Preparation of cyclic 2',3'-monophosphates of oligoadenylates (A2'p)nA > p and A3'p(A2'p)n-1A > p.

The action of the guanylyl-preferring RNase from Bacillus intermedius (binase) on a mixture of oligoadenylates with randomly distributed 2'-5' and 3'-5' internucleotide bonds [(A2'/3'p)n] under conditions sufficient for complete hydrolysis of poly(A) results in a mixture containing a single circular oligoadenylate and two series of linear oligoadenylates ending in cyclic 2',3'-phosphate. Individual compounds formed upon digestion of (A2'/3'p)n with binase have been isolated. Their structure was determined on the basis of their chemical and enzymatic conversions and confirmed by 1H-, 13C- and 31P-NMR spectra.

Laser photofootprinting of d(C).d(G).d(G) intramolecular triplex.

Supercoiling-induced structural transition of the d(C24GC21).d(G21CG24) sequence in plasmid DNA in the presence of Mg2+ at neutral pH results in alterations of efficiencies of not only single-quantum (pyrimidine[6-4]pyrimidone adducts) but also two-quantum (alkali-sensitive lesions of dG residues) photomodifications of nucleoside residues within this sequence. The generation of both types of photoreactions was achieved by the application of high-intensity laser UV radiation (intensity approximately 10(11) W/m2, pulse duration approximately 10(-8) s, lambda = 266 nm) for irradiation of a plasmid DNA.

Principles of selective inactivation of viral genome. VIII. The influence of beta-propiolactone on immunogenic and protective activities of influenza virus.

The influence of beta-propiolactone action on the immunogenic and protective activity of the influenza virus A/WSN/33 (H1N1) has been studied. The production of antibodies against virion surface antigens in mice immunized intramuscularly by the modified virus was enhanced with the increase of inoculating dose from 6 x 10(7) to 1.5 x 10(8) viral particles per animal.

Principles of selective inactivation of viral genome. VII. Some peculiarities in determination of viral suspension infectivity during inactivation by chemical agents.

When the infectivity of the influenza virus is determined by means of titration on chicken embryos, calculating the infection titre according to Reed and Muench, the course of inactivation with beta-propiolactone shows an anomaly - the fraction of infected embryos in a batch initially increases and then decreases as the degree of dilution of the virus-containing sample is increased. This anomaly occurs because a slight dilution lowers the agent concentration insufficiently so that inactivation goes on after the dilution of the sample before and/or after the inoculation of the solution into the embryo. The anomaly can be avoided either by neutralizing or removing the agent prior to titration or by starting titration from high dilutions.

Principles of selective inactivation of viral genome. VI. Inactivation of the infectivity of the influenza virus by the action of beta-propiolactone.

The kinetics of inactivation of the infectivity of the influenza virus by beta-propiolactone have been studied. Rate constants have been determined for inactivation of the A/Leningrad/385 (H3N2) and B/Leningrad/489/80 influenza virus under the action of beta-propiolactone on a virus-containing allantoic fluid and on a purified viral suspension. The data obtained allow calculation of the time required for inactivation of the influenza virus infectivity to a given extent in virus-containing solutions at any initial concentration of beta-propiolactone.