Julius S. Youngner

Monolayer Tissue Cultures. I. Preparation and Standardization of Suspensions of Trypsin-Dispersed Monkey Kidney Cells.

Summary An adaptation of the method of Dulbecco for preparation of trypsin-dispersed monkey kidney cell suspensions has been described. Procedures employed yield quantitatively standardized cell suspensions which can be used in the preparation of large numbers of replicate cultures.

Patterns of Interferon Appearance in Mice injected with Bacteria or Bacterial Endotoxin.

PREVIOUS work1 has shown that the intravenous injection of large numbers of live Brucella abortus into chickens results in the appearance in the serum of a viral inhibitor with the properties of interferon. Inhibitor reached maximum levels about 12 h after inoculation. It was also reported that large numbers of Newcastle disease virus (NDV) particles produced maximum levels of interferon in chickens about 12 h after intravenous inoculation. Injection of large doses of other gram-positive and -negative bacteria or bacterial endotoxins failed to produce demonstrable inhibitors in the circulation of chickens at 6–8 h.

Formaldehyde treatment and safety testing of experimental poliomyelitis vaccines.

an experimental vaccine, and for safety testing, as yet have not been published. It is the purpose of this communication to discuss the principles underlying the procedures being followed in preparing material for more extensive studies than have been carried out thus far; essentially, this represents a discussion and an elaboration of the specifications which have been prepared for processing the vaccine for this purpose. A fuller presentation and documentation of details here referred to will be covered in several reports to be made in the appropriate technical journals.

Influence of Inhibitors of Protein Synthesis on Interferon Formation in Mice.

Abstract The existence of preformed interferon in the tissues of intact animals has been clearly demonstrated by the experiments reported. This was shown by the finding that doses of puromycin or cycloheximide which effectively inhibited protein synthesis did not prevent the appearance of circulating interferon in mice injected with bacterial endotoxin. In contrast, interferon induction by Brucella abortus or NDV was eliminated by blockade of protein synthesis. Further evidence for the presence of preformed interferon in intact mice was provided by experiments in which only cycloheximide was injected. Effective blockade of protein synthesis was accompanied by the appearance in the circulation of significant amounts of a viral inhibitor which was indistinguishable from virus-induced interferon.

Efficacy of a cold‐adapted, intranasal, equine influenza vaccine: challenge trials

A randomised, controlled, double-blind, influenza virus, aerosol challenge of horses was undertaken to determine the efficacy of a cold-adapted, temperature sensitive, modified-live virus, intranasal, equine influenza vaccine. Ninety 11-month-old influenza-naïve foals were assigned randomly to 3 groups (20 vaccinates and 10 controls per group) and challenged 5 weeks, 6 and 12 months after a single vaccination. Challenges were performed on Day 0 in a plastic-lined chamber. Between Days 1 and 10, animals were examined daily for evidence of clinical signs of influenza. Nasal swabs for virus isolation were obtained on Day 1 and Days 1 to 8 and blood samples for serology were collected on Days 1, 7 and 14. There was no adverse response to vaccination in any animal. Following challenge at 5 weeks and 6 months, vaccinates had significantly lower clinical scores (P = 0.0001 and 0.005, respectively), experienced smaller increases in rectal temperature (P = 0.0008 and 0.0007, respectively) and shed less virus (P<0.0001 and P = 0.03, respectively) over fewer days (P<0.0001 and P = 0.002, respectively) than did the controls. After the 12 month challenge, rectal temperatures (P = 0.006) as well as the duration (P = 0.03) and concentration of virus shed (P = 0.04) were significantly reduced among vaccinated animals. The results of this study showed that 6 months after a single dose of vaccine the duration and severity of clinical signs were markedly reduced amongst vaccinated animals exposed to a severe live-virus challenge. Appropriate use of this vaccine should lead to a marked reduction in the frequency, severity and duration of outbreaks of equine influenza in North America.

Characterization of a specific kinase inhibitory factor produced by vaccinia virus which inhibits the interferon-induced protein kinase.

When mouse L cells are infected by vaccinia virus, a specific kinase inhibitory factor is produced which inhibits the interferon-induced, double-stranded RNA-dependent protein kinase (P. Whitaker-Dowling and J. S. Youngner (1983) Virology 131, 128-136). This inhibitory factor appears early in vaccinia infection (90 min) and its production requires protein synthesis. It inhibits the phosphorylation of the alpha subunit of protein synthesis initiation factor eIF-2 and it is active in mixed extracts of IFN-treated cells and vaccinia-infected cells. The vaccinia-mediated inhibition of the IFN-induced protein kinase is not due to a specific phosphatase or a specific protease and can be reversed by the addition of excess double-stranded RNA. Evidence is presented which suggests that the specific kinase inhibitory factor interacts in a stoichiometric manner with the double-stranded RNA which is required for the activation of the interferon-induced protein kinase.

Viral Persistence: Evolution of Viral Populations

There is an extensive literature dealing with persistent infections established by a wide variety of animal viruses. Several mechanisms have been suggested that may be involved in the establishment and maintenance of persistent infection by a normally virulent, cytolytic virus. One of these mechanisms, which involves defective-interfering (DI) virus particles in the initiation and regulation of some persistent infections, is discussed in Chapter 3 of this volume. This chapter will concentrate on another aspect of persistent viral infection, namely, the evolution of virus populations in infections initiated by virulent viruses in cell culture model systems or in immunologically competent animals. A comprehensive survey of the findings with many different groups of viruses will be followed by a discussion of the patterns of virus evolution during persistent infection and the implications of these changes in systems in which cytolytic viral infections are converted to more temperate host-virus interactions. Persistent infections in which the evolution of the virus population has not been studied will be mentioned but are outside the main focus of this review.

Interferon Production in Chickens Injected with Brucella abortus

Intravenous injection of large numbers of live, virulent Brucella abortus in chickens resulted in the appearance in the serum of a viral inhibitor indistinguishable from interferon. Inhibitor was detected as early as 3 hours after inoculation of brucellae and reached a peak between 6 and 12 hours.

Vaccinia rescue of VSV from interferon-induced resistance: Reversal of translation block and inhibition of protein kinase activity

Coinfection with vaccinia virus rescues vesicular stomatitis virus (VSV) from the inhibitory effects of interferon (IFN) in mouse L cells. While vaccinia infection does not significantly affect VSV RNA synthesis, coinfection with vaccinia dramatically increases VSV protein synthesis in IFN-treated cells. Evidence is provided that vaccinia inhibits the activity of the IFN-induced dsRNA-dependent protein kinase.

Epidermal powder immunization of mice and monkeys with an influenza vaccine

Epidermal powder immunization (EPI) with an influenza vaccine and an adjuvant such as QS-21, LTR72, or cholera toxin elicited augmented serum and mucosal antibody responses in mice. Rhesus macaques, which have an immune system and skin structure similar to humans, were used to further evaluate the immunogenicity of the influenza vaccine following EPI. EPI of rhesus macaques with an influenza vaccine and QS-21 adjuvant elicited significantly higher serum hemagglutination inhibition (HI) titers than antigen alone administered by EPI or by intramuscular (IM) injection using a needle and syringe. In the absence of QS-21, EPI and IM injection elicited comparable HI titers in the monkeys. This study suggests that EPI is a promising technique for administering human vaccine and that QS-21 augments the immunogenicity of co-administered influenza vaccine.