Ann Schluederberg

Measles virus RNA.

Abstract RNA has been isolated from measles virions which sediments with a coefficient of 52.2 S when compared with 50 S RNA from SV 5 virions.

Comparative molecular weight estimates of measles and subacute sclerosing panencephalitis virus structural polypeptides by simultaneous electrophoresis in acrylamide gel slabs.

Summary Structural polypeptides of a measles virus strain isolated from a case of subacute sclerosing panencephalitis (SSPE) were compared with those of the Edmonston strain by electrophoresis in acrylamide gel slabs containing sodium dodecyl sulfate. The smallest polypeptide, which appears to be the membrane protein, of the SSPE strain migrated more slowly than the corresponding measles polypeptide, indicating molecular weights of 40,000 and 38,000 daltons, respectively. The five other proteins successfully compared showed identical mobilities. A greater concentration of one of these (66,000 daltons) was seen in SSPE virions.

Actinomycin D: Renewed RNA Synthesis after Removal from Mammalian Cells

Suppressed RNA synthesis exceeded control rates 2 hours after removal of actinomycin from serial lines of green monkey kidney cells in exponentially dividing monolayer cultures. Enhanced synthesis was directly related to the dose of actinomycin, and release from inhibition was temperature dependent. A broad range of RNA sizes was made after removal of drug, but cytoplasmic and nucleolar sedimentation profiles were abnormal for at least 20 hours.

A salt-dependent hemagglutinating particle from measles-infected cells

Abstract A salt-dependent agglutinin (SDA) has been isolated from measles-infected cells which adsorbs to erythrocytes only in hypertonic salines. SDA appears to agglutinate only those red blood cells already shown to be susceptible to measles hemagglutination, and receptors are resistant to receptor-destroying enzyme. In contrast to other measles hemagglutinating particles, SDA can be recovered from agglutinated red blood cells by elution into isotonic saline. SDA hemagglutination is specifically inhibited by measles convalescent sera. SDA contributes up to 50% of measles complement-fixing antigen activity of infected cell extracts. It induces the production of HI and neutralizing antibodies when injected into guinea pigs. SDA titers are highly dependent upon temperature, although adsorption to erythrocytes is not. Titers at 37° increase as a function of charge and concentration of anion and of pH. There was no dissociation or aggregation of SDA in activating salt concentrations as shown by zonal sedimentations. SDA sediments with a coefficient of 22 S and has a buoyant density in CsCl of 1.30 g/ml. Chemically it appears to be a protein with characteristics similar to those associated with the hemagglutinating activity of the measles envelope. The possibility that SDA represents a precursor of the measles envelope is discussed.

Viral RNA synthesis in measles virus-infected cells☆

Abstract Sedimentation analysis of measles virus-specific cytoplasmic RNA at different times after infection revealed several size classes. The three specific components found in greatest amount were estimated to have sedimentation coefficients of 20 S, 27 S, and 35 S. A fourth component, 52 S, sedimented with characteristics of viral RNA. 20 S RNA appeared later than the other size classes, and accounted for an increasingly greater proportion of the total. However, with a temperature-sensitive mutant synthesis of all three major components was turned off simultaneously by transfer of infected cultures from permissive to nonpermissive temperature. Subgenomic-size RNA was found in virion preparations made by undiluted passage, but not after serial passage of diluted inoculum.

Neuraminidase associated with measles virus

Abstract No neuraminidase activity was found in highly concentrated measles virus preparations. Enzyme activity previously reported has been attributed to a latent virus.

Inhibition of measles virus replication and RNA synthesis by actinomycin D

Abstract Measles virus replication and RNA synthesis in Vero cells are inhibited by actinomycin at concentrations which inhibit cellular RNA synthesis. Drug present from the 2nd to the 24th hr post infection inhibited infectivity but not hemagglutinating activity or cell fusion. Infectivity was much less sensitive to drug added during the second 24-hr period, and 52S RNA was labeled and incorporated into virions during this later time interval.

The Role of the Nucleus in Measles Virus Replication

Data bearing on the appearance of measles-specific components in infected-cell nuclei have been reviewed. There is suggestive evidence that nuclear compartmentalization may be host-dependent and that nuclear accumulations may increase when virus release is blocked. It remains uncertain whether the presence of viral components in the nucleus is an incidental or a required stage in measles virus replication. We noted, however, that radioactively labeled measles RNA was demonstrated in nucleoplasmic fractions following short exposures to [3H]-uridine, and that it appeared to accumulate in association with the nucleus late in infection. We recently have been examining nuclei isolated from measles virus infected cells for viral polymerase activity, but none has been demonstrated.It was previously shown that measles virus will replicate in cells whose DNA functional integrity has been impaired by irradiation or drugs. Nevertheless, it has been reported that actinomycin D will inhibit virus replication. New data are presented which provide additional evidence that this drug may inhibit viral replication by a direct effect on genome synthesis. The results of virus growth in cells exposed to cordycepin orα-amanitin are also reported.

The behavior of a newly described acute-phase protein in inflammatory joint disease

Rho, a newly characterized acute-phase protein, was present in high titer in a group of 109 patients with various rheumatic diseases. Statistically significant titer elevations were demonstrated in patients with rheumatoid arthritis (RA), ankylosing spondylitis, and gout. In individual RA patients, serial titers failed to correlate with disease activity or with rheumatic seropositivity. The natural behavior ofrho antigen is contrasted with that of C-reactive protein. Comments are made regarding the possible association of rubella infection with rheumatoid arthritis.

Nucleus-associated RNA in measles virus-infected cells.

Abstract Measles virus RNA was found in the nuclear fraction of infected Vero cells. 24-hr labeling periods revealed heterogeneously sedimenting 15–50 S RNA associated with a membrane-containing particulate. Viral RNA isolated after shorter labeling periods was larger in size (30–50 S) and associated with both nucleoplasmic and particulate fractions.