Fusion AML1 transcript in a radiation-associated leukemia results in a truncated inhibitory AML1 protein.

AML1 is a transcription factor that is essential for normal hematopoietic development. It is the most frequent target for translocations in acute leukemia. Recently, fluorescence in situ hybridization was used to identify a novel syndrome of radiation-associated secondary acute myelogenous leukemia that had AML1 translocations. Using polymerase chain reaction, the AML1 fusion transcript was isolated from the patient who had a t(19;21) radiation-associated leukemia. The AML1 gene is fused out of frame to chromosome 19 sequences, resulting in a truncated AML protein bearing the DNA binding domain but not the transcriptional activation domain. This fusion AML1 protein functions as an inhibitor of the normal AML1 protein. (Blood. 2001;97:2168-2170)

Maximum entropy restoration of blurred and oversaturated Hubble Space Telescope imagery.

A brief introduction to image reconstruction is made and the basic concepts of the maximum entropy method are outlined. A statistical inference algorithm based on this method is presented. The algorithm is tested on simulated data and applied to real data. The latter is from a 1024 × 1024 Hubble Space Telescope image of the binary stellar system R Aquarii, which suffers from both spherical aberration and detector saturation. Under these constraints the maximum entropy method produces an image that agrees closely with observed results. The calculations were performed on the MasPar MP-1 single-instruction/multiple-data computer.

Analysis of internal proteins of influenza A (H2N2) viruses isolated from birds in East Germany in 1983.

Proteins and RNAs of influenza A (H2N2) viruses isolated from birds in 1983 in East Germany were compared antigenically with those of H2N2 human strains. The electrophoretic mobility of the viral proteins and of the S1-treated double-stranded RNAs from two human and six avian strains, as well as the results of EIA-tests using monoclonal antibodies to their matrix protein and nucleoproteins indicate an antigenic relationship between the avian isolates and human strains of H2N2 subtype. One of the avian strains had a reduced amount of matrix protein.

[The detection of antibodies to HIV protein p24 in human blood sera by the method of lanthanide immunofluorescent analysis]. / Vyiavlenie antitel k belku p24 VICh v syvorotkakh krovi cheloveka metodom lantanidnogo immunofliuorestsentnogo analiza.

A competitive time-resolved fluoroimmunoassay (TR-FIA) system for the detection of antibodies to protein p24 of HIV was developed on the basis of monoclonal antibodies. The advantages of this test system over analogous enzyme immunoassay system and commercial test system "Antigen" (USSR) were demonstrated. The newly developed test system of TR-FIA was used for examination of sera from HIV-infected persons.

[The strain-specific diagnosis of influenza by using lanthanide immunofluorescence analysis based on monoclonal antibodies to the hemagglutinin of the influenza A virus]. / Shtammospetsificheskaia diagnostika grippa s ispol'zovaniem lantanidnogo immunofliuorestsentnogo analiza na osnove monoklonal'nykh antitel k gemaggliutininu virusa grippa A.

Nine monoclonal antibodies (MCA) to hemagglutinin of influenza A/Taiwan/1/86 (H1N1) virus and 5 MCA to influenza A/Mississippi/1/85 (H3N2) virus were generated and characterized. The MCA were used for the development of diagnostic test systems on the basis of time-resolved fluoroimmunoassay. The same MCA were used as primary and detecting antibodies in the test system specific for HA of the H1 serosubtype, whereas in the test system specific for influenza A serosubtype H3 virus MCA of different epitope appurtenance were used as primary and secondary antibodies. The sensitivity of the test system for HA of serosubtype H1 was found to be 10 ng/ml and that for serosubtype H3 5 nh/ml. The developed test systems were tried on the clinical material collected during the epidemic periods of 1983-1989.

[Standardization of conditions for detecting the internal proteins of the influenza virus in studying their antigenic properties in solid-phase immunoenzyme analysis]. / Standartizatsiia uslovii vyiavleniia vnutrennikh belkov virusa grippa pri issledovanii ikh antigennykh svoistv v tverdofaznom immunofermentnom analize.

