A New Count of Allantoic Cells of the 10-Day Chick Embryo

The administration of cortisone to chick embryos inoculated with large quantities of inactive influenza B virus results in a rate of viral increase greater than is concommittantly observed with inocula of comparable infectivity which are devoid of inactive particles. Thus, more than a mere negation of autointerference is effected. It is concluded that in the presence of cortisone reactivation has occurred of non-infective virus to a state in which it can participate in viral synthesis. Cortisone-induced viral reactivation is dependent upon a high partide/cell ratio and is thus analogous to the previously described phenomenon of "multiplicity reactivation." Cortisone does not influence either homologous or heterologous viral interference unless reactivation of the inactive interfering virus occurs. Virus reactivable with cortisone possesses both interfering and enzymatic properties. Reactivation of virus with cortisone cannot be effected in vitro but is mediated by the host cell. Two hypotheses concerning the action of cortisone are presented.

Section: Ma2ericds and Methodsmentioning

confidence: 99%

Section: Ma2ericds and Methodsmentioning

confidence: 99%

Reactivation of Non-Infective Virus in a Cortisone-Injected Host

1955

“…Estimations of the number of host cells of the chorinailantoic membrane are based on studies by Tyrrell et al (11) in which the number of chorioallantoic membrane cells of the 10 day old chicken embryo has been defined as 1.8 X 107. A more recent estimate by Cairns and Fazekas (12) is about twice this number (3.1 X 107).…”

Section: Relation Of Number Of Viral Particles To Number Of Host Chormentioning

confidence: 99%

The Influence of Cortisone on Experimental Viral Infection

1957

Earlier publications have presented evidence that the course of influenza virus infection in chicken embryos, mice, and tissue culture is strikingly affected by the administration of corticosteroid hormones. It has been shown that under appropriate experimental conditions final yields of virus are increased (1-3), that antibody formation, acquired immunity (4), and inflammatory reaction (3) are depressed, that the survival time of infected chicken embryos is prolonged (3), and that "multiplicity reactivation" of non-infective virus is clearly demonstrable (5).Ensuing studies have clarified the mechanisms of cortisone action in the influenza virus-chicken embryo system. The results of these studies are presented in this and two companion papers. It will be demonstrated that cortisone and related steroids have two distinct effects on the course of influenza virus multiplication: (a) inhibition of viral synthesis, and (b) inhibition of the autointerference caused by large numbers of viral particles. Yields of virus will be shown to be the resultant of these two contrasting effects.The present paper is concerned with the influence of cortisone on the dynamics of influenza virus increase. It will be evident that consideration of these kinetics has been essential in defining the mechanisms of cortisone action. Materials and MethodsViruses.--The Lee strain of influenza B virus and the PR8 strain of influenza A virus were used as allantoic fluid suspensions. Dilutions of virus were made in 0.01 M phosphate buffered NaC1 (0.85 per cent) solution. To "inactive" viral inocula derived from thermally inactivated virus were added streptomycin (1 mg./ml.) and penicillin (100 units/ml.). Preparations designated as "active" virus were prepared as suggested by Horsfall (6, 7) to contain a relatively high proportion of infective viral particles (see Kilbourne (5)). Viruses were stored at --68°C. in a special CO~ box in which CO2 is excluded from the specimen compartment (8). RDE *

“…reference 6). Recent determinations in 10-day-old chick embryos revealed that this figure is high and that it is nearer 107 .4 (10). Previous reports indicate that between 50 and 95 per cent of the seed virus becomes adsorbed onto the allantoic cells (11)(12)(13)(14).…”

Section: Discussionmentioning

confidence: 99%

Studies on Host-Virus Interactions in the Chick Embryo-Influenza Virus System

Paucker

Henle

1955

In the preceding paper of this series (1) evidence has been presented which shows that standard seeds of influenza virus, heated for several days at 37°C., resemble in many respects those obtained by serial passage of undiluted infected allantoic fluid as described by ,con Magnus (2, 3). Both yielded on passage in the chick embryo large quantities of hemagglutinins (HA) but relatively little infectious virus, provided they were injected in sufficient concentrations. Correspondingly, the ID~0/HA ratios of the yields were considerably lower than those noted in standard preparations of virus. Little or no non-infectious hemagglutinins (NIHA) were found when both the "undiluted passage" (UP) or heated standard (ST) seeds were diluted 100-to 1000-fold prior to injection and virus material of near standard composition was obtained. However, there exist also considerable differences between the two types of seed preparations with respect to the progenies they produce. The yields from UP seeds never revealed ID~0/I-IA ratios lower than 10 ~, whereas those derived from heated ST virus showed ratios as low as 101 . On the other hand, the ratios obtained in the first few undiluted passages decreased by as much as 2 log10 unites below those of the seeds used (2-4), while the yields of heated standard virus revealed always ratios equal to or greater than those of the inocula (1). This became more evident when UP and heated ST seeds were compared on the basis of equal IDs0 and HA concentrations. Both yielded similar quantities of HA, but the former produced considerably less infectious virus.It is the purpose of this report to present data on some of the quantitative aspects of passages of standard virus which had been heated at 37°C. for increasing periods of time. The results indicate that the inactivated virus in the inocula interferes with second infectious cycles but does not significantly