[HIV-1 assembly is initiated by p17 matrix protein].

HIV-1 matrix protein (MA) is multifunctional structural protein located on N-terminus of Gag precursor p55 and responsible for its transport to plasma membrane, the site of virus assembly. Here, it has been shown that MA is cleaved from Gag precursor at early stage of the virus infection and participates in virus assembly. MA is transported into the nuclei wherein it associates with viral RNA (vRNA). The MA-vRNA complex is transported to plasma membrane. Mutant MA which lost its membranotropic signal does not reach plasma membrane and MA-vRNA complex remains in the nuclei and cytoskeleton. Thus, MA seems to deliver vRNA from the nuclei to plasma membrane through cytoskeleton initiating virus assembly.

[The maturation steps of human immunodeficiency virus and the role of proteolysis].

HIV-1 virions are as immature noninfectious particles lacking a central core. Shortly after budding, virions temporally mature and acquire cores and infectious activity. The cause of maturation remains poorly studied. We have revealed that the virions produced early after infection following 24-36 hours, never mature and remain noninfectious, and only virions produced 48-72 hours after infection mature. The mature virions contain 3 times more genomic viral RNA than "early" virus. The "early" virions contain the same proteolytically cleaved Gag proteins as mature virions in contrast to the accepted version. The virus protease inhibitor Indinavir sulfate (IS) fully blocks infectivity when added early after infection. The early proteolysis of Gag precursor in the infected cells and inclusion into the virions of cellularly cleaved matrix protein (cMA) are shown in the IS-treated cells. cMA is associated with genomic viral RNA.

[Effects of novel antiviral agents on HIV-1 replication].

Two groups of the antiviral agents: 1) adamantane- and norbornen-containing compounds with in-built cholesterol to potentiate the membranotropic properties and 2) synthetic matrix protein peptides (peptides A and B) were found to have effects on HIV replication. The agents of the former group produced antiviral activity only when added in combination with the virus. Peptide A (matrix protein 43-60 amino acids) inhibited viral replication when added in both the early and late periods. Fluorescein-labeled peptide A was detectable in the cytoplasm and nucleus (although adsorption of a portion of the peptides cannot be excluded onto the cell surface). Peptide A was shown to inhibit Gag precursor p55 transport from the nuclei to the plasma membrane, the site of virus assembly. Peptide B had no antiviral activity.

[Role of cellular proteins in the life cycle of human immunodeficiency virus].

The paper shows a role of cellular proteins that control the early and late stages of HIV infection due to the keen genetic parasitism of human immunodeficiency virus (HIV). In its early life cycle, the virus uses the cell receptors CD4, CCR5, G-protein processor, and actin filaments of the cytoskeleton for nuclear transport. The cellular proteins transport the preintegration complex through the nuclear pores and assist complementary DNA to integrate with cellular DNA. At late stages, the cellular proteins provide the transport of viral components to the assemblage site--lipid rafts, the strong binding to them, the insertion of glycoproteins into the viral particle, and the cellular escape of the virus. To inhibit the cellular mechanisms involved in the infectious process is a new antiviral strategy approach to treating AIDS.

[Assembly and maturation of HIV-1--targets for new anti-HIV compounds].