The influence of the conditions of adsorption and virion destruction by freezing-thawing and detergents on the detection of M1 and NP proteins of different influenza virus strains by solid-phase enzyme immunoassay with direct virion adsorption on polystyrene was studied. It was found that for the detection of M1 protein the optimal conditions included virion disruption with detergent and adsorption to polystyrene at 4 degrees C, and for NP protein disruption by freezing-thawing at adsorption to polystyrene at 37 degrees C. In the study of the antigenic properties of protein M1 of different influenza virus strains using monoclonal antibodies it was shown to be necessary, first, to achieve maximum detection of proteins and, second, to standardize the amount of the adsorbed antigen with polyclonal antibodies.

[Stat-diagnosis of influenza using lanthanide immunofluorescence analysis]. / Ekspress-diagnostika grippa s pomoshch'iu lantanidnogo immunofliuorestsentnogo analiza.

A test system for influenza diagnosis has been developed on the basis of monoclonal antibodies to influenza A and B virus proteins using the principles of lanthanide immunofluorescence analysis. The diagnostic test system was shown to be highly specific in detecting influenza A and B virions in model systems. For the one-step variant of a double sandwich used in the study, the total time of diagnostic experiment using clinical materials was shown to be reduced to 15-20 min.

[Indication of the influenza virus in clinical samples using immunoenzyme and lanthanide immunofluorescence analyses]. / Indikatsiia virusa grippa v klinicheskikh obraztsakh s pomoshch'iu immunofermentnogo i lantanidnogo immunofliurestsentnogo analizov.

A comparative study of the potentials of enzyme-immunoassay (EIA) and lanthanide immunofluorescent assay (LIFA) for influenza virus detection in nasopharyngeal aspirates and nasopharyngeal washings was carried out. Monospecific and polyclonal antisera to hemagglutinin polyclonal antisera to matrix protein as well as polyclonal and monoclonal antisera to nucleoprotein were used. The nasopharyngeal aspirates were shown to contain virus-specific antigens in the amounts sufficient for influenza virus detection with polyclonal and monoclonal antibodies. There was a good correlation between chromophore results by EIA and fluorescence level in LIFA. The sensitivity of the test systems used (EIA and LIFA) was shown to be insufficient for the detection of virus-specific material in the nasopharyngeal washings. Besides, there was no correlation between the results obtained by different test systems. It was concluded that nasopharyngeal aspirates should be collected for rapid influenza diagnosis by EIA and LIFA.

[Heterogeneous distribution of influenza A matrix protein in polyacrylamide gel, detected using an immunoblotting method with monoclonal antibodies]. / Geterogennoe raspredelenie v poliakrilamidnom gele matriksnogo belka virusa grippa A, vyiavliaemoe metodom immunoblota pri ispolzovanii monoklonal'nykh antitel.

The immune blotting method using monoclonal antibodies to Ml protein showed protein Ml to migrate in several bands in polyacrylamide gel electrophoresis (PGE) of influenza A virus polypeptides. The heterogeneous distribution of Ml protein in PGE is due to the formation of aggregates: dimers, trimers, and polymers of a higher order. The capacity of Ml protein for aggregation is typical not of all influenza virus strains and most likely is not associated with gel overloading. Since dimers and trimers of Ml protein comigrate in the gel with virus-specific proteins such as NP and proteins of a polymerase complex, this circumstance should be take into consideration in using PGE for isolation of pure influenza virus proteins.

Antigenic reactivity of matrix protein and nucleoprotein of influenza virus as detected by EIA after dissociation with different detergents.

