Background: The lack convenient and inexpensive small animal model of HIV infection hampers significantly the research on immunopathogenesis, antiviral drugs, and vaccines.Objectives: Development of HIV model in small animals, i.e., cotton rats, was undertaken.Study design: Cotton rats of both sexes were exposed to highly replicating HIV-1(zmb) strain by intraperitonial and retrobulbar routes. The infection was evaluated by morphological and clinical criteria and by amplification of HIV DNA integrated in animal tissues.Results: Six months after intraperitoneal infection the lymphoid tissues of all inoculated animals exhibited integrated proviral DNA. Despite viral integration no active systemic HIV replication was observed. Brain and spleen morphological changes indicated the presence of the inflammatory reaction, which was followed by a degenerative process. Clinical manifestations of the infection, while varied, revealed relative weight loss at three months after infection; apparent respiratory disorders; and death of some animals with signs of cachexia and alopecia.Conclusions: Clinical, morphological, and virology assessment of infected animals indicate that the virus crosses the interspecies barrier and cotton rats can be used as a small animal model of HIV infection. (C) 2004 Elsevier B.V. All rights reserved.

The scrapie prion protein (PrP(Sc)) has been shown to induce apoptosis of rat cortical neurons in vitro. Here we demonstrate that the toxic effect displayed by PrP(Sc) can be blocked by sulfated colominic acid (polymer of N-acetylneuraminic acid). This compound acts neuroprotectively at a concentration of > or = 0.3 microg/ml when preincubated with the neurons or PrP(Sc). Rat cortical cells also undergo apoptosis after incubation with the HIV-1 coat protein gpl20 in vitro. This effect was abolished also by sulfated colominic acid when preincubated with the cells or gpl20. Addition of 0.3 microg/ml of compound resulted in an increase in cell viability by about 1.6-1.9-fold compared to cultures incubated for 18 h with 30 ng/ml of PrP(Sc) or 20 ng/ml of gpl20 alone (containing about 40% viable cells). Sulfated colominic acid does not act as antagonist of NMDA receptor channels at concentrations of up to 3 microg/ml when co-administered with 100 microg/ml of NMDA. It displayed a strong cytoprotective effect on human T lymphoblastoid CEM cells exposed to HIV-1; a 50% protection occurred after preincubation of the cells with 0.43 microg/ml of compound. At the same concentration, the compound caused an inhibition of HIV-1-induced syncytium formation. Sulfated colominic acid may be a promising compound for treatment of dementia caused by PrP(Sc) and HIV-1 infections.

The results of the three-year observation of female patient St. in whose blood antibodies to HIV disappeared in the course of time and the results of the laboratory study of the blood sera of children born of HIV-infected mothers are presented. In these patients correct diagnosis could be made only with the use of a complex of virological and molecular-biological methods.

The RNA stem-loop structure of the trans-activating region TAR sequence of human immunodeficiency virus-1 mRNA is the binding site for a number of host cell proteins. A virtually identical set of proteins from HeLa nuclear extracts was found to bind to the predicted RNA hairpin element of prion protein (PrP) mRNA, as demonstrated in UV cross-linking/RNase protection and Northwestern assays. We show that the cellular TAR loop-binding protein, p68, is among those proteins which associate with PrP RNA. Competition experiments with various TAR RNA mutants revealed that binding of partially purified p68 to PrP RNA stem-loop occurs sequence-specifically. The 100-kDa 2-5A synthetase which is involved in the cellular antiviral defense was able to bind to PrP mRNA stem-loop in Northwestern blots with cytosolic proteins from HeLa cells treated with interferon. However, the PrP RNA failed to activate this enzyme in vitro, in contrast to TAR RNA.

The integrative form of infection was obtained in cotton rats intraperitoneally or retrobulbarly infected with the highly-productive strain Zmb HIV-1. Clinically, it appeared as reduced animal weight gain and high mortality rates in the disease terminal stage. The proviral DNA was detected by the polymerase chain reaction in the genomes of cerebral and splenic cells in most animals. A comprehensive study of the time course of morphological changes within 6 months showed impairments in some CNS cells, giving rise to glial nodules and neurone dystrophy. It should be noted that the most profound changes were observed when the virus had been intraperitoneally injected. It was found that some pathomorphological changes were similar to those seen in human neuro-AIDS. In the spleen, HIV-1 first stimulated an immune response, caused an increase in the extent of white bulb follicles and an active formation of germinative centers, then involution of lymphoid formations took place.

