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Biomedical subjects

V Vonka

Publications and source records attributed to V Vonka.

At least 19 recordsLinked to original sources
PubMed1979

Immunogenicity of subviral herpes simplex virus preparations. I. Formation of neutralizing antibodies in different animal species after administration of herpes simplex virus solubilized antigens.

Production of neutralizing antibodies was followed in guinea pigs, rabbits, hamsters and mice immunized with crude antigen extracts (AM) from human diploid cells infected with herpes simplex virus type 1. The AM induced relatively high levels of neutralizing antibodies in all four species. The antibodies were predominantly complement-requiring and remained so even after administration of repeated AM doses. With the strains used, the antibody response was predominantly type specific and, surprisingly, the type specificity of sera usually increased after administration of repeated doses of AM. Guinea pigs seemed to be the best responsive animal species. They developed the highest levels of antibodies and complement-nonrequiring antibodies were seen in them earlier than in the other animal species. The dose-response experiments carried out in guinea pigs indicated that after a single dose administration the ratio between complement-requiring and complement-nonrequiring antibodies was dependent on the amount of antigen administered. When AM was given without adjuvant less efficient antibody production wws observed than after the administration of the same amount of antigen with adjuvant.

Animals↗
PubMed1979

Replication of two influenza virus strains and a recombinant in HEF and LEP cells.

The replication of influenza viruses A/NWS-D, A/WS-MK and their r12 recombinant in human embryo fibroblast (HEF) and human diploid fibroblast (LEP) cell lines was studied. In HEF cells virus NWS-D and recombinant r12 induced synthesis of virus-specific macromolecules and produced infectious virions; virus WS-MK induced synthesis of virus complementary RNA (cRNA), virion RNA (vRNA), protein, RNP and non-infectious virions, but haemagglutinin cleavage was impaired and the virions formed contained uncleaved haemagglutinin. In LEP cells, infectious virions were formed only by virus NWS-D; viruses WS-MK and r12 induced synthesis of virus cRNA, vRNA, proteins and RNP; virus r12 had the haemagglutinin cleaved, whereas in virus WS-MK this process was impaired; neither virus WS-MK nor r12 was capable of forming virions. Analysis of the recombinant r12 genome showed that it had only inherited a single gene from NWS-D, the one coding for neuraminidase, having inherited all others (P1, P2, P3, HA, NP, M, NS) from WS-MK. The data obtained suggested that the inability of virus WS-MK to form infectious virions in HEF cells is due to the character of its neuraminidase, which is incapable of participating in haemagglutinin cleavage. The deficient reproduction of this virus in the other host-cell system (LEP) is apparently associated with some characteristics of another protein (other proteins) of this virus.

Animals↗
PubMed1979

Blocking of acid-fixed nuclear binding of Epstein-Barr virus nuclear antigen (EBNA) by different DNA species.

Treatment of Epstein-Barr virus-determined nuclear antigen (EBNA) with DNA resulted in blocking of its ability to convert acid-fixed EBNA-negative cell nuclei to an EBNA-positive form. Epstein-Barr virus (EBV) DNA, herpes simplex virus type 2 (HSV-2) DNA and DNA isolated from three lymphoblastoid cell lines differed in their potency to block this reaction. EBV DNA was found to be about three times more effective than cellular DNAs in abolishing the ability of DNA-cellulose-purified EBNA to convert acid-fixed nuclei to the EBNA-positive form; the effect of HSV-2 DNA was of intermediate character. No difference was found between the blocking potency of DNAs isolated from EBV-genome-negative Ramos cells and EBV-genome-positive Raji and P3HR-1 cells.

Antigens, Viral↗
PubMed1979

A vesicular stomatitis virus (cytomegalovirus) pseudotype and its use in neutralization tests.

Infection with vesicular stomatitis virus (VSV) of human diploid cells preinfected with the AD-169 strain of human cytomegalovirus (CMV) resulted in the formation of a VSV (CMV) pseudotype. Its formation was favored by increasing the bicarbonate content in doubly-infected cultures. The pseudotype was capable of infecting not only human but also rabbit cells. Pseudotype particles formed after infection with the tl 17 mutant of VSV, which carries a thermolabile lesion in its neutralization antigen, were more stable at 45 degrees than the original tl 17 virus. The pseudotype was used in the neutralization test with human sera. All sera positive for CMV antibody in the complement-fixation (CF) test were also reactive in the neutralization test. In addition, numerous sera negative for CMV antibody in the CF test neutralized the pseudotype.