Solid phase enzyme-immunoassay (EIA) was employed to assess the antigenic reactivity of matrix protein (M) and nucleoprotein (NP) of influenza A virus adsorbed to polystyrene in the presence of different detergents such as beta-octaglucoside (OG), Triton X-100, Tween-20, sodium dodecylsulphate (SDS), sodium deoxycholate (Doch-Na), Nonidet P-40 (NP-40), and sarcosyl at concentrations ranging from 0 to 2%. The antigenic reactivity of NP was the highest in the absence of detergents. For M protein, Doch-Na, SDS, NP-40 and sarcosyl of 0.05-0.1% enhanced the chromatophoric response in EIA 1.5-2 times. In contrast, the antigenic reactivity of M protein remained unchanged after OG or Triton X-100 treatments, and it decreased in the presence of Tween-20.

[Isolation and characteristics of monoclonal antibodies to influenza virus types A and B]. / Poluchenie i kharakteristika monoklonal'nykh antitel k virusam grippa tipov A i B.

Monoclonal antibodies (MCA) to influenza type A (10F) and B (5H and 6H) viruses have been prepared. By immunoblotting method, MCA 10F were found to be specific for NP-protein of influenza A virus, and MCA 5H and 6H to be specific for hemagglutinin of influenza B virus. It was established that the 10F clone interacted with all the investigated influenza A virus strains with different antigenic formulae (H1N1, H2N2, H3N2) and could be used for typing of this virus type. Clones 5H and 6H react specifically with hemagglutinins of influenza B viruses isolated in 1940, 1979, and 1983 which makes them useful for diagnosis of influenza B.

Simultaneous determination of the level of antibodies to influenza virus surface and internal proteins by enzyme-linked immunosorbent assay.

Enzyme-linked immunosorbent assay (ELISA) has been adopted for simultaneous determination of the levels of antibodies to different influenza virus proteins in human sera with known haemagglutination-inhibition (HI) titre. Whole virus of serotypes H1N1 and H3N2, haemagglutinin (HA), matrix (M) and nucleoprotein (NP) proteins have been used as antigens. For detection of antibodies bound to the antigen, peroxidase labelled Staphylococcus protein A conjugate has been used. Correlation of the ELISA and HI titres of anti-HA antibody has been demonstrated. The use of isolated HA as antigen increased the specificity of ELISA. The analysis of human reconvalescent sera has shown that increase in the titre of antibodies to internal proteins does not always coincide with the increase of antibody level to HA. Out of 8 sera with significant increase of the HI titre to the H3 subtype 5 specimens showed 4-fold increase of antibody titre to NP protein. The antibody titre to M protein was elevated in 2 sera only, while 1 serum showed no rise of antibody response to the tested viral proteins.

The influence of the isolation technique of influenza virus nucleoprotein on its antigenic properties.

ELISA has been used to study the antigenic properties 1. of influenza virus nucleoprotein (NP-1) isolated from virions with the help of preparative polyacrylamide gel electrophoresis (PAGE); 2. of virion ribonucleoprotein (NP-2), and 3. of NP structures prepared by dissociation of ribonucleoprotein into RNA and protein in sucrose gradient containing NaCl (NP-3). The investigation of immunologic cross-reactivity has shown complete identity of NP-2 and NP-3 and their striking difference from NP-1. In contrast to NP-2, NP-3 was not contaminated by other virus antigens, it was a good immunogen and could be used for preparation of monospecific antisera of high titre. NP-1 did not induce a high antibody response,however, like NP-2 and NP-3, it retained its capacity to react with antisera to native virus. Owing to its simple production and high yield, this protein can be used in serodiagnosis for testing the antibody level against NP-protein in convalescent sera.

[Possibility of detecting the matrix protein of the influenza virus in intact and disrupted virions by immunoenzyme analysis and immune electron microscopy]. / Issledovanie vozmozhnosti vyiavleniia matriksnogo belka virusa grippa v intaktnykh i razrushennykh virionakh s ispol'zovaniem immunofermentnogo analiza i immunnoi élektronnoi mikroskopii.

