摘要:

Isopycnic centrifugation of infantile gastroenteritis virus (orbivirus group) in a CsCl gradient produced up to four bands at densities 1.38,1.36,1.30 and 1.28 g/ml. The particles in the bands had sedimentation coefficients of 380–400S, 520–530S, 270–280S and 320–330S, respectively. Whereas the 1.38 and 1.36 g/ml particles contained RNA, the 1.30 and 1.28 g/ml particles lacked RNA. Upon heating at 37°, the 1.36 g/ml particles broke down into particles of higher and lower

ISSN:0300-5526    

DOI:10.1159/000149951

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Acute hemorrhagic conjunctivitis (AHC) virus strains isolated in eight different areas during epidemics of AHC were tested for the reproductive capacity at 33, 37 and 39°. All of the 25 strains tested grew better at 33° but restrictively at 39°. The degree of temperature sensitivity varied slightly from one strain to the other, but generally exceeded that of attenuated poliovirus type 1, strain LSc2ab. Temperature-resistant clones were selected by repeated passages of originally temperature-sensitive prototype strains at supra-optimal temperature. The importance of using a low temperature (32–34°) for isolation of virus from external tissues of the body and for subsequent passages has been emphasized. It was suggested that the relatively low temperature of the conjunctiva has played a role in perpetuating temperature sensitivity of this

ISSN:0300-5526    

DOI:10.1159/000149952

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

In genetic recombination experiments with the mouse-lung-adapted human influenza A/Engl/l/61 (H2N2) and an avian influenza strain A/Rostock/34 (FPV) (HavlNl) which is avirulent for the mouse lung, recombinants in which hemagglutinin and neuraminidase were either segregated (Hav1N2; H2N1) or not segregated (HavlNl) were selected. The recombinants were studied for mouse-lung virulence and their ability to propagate in mouse kidney cells, mouse embryo fibroblasts, chick embryo kidney cells and chick embryo fibroblasts. An association between plaque formation in mouse kidney cells and mouse-lung virulence was found.

ISSN:0300-5526    

DOI:10.1159/000149953

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Avian myeloblastosis virus (AMV) was harvested at different time intervals from chick leukemic myeloblasts, and the rate of the maturation process of AMV was estimated on the basis of morphological changes in the virions and conversion of genomic viral RNA. The change from immature virions characterized by the presence of an electron-lucent center to the condensed mature form (with dense nucleoid) was accompanied by the conversion of 30–40S RNA to 60S RNA. Both processes were quantitatively defined, correlated, and found to proceed in parallel at the same speed. Early stages of maturation were characterized by a high turnover of immature to mature virions; 31–40% of the mature forms were found in 3.5-min virus harvests. The rate of this process decreased with time. The 17-hour harvests still revealed the presence of 10–15% of immature virions. The course of the maturation process is disc

ISSN:0300-5526    

DOI:10.1159/000149954

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Proteins showing affinity for DNA in HSV-1- and HSV-2-infected cells were compared by DNA-cellulose chromatography and PAGE. The proteins observed depended on the type of virus used to infect the cell; however, several examples of analogous poly-peptides were present in cells infected by both virus types. Proteins showing highest affinity for DNA-cellulose were similar in molecular size in cells infected by both virus types.

ISSN:0300-5526    

DOI:10.1159/000149955

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Intramitochondrial virions (IMV), in many respects structurally similar to ‘C-type1 viruses of higher organisms, are synthesized in close topographical association with inner mitochondrial membranes of the viper spleen cell line, VSW. Cristal membranes contribute to the formation of a trilaminar viral envelope, whereas the outer mitochondrial membrane does not appear to play any structural role in virion maturation. Two schematic models, correlated with electron microscopic images, are presented to depict: (a) the relative location of the particles within a three-dimensional view of the mitochondrion, and (b) the sequence of virion-mitochondrial membrane relationships during morphogenesi

ISSN:0300-5526    

DOI:10.1159/000149956

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Virus shedding patterns of neonatal gnotobiotic piglets infected with the reovirus-like agent of human infantile gastroenteritis were studied. Fecal viral counts were highest before or at the onset of diarrhea. In diarrheic piglets, viral particles were usually observed for only 1–2 days after the onset of diarrhea, and total duration of shedding was 2–6 days. One infected piglet shed virus for 4 days but did not develop diarrhea. The presence of virus at or about the time of illness is consistent with the induction of diarrhea in piglets inoculated with the human reovirus-like ag

ISSN:0300-5526    

DOI:10.1159/000149957

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

RNAs associated with polyribosomes in plants infected with the U2 strain of tobacco mosaic virus (TMV) or with sunnhemp mosaic virus have been isolated. Most are about 0.35 × 106 daltons in weight. They translate efficiently in vitro to produce their respective coat proteins which were identified by their serological behavior and peptide composition. They also reassemble in vitro with coat protein. The coat protein of sunnhemp mosaic virus reassembles more quickly than that of TMV U2

ISSN:0300-5526    

DOI:10.1159/000149958

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Particles of the U2 strain of tobacco mosaic virus (TMV) were partly disassembled by SDS, treated with RNases and then phenol, and yielded RNA molecules one quarter to half the size of the intact virus genome. These molecules, when translated in vitro, produced the coat protein of the virus. Reassembly experiments indicated that the active messenger molecules were those that most rapidly reassembled with coat protein; the rate of reassembly was greatly diminished by treatment with spleen phosphodiesterase. Particles of sunnhemp mosaic virus (the bean strain of TMV) resist disassembly by detergent much more than those of the U2 strain of TMV.

ISSN:0300-5526    

DOI:10.1159/000149959

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

A technique that ‘systemically inoculates’ cowpea leaves with cowpea chlorotic mottle virus (CCMV) is described. The upper leaves of cowpea plants are maintained at 10° and allowed to become infected with inoculum from lower leaves maintained at 32°; when the whole plant is shifted to 25°, synchronous virus replication starts in the upper leaves. Following the shift to 25°, no infectivity could be detected during the first 6 h, after which the infectivity increased exponentially between 8 and 20 h and linearly between 20 and 72 h. The time-courses of effectiveness of different inhibitors occurred sequentially and at different times during the infection. An actinomycin-D-sensitive step occurred at 10°, prior to the shift to 25°. A 2.0 Mm guanidine-sensitive step occurred between 4 and 20 h and a cycloheximide-sensitive step occurred between 12 and 48 h after the shift to 25°. When the upper leaves were maintained at 5° while the infected lower leaves were at 32°, viral inoculum did not move into them. However, rapid systemic infection occurred during the first 6 h after a shift of the whole

ISSN:0300-5526    

DOI:10.1159/000149960

出版商:S. Karger AG    

年代:1976

数据来源: Karger