The data on observations, lasting over the period of 6 months, on cotton rats given large doses of highly replicating strain HIV-1zmb by retrobulbar and intraperitoneal injections are presented. The study revealed that in all animals subjected to intraperitoneal infection lymphoid tissue contained integrated areas of protovirus DNA of HIV-1 three months later and cerebral tissue, five months later. Six months after retrobulbar infection the specimens of lymphoid tissue contained protovirus DNA in 100% of cases and the specimens of cerebral tissue, in 80% of cases. Clinical and morphological investigations established the presence of the inflammatory process, though no signs of HIV replication in the body of animals were detected. Polymerase chain reaction is proposed as criterion for the evaluation of HIV infection in animals.

A number of cellular proteins were identified that bind to the predicted RNA stem-loop structure of prion protein (PrP) RNA; a virtually identical set of RNA-binding proteins was found to associate with the trans-activating region TAR of the human immunodeficiency virus-1. The predicted hairpin elements of the PrP mRNA contain, like TAR RNA, a CUGGG sequence in the loop and a uridine and adenine bulge in the stem; these features are unique among cellular RNAs. UV cross-linking of RNA.protein complexes formed between PrP RNA and HeLa nuclear protein yielded four prominent RNase-resistant complexes, in addition to some minor bands, which migrated at approximate to 90, 68, 42, and 37kDa under denaturing conditions. The presence of multiple PrP RNA-binding, as well as TAR RNA-binding polypeptides was also demonstrated in Northwestern assays with nuclear extracts from mouse ascites, liver, and spleen, whereas only one PrP RNA-binding protein (a doublet with an approximate molecular mass of 35kDa) was found in brain extract from rat. The nuclear beta-galactoside-specific lectin, CBP35 (carbohydrate-binding protein with a molecular mass of 35 kDa), which has been identified in nuclear ribonucleoprotein (RNP) complexes from a variety of mammalian tissues and cells, was among those proteins which bind to PrP RNA. The cellular prion protein, PrPC, was found to be unable to bind PrP RNA directly; however, this protein could be detected in the RNP/CBP35 complex formed between PrP RNA and rat brain extracts. Association of PrPC with RNP/CBP35 complex was abolished by RNase treatment. CBP35 could be also detected in purified infectious scrapie prions, suggesting a possible role in prion replication.

The article deals with the results of the experiment substantiating the in vitro model of HIV neuro-infection. In this work primary glial (astrocytic) tissue cultures obtained from normal human and animal (guinea pig) brain tissue were used. As revealed in this investigation, the following phenomena could be observed in human brain tissue monolayer culture, infected with HIV and subsequently subcultured: (a) the stimulation of tissue-cell growth; (b) the formation of multinuclear glial cells; (c) the presence of virus-specific proteins in astrocyte cytoplasm, detected by immunofluorescent and electrophoretic techniques; (d) the presence of HIV-1 DNA provirus in infected astrocytes. Cyto-destruction was not observed, reverse transcriptase activity was absent.

The mismatched double-stranded RNA (dsRNA), poly(I).poly(C12U), also termed Ampligen, exhibits a strong antiviral and cytoprotective effect on cells (human T-lymphoblastoid CEM cells and human T-cell line H9) infected with the human immunodeficiency virus type 1 (HIV-1). Untreated H9 cells infected with HIV-1 start to release the virus 3 days post-infection, while in the presence of 40 micrograms/ml (80 micrograms/ml) of poly(I).poly(C12U) the onset of virus production and release is retarded and does not occur before day 5 (day 6). We demonstrate that poly(I).poly(C12U) markedly extends the duration of the transient increase of 2',5'-oligoadenylate (2-5A) synthetase mRNA level and activity preceding virus production after infection of cells with HIV-1. Treatment of HeLa cells with poly(I).poly(C12U) was found to cause a significant increase in total (activated plus latent) 2-5A synthetase activity; no evidence was obtained that the level of latent (nonactivated) 2-5A synthetase is changed in cells treated with dsRNA plus interferon (IFN). Poly(I).poly(C12U) is able to bind and to activate 2-5A synthetase(s) from HeLa cell extracts. Addition of poly(I).poly(C12U) to HeLa cell extracts results in production of longer 2-5A oligomers (> or = 3 adenylate residues), which are better activators of RNase L. Both free and immobilized poly(I).poly(C12U) also bind to the dsRNA-dependent protein kinase (p68 kinase), resulting in autophosphorylation of the enzyme. Activation of the kinase by the free RNA occurs within a limited concentration range (10(-7) to 10(-6) grams/ml). Addition of HIV-1 Tat protein does not affect binding and activation of p68 kinase to poly(I).poly(C12U)-cellulose but strongly reduces the binding of the kinase to immobilized TAR RNA of HIV-1. We conclude that poly(I).poly(C12U) may antagonize Tat-mediated down-regulation of dsRNA-dependent enzymes.

