[Inactivation of the inductor virus (Newcastle disease virus) during the isolation of porcine leukocyte interferon]. / Inaktivatsiia virusa-induktora (virus bolezni N'iukasla) v protsesse polucheniia svinogo leikotsitarnogo interferona.

The use of the routine method for inactivation of the inductor virus by acidification of interferon to pH 2.0 resulted in a significant decrease in the antiviral activity of pig leukocytic interferon, since the preparation was highly sensitive to changes in the pH values. The use of 0.1 per cent solution of formalin provided complete inactivation of the virus. The antiviral activity of interferon treated with formalin was on an average 5 times higher than that of the preparation incubated at pH 2.5-2.6. Precipitation of pig interferon with polyethylene glycol promoted both increasing of the titers of the antiviral activity of the preparation and elimination of the formalin residues from it. Interferon prepared with this procedure was not toxic in tissue cultures, had no side effects when applied to the eye mucosa and was absolutely harmless when administered to animals. It was shown that inactivation of the inductor virus with formalin was in principle possible in human leukocytic interferon.

[Interferon production in suspensions of swine and human leukocytes on media containing aminopeptide, hemohydrolysate and bovine amniotic fluid]. / Poluchenie interferona v suspenzii svinykh i chelovecheskikh leikotsitov na sredakh s aminopeptidom, gemogidrolizatom i amnioticheskoi zhidkost'iu korov.

Production of different kinds of interferon in imported media (medium 199, Eagle's medium) greatly impedes the organization of large-scale interferon production in this country. The search for national substitutes of these media is important therefore. This paper deals with a comparative study of the use of national aminopeptide and hemohydrolysate preparations for interferon production. It was shown that substitution of serum with BAF in preparations of human and swine interferon increased their activity 2- and 4-fold, respectively, and the amount of protein was reduced 10-fold. Specimens of interferons produced with the addition of AP were less effective because the amount of protein increased 4-20-fold while the antiviral activity increased insignificantly. The most effective were interferon preparations obtained with hemohydrolysate medium. Their activity being similar, the amount of protein in interferon samples increased 11/2-2-fold only. Thus, aminopeptide and hemohydrolysate can effectively substitute medium 199 for production of leukocyte human and swine interferon.

[Swine blood leukocytes--new source of production of inferferon active in human cells]. / Leikotsity krovi svinei--novyi istochnik polucheniia interferona, aktivnogo v kletkakh cheloveka.

Swine blood leukocytes have first been found capable of producing interferon the antiviral activity in human cells of which is comparable to that of native human leukocyte interferon. The influence of various factors on production of porcine leukocyte interferon active in human cells were studied. Thus, when serum was substituted with MAF in the medium used for leukocyte cultivation the titer of the produced interferon increased 4--16-fold and the content of protein impurities in the preparation decreased 10-fold or more. Marked individual interferon-producing capacity of blood leukocytes from different swine and seasonal variations in the level of this capacity were established. The optimal conditions for porcine leukocyte interferon production are: the use of leukocytes in the first few hours after bleeding of the animals; leukocyte concentration in the medium 10 million cells per 1 ml; medium 199 with 10% MAF; New-castle disease virus as interferon inducer in a dose of 10--100 CPD50 per cell. Priming of leukocytes with interferon enhanced their interferon-synthesizing capacity 2--8-fold. This new source of interferon production is readily available, and interferon is useful for public health and veterinary needs.

[Persistence of lymphocytic choriomeningitis virus in a transplantable line of Detroit-6 cells]. / Persistensiia virusa limfotsitarnogo khoriomeningita v perevivaemoi linii kletok Detroit-6.

Defective LCM virus was found to persist in Detroit-6 cells. The persisting virus was not infectious for susceptible mice and some cell cultures. Its antigenic properties were enhanced to detectable levels in the CFT by cocultivation with LSV5 cells only. No reversion to its pathogenic properties, however, occurred either after 8 subpassages of the cocultivated cells or after blind passages of these cells in suckling mouse brains. The cytogenetic analysis, and the pattern of antigen fluorescence (IIF) revealed similarities between HeLa and D-6 cell lines persistently infected with LCM virus. The highest intensity of LCM virus antigen coincided with the period of maximum miotic activity of D-6-LCM cells, indicating a correlation between synthesis processes in the cells and reproduction of the persisting virus. Upon superinfection of D-6-LCM cells with homo- and isologous viruses no increase in the percentage of the antigen-containing cells was observed. No detectable interferon was found in the D-6-6CM system.

[Comparative study of 2 transplantable lines of murine L cells]. / Sravnitel'noe issledovanie dvukh perevivaemykh linii myshinykh kletok L.

A continuous line of mouse L cells chronically infected with SV5 paramyxovirus differs from mouse L0 cells free from this virus in the mitotic activity and karyologic features. The LSV5 line is characterized by inhibition of the mitotic activity, a decrease in the number of chromosomes and the presence of the marker chromosome. LSV5 and L0 cell cultures do not differ in the number of pathological mitoses, structural aberrations of chromosomes and the cytomorphological picture. The persisting SV5 virus can be detected in LSV5 line cultures by a number of methods (immunofluorescence, virological methods, etc.).

Use of duck embryo cell cultures for the study of arbovirus reproduction.

Duck embryo cell (DEC) cultures were used for the study of arbovirus reproduction. High sensitivity of DEC cultures to Japanese encephalitis, West Nile, Tyuleniy, Sakhalin and Baku viruses was established. DEC cultures are recommended for investigation of arbovirus reproduction.