Much progress has been recently made in research of the final stages of the HIV-1 life cycle, i.e. of its assembly, gemmation and maturation. The virus was shown, in particular, to use widely cell mechanisms in its replication and assembly. The TSG 101 cellular endosomal sorting protein interacting with the p6 viral protein is necessary for gemmation. Cyclophilin and HP68 (cell proteins) needed for marphogenesis of the virus were identified. The recently obtained data on the interaction of Vif (a viral protein) and Apobec (a cell protein) showed that HIV-1 has an action mechanism overcoming the cell barriers. The "early" virus phenomenon, which is deprived of any mature structure or the ability to infect and does not contain mature Gag and Env proteins, illustrates that the proteolytic pressing of the Gag p55 precursor is not enough for the maturation of the virus and additional viral or cellular factors are needed for the virus to become infectious. Although the current antiviral therapy has been successful enough, it is far from being effective in all cases; one of the reasons is resistance to chemodrugs developing rapidly in patients. Fast mutations and exceptional plasticity of the viral genome (which helps the virus to develop rapidly resistance to drugs) belong to the major problems. The circulation of persistent virus variants has been quickly increasing. There is an urgent need in developing new antiviral drugs acting on new viral targets; progress in experimental virology would speed it up. Thus, new drugs can be created, which block the activity of Vif, that would make Apobec block the virus replication. Compounds can be developed, which block the interaction of cyclophilin and TSG101 with viral proteins. The recently described importance of cholesterol in the sexual transfer of viruses is expected to bring simple and inexpensive compounds destroying cholesterol in the mucous tunic of genitals into clinical use. The identification of additional factors needed for the maturation of the virus and for its becoming infectious can be a basis for the development of drugs blocking their packaging into virions. Future research is expected to define new targets for the chemotherapy of AIDS and to promote the designing of new chemodrugs.

[An analysis of the potential areas of recombination in the hemagglutinin genes of animal influenza viruses in relation to their adaptation to a new host--man]. / Analiz potentsial'nykh uchastkov rekombinatsii v genakh gemaggliutinina virusov grippa zhivotnykh v otnoshenii ikh adaptatsii k novomu khoziainu--cheloveku.

The authors tried to decode the mechanism of influenza viruses species adaptation in the process of host changing. The functionally important replacement in the surface pocket domains were revealed, particularly in the conservative region 221-241, involving fibronectin-like part. Close replacements were revealed in the region 141-161. The method of construction of heteroduplexes between hemagglutinin RNA of duck, pig, and human viruses was used. The method showed that all heteroduplexes formed recombinogene structures. An unexpected effect of directional recombination was elicited for hemagglutinin RNA heteroduplexes in cases of duck-pig and human-pig viruses. During the directional recombination the following processes took place: the receptor-binding site of animal type was transmitted to the duck virus, while the human receptor-binding site was transmitted to the pig virus. According to the experimental data, a new hypothesis is formulated: the cascade mechanism of directional recombination for duck, animal and human viruses makes it possible for the recombinant viruses to overcome interspecies barriers.

[HIV-1 p17 matrix protein is transported into the cell nucleus and binds with genomic viral RNA]. / Matriksnyi belok p17 VICh-1 transportiruetsia v kletochnoe iadro i sviazyvaetsia s genomnoi virusnoi RNK.

We have shown that gag polyprotein p55 is cleaved in cytosol rapidly after its synthesis, during 2 h, and p17 enters the nuclei while p24 resides in cytosol. To determine whether the nascent p17 is associated with viral genomic RNA in the nuclei, the cells were fractionated, the viral complexes were immunoprecipitated by monoclonal antibodies against gag proteins, and RNA was extracted and analyzed by slot and blot hybridization. Monoclonal antibodies against p17 precipitated all the viral RNA from the nuclei including full-size genomic RNA and essential part from membranes while monoclonal antibodies against p24 did not precipitate any viral RNA from the nuclei. These data suggest that matrix protein is linked to genomic RNA in the nuclei and rise the possibility that p17 may transfer viral nucleocapsids from the nuclei to plasma membranes, the site of virus assembly.

[The acceleration of experimental influenza B infection under the influence of gangliosides]. / Uskorenie éksperimental'noi grippoznoi B infektsii pod vliianiem gangliozidov.

The influence of mono-, di-, and trisialogangliosides on the dynamics of influenza B virus reproduction in human embryo fibroblast (HEF) cell culture and human diploid cells was established. The cells were treated with neuraminidase of non-cholera vibrio for removal of natural receptors followed by treatment with gangliosides. Virus reproduction was assessed by infectious titres for chick embryos and HA test of the culture fluid at certain intervals. Gangliosides restored influenza virus reception and enhanced the infectious process as compared with the controls. Treatment with gangliosides of HEF culture of low sensitivity increased its susceptibility to virus markedly.

[Persistence of the influenza virus in children with congenital CNS pathology]. / Persistentsiia virusa grippa u detei s vrozhdennoi patologiei TsNS.