The large immune stratum and intense collective immunity to virus hepatitis A among the urban population of Byelorussia are characteristic of hyperendemic territory. The geometric mean of the antibody titer has been noted to increase with age, which is probably due to repeated infections of persons who have already had the disease. The use of this value for the characterization of collective immunity and epidemiological situation has been proposed.

The large immune stratum and intense collective immunity to virus hepatitis A among the urban population of Byelorussia are characteristic of hyperendemic territory. The geometric mean of the antibody titer has been noted to increase with age, which is probably due to repeated infections of persons who have already had the disease. The use of this value for the characterization of collective immunity and epidemiological situation has been proposed.

Both variants of HIV-1 reported in the literature: slow/low and rapid/high types, were detected among the strains isolated from the subjects examined in 4 foci of HIV-1 infection in the south of the RSFSR and Byelorussia. All the 17 strains isolated in the southern RSFSR foci belonged to the slow/low type and had a low and unstable replication potential in donor peripheral blood mononuclear cells and in MT-4 cell line. All of them were isolated from subjects with asymptomatic infection and from children with initial clinical manifestations of the disease. Only one strain isolated in Byelorussia belonged to the rapid/high type. Its replicative activity was very similar to that of the classical HIV-1 - HTLV-IIIB strain. Long-term (up to 7 months) propagation of slow/low strains did not result in any increase of their replicative activity. The capacity to form syncytia was found not only in the rapid/high type strains but also in the majority of slow/low strains under study.

Primary human glial fibrillary acidic protein-positive (GFAP+) brain cells (enriched population) have successfully been infected with human immunodeficiency virus type 1 (HIV-1) in vitro, when cocultivated with HIV-1-producing H9 cells. Direct incubation of brain cells with HIV-1 resulted only in a limited infection. The percentage of HIV+ cells increased from 5% in passage 1 to 40% in passage 8. Simultaneously with the increase of infected cells, the reverse transcriptase activity in the culture medium increased and reached maximal values in passage 8. The infected cells also produced intact viral particles. In the early phase of cultivation the HIV-infected cells displayed a significantly higher proliferation rate than the uninfected controls. At passage number 8 the HIV-infected GFAP+ cells had almost totally lost the ability to grow, while the controls proliferated at a rate almost unimpaired from the beginning of the cultivation. Up to 10 to 15% of the HIV-infected GFAP+ cells contained at passage number 5 more than 3 nuclei. Memantine (1-amino-3,5-dimethyladamantane), a blocker of the N-methyl-D-aspartate receptor channels, was found to display a significant anti-HIV effect (at a concentration of 1 microgram/ml) on enriched cultures of GFAP+ cells in vitro.

Human rotavirus strain 649 was isolated from a child with clinical picture of acute intestinal infection in the West European part of the U.S.S.R. This strain was adapted to MA-104 (rhesus monkey kidney) cells. By electrophoresis and haemagglutination it differed from the human rotavirus strain Wa and from the simian strain Sa-11. The productive reproduction of human rotavirus strain 649 may allow its use for the preparation of antigens for diagnostic, immunoprophylaxis, and treatment.

Both variants of HIV-1 reported in the literature: slow/low and rapid/high types, were detected among the strains isolated from the subjects examined in 4 foci of HIV-1 infection in the south of the RSFSR and Byelorussia. All the 17 strains isolated in the southern RSFSR foci belonged to the slow/low type and had a low and unstable replication potential in donor peripheral blood mononuclear cells and in MT-4 cell line. All of them were isolated from subjects with asymptomatic infection and from children with initial clinical manifestations of the disease. Only one strain isolated in Byelorussia belonged to the rapid/high type. Its replicative activity was very similar to that of the classical HIV-1--HTLV-IIIB strain. Long-term (up to 7 months) propagation of slow/low strains did not result in any increase of their replicative activity. The capacity to form syncytia was found not only in the rapid/high type strains but also in the majority of slow/low strains under study.