Edwin D. Kilbourne

Identification in a recombinant influenza virus of structural proteins derived from both parents.

Abstract A stable antigenic hybrid was isolated following recombination of A 0 /NWS and A 2 /RI/5 − influenza viruses (Kilbourne et al. , 1966). This recombinant (X-7) was inhibited in hemagglutination inhibition and neutralization tests with antiserum to the A 0 parent, but a minor A 2 component was also demonstrable by complement fixation and reduction in viral plaque size. The recombinant, the A 0 parent, and an antigenically identical variant of the A 2 parent were disrupted with sodium dodecyl sulfate, and their component proteins were isolated after separation by electrophoresis on cellulose acetate. It was shown by peptide mapping experiments and by immunologic methods that the recombinant virus possessed the hemagglutinin and the internal antigen of the A 0 parent and the neuraminidase of the A 2 virus. The recombinant virus exhibited one new property possessed by neither parent: an unusually rapid rate of elution from erythrocytes.

Recombination of influenza A viruses of human and animal origin.

Simultaneous infection of the allantoic sac of the chick embryo with influenza A/equine 1/56 and any of three recombinants derived from human influenza viruses produced stable hybrids with antigens from each parent strain. These hybrids contain the hemagglutinin protein of the equine virus and the neuraminidase of the human strains. The experiments demonstrate genetic homology of human and equine influenza A viruses and suggest the possibility of their recombination in nature.

GENETIC STUDIES OF INFLUENZA VIRUSES. II. PLAQUE FORMATION BY INFLUENZA VIRUSES IN A CLONE OF A VARIANT HUMAN HETEROPLOID CELL LINE.

Abstract Plaque formation with representative strains of all major influenza A virus subtypes and with influenza B (Lee) virus has been obtained in a clone (clone 1-5C-4) of a human cell line of apparently unique susceptibility. The efficiency of plaque formation relative to egg infective dose (EIU) varies with the strain of virus, ranging from 2 to 70%. The clone (1-5C-4) has remained stable with respect to viral susceptibility for at least 36 transfers in mass culture during a period of 9 months. Certain strains of virus formed plaques of characteristic and distinctive type of potential value in genetic studies. Kinetic studies of the virus-cell interaction with NWS indicated that adsorption proceeded rapidly. However, about 40% of inoculated virus was unadsorbed. Adsorption not reversed with antiserum was a slower process and required 3–4 hours. Single-cycle infection with a high input multiplicity of virus required 20 hours for completion and resulted in a yield of 4 PFU/cell.

Induced Reactivation of Herpes Simplex Virus in Healed Rabbit Corneal Lesions.

Summary Herpes simplex virus was inoculated into corneas of 8 rabbits with the induction of herpetic keratitis which proceeded to healing. The animals were then sensitized to horse serum and an Arthus reaction was induced in the healed cornea. Herpes simplex virus was repeatedly recov–ered in rabbit kidney cell culture from swab–bings taken from these corneas. This phenomenon was observed 7 times in 19 at–tempts at induction. While there were several instances of spontaneous virus release, none occurred during the 14 day post–Arthus period in the unchallenged eyes of animals in which bilateral infection had been induced previously.

Genetic studies of influenza viruses: III. Production of plaque-type recombinants with A0 and A1 strains

The passage of newly isolated, filamentous Asian (A2) influenza viruses in the presence of non-infective PR8 (A) virus results in the rapid emergence of virus of Asian (A2) antigenicity but PRS-like growth capacity and spherical morphology. Evidence is presented that this effect results from genetic interaction of the infective Asian and non-infective PR8 viruses rather than from spontaneous change of the Asian strain. It is concluded that influenza viral morphology, growth rate and growth capacity are associated genetic traits which distinguish unadapted from adapted strains, and which are transferable by recombination. A pragmatic consequence of these experiments is the fact that conditions have been defined for the rapid adaptation of early passage influenza virus isolates to the chick embryo allantoic sac. Such adaptation is attended by an increase in viral yield which has obvious implications for vaccine production during future epidemics with new antigenic types.

Chapter 6 - Inhibition of Viral Neuraminidase As a New Approach to the Prevention of Influenza*

Publisher Summary This chapter discusses the inhibition of viral neuraminidase as a new approach to the prevention of influenza. The usual objective of viral chemotherapy or immunoprophylaxis is the complete inhibition or restriction of infection. Another stratagem that has received insufficient attention is to achieve a lesser victory through a quantitative and partial limitation of infection sufficient to prevent disease but insufficient to inhibit the desirable immunizing effects of that infection. The chapter summarizes the basic approaches available for antiviral prophylaxis. In diseases with long incubation periods, such as rabies or even measles, administration of neutralizing antibody after infection can prevent or modify the evolution of disease. It is conceivable that sharp inhibition of viral replication by chemotherapy after the initiation of disease can have a similar effect. Another virtually untried approach is to immunize with minor antigenic components of the virus or to inhibit viral biological activities that are not essential for initiation of infection.

Induction of viral interference in mice by aerosols of inactivated influenza virus.

Summary Inactivated influenza viruses administered to mice intranasally or by aerosol induced transient heterologous immunity to infective influenza viruses. This immunity was reflected by reduction of pulmonary viral titers and by a reduced occurrence of gross lesions. This effect is considered to be an example of viral interference in that it required time to develop and persisted for at least 3 days; and because protective activity of inactivated viruses in mice could be correlated with interfering activity in the chick embryo. Interference modified but did not completely inhibit infection, and strain specific immunity of lessened degree developed to the challenge virus following the modified infection.

Effect of Hydrocortisone on Growth and Detachment of Human Heteroploid Cells in Maintenance Media.

Summary Nuclear enumeration studies of a human heteroploid conjunctival cell clone in monolayer cultures were performed in order to investigate the sustaining effect of near-physiological concentrations of hydro-cortisone on cells in maintenance media. This effect was associated with a slight and inconstant decrease in the limited cell proliferation that occurs in maintenance medium and with a considerable and significant decrease in the detachment of cells from the glass surface.

Interferon production in neonatally thymectomized mice.

Summary No significant difference in serum interferon titers could be demonstrated in neonatally thymectomized and litter mate control mice inoculated with NDV intravenously. Although the blood lymphocyte counts of the thymectomized mice were not consistently depressed, there was other evidence that the lymphoid tissue of these animals was markedly altered.