Comparative study of antigenic properties of potato virus X and its coat protein in solution and after adsorption to solid supports.

Different ELISA procedures were used to compare the antigenic properties of intact potato virus X (PVX) and its dissociated protein. It was found that when the reaction took place in solution (competition ELISA), the intact virus reacted with polyclonal antibodies against the intact PVX (Ab-PVX) much more strongly than did the dissociated PVX coat protein (Pr), and the dissociated protein reacted with the homologous polyclonal antibodies (Ab-Pr) more strongly than did the intact PVX. However, if these two antigens were absorbed directly to polystyrene wells (in direct ELISA), they acquired similar reactivities with Ab-Pr, while the intact PVX still reacted more strongly with the Ab-PVX than did the dissociated protein. Differences in reactivity with Ab-Pr and Ab-PVX were not observed between PVX absorbed to polystyrene plate wells (direct ELISA) and to immunoglobulin-coated wells (double antibody sandwich ELISA). These results are not in agreement with the currently accepted view of PVX virions disruption (denaturation) upon adsorption to plastic.

[Comparison of antigenic properties of the X-potato virus and its coat proteins. Effect of proteolytic cleavage on antigenic characteristics]. / Sravnenie antigennykh svoistv x-virusa kartofelia i ego belka obolochki. Vliianie proteoliticcheskogo rasshchepleniia na antigennye kharakteristiki.

Antigenic properties of intact potato virus X (PVX) particles and of PVX coat protein (CP) preparations were compared using different modifications of ELISA test. In the competitive ELISA test (reaction in solution) antibodies to intact virus react much stronger with PVX than with CP while antibodies to CP react much stronger with CP than with PVX. In the direct ELISA test (reaction on the solid support) the difference in reactions of antiCP antibodies with PVX and CP is eliminated while the one in reactions of antiPVX antibodies with these antigens remains. No difference was registered in reactivity of PVX absorbed directly on polystyrene or on immunoglobulin-coated wells (sandwich ELISA) to antiCP antibodies.

The site-specific deletion in plasmid pBR322.

The formation of a deletion derivative of plasmid pBR322, designated pBR322 delta 1, was observed during cloning of various eukaryotic DNAs, when the BamHI site of the plasmid vector was used for construction of the recombinant molecules. The restriction analysis of six independently isolated pBR322 delta 1 plasmids allowed establishment of their complete identity. Similar deletion derivatives were also formed as a result of transformation of Escherichia coli cells by the linear form of vector pBR322 produced by BamHI cleavage, but not by SalI or HindIII. The endpoints of the deletion in one of the pBR322 delta 1 plasmids occurred at positions 375 and 16666 bp from the EcoRI site, as determined by sequence analysis. Formation of pBR322 delta 1 is most probably due to site-specific recombination between the sequence in the 1666-1670 bp region and the BamHI end of the linear pBR322 molecule. THe deletion was not controlled by the recA system of the host bacteria.

[Infectivity of the DNA of PM-2 phage]. / Infektsionnost' DNK faga PM-2.

The infectivity of PM-2 phage free DNA was studied versus competent cells of marine bacteria Pseudomonas Bal-31 depending on the time of incubation with the bacterial cells, on the DNA and calcium concentration in the solution. Optimal conditions for the infection are the following: DNA concentration about 3 microgram/ml, CaCl2 concentration 0.1 M, incubation time 20 min.

[Bacteria-infectious viruses in Penicillium chrysogenum strains with differing antibiotic activity]. / Virusy infektsionnye dlia bakterii v shtammakh Penicillium chrysogenum s razlichnoi antibioticheskoi aktivnosti

A new virus capable of replication on E. coli C was isolated from Penicillium chrysogenum. Six strains of P. chrysogenum differing in the cultural-morphological and biochemical properties and the titer of virus PBV5 were studied. The data provided a supposition that there were definite connections between the titer of virus PBV5 in the mycelium and the fungus ability for the antibiotic production.

[PBV5 virus induction in Penicillium chrysogenum mycelium]. / Induktsiia virusa PBV5 v mitselii Penicillium chrysogenum

The effect of some physical (increased temperature, UV light) and chemical (N-nitrosomethylbiuret, proflavin, acridine orange) factors on the virus titer in 2 strains of Penicillium chrysogenum was studied. Thermoinactivation of the virus and its induction under the effect of UV light and proflavin were shown. Slight induction was observed with N-nitrosomethylbiuret and acridin orange. It was supposed that induction of the virus in the mycelium of Penicillium chrysogenum was spontaneous.

[Biological and physicochemical properties of virus PBV-1, isolated from Penicillium brevi compactum]. / Nekotorye biologicheskie i fiziko-khimicheskie svoistva virusa PBV-1, vydelennogo iz Penicillium brevi compactum

High infectivity of PBV-1 virus for different strains of E. coli has been demonstrated. Sizes of the virus particle are; head diameter 513 angstrom, length of the process 1500 angstrom, diameter of the process 60 angstrom. The buoyant density of the virus in cesium chloride density gradient is 1.49 g/cm3, in cesium sulphate-1.39 g/cm3, the sedimentation constant of the virus particle is 380S; molecular weight is 52.8 plus or minus 1.9 times 10-6 daltons. The PBV-1 virus contains double-stranded DNA with the melting temperature in 1 SSC (0.15 M NaCl plus 0.0015 M sodium citrate, pH 7.0) and in 0.1 SSC-88.5 degrees C, respectively. The buoyant density of DNA in cesium chloride gradient is 1.7058 g/cm3 and in cesium sulphate 1.424 g/cm3. The content of GC-pairs calculated by the melting temperature is 46.5% and by the buoyant density 46.7%. On the basis of DNA sedimentation constant value (30S) the average molecular weight of DNA has been calculated to be 23.7 times 10-6 daltons.