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Biomedical subjects

R Crainic

Publications and source records attributed to R Crainic.

At least 73 records · Page 4Linked to original sources
PubMed1983

Functional basis of poliovirus neutralization determined with monospecific neutralizing antibodies.

Antibody-mediated poliovirus neutralization was studied by using a series of 13 monospecific neutralizing antibodies. These antibodies were found to recognize seven individual viral epitopes, several of which functionally overlap one another. Each epitope was capable of undergoing variation so that the variant virus was no longer capable of being neutralized by antibody directed against that epitope. The measured degree of variation for each site varied from -3.1 to -4.2 log10 variant PFU per wild-type PFU. Under nonsaturating but neutralizing conditions, the antibodies, with the exception of those directed to one specific epitope, failed to completely inhibit the virion's binding to the cell. Similarly, none of the neutralizing antibodies completely inhibited viral penetration, but all prevented virus-specific transcription. A strong correlation was established between the binding of each of the neutralizing antibodies, with one exception, to the virion and a significant shift in the virion's pI from 7.0 to ca. 4.0.

Antibodies, Monoclonal↗
PubMed1983

Induction of neutralizing antibodies by type 1 poliovirus VP1 capsid polypeptide.

Sera against purified VP1, VP2, and VP3 poliovirus capsid polypeptides of type 1 poliovirus were prepared in rabbits. Each serum was demonstrated to be specific for the polypeptide against which it was raised by immunoprecipitation with labeled, individualized capsid polypeptides. One of the anti-VP1 sera had a neutralizing capacity against type 1 poliovirus. It was the only one which reacted in immunoprecipitation with D-antigenic infectious particles.

Animals↗
PubMed1982

[Structural polypeptide VP1 in poliovirus type 1 induced by neutralizing antibodies].

Anti-type 1 (Mahoney) poliovirus neutralizing antibodies were obtained by immunizing rabbits with structural polypeptide VP1. This polypeptide was isolated from the virion by PAGE-SDS electrophoresis and extracted from the gel by electroelution. Anti VP2 and anti VP3 sera prepared in the same was did not display any significant antipolio neutralizing activity.

Antibodies↗
PubMed1981

Freeze-dried erythrocytes for an indirect hemagglutination test for detection of cytomegalovirus antibodies.

An indirect hemagglutination test with lyophilized, fixed, tanned, and cytomegalovirus (CMV)-sensitized sheep erythrocytes for the detection of CMV antibodies is reported. To avoid nonspecific hemagglutination, cells were fixed with glutaraldehyde or Formalin directly in whole blood. The lyophilized, CMV-sensitized erythrocytes obtained by this technique were stable up to 9 months at 37 degrees C and retained the same reactivity at fresh, CMV-sensitized cells. Indirect hemagglutination performed with lyophilized, sensitized cells was highly efficient in detecting CMV-antibodies as compared with complement fixation and enzyme immunoassay.

Animals↗
PubMed1981

Determination of type 1 poliovirus subtype classes with neutralizing monoclonal antibodies.

Hybridomas secreting neutralizing monoclonal antibodies (MA) against type 1 poliovirus were developed by fusion of mouse myeloma cells with splenocytes of immunized mice. Strain-specific MA selected for their capacity to neutralize wild (Mahoney) or attenuated (Sabin, LSc 2ab) poliovirus strains were used for identification of field isolates. A simple and reliable neutralization-index-assay was developed and used to test for intratypic serodifferentiation of poliovirus with the selected MA. Three subtype classes of type 1 poliovirus have so far been identified by testing 4 reference strains and 96 field isolates: Mahoney-like, LSc-like, and strains not recognized by either anti-Mahoney or anti-LSc MA. Neutralizing MA proved an excellent tool for unequivocal antigenic characterization of different poliovirus strains.

Animals↗
PubMed1981

Cell substrate and risk in killed poliomyelitis vaccine.

By using 3H-T labeled HeLa cell DNA it was possible to evaluate the quantity and the state of substrate DNA present in crude and purified killed poliovaccine. The results showed that 1.7 x 10(5) pg/ml of DNA is present in crude vaccine while in purified vaccine this product can not be detected (the limit of the detection method was 1.1 x 10(2) pg/ml). The theoretical problems of the risk of the formation of poliovirus pseudotypes and the potential contamination of the vaccine with a type C retrovirus are examined.

Cell Line↗
PubMed1980

Quantitation of cell DNA in the evaluation of heteroploid cells as substrate for the preparation of killed viral vaccines.

To evaluate the risk of using heteroploid cell lines as substrates for viral vaccine production, the presence of cell DNA in poliovirus suspensions was examined. The time course of [3H]-thymidine-labeled HeLa cell DNA release during lytic infection with type 1 poliovirus was investigated. More DNA was found in filtered supernatants of poliovirus-inoculated cultures than in control cell supernatants. DNA concentration increased with time, paralleling virus release, but did not exceed 1.5% of the total DNA content of the culture. Only about 10% of this cell DNA was resistant to DNase treatment. By both ion-exchange chromatography and rate-zonal centrifugation it was possible to remove practically all cell DNA contaminating filtered poliovirus suspensions. Results obtained in this study permitted quantitative evaluation of cell substrate DNA present in poliovirus suspensions during successive steps of killed poliovirus vaccine preparation. Based on the sensitivity of our method, the amount of residual DNA was estimated at less than 0.02 pg per dose of purified vaccine.

Centrifugation, Zonal↗
PubMed1980

Presence and quantification of cell substrate DNA in inactivated poliovirus vaccine.

In order to follow the fate of cell substrate DNA in inactivated poliovirus vaccine (IPV), experiments simulating different steps in IPV preparation were performed. For this purpose, 3H-thymidine-labeled HeLa cell DNA released during lytic infection with Mahoney type 1 poliovirus strain was used as tracer. Low speed centrifugation (1500 xg for 15 min.) of crude virus suspension removed on the average 98.5% of the total labeled cell substrate DNA. Repeated freezing and thawing of the crude virus suspension before centrifugation did not increase the residual 1.5% radioactivity found in the supernatant. This level of contamination was not significantly influenced by filtration of the supernatant through a 0.22 micrometer pore size membrane filter. DEAE-Sepharose CL-6B chromatography of poliovirus suspensions containing large amounts of 3H-thymidine labeled HeLa cell extracts completely removed the contaminating substrate DNA. These data showed that IPV free of cell substrate DNA can easily be obtained by a usual purification procedure.

Centrifugation↗
PubMed1969

Recombination between guanidine-resistant and dextran sulfate-resistant mutants of type 1 poliovirus.

Mixed infection of monkey kidney cells with two mutants of the LSc2ab strain of poliovirus, one resistant to guanidine and the other resistant to both dextran sulfate and 2-(alpha-hydroxybenzyl)-benzimidazole (HBB), yielded progeny in which the number of gua(r)dex(r) particles exceeded by a factor of 7 to 10 the expected number of similar particles occurring through spontaneous mutation; recombination would explain the fairly high excess of doubly mutant particles that was obtained. Scoring of HBB resistance in 50 gua(r)dex(r) clones suggested that, during recombination, resistance to dextran sulfate is not associated with HBB resistance.

Animals↗