Electropherotypes and serotypes of human rotavirus in Estonia in 1989-1992.

The electropherotypes and serotypes of human rotaviruses circulating in Tallinn (Estonia) in 1989-1992 have been studied. Rotaviruses were found in 372 (25.8%) of 1,442 faecal specimens of pediatric patients with acute diarrhea. Polyacrylamide gel electrophoresis of RNA from 318 isolates has revealed 41 electropherotypes. Frequent genomic alterations, including a shift of predominant electropherotypes, were observed during the study period. The serotype of 158 (50.3%) of 314 tested rotavirus isolates was identified using ELISA with VP7-specific monoclonal antibodies against 4 established human rotavirus serotypes. Serotype G1 was found to be largely predominant and accounted for 70.9% of the typeable specimens, serotypes G4, G2, and G3 accounted for 12%, 9.5%, 7.6%, respectively. A major shift to serotype G4 took place in 1990-1991. Serotype G1 was represented by the largest number of electropherotypes. All G1, G3 and G4 isolates were of "long" and all G2 isolates were of "short" electropherotypes. According to our results the isolates of an identical electropherotype belong to the same serotype.

Effect of UV-irradiation on rotavirus.

The effect of UV-irradiation on SAll rotavirus infectivity was followed. The time course of infectivity inactivation in general showed an one-hit pattern. Two basic effects of UV-irradiation on virus particles were investigated: the phenomenon of RNA-protein linkages and the formation of uracil dimers. To determine the number of uridine dimers, 3H-uridine labelled purified rotavirus was exposed to UV-irradiation, subsequently the RNA was extracted and analysed by ascending paper chromatography. Formation of photodimers was found to be an important mechanism of rotavirus inactivation at conventional UV-irradiation; the RNA-protein linkages were registered at high irradiation doses only.

[Interferon-stimulating properties of immunomodulators]. / Interferonstimuliruiushchie svoistva immunomoduliatorov.

The interferon-stimulating effect of immunomodulators is manifested after their combined inoculation with double-stranded NRAs (dsRNA) of natural and synthetic origin, and depends upon the time of administration of an inducer with respect to an immunomodulator and upon the dose of dsRNA. It is manifested as prolongation of interferon circulation in the bloodstream of animals up to 3 days when inosiplex is used as an immunomodulator. A still greater effect is observed when its derivative ASK is used instead of inosiplex. The interferon-stimulating effect of immunomodulators is due to cells of the immune system.

[Discovery and quantitative determination of intestinal viruses by the detection of viral antigens in infected cells using an immunoperoxidase method]. / Obnaruzhenie i kolichestvennoe opredelenie kishechnykh virusov s pomoshch'iu detektsii virusnykh antigenov v zarazhennykh kletkakh immunoperoksidaznym metodom.

The use of immunoperoxidase method for detection of virus antigens in a fixed infected cell monolayer on microplates (cellular immunoperoxidase method, CIPM) for poliomyelitis and hepatitis A virus as well as for human and simian SA II rotaviruses is described, as well as the method of quantitation of rotaviruses by counting of virus multiplication foci. The CIPM combines the advantages of the methods based on the infectivity determinations and of immunochemical methods, and may be used both for diagnosis and for detection and quantitation of enteric viruses.

[The role of immunocytes in interferon production in mice in response to inosiplex induction]. / Rol' immunotsitov v produktsii interferona u myshei v otvet na induktsiiu inozipleksom.

Studies in CBA mice showed that after intraperitoneal injection of inosiplex in a dose of 25 mg/mouse interferon could be detected in the blood serum, peritoneal exudate, and spleen of the animals, the peak of its production being observed in 3-4 days. Interferon was produced by T- and B-lymphocytes. The former were characterized by delayed interferon synthesis while the latter released interferon into the medium as early as 24 hours after induction. The regulatory role of the cells of the monocyte-macrophage system is discussed.

[Interferon-inducing and antiviral effects of inosiplex in combination with high-molecular interferon inducers]. / Interferonindutsiruiushchii i protivovirusnyi éffekty inozipleksa v kombinatsii s vysokomolekuliarnymi induktorami interferona.