Sick infants born to mothers who experienced influenza during pregnancy were examined. The cerebrospinal fluid, serum and blood cells were collected from such children with signs of congenital immune deficiency and progressive pathology of the central nervous system. None of the specimens yielded infectious influenza virus, but by means of molecular hybridization virus-specific genetic sequences were found in small amounts in the cerebrospinal fluid and serum and in high concentrations in blood cells. Persistence of genes NP, M and H1 of influenza A/H1N1 virus was observed in the blood cells of one infant for 83 days (the observation period). At the same time, the lack of antibodies to viral M protein in serum of this baby was demonstrated by the immune blotting method.

[Formation of virus-like particles by HIV-1 Gag proteins, expressed by a recombinant vaccinia virus]. / Obrazovanie virusopodobnykh chastits belkov Gag VICh-1, ékspressiruemym rekombinantnym virusom ospovaktsiny.

Monkey kidney cells CV-1 were infected with recombinant vaccinia virus carrying HIV-1 gag gene with a deletion of 230 nucleotide pairs from the 3'-terminus. The main gene product detected in the lysates of infected cells was the gag precursor rp50. The protein was accumulated on the cell membranes suggesting that it had a myristylated N-terminus, and was cleaved by a recombinant virus specific protease with the formation of two proteins, p17 and p24 corresponding in molecular masses to mature gag proteins. Virus-like particles similar to immature HIV virions were budding from the surface of infected cells. They look like the ring of optically dense material covered with a lipid bilayer, of the same size (100-120 nm) and of the same density in a sucrose gradient (1.16-1.18 g/ml) as HIV-1 virions. The particles contained rp50 and cellular heterogeneous RNA. Thus, the unprocessed gag precursor with deleted 77 amino acid residues from the C-terminus is able to form virus-like particles in the absence of env proteins and virus-specific RNA, and these particles are budding from the cell surface. The question about the use of extracellular Gag-particles for AIDS diagnostic work and construction of vaccines is discussed.

[Changes in the protease activity in the lungs of mice infected with the influenza A virus]. / Izmenenie proteaznoi aktivnosti v legkikh myshei, zarazhennykh virusom grippa A.

In uninfected animals, the level of protease and protease-inhibiting activities in the serum are in balance which is broken after influenza A virus infection. Most profound changes occur within the first few hours after infection. In 6 hours postinfection the amount of protease decreases both in the lungs and serum of the infected animals, and the protease-inhibiting activity increases. In the period of the highest accumulation of the infectious virus 2 days after infection, proteolytic activity also decreases, this decrease coinciding with that of the inhibiting activity. The third period of increased protease activity also coincides with amplification of infectious virus progeny and appears to be associated with consequences of virus infection and bacterial superinfection.

[The enhancement of the penetration of the human immunodeficiency virus into cells with the aid of a helper virus]. / Usilenie proniknoveniia virusa immunodefitsita cheloveka v kletki s pomoshch'iu virusa-pomoshchnika.

Penetration of human immunodeficiency virus (HIV) into the cells of lymphoblastoid T-cell line H9 was studied using 35S-methionine-labeled virus by demonstration of virus-specific proteins in the cytoplasm of the infected cells. Purification of the virus by ultracentrifugation through 30% glycerol was shown to lead to virus aggregation and its partial destruction manifested by the loss of gp120 protein, therefore unlabeled concentrated virus was used mainly with subsequent determination of virus-specific proteins by immune blotting. The addition of Sendai virus inactivated with UV rays to HIV increased the amount of HIV associated with cells as well as the amount of virus-specific proteins in the cytoplasm of the infected cells.

[The characteristics of the interaction of the proteins comprising the virions of the human immunodeficiency virus type 1]. / Osobennosti vzaimodeistviia belkov v sostave virionov virusa immunodefitsita cheloveka tipa 1.

