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Biomedical subjects

V Vonka

Publications and source records attributed to V Vonka.

At least 91 records · Page 5Linked to original sources
PubMed1990

Phosphonylmethyl ethers of acyclic nucleoside analogues: inhibitors of HSV-1 induced ribonucleotide reductase.

Diphosphates of N-(S)-(3-hydroxy-2-phosphonylmethoxypropyl) and N-(2-phosphonylmethoxyethyl) derivatives of purine and pyrimidine heterocyclic bases inhibit HSV-1 encoded ribonucleotide reductase. Of the compounds studied, the most efficient inhibitors of CDP reduction (at 5.1 mumols.l-1) by the HSV-1-encoded enzyme are HPMPApp (IC50 = 0.9 mumols.l-1) and PMEApp (IC50 = 8 mumol.l-1). PMEApp does not inhibit the enzyme isolated from the mutant HSV-1 KOS strain PMEAr which is resistant to PMEA at a concentration of 100 micrograms/ml. The enzyme isolated from the PMEA-resistant virus strain is also insensitive to inhibitory effects of hydroxyurea and HPMPApp. Thus, the inhibitory potency of HPMPApp and PMEApp toward HSV-1 encoded ribonucleotide reductase might be connected with the anti-HSV activity of HPMPA and PMEA.

Adenine↗
PubMed1990

Synthetic peptides derived from E7 region of human papillomavirus type 16 used as antigens in ELISA.

Nine overlapping peptides (20 amino acid) covering the entire sequence of early antigen E7 of human papillomavirus type 16 (HPV-16) were synthesized and tested as antigens with human sera in ELISA. Five of these peptides (no. 1 to 5 counting from the N terminus of the E7 protein) reacted with a pool of sera from HPV-16-infected individuals (as determined by molecular hybridization with their biopsy specimens); one (no. 5) was also reactive with pools of HPV-18- and HPV-6- or 11-infected individuals. Sera from 24 patients with cervical intraepithelial neoplasia (CIN) and from 29 invasive cervical carcinoma (INCA) patients were tested for the presence of antibodies reactive with peptides, no. 1 to 4 covering amino acids 1 to 50 and with peptide no. 5 covering amino acids 41 to 60. Only one of the sera from CIN patients was reactive with peptides no. 1 (amino acids 1 to 20) and no. 4 (amino acids 31 to 50). However, the majority of these sera reacted with peptide no. 5. The occurrence of this antibody was only slightly less frequent in sera from healthy subjects compared to CIN patients. On the other hand, sera from the INCA patients were reactive with the peptides no. 1 to 3 more frequently than the sera from matched control subjects. Positive reactions of sera from INCA patients were most frequently seen with no. 2; 24% of these sera but only 7% of the controls were reactive with no. 2 peptide. The present data suggest that no. 1 to 3 are HPV-16-specific, whereas no. 5 is broadly cross-reactive.

Amino Acid Sequence↗
PubMed1990

Presence and type specificity of papillomavirus antibodies demonstrable by immunoelectron microscopy tests in samples from patients with warts.

Sera from 75 patients with warts were tested for antibodies against human papillomaviruses (HPVs) in an immunoelectron microscopy test. A group of 40 patients' sera were tested against a pooled suspension of the HPVs extracted from their warts and 90% of the sera were found to be antibody-positive. Prior to serological investigation viruses from a second group of 35 patients were typed by dot blot hybridization with HPV-1 and HPV-2 DNA. According to these results the patients were divided into type 1, type 2 and non-1, non-2 virus carriers. Sera of these patients were first tested for antibodies reactive with their homologous viruses and then for antibodies against type 1 virus. More than 80% of the patients possessed antibodies against their homologous viruses, but only a small minority of sera from type 2 and non-1, non-2 virus carriers were reactive with type 1 viruses. These results suggest that the antibody reactive in the immunoaggregation test is type-specific.

Adolescent↗
PubMed1990

Presence of antibody reactive with synthetic peptide derived from L2 open reading frame of human papillomavirus types 6b and 11 in human sera.