ELISA and immune electron microscopy were used to study possible causes of the detection of antigenic reactivity of influenza virus matrix protein in purified virus suspension directly adsorbed on polystyrene. No interaction of antibody to M protein with the surface of virus and subvirus particles was observed. The process of virus sorption on polystyrene for a long period was shown not to lead to disruption of intact virus particles, and the detection of the internal matrix protein in preparations of purified influenza virus was due only to the presence of partially or completely destroyed virions in the viral suspension.

[Circular dichroism study of the ribonucleoprotein structure of Sendai virus isolated from infected chick embryo cells]. / Issledovanie metodom krugovogo dikhroizma struktury ribonukleoproteida virusa Sendai, vydelennogo iz zarazhennykh kletok kurinogo émbriona.

Thermostability and secondary structure of RNA, a component of ribonucleoprotein (RNP) of Sendai virus isolated from infected chick embryo cells (cRNP) and from virions (vRNP) were studied by the method of circular dichroism. The secondary structure of RNA in cRNP was shown to be practically no different from that of free RNA whereas incorporation of RNA into vRNP was accompanied by a significant decrease in the number of paired bases in it. Comparison of thermodenaturation parameters of cRNP and vRNP also revealed significant differences in their structural organization. Thus, melting of cRNP as well as of free RNA is of markedly non-cooperative nature indicating poor RNA-protein interactions in the complex. In contrast, the process of vRNP thermodenaturation occurs in a step-wise manner in a narrow temperature range indicating a significant role in the maintenance of this RNP structure of both RNA-protein and, apparently, protein-protein interactions.

[Morphological and structural studies of Sendai virus ribonucleoprotein]. / Morfologicheskie i strukturnye issledovaniia ribonukleoproteida virusa Sendai.

The structure and morphology of Sendai virus ribonucleoprotein (RNP) with native and split protein subunits were studied by the method of circular dichroism and electron microscopy. Cleavage of the polypeptide fragment from RNP protein subunits was shown to cause changes in the secondary structure of RNP in situ but not to affect the RNP morphology; when stained with uranyl acetate both RNP types had an appearance of spiral strands.

[Effect of formaldehyde on the ribonucleoprotein structure of Sendai virus]. / Issledovanie vliianiia formal'degida na strukturu ribonukleoproteida virusa Sendai.

The effect of formaldehyde on the conformation of Sendai virus ribonucleoprotein (RNP) was studied by electron microscopy and a spectrophotometric method. The effect of formaldehyde on RNP conformation was found to depend strongly on the ionic strength of the solution. Under conditions of a low ionic strength in the presence of 1.5% formaldehyde the tightly coiled rods of RNP stained with uranyl acetate become loosely coiled or almost completely extended. At the same time, formaldehyde reaction with RNP results in a decrease in extinction of the RNP suspension in the 250 to 290 spectral region. However, RNP incubation with formaldehyde in the presence of 0.5M NaCl caused no changes in the morphology and spectral properties of the RNP under study. The results indicate that formaldehyde cannot be used for fixation of Sendai virus nucleocapsids before negative staining for electron microscopy examinations.

[Effect of the isolation method and staining procedure on the morphology of the virion ribonucleoprotein of Sendai virus]. / Vliianie metoda vydeleniia i sposoba kontrastirovaniia na morfologiiu virnionnogo ribonukleoproteida virusa Sendai.

Electron microscopic examinations of morphology of Sendai virus ribonucleoprotein (RNP) isolated from purified virions by two methods and simultaneous staining of the preparations with uranyl acetate and phosphotungstate acid (PTA) were carried out. The staining method was shown not to influence the kind of nucleoproteins which had been isolated from disrupted virions by sucrose density gradient centrifugation. With both strains RNP appeared as strongly helixed filaments. The staining method, however, strongly influenced morphology of RNP isolated from disrupted virions by equilibrium centrifugation in cesium chloride density gradient. After uranyl acetate staining RNP had an appearance of hard filaments whereas in the same preparation stained with PTA partially and completely unwound spirals of nucleocapsid were found alongside with strongly spiralized structures.