It has been shown that the immunostimulant inosiplex (IP) is capable of inducing interferon production in mice and of stimulating interferon induction by high-molecular inducers. The combined use of IP and poly (G)-poly (C) or dsRNA (RFf2) leads to a longer interferon circulation in the blood. All the combination schemes ensuring the effect of interferon production prolongation were tested for anti-viral activity. The prophylactic administration of the drugs permitted the attainment in mice of the increased resistance to experimental influenza.

[Interferon-inducing activity of a tilorone hydrochloride preparation]. / Interferonindutsiruiushchaia aktivnost' preparata tilorona gidrokhlorida.

The experiments on CBA mice showed that tyloron hydrochloride was an active inductor of interferon. The maximum production of interferon in blood (2560 units/ml) was achieved with oral administration of tyloron in a dose of 400 mg/kg. It was demonstrated that the character of interferon accumulation in different organs depended on the route of tyloron administration. When the inductor was administered orally, the highest levels of interferon were observed in the intestine (5000 units/g) and blood (320-640 units/ml). When the inductor was injected intraperitoneally, significant levels of interferon were detected in the animal brain (at least 5000 units/g). After intramuscular injection of the inductor insignificant levels of interferon were practically detected in all the organs. Participation of the brain cells and blood elements in production of interferon is discussed.

[Effect of immunostimulants on the intensity of vaccinal antirabies immunity]. / Vliianie nekotorykh immunostimuliatorov na napriazhennost' vaktsinal'nogo antirabicheskogo immuniteta.

Experiments in BALB/c and CBA mice demonstrated that among 5 immunopotentiators (RFf2, a complex of polyguacylic and polycytidylic acids (GC), glucosomuramyldipeptide, levamisole, and dsRNA) a significant immunostimulating effect on the intensity of rabies immunity to intracerebral challenge with street rabies virus was exerted by RFf2 interferon inductor or by a combination of inosiplex + + GC + vaccine. A correlation between the immunostimulating and protective (therapeutic) activity of the drugs was established.

[Effect of immunomodulators on humoral antirabies immunity]. / Vliianie nekotorykh immunomoduliatorov na gumoral'nyi antirab- cheskii immunitet.

Studies of the effect of 10 immunopotentiators on humoral immunity to rabies in inbred and randombred mice demonstrated the most marked stimulation to be exerted by interferon inductors of the type of double -stranded RNA. A combination of inosiplex + dsRNA + vaccine enhanced both interferon production and humoral immunity to rabies.

[Effect of the combined use of dextran sulfate and double-stranded RNA on interferon production]. / Effekt sochetannogo primeneniia dekstran-sul'fata s dvunitchatymi RNK v otnoshenii produktsii interferona.

The studies were performed on CBA mice. It was shown that polynucleotide inductors (poly I-poly C, RFf2 and poly G-poly C) stimulated production of interferon with a peak attained 4-6 or 24 hours after the induction. Intraperitoneal injection of dextran sulfate in a dose of 200 micrograms/m induced production of interferon in small amounts (80-120 units). The production peak was observed in 12 hours. The combined use of dextran sulfate and the polynucleotide inductors provoked an increase in the interferon production. The effect was of a synergistic nature. The cells of the immunocompetent system were the target of the dextran sulfate effect in the host, which was shown experimentally with a culture of mouse lymphocytes.

[Inosiplex-dependent interferon production in vivo and in vitro]. / Inoziplekszavisimaia produktsiia interferona in vivo i in vitro.

Inosiplex, an immunopotentiator, was shown to be capable of inducing interferon synthesis in vivo and in cell culture. Its concentrations of the order of 25 mg/mouse were to be most effective. The time course of production showed a late peak at 72 hours. The resulting interferon was not neutralized by antiserum to alpha- and beta-interferons. L929 cells of peritoneal exudate and splenocytes could synthesize interferon after treatment with inosiplex. The use of mixed cultures of these cells increased the effectiveness of interferon induction.