Treatment of virions of human immunodeficiency virus type 1 (HIV-1) with ionic and nonionic detergents (NP-40, octylglucoside, sodium deoxycholate) exerted an effect on the virus uncommon for enveloped viruses: instead of solubilization, both glycoproteins (gp120 and gp41) were found in subviral particles, whereas the core protein p24 was found in the supernatant fluid after the removal of subviral particles by centrifugation. The matrix protein p17 and unprocessed molecules of the precursor protein p55 were associated with subviral particles. The above data confirm the proposed model of the HIV-I structural organization according to which glycoproteins are incorporated into the isometric matrix formed by protein p17. Our data indicate that the core protein p24 is not incorporated into the matrix and not associated with nucleocapsid proteins.

[The RNA electrophoretypes of the rotaviruses circulating in Moscow and Leningrad in the winter of 1987-1988]. / Elektroforetipy RNK rotavirusov, tsirkuliruiushchikh v Moskve i Leningrade zimoi 1987--1988 gg.

Analysis of electrophoretypes of RNA of rotavirus which had circulated in Moscow and Leningrad in the winter of 1987-1988, detected by enzyme immunoassay (EIA), was carried out. RNA electrophoresis was performed in 10% polyacrylamide gel (PAG) followed by silver staining, Most of the strains isolated in Moscow and Leningrad had a long phoretype (67% and 77%, respectively. The greatest variations in PAG mobility were found in segments 2, 3, and 7-9, segments 1, 4, 10, and 11 showed most unchangeable mobility. According to the pattern of segment migration, 3 variants of the long phoretype and 5 variants of the short phoretype were distinguished. In Moscow the ist variant (confluent 2nd and 3rd segments as well as 7th and 8th segments) of the long phoretype was predominant, which was isolated in approximately 70% of all cases of infection; in Leningrad the dominating variant was intermediate between the 1st and 2nd phoretype (slower migration of the 2nd segment). Variants of the sport phoretype were characterized by greater variability and lack of the dominating strain. The potentials of rotavirus RNA electrophoresis as a method of molecular epidemiology are discussed.

[Conservativism of the matrix protein of paramyxoviruses]. / Konservatizm matriksnogo belka paramiksovirusov.

Cross reactions among paramyxoviruses were determined by the immunoblot method. Human parainfluenza viruses, types 1-3, avian parainfluenza virus type 4, mumps, Sendai, and measles viruses were used. Antisera to human parainfluenza viruses were shown to cross-interact with proteins NP and M of other types, and all antisera to the members of Paramyxovirus genus cross-reacted with M proteins of other paramyxoviruses. No cross reactions with measles virus proteins were observed. It is concluded that M protein is the most conservative protein of paramyxoviruses.

[The effect of gangliosides on experimental influenza infection]. / Vliianie gangliozidov na éksperimental'nuiu grippoznuiu infektsiiu.

Experiments in two strains of mice; CBA, susceptible to influenza, and CBAXC57Bl/cXFl, resistant to it, demonstrated stimulation of influenza infection caused by gangliosides. The stimulating effect of gangliosides (GMl, GDla, GTlb) seems to be explained by their insertion into plasma membranes of epithelial cells of the respiratory tract and by an increase, due to it, of the number of superficial virus-specific receptors.

[Monoclonal antibodies, interacting with antigenic determinants of the human immunodeficiency virus]. / Monoklonal'nye antitela, vzaimodeistvuiushchie s antigennymi determinantami virusa immunodefitsita cheloveka.

Twenty-five hybridomas of CMK series were generated which produced monoclonal antibodies (MCA) to human immunodeficiency virus (HIV). The MCA were shown to react with HIV antigenic determinants in enzyme-immunoassays to titres 5 X 10(3)--10(5). It was established by immunoblot that some MCA interact with HIV proteins having molecular weights of 60-80 KD, and other MCA with proteins of low molecular weight (9-17 KD). Using recombinant proteins--products of env and gag genes, the immunoblot showed 5 MCA to be specific for proteins of the env gene and 5 others for proteins of the gag gene. Comparative enzyme immunoassays of interaction of MCA of the CMK series with viruses of infectious anemia of horses and HIV led to the conclusion that 4 MCA recognize common determinants of the lentiviruses under study whereas 5 other MCA react specifically with HIV alone.