[Immunogenicity and stability of a Soviet inactivated cultured vaccine against Japanese encephalitis]. / Immunogennost' i stabil'nost' otechestvennoi kul'tural'noi inaktivirovannoi vaktsiny protiv iaponskogo éntsefalita.

Six immunologically active vaccine batches inducing a specific antibody to Japanese encephalitis (JE) virus were obtained in serial manufacture of the preparation. In HI tests, the minimal antibody titre was 1:80, the maximal 1:320, neutralization index 1g was 3.7 to 5.2. The data on the stability of the antigenic potency of the vaccines in relation to the duration of storage at 4 degrees-6 degrees C are presented (the follow-up period 3 years). A certain relationship was found between the antigenic potency of the preparation and the titre of the initial infectious tissue culture virus. Also, a definite correlation was found between the initial immunogenic potency of the vaccines and their stability in storage. After 3 years of storage, three vaccine lots remained antigenically active, namely those which after manufacture had induced antihemagglutinins in titres 1:160 to 1:320. The antigenic activity of 6 vaccine batches prepared from the production strain Peking-1 (Nakayama serotype) was studied against the predominant strain of Jagar-10 serotype. All the freshly prepared vaccine batches were found to induce production of antihemagglutinins to both serotypes of JE virus, whereas virus-neutralizing antibodies were found only to the test strain Nakajama-NIH homologous to the vaccine Peking-1 strain. After 1 year of storage, four vaccine batches lost their capacity to induce production of antihemagglutinins to Jagar-01 strain, two batches induced antibody in low titres. This fact should be considered in evaluation of postvaccination immunity status in humans.

[RAMT cell line as a substrate for the propagation of vaccinal viral strains]. / Liniia kletok RAMT kak substrat dlia razmnozheniia vaktsinnykh shtammov virusov.

Properties of the PAMT cell line which are deficient in hypoxanthine guanyl phosphoribosiltransferase were studied. The PAMT cell line derived from African green monkey kidney tissue may be identified by selective nutrient media, contains no contaminants, is not tumorigenic, is susceptible to a wide range of viruses. Titres of poliomyelitis, tick-borne encephalitis, and carnivore plague viruses were similar in cell cultures grown in the medium with 10% serum and in those adapted to growth in the medium containing 1% serum. The properties of PAMT cell line allow it to be used in manufacture of killed virus vaccines.

Comparative study of infectious and formaldehyde-inactivated tick-borne encephalitis virus particles.

The structure and properties of infectious and formaldehyde-treated particles of tick-borne encephalitis virus, concentrated and purified by chromatography on macroporous glass, were studied. In addition to complete virions, such preparations contain some incomplete forms that differ in density, morphology and protein composition (incomplete forms do not contain nucleocapsid protein). The physico-chemical analysis of complete virions showed that formaldehyde treatment causes a) the formation of glycoprotein dimers and b) a portion of nucleocapsid protein to become tightly cross-linked with viral RNA. Formaldehyde treatment of incomplete forms resulted only in the formation of a small amount of glycoprotein dimers. Incomplete forms and glycoprotein extracted from inactivated preparations had protective and antigenic activity.

[Comparison of methods for the large-scale culture of cells and viruses]. / Sravnenie metodov krupnomasshtabnogo kul'tivirovaniia kletok i virsuov.

The paper presents the results of experiments on propagation of primary, secondary, and continuous diploid and heteroploid human and animal cells in 2 different systems for large-scale propagation: in perfusion tank with Rashig rings and in tanks with microcarriers. Both methods of large-scale cultivation produce higher cell yields than the traditional cultivation methods. A yield of tick-borne encephalitis virus per 1 cell in the perfusion cultivator was 12 times as high as in roller cultures. Poliomyelitis virus titres were practically equal with both methods of large-scale cultivation and with the conventional method (7.73 lg PFU/ml in GMKC on microcarriers). The method of cultivation on microcarriers is more acceptable and advantageous as it gives higher yields of cells necessary for growth of poliomyelitis virus.

[Chromatography of formalin-inactivated tick-borne encephalitis viruses on macroporous glass]. / Khromatografiia inaktivirovannogo formalinom virusa kleshchevogo éntsefalita na makroporistykh steklakh.

The results of further development of methods for chromatographic concentration and purification of tick-borne encephalitis virus on columns with porous glass using formalin-inactivated virus suspensions are presented. The method of adsorption chromatography on porous glass under optimal conditions concentrates inactivated TBE virus 20-40-fold with simultaneous purification from protein by 93%-95%. Inactivated virus was shown to keep on glass better than infectious virus. Gel filtration chromatography removes 99.2%-99.8% of protein impurities from inactivated TBE virus preparations giving a complete or nearly complete "yield" of virus particles. The sequential use of adsorption chromatography and gel filtration produced concentrated, most highly purified TBE virus preparations containing no more than 2 microgram/ml protein. Chromatographic virus preparations were immunologically active in experiments in laboratory animals.

[Concentrated purified vaccine against tick-borne encephalitis prepared by means of zonal ultracentrifugation. Development of the preparation]. / Kontsentrirovannaia ochishchennaia vaktsina protiv kleshchevogo éntsefalita, prigotovlennaia metodom zonal'noiogo ul'tratsentrifugirovaniia. Razrabotka preparata.

A concentrated and purified (lyophilized) preparation with a high immunological activity was obtained from formalin-inactivated tissue culture suspensions of tick-borne encephalitis (TBE) virus. Its high immunogenicity was demonstrated in mouse protection tests against fatal challenge with TBE and in the studies of antibody production in monkeys of two species. The preparation was shown to contain no infectious TBE virus, to be safe for small laboratory animals and monkeys. Trials of the preparation in 19 volunteers demonstrated it to be well tolerated and to induce virus-neutralizing antibody production in man. It also sensitized lymphoid cells when inoculated subcutaneously with Al2O3. These experimental materials indicate the possibility of developing a highly potent vaccine against tick-borne encephalitis by concentration and purification of TBE particle suspensions.