Nine oligopeptides corresponding to segments of different open reading frame (ORF) proteins of human papillomavirus (HPV) 6b and HPV-16 were prepared and tested for reactivity with human sera in enzyme-immunoassay (ELISA). Of these only heptadecapeptide derived from L2 ORF of HPV-6b, and encoded also by L2 ORF of HPV 11, was reactive with some human sera. Over 400 human sera of different origin were tested for the presence of antibody to this antigen. While less than 15% of sera from healthy subjects or cervical carcinoma patients were found antibody positive, sera from the majority of condylomata accuminata (CA) patients were reactive. The antibody titres varied from 1:10 (initial serum dilution) to 1:80; in this respect there was no marked difference between sera from CA patients and the other subjects. The prevalence of antibody was higher among promiscuous than nonpromiscuous women. This is in line with the assumption that sexual intercourse is the most important route of HPV 6 and 11 transmission.

Amino Acid Sequence↗
PubMed1990

[Reactivity and immunologic activity of polyvalent split influenza vaccine in children].

In a group of 144 children (six months to 15 years) three doses vaccine were administered. The latter contains the main strains of the influenza type A and strain type B. From the clinical evaluation ensued that this vaccine in children is areactogenic even after repeated doses. The morbidity was followed up for 18 months and during this period in the immunized communities no case of influenza was recorded. The antibody levels were assessed by the haemagglutination-inhibition test (HIT) and the enzyme test (NIT) The assessed HI titres were high after the second and third dose, in particular as regard subtype H3N2 and H1N1. The titres against subtype H2N2 and type B were markedly lower. Antibodies against neuraminidase were highest against subtype N1 and type B, lowest against N2. The dynamics of the formation of antineuraminidase antibodies was similar as that of haemagglutination-inhibition antibodies. Based on these results the vaccine is evaluated as very satisfactory and after approval by the Ministry of Health and Social Affairs this vaccine will be used for a field trial in 1-2 thousand children where above all the protective effect of the vaccine will be investigated. This vaccine is intended for children, with the aim to induce complex immunity against influenza.

Adolescent↗
PubMed1989

[EBV-specific antibodies in patients with nasopharyngeal cancer and tonsillar cancer. Follow-up of over 4 years].

26 NPC patients and 47 TC patients were investigated clinically, and in the sera of these patients EBV-specific antibodies were determined. No relapse occurred in 11 patients with NPC and in 17 patients with TC during the period of 4 years. In addition to the determination of antibodies we looked for EBNA in 3 undifferentiated NPC and 4 undifferentiated TC, and for EBV-DNA in 2 of these NPC and one of these TC. The 3 NPC and 4 TC tested for EBNA showed this antigen in the cells. 2 NPC and 1 TC showed EBV-DNA with in situ hybridization technique. In the blot hybridization according to Southern the Eco R 1 fragment of both NPC was identical with the Eco R 1 fragment of the positive control of P 3 HR 1 cells. The 15 NPC-patients with tumour (4 with primary NPC, 11 with relapse) in the observation period showed higher IgA-VCA titres than the NPC patients free of relapse during this time. Subsequent to therapy, IgG-VCA titres decreased. Most of the NPC-patients with tumour during the time of testing mentioned before had IgA-VCA once or several times. Most of half of these patients had IgA-EA, but there was no patient without relapse. IgA-VCA increase and the presence of IgA-EA may be the first sign of a relapse. Thus, intensive research into this phenomenon will be required. No remarkable difference could be found in EBV-specific antibody patterns between TC patients without relapse and TC patients with tumour progression or relapse.

Adolescent↗
PubMed1989

Some immunological characteristics of subjects suffering from frequent herpes simplex virus recrudescences.