Adult↗
PubMed1979

Effects of cytosine arabinoside on the incorporation of pyrimidine nucleosides into hamster cells transformed by herpes simplex type 1 and type 2 viruses and by human cytomegalovirus.

The incorporation of 3H-thymidine and 3H-deoxycytidine into acidoprecipitable fraction of hamster cells transformed by herpes simplex viruses type 1 and type 2 and of 3H-thymidine into hamster cells transformed by human cytomegalovirus was found to be resistant to the action of cytosine arabinoside. More 3H-thymidine was incorporated into these cells in the presence than in the absence of the drug. Similar stimulaton of 3H-thymidine uptake could be achieved by using unlabelled deoxycytidine instead of cytosine arabinoside. Incorporation of both nucleosides into spontaneously and SV40 transformed cells was efficiently inhibited by the drug.

Animals↗
PubMed1978

Study of Epstein-Barr virus-determined nuclear antigen (EBNA) by chromatography on fixed cell nuclei.

Low ionic strength (50 to 100 mM NaCl) and pH 6.0 were found to be optimal conditions for in vitro conversion of Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA)-negative nuclei to EBNA-positive nuclei by addition of the complement-fixing (CF) antigen extracted from Raji cells. In vitro conversion of nuclei to EBNA-positively was sensitive to DNase but not to RNase treatment. This suggests that nuclear DNA is a specific target substance to which EBV-CF antigen binds. If nuclei were fixed with methanol/acetic acid and subsequently treated with 0.6 M NaCl, EBNA could be eluted from in vitro-converted Ramos nuclei with 0.3 and 0.4 M NaCl. The same conditions were also found to be optimal for the adsorption and elution of EBV-CF antigen in DNA-cellulose chromatography. This indicates that the DNA-binding properties of EBNA antigen can be studied by "chromatography" on fixed nuclei followed by the ACIF test. The obvious advantages of this method over chromatography on DNA-cellulose are its simplicity, the possibility of testing many samples in one experiment and, especially, the use of minimal amounts of material. Significant differences in elution patterns for EBNA were found when nuclei derived from different cell lines (Ramos, Raji, and P3HR-1) were converted in vitro to EBNA-positivity. EBNA is eluted from in vitro-converted nuclei of EBV genome-positive P3HR-1 cells at an almost 0.1 M higher concentration of NaCl than is necesssary for a similar degree of elution from nuclei of EBV genome-negative Ramos cells.

Acetates↗
PubMed1978

Determination of virus-specific antigens in extracts from herpes simplex virus-infected cells by a Cr release inhibition test.

A 51cr release inhibition test (CRIT) was developed for determining herpes simplex virus type 1 antigens in infected cell extracts. Among the factors studied were the optimal concentrations of complement, antibody, and infected target cells. Under standardized conditions, the relationship between antigen content and inhibition of chromium release was linear in a semilogarithmic plot, indicating that the antigen content can be determined from testing two dilutions of a given preparation. Other tests showed that infected cells cryopreserved at -70 degrees C for periods exceeding 3 months can be used in CRIT. Five different batches of infected cell extracts were tested in both CRIT and blocking neutralization tests with comparable results being obtained, suggesting that both tests measure the same activity.

Animals↗
PubMed1978

UV-inactivation of Epstein-Barr virus: differences in early antigen expression in two different non-productive cell lines and influence of caffeine.

Two non-productive Epstein-Barr (EB) virus genome-carrying lymphoblastoid cell lines, namely Raji and NC37, were used for studying the effect of UV irradiation on the ability of P3HR-1 EB virus to induce early antigen (EA) formation. In NC37 cells infected with UV-irradiated virus the formation of EA was delayed; thus the slope of inactivation curve based on the early (24 hr) reading was steeper than that based on the late (72 hr) reading. This was not observed in Raji cells. Caffeine did not influence the percentage of EA positive cells in cultures infected with untreated virus; however, the drug exhibited a marked inhibitory effect on EA production after infection with UV-irradiated virus. The sensitivity to caffeine effect decreased more rapidly with time after infection of Raji than of NC37 cells, suggesting a higher degree of readiness of the host cell repair system in the former than in the latter cells. The caffeine effect was merely directed against the synthesis of R (restricted) component of EA; its influence on the D (diffuse) component formation was negligible.

Antigens, Viral↗
PubMed1977

Epstein-Barr virus antibodies in tonsillar carcinoma patients;.

Sera from 18 tonsillar carcinoma patients and from 18 matched control subjects were examined for the presence of antibodies to viral capsid antigen (VCA), early antigen (EA) and nuclear antigen (EBNA) of EB virus. Antibodies to all three antigens were found more frequently and in significantly higher titres in the tonsillar carcinoma patients than in control subjects.

