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Biomedical subjects

E Tomas

Publications and source records attributed to E Tomas.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

Effects and mechanism of the interaction between ceruloplasmin and some viruses or subviral components.

The results of investigations concerning the interaction between ceruloplasmin (a serum nonspecific inhibitor) and some myxo- and paramyxoviruses, as well as certain viruses with oncogenic potential (herpes virus, SV--40) are reviewed. The data presented point out the inhibiting action of ceruloplasmin on virus multiplication and the ceruloplasmin-induced modification in the antigenicity of Sendai virus and subviral fractions. The stages and mechanisms of ceruloplasmin action are discussed.

Animals↗
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Structural particularities of parainfluenza type 1 (Sendai) virus progens obtained by cultivation in the presence of ceruloplasmin.

Sendai virus multiplication in the presence of ceruloplasmin resulted in the appearance of qualitatively modified progens. There was an increase in the proportion of incomplete virus particles and a decrease in hemagglutinin and neuraminidase activities, in virus infectivity and antigenicity (with the exception of subviral fractions with predominant hemagglutinating activity). Virus progens obtained in the presence of ceruloplasmin had a higher sensitivity to detergent treatment; virus ghosts formed by re-aggregation of envelope fragments could be observed in the electron microscope.

Animals↗
PubMedDate not supplied

Considerations about the possible function of ceruloplasmin in influenza and parainfluenza virus infections.

The experimental data reveal that ceruloplasmin is a serum nonspecific factor acting during the early and late stages of infection with some respiratory viruses. This complex action seems to be based both on the enzymatic activity and on the copper-glycoprotein structure of ceruloplasmin. The changes in progen antigenicity produced by ceruloplasmin are probably involved in the mechanism of the antigenic shift and drift.

Animals↗
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Light scattering from polycation--virus--oligocation mixtures.

The effect of a polycation (histone H2A) and of oligocations (spermine, spermidine and putrescine) on Sendai and influenza virus particles was investigated by light scattering measurements at 90 degrees and at various wavelengths. The method allows the study of the changes in the size and shape of virus particles in suspension.

Cations↗
PubMedDate not supplied

The relationship between Sendai virus envelope antigens and the immune response in the presence and absence of ceruloplasmin.

The immune response of rabbits inoculated with different Sendai virus glycoprotein antigens depends on the structural identity of the protein support as well as on the mode of organization and structural homogeneity of the solubilized virus envelope. Incubation of the antigens with ceruloplasmin leads to modifications in the immune response, owing to the interaction with the active hemagglutinating and enzymatic sites.

Animals↗
PubMedDate not supplied

Some particularities of Sendai virus multiplication in chorioallantoic membrane fragments.

Marked differences were recorded in the kinetics of infectant and hemagglutinating (HA) activities of parinfluenza type 1 (Sendai) virus grown in chorioallantoic membrane (CAM) fragments in roller tubes with or without daily changes of the culture medium. The differences were dependent on cultivation conditions, the time interval post inoculation and the state of the CAM cells. Taking into account these conditions, it is possible to obtain either highly infectant virus or virus with low infectivity but high HA activity.

Allantois↗
PubMedDate not supplied

Investigations concerning the cultivation of myxo- and paramyxoviruses on chorioallantoic membrane fragments. Note I. Data on the multiplication of several myxo- and paramyxoviruses.

Influenza viruses A(H1N1) and A(H3N2) and parainfluenza viruses (Sendai mumps) were cultivated in chorioallantoic membrane (CAM) fragments maintained in media with different formulae, with or without daily medium changes, in roller or stationary tubes. Inoculation was performed either directly on CAM fragments in Petri dishes or by dilution of the virus-containing material in the medium. Infectant titers obtained in CAM fragments were similar to those recorded in embryonated eggs at 48 hours post inoculation (p.i.) in the case of influenza virus A(H1N1) and at 72 hours p.i. in that of Sendai and influenza A(H3N2) viruses; at 96 hours p.i. all the three viruses had titers superior to those found in the egg.

Animals↗
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Some characteristics of Sendai virus envelope solubilization by different detergents.

Gel-filtration through Sepharose-2B of Sendai virus envelopes solubilized by Tween-20 or Triton X-100 treatment allows the separation of two elution peaks, hemagglutinin (HA) activity being detected only in the peak corresponding to large envelope fragments. Solubilization of the same virus envelopes with N-octylglycoside (NOG) results in a single elution peak, exhibiting both HA and neuraminidase activities. The results obtained suggest : 1) the similar envelope composition of the different virus populations, and 2) the different mechanisms of solubilization, in relation to the detergent used for disruption. The advantages of virus disruption by NOG are discussed.

Chromatography, Gel↗
PubMedDate not supplied

Relationships between ceruloplasmin and viral immunity.

Experimental data are reviewed with reference to the role of ceruloplasmin as a nonspecific factor of viral immunity. Ceruloplasmin would act a) by an inhibition of virus multiplication, resulting in a "slow-motion" infection, which promotes immunization; b) by leading to the synthesis of a virus population rich in defective interfering particles, and c) by the direct modulation of the immune response.

Animals↗
PubMedDate not supplied

Comparative study of some characteristics of influenza virus A/PR8/34 (H1N1) cultivated on chorioallantoic membrane fragments in the presence of ceruloplasmin or of parainfluenza type I (Sendai) virus.

Multiplication of influenza virus A/PR8/34 (H1N1) in the presence of either ceruloplasmin or parainfluenza type I (Sendai) virus results in the appearance of progens different from the parental virus as regards some of their biological properties. The role of viral envelope changes in acquiring new characteristics is discussed.

Allantois↗
PubMedDate not supplied

The effect of ceruloplasmin on the multiplication and on some biological and physico-chemical characteristics of influenza virus A/PR8/34 (H0N1) cultivated on chorioallantoic membrane fragments. Note 1. Kinetics of virus multiplication and of some biological characteristics in the presence and absence of ceruloplasmin.

The presence of ceruloplasmin in the inoculum inhibits the multiplication of influenza virus A/PR8/34 (H0N1) in chorioallantoic membrane fragments. Virus corpuscles that remain uncoupled to ceruloplasmin infect the host cells and their replication results in progens whose properties differ from those of controls inoculated in the absence of ceruloplasmin. The variation in time of the characteristics of the respective virus progens is discussed.

Allantois↗