I. The Properties of Interferon. The Formation and Action of Interferon Induced in Cell Cultures and Chick Embryos.- 1. The Principal Properties of Interferon.- 1.1. Physicochemical properties.- 1.2. Species specificity.- 1.3. Antigenic properties.- 1.4. Conclusion.- 2. The Formation of Interferon in Cell Cultures and Chick Embryos.- 2.1. The interferon-inducing activity of viruses.- 2.1.1. The interferon-inducing action of poxviruses.- 2.1.2. The interferon-inducing activity of myxoviruses.- 2.1.3. The interferon-inducing activity of rhabdoviruses.- 2.1.4. The interferon-inducing activity of herpes viruses.- 2.1.5. The interferon-inducing activity of arboviruses.- 2.1.6. The interferon-inducing activity of other viruses.- 2.2. Nonviral induction of interferon in cell cultures.- 2.3. Factors influencing the intensity of interferon production.- 2.4. Comparative study of the induction of interferon by viruses in different cell cultures.- 2.5. Dynamics of formation and liberation of interferon in cell cultures.- 2.6. Blocking of the formation and action of interferon by viruses.- 2.7. Conclusion.- 3. The Action of Interferon in Cell Cultures.- 3.1. The sensitivity of viruses and cells to inferferon.- 3.2. Methods of indication and assay of interferon.- 3.3. Studies of the sensitivity of some virus-cell systems to interferon.- 3.4. Conclusion.- 4. Interferon Production by Human and Animal Leukocytes.- 4.1. Interferon production by rabbit and mouse blood leukocytes.- 4.2. Interferon production by monkey blood leukocytes.- 4.3. Interferon production by suspensions of human leukocytes.- 4.3.1. Importance of the blood group.- 4.3.2. Effect of incubation medium for leukocytes with virus on quantity of interferon formed.- 4.3.3. Effect of leukocyte concentration in suspension on interferon production.- 4.3.4. Effect of reaction of the medium.- 4.3.5. Effect of incubation temperature.- 4.3.6. Importance of the species of inducing virus and the multiplicity of infection.- 4.3.7. Dynamics of interferon production by human leukocytes.- 4.3.8. The properties of leukocytic interferon.- 4.4. Interferon production in growing cultures of human leukocytes.- 4.5. Conclusion.- II. Effect of Exogenous Interferon and Stimulators of Endogenous Interferon on Virus Infections.- 5. Effect of Exogenous Interferon on Virus Infections.- 5.1. Action of exogenous interferon on experimental virus infections.- 5.2. Clinical trials of exogenous interferon.- 5.3. Conclusion.- 6. Effect of Stimulators of Endogenous Interferon on Experimental Virus Infections.- 6.1. Stimulation of endogenous interferon by intravenous and other methods of injection of inducers of virus origin.- 6.2. Effect of virus inducers of interferon formation on experimental virus infections.- 6.3. Stimulation of endogenous interferon by double-stranded RNAs and their effect on virus infection.- 6.4. Stimulation of endogenous interferon by other nonviral inducers and its effect on experimental virus infection.- 6.5. Tolerance or hyporeactivity in interferon production.- 6.6. Conclusion.- 7. Clinical Trials of Stimulators of Endogenous Interferon.- 7.1. Stimulation of endogenous interferon in man and its effect on virus infections.- 7.2. Interferon-inducing properties of living influenza vaccine virus.- 7.3. Interferon-inducing properties of partially UV-inactivated A2 influenza virus.- 7.4. Interferon-inducing properties of inactivated viruses.- 7.5. Effect of stimulators of endogenous interferon on survival of influenza vaccine virus.- 7.6. Conclusion.- III. Interferon Formation and Virus Infection.- 8. Interferon Formation in the Body during Virus Infections and Its Pathogenic Role.- 8.1. Interferon formation in virus infections of animals.- 8.2. Interferon formation in human virus infections.- 8.3. Effect of various factors on interferon production in vivo.- 8.4. Interferon production in the immune organism.- 8.5. The role of interferon in the pathogenesis of virus infections.- 8.6. A study of interferon formation in vivo and in vitro (by leukocytes) in experimental virus infections.- 8.6.1. Interferon formation in experimental influenza.- 8.6.2. Interferon formation in experimental ectromelia.- 8.6.3. Interferon formation in experimental Western equine encephalomyelitis (WEE).- 8.6.4. Interferon formation in vivo in animals of different ages.- 8.6.5. Individual differences in interferon formation.- 8.6.5.1. Individual differences in serum interferon production in noninbred and inbred mice.- 8.6.5.2. Individual interferon production in mice infected with WEE virus.- 8.6.5.3. Individual differences in serum interferon production in rabbits and guinea pigs.- 8.6.6. Effect of cooling, internal irradiation, and ACTH on production of serum interferon in mice.- 8.7. Relationship between interferon formation and sensitivity of animals to some virus infections.- 8.7.1. Relationship between interferon formation and reproduction of viruses in chick embryos of different ages.- 8.7.2. Relationship between the reproduction of WEE virus and interferon formation in the mouse brain.- 8.7.3. Relationship between individual interferon formation and susceptibility of animals to WEE virus and to fixed rabies virus.- 8.7.4. Relationship between individual interferon formation and skin reaction of rabbits to vaccinia virus.- 8.8 Relationship between the pathogenicity and interferon-inducing ability of strains of vaccinia virus.- 8.9. Conclusion.- 9. Interferon Formation in Man under Normal and Pathological Conditions.- 9.1. Interferon production by leukocytes of healthy persons of different ages. Detection of interferon in the urine and serum.- 9.2. Interferon production by the leukocytes of newborn infants.- 9.3. Production of leukocytic interferon by patients with leukemia.- 9.4. Production of leukocytic interferon in other internal diseases.- 9.5. Interferon formation in children vaccinated against smallpox.- 9.6. Interferon production in adults with influenza.- 9.7. Interferon production in children with acute respiratory virus infections and its correlation with the production of leukocytic interferon.- 9.8. Conclusion.- Mechanism of Formation and Action of Interferon.- Conclusions and Prospects.