Aged↗
PubMed1977

Differential expression of D and R components of Epstein-Barr virus early antigen after superinfection and after induction with 5-iododeoxyuridine.

Three non-productive human lymphoblastoid cell lines, NC-37, RAJI and L-1, either superinfected with Epstein-Barr (EB) virus from P3HR-1 cells or treated with 5-iododexyuridine (IUDR), were studied for the development of early antigen (EA) of EB virus. In all three superinfected cell lines, both the restricted (R) and diffuse (D) componets of EA were synthesized, with R-component formation preceding D-component synthesis. After IUDR treatment both components of EA were only formed in RAJI cells, while in NC37 and L-1 cells only the R-component was synthesized.

Antigens, Viral↗
PubMed1977

Production and some properties of neutralizing antigens of herpes simplex virus.

Human diploid cells (LEP) infected with herpes simplex virus (HSV) type 1 were extracted by treatment with Nonidet P-40. The content of antigens reactive with neutralizing antibody in the clarified extract was measured by the blocking test. Influence of various factors on the production of the blocking antigens (BA) was tested. Highest BA titres in LEP cells were achieved at a multiplicity of infection (m.o.i.) of 0.5 TCD50/cell, medium 199 and 22 to 29 hours incubation at 37 degrees C. The use of resting cultures or the presence of cytosine arabinoside in medium reduced the BA production. The activity of BA was reduced by repeated freezing and thawing. The antigen was stable at -20 and -70 degrees C. One hour heating at 60 degrees C resulted in a marked decrease of the antigen titre. BA was resistant to formalin; formalin treatment did not influence its thermosensitivity.

Antigens, Viral↗
PubMed1976

Replication of cytomegalovirus in human epitheloid diploid cell line.

Human diploid BAMB cells with epitheloid morphology, which had been derived from amniotic fluid cells, were capable of supporting the replication of human cytomegalovirus (CMV), without prior treatment of the cells with halogenated pyrimidines. The growth of this virus in BAMB cells and in human diploid fibroblastoid (LEP) cells was compared in parallel tests. Virus replication was slower and less efficient in the former than in the latter system. The most characteristic morphological feature of the CMV-infected BAMB cells was the formation of multinucleated giant cells which frequently contained more than a hundred nuclei; such cells were not seen in LEP cultures. The development of ultrastructural changes was slower in BAMB cells than in LEP cells. The additional most marked differences concerned the place of viral envelopment and the production of cytoplasmic dense bodies. While in LEP cells most nucleocapsids were enveloped from the inner leaflet of the nuclear membrane, in the other system a great majority of the particles acquired their envelopes by budding into vacuoles. Cytoplasmic dense bodies were rare in infected LEP cells but very frequent in BAMB cells. Budding of these structures into vacuoles was also observed.

Cell Line↗
PubMed1976

Thymidine-kinase in cytomegalovirus infected cells.

In human diploid fibroblast LEP cells infected with AD169 strain of human cytomegalovirus (CMV) a sharp increase of cytosol thymidine kinase activity was observed. The properties of the cytosol enzymes from infected and non-infected cells were compared. No significant differences between the enzymes from infected and control cells were observed in substrate specificity, pH dependence, thermostability and relative electrophoretic mobility. Human sera containing high titres of CMV complement-fixing antibodies did not neutralize the enzyme from infected cells. It is concluded from these results that the increase of cytosol thymidinekinase activity in CMV-infected cells was due to an enhancement of cellular thymidine kinase.

Antibodies, Viral↗
PubMed1976

Inhibitory effect of herpes simplex virus type 1 on type 2 virus replication.

Simultaneous infection with herpes simplex type I and type 2 viruses of chick embryo fibroblasts (CEF), which are only permissive for type 2 virus, or rabbit embryo fibroblasts (REF), which are permissive for both virus types, resulted in a marked reduction of type 2 virus production. This effect was dependent on the m.o.i. of type I, being expressed at a high rather than a low m.o.i. The rate of interference decreased with the prolongation of the interval between infection with type 2 and type I viruses. No evidence suggestive of interferon involvement was obtained. Partial inactivation of type 2 virus by ultraviolet irradiation enhanced the inhibitory effect of type I virus. On the other hand, u.v. irradiation of type I virus resulted in a progressive loss of inhibitory activity. The results of the present experiments suggest that a type I genome function is responsible for the interfering effect, and that an early step in the growth of type 2 virus is sensitive to the particular type I virus product involved.

Animals↗