Some parameters of specific and non-specific immunity were tested in a group of 44 subjects suffering from frequent herpes simplex type 1 (HSV-1) or herpes simplex type 2 (HSV-2) recrudescences. The tests performed included determinations of (i) HSV complement-independent and complement-dependent neutralizing antibodies, (ii) antibodies to glycoprotein C of HSV-1 and glycoprotein G of HSV-2, (iii) antibodies to viral capsid and early antigens of Epstein-Barr virus, (iv) antibodies to tetanus toxoid, (v) serum levels of IgM, IgG, IgA, transferrin, prealbumin and C'3 and C'4 components of complement, (vi) active and total T lymphocytes, (vii) phagocyting activity of polymorphonuclear neutrophils, eosinophils and mononuclear cells, (viii) skin reactivity to tuberculin, toxoplasmin, candidin, tetanus and diphtheria toxoids. In the patients the following deviations from the control groups were noted: (i) Antibody levels to homotypic but not to heterotypic HSV were enhanced, (ii) serum IgM levels were elevated, (iii) percentages and numbers of active and total T lymphocytes were decreased, (iv) phagocyting activity of neutrophils was depressed but that of eosinophils was increased.

Adolescent↗
PubMed1988

Antibody response to Epstein-Barr virus antigens in patients with chronic viral infection.

We tested antibody titres against Epstein-Barr virus (EBV) antigens in patients suffering from chronic viral disease and compared them with those determined in sex- and age-matched healthy controls. Patient sera showed signs of active EBV infection [antibodies against early antigen (EA) and/or viral capsid antigen (VCA) in the IgM or IgA classes] significantly more frequently than the control group. Correspondingly, geometric mean titres (GMT) of antibodies against all viral antigens were elevated in the patients. The strongest association with EBV was observed in patients whose clinical symptoms closely resembled infectious mononucleosis: 92% of the subjects in this subgroup possessed anti-EA and 41 and 25% had IgM and IgA anti-VCA antibody, respectively. In patients with signs of lymphoproliferation only and in those suffering from frequent respiratory infections the association with EBV was less marked but still significant. Patients with transient defects in humoral and cellular immunity mounted higher titres against VCA in the IgG class than those without immune defects.

Adult↗
PubMed1988

Epstein-Barr virus nuclear antigen type 1 binding: electron microscopy.

Epstein-Barr virus (EBV) nuclear antigen type-1 (EBNA-1) was extracted and purified from Raji cells by chromatography on DNA-Sepharose and Blue-dextran Sepharose. Its complexes with plasmid pM765-10 derived from EBV (strain M-ABA) DNA were visualized by electron microscopy. The criteria of specificity were as follows: (1) preferential binding of EBNA-1 to the ori-P region of pM765-10; (2) specific enlargement of EBV DNA/EBNA-1 complexes with anti-EBNA-1 (IR-3) IgG antibody; and (3) resistance of the resulting EBV DNA/EBNA-1/anti-EBNA-1 antibody complexes to treatment with 1.5 M NaCl. The optimal conditions for the formation of EBV DNA/EBNA-1 complexes were 50 to 150 mM NaCl and pH 6.0. A balanced equilibrium of EBNA-1 and pM765-10 was necessary to achieve both a high yield and specificity of EBV DNA/EBNA-1 complexes.

Antigens, Viral↗
PubMed1988

Absence of cytomegalovirus, Epstein-Barr virus, and papillomavirus DNA from adenoma and adenocarcinoma of the colon.

Biopsy specimens from 13 patients with adenocarcinoma of the colon and from 10 patients with endoscopic polypectomies for colon adenoma were examined for the presence of the DNA of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human papillomavirus (HPV) types 2, 6, 16 and 18. The specific activities of viral DNA probes obtained by nick--translation ranged from 10(7) to 10(8) cpm/micrograms DNA. By Southern blot hybridization with an estimated sensitivity of 10 pg virus DNA which corresponded to 0.05 virus genome equivalents per cell we failed to detect any virus DNA in the biopsy material tested.

Adenocarcinoma↗
PubMed1988

Epstein-Barr virus (EBV) antibodies in children with non-Hodgkin's lymphomas.

