摘要:

Patterns of cellular RNA synthesis during poliovirus (types 1 2 and 3) and mengovirus infections in HeLa, HEp-2, Vero and L-cells were investigated by means of high-resolution autoradiography, kinetics of 3H-uridine incorporation, and sucrose gradient centrifugation. Only mengovirus-infected L-cells showed an early and exponential inhibition of hnRNA and rRNA synthesis. The other cell lines tested, whether infected with polio- or mengovirus, exhibited a slowly and linearly decreasing cellular RNA synthesis, with hnRNA production suppressed completely, although somewhat later than in L-cells, and rRNA synthesis continuing at a gradually reduced rate during the entire viral growth cycle. Locations of cleavage steps of rRNA precursor molecules are discussed.

ISSN:0300-5526    

DOI:10.1159/000148984

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

An examination of the effect of supraoptimal temperatures upon tobacco mosaic virus (TMV) RNA replicase demonstrated that the enzyme activity rapidly decreased at 40° whether incubated in vitro after extraction or in leaves at that temperature prior to extraction and assay. The loss of replicase activity paralleled the decline in capacity for in vivo incorporation of 32P into TMV RNA at 25° following different periods of incubation at 40°. The optimal temperature for replicase activity in vitro was 35°, and greater activity occurred at 40 than at 25°. After about 15 min incubation at 40°, in vivo incorporation 0f 32p into double-stranded TMV RNA became temperature-sensitive. This function could not be reproduced with the in vitro replicase s

ISSN:0300-5526    

DOI:10.1159/000148985

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Herpes simplex virus type 1 (HSV-1), strain ANG, was passaged serially at high MOI or undiluted on RC-37 cells. The yields of infectious virus decreased and increased periodically with a maximum of about 3 log units variation in titer. The amount of newly synthesized HSV-1 DNA, however, did not vary by more than a factor of 2. On the other hand, the fraction of total HSV-1 DNA associated with virions was reduced at passage numbers coinciding with the minima in the yields of infectious progeny virus. Apparently, low yields of infectious virus mainly reflected a reduced efficiency of packaging of viral DNA into mature virus particles. One step in the process of virus maturation which appeared to be impaired was the assembly of nucleocapsids. HSV-1 ANG was shown to be capable of generating different classes of defective particles in independent series of virus passages at high MOI.

ISSN:0300-5526    

DOI:10.1159/000148986

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effect of caffeine on cytomegalovirus (CMV) replication in human embryo lung (HEL) and human embryo kidney (HEK) cells was studied. In HEL cultures, nonirradiated CMV yielded up to 6.7 times more plaques in caffeine-treated cultures than in control cultures. Virus growth curves exhibited different profiles, depending on the time of treatment of the cultures with the drug. Incorporation of [3H] TdR into virus DNA was enhanced and began about 24 h earlier in the caffeine-treated cultures than in the untreated cultures. A relationship between decreased incorporation of [3H] TdR into cellular DNA caused by caffeine and increased virus replication was observed in the HEL cells. In caffeine-treated HEK cultures, CMV replicated better than in untreated cultures in which virus growth was transitory and decreased after 10 days of incubation. The infectivity of CMV irradiated with UV light doses of 3,120–12,480 erg/mm2 decreased as a function of the UV dose. The extent of multiplicity reactivation of the irradiated virus increased when irradiated with higher UV doses. The effect of caffeine on the infectivity of UV-irradiated CMV depended on the dose with which the virus was irradiated. Caffeine increased the infectivity of CMV irradiated with the lowest UV dose (3,120 erg/mm2) but did not increase the infectivity of virus irradiated with 12,480 erg/mm2. Multiplicity reactivation of the UV-irradiated CMV was inhibited by caffeine regardless of the UV dose with which the virus was irradiate

ISSN:0300-5526    

DOI:10.1159/000148987

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Hepatitis B core antigen (HBcAg) particles, approximately 27–28 nm in diameter and p = 1.30–1.35 g/cm3, were purified from the liver of a chimpanzee experimentally infected with hepatitis B virus (HBV) while under cyclophosphamide treatment. The purified HBcAg particles incorporated radioactive deoxythymidine triphosphate. The product was precipitable by trichloroacetic acid and sensitive to DNase, but resistant to digestion by RNase. The reaction required four deoxyribonucleoside triphosphates -dATP, dCTP, dGTP and dTTP. Exogenous template did not enhance the reaction. From these findings, it was suggested that HBcAg particles purified from the HBV-infected chimpanzee liver contained DNA polymerase and endogenous

ISSN:0300-5526    

DOI:10.1159/000148988

出版商:S. Karger AG    

年代:1978

数据来源: Karger