商:S. Karger AG    

年代:1978

数据来源: Karger