Antibody titres against Epstein-Barr virus (EBV) antigens in children suffering from non-Hodgkin's lymphoma (NHL) were determined. IgG antibody titres against the viral capsid antigen (VCA) and early antigen (EA) exceeded those found in healthy control subjects. On the other hand, antibody titres against EBV-determined nuclear antigen (EBNA complex) were generally lower than in the control group. The most striking phenomenon observed in the patient group was the frequent activation of latent virus infection as revealed by the periodical appearance of anti-EA and IgM class anti-VCA antibodies. Antibody titres against EBV antigens were generally lower among patients with progressing disease than in those with a more favourable course of the illness. The closest relation to EBV based on serological findings, was detected in lymphoblastic lymphomas of Burkitt-type histology, poorly differentiated lymphocytic lymphomas, and in lymphomas localized in the abdomen. The question whether EBV might be involved in a certain proportion of the cases examined is discussed and further approaches to elucidate this problem are suggested.

Adolescent↗
PubMed1987

Electron microscopy of binding of Epstein-Barr virus (EBV) nuclear antigen (EBNA-1) to EBV DNA.

Specific binding sites for Epstein-Barr virus (EBV) nuclear antigen (EBNA-1), isolated and semipurified from EBV-transformed nonproductive Raji cells, were visualized on the molecule of EBV DNA by electron microscopy and mapped. Two measures had to be applied to counteract the limited purity of the EBNA-1 preparation: (i) EBV DNA/EBNA-1 complexes were specifically enlarged by binding with anti-EBNA-1 (IR-3) IgG antibody. (ii) DNA-binding proteins that did not react with the anti-EBNA-1 antibody were eluted from EBV DNA with 1.5 M NaCl, taking advantage of the resistance of DNA/EBNA-1/anti-EBNA-1 antibody complexes to the high-salt treatment. EBNA-1 bound at the highest relative frequency (greater than 30%) to the EBV DNA map positions of 8.8 +/- 0.3, 10.3 +/- 0.5, and 46.6 +/- 1.2 kb. It bound with a lower but still statistically significant frequency (16%) to the map positions of 64.5 +/- 1.0, 89.7 +/- 1.6, 129.6 +/- 1.1 kb.

Antigens, Viral↗
PubMed1987

Immunogenicity of a synthetic peptide corresponding to a portion of the heavy chain of H3N2 influenza virus haemagglutinin.

Rabbits were immunized with a synthetic octadecapeptide corresponding to the sequence ser-91 to leu-108 of the haemagglutinin heavy chain of H3N2 influenza A viruses. They developed antibodies reactive in solid-phase radioimmunoassay (SPRIA) with the peptide and with haemagglutinins of various H3N2 viruses but not of heterotypic H1N1 and H2N2 viruses. The antibodies were also non-reactive in the haemagglutination-inhibition or neutralization test. Influenza H3N2 virus replicated in the lungs of mice immunized with the peptide to the same extent as in the control mice. Of 27 human sera possessing anti-H3N2 activity or seven sera from rabbits immunized with either virions or haemagglutinins of various influenza A viruses, none was reactive with the peptide in SPRIA.

Antigen-Antibody Complex↗
PubMed1986

Prospective study on the relationship between cervical neoplasia and herpes simplex type 2 virus. III. Presence of herpes simplex type-2 antibody in sera of subjects who developed cervical neoplasia later in the study.

Paired sera taken from 63 subjects who developed cervical neoplasia in the course of a prospective study on this disease were examined for the presence of herpes simplex virus type 2 (HSV-2) antibody. The first serum was taken at enrollment into the study, while the second was obtained after development of the disease, i.e. 2-4 years later. Simultaneously, paired sera from a group of control subjects, who remained free of any cytological and colposcopical abnormalities throughout the study, were also investigated. Controls were matched with patients by age, age at first intercourse, number of sexual partners, smoking habits and history of diathermoelectrocoagulation of ectopic epithelium and transformation zone of the cervix. The first sera from these subjects were obtained at enrollment while the second ones were taken at the end of the study, i.e. 5 to 7 years later. Antibody titres were remarkably stable in both patients and control subjects. Seroconversions from HSV-2 negativity to HSV-2 positivity as measured by the increase in the II/I ratio or development of antibody reactive with HSV-2-specific glycoprotein G were rare and no significant differences between the patients and control subjects were detected. This indicates that the development of the disease was apparently not followed by immediate or early activation of latent HSV-2 infection.

Antibodies, Viral↗