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Biomedical subjects

W Jilg

Publications and source records attributed to W Jilg.

At least 37 records · Page 2Linked to original sources
PubMed2000

Sensitive and accurate quantitation of hepatitis B virus DNA using a kinetic fluorescence detection system (TaqMan PCR).

The laboratory diagnosis of hepatitis B virus (HBV) infection is based mainly on serological assays. Yet the detection and quantitation of viral DNA is necessary when addressing directly the question of infectivity or when monitoring the viral load during therapy. Standard hybridization assays allow for exact quantitation, but their sensitivity is limited to 10(5)-10(6) viral genomes per ml of serum. The most sensitive tests for HBV DNA are nested PCR systems, which recognize virtually one molecule of the target DNA per reaction. However, these assays only provide very coarse quantitative statements. To take advantage of both methods, a new assay for HBV DNA is described based on the commercial TaqMan system. This assay is capable of quantifying HBV DNA from the theoretical lower limit up to 10(10) genome equivalents per ml of serum and, thus, covers the complete range of naturally occurring states of infections. The method was calibrated on the basis of serial plasmid dilutions and compared with a well-established nested PCR system. More than 100 HBV positive sera and serial dilutions of the Eurohep standard for both ad and ay subtypes were analyzed. The assay reliably detected all HBV positive samples. It shows minimal run-to-run deviations, allows for quantitation that covers eight orders of magnitude, and finally, completely avoids the risk of cross-contamination by PCR products. Thus, this technique combines the sensitivity of PCR amplification and the quantitation potential of hybridization tests and it is time efficient and safer.

DNA, Viral↗
PubMed2000

The economic burden of hepatitis B in Germany.

Despite the widespread distribution of Hepatitis B virus (HBV) infection and the ongoing controversy about HBV immunization, surprisingly few published studies examined in detail the economic impact of HBV infection in Europe. Therefore, we investigated a cohort of 180 patients throughout Germany to evaluate the economic burden of HBV-associated disease. In 58 patients with acute and 122 patients with chronic HBV infection, cost-consuming events including direct medical costs and work-loss costs were documented. The direct costs were DM 7702 (95% confidence interval (CI): 5473-9931) for each acute HBV infection and DM 4247 (CI: 1601-6893) per patient-year of chronic HBV infection, with marked differences between different stages of HBV disease. The derived overall costs (1997 price levels) per year were DM 10,018 (CI: 7613-12,421) and DM 4860 (CI: 2185-7536), respectively. Based on crude population-based estimates (30,000 acute and 420,000 chronic HBV cases), we calculated the total HBV-related costs in Germany to exceed DM 1200 millions in 1997 (CI: 924.2-1536.7), with the treatment of patients with chronic active HBV disease as the major cost determinant. Previously published data from Germany probably overestimated the financial impact of acute HBV infection. In summary, our results illustrate the ongoing economic importance of this potentially life-threatening, but preventable disease and support the call for more accurate HBV surveillance and control in Germany.

Adult↗
PubMed2000

High genetic variability of the group-specific a-determinant of hepatitis B virus surface antigen (HBsAg) and the corresponding fragment of the viral polymerase in chronic virus carriers lacking detectable HBsAg in serum.

Chronic carriers of hepatitis B virus (HBV) usually show hepatitis B surface antigen (HBsAg) in their sera, which is considered the best marker for acute and chronic HBV infection. In some individuals, however, this antigen cannot be detected by routine serological assays despite the presence of virus in liver and peripheral blood. One reason for this lack of HBsAg might be mutations in the part of the molecule recognized by specific antibodies. To test this hypothesis, the HBV S gene sequences were determined of isolates from 33 virus carriers who were negative for HBsAg but showed antibodies against the virus core (anti-HBc) as the only serological marker of hepatitis B. Isolates from 36 HBsAg-positive patients served as controls. In both groups, a considerable number of novel mutations were found. In isolates from individuals with anti-HBc reactivity only, the variability of the major hydrophilic loop of HBsAg, the main target for neutralizing and diagnostic antibodies, was raised significantly when compared with the residual protein (22. 6 vs 9.4 mutations per 1000 amino acids; P<0.001) and with the corresponding region in the controls (22.6 vs 7.5 exchanges per 1000 residues; P<0.001). A similar hypervariable spot was identified in the reverse transcriptase domain of the viral polymerase, encoded by the same nucleotide sequence in an overlapping reading frame. These findings suggest that at least some of the chronic low-level carriers of HBV, where surface antigen is not detected, could be infected by diagnostic escape mutants and/or by variants with impaired replication.

Amino Acid Substitution↗
PubMed2000

[Diphtheria antitoxin level 2 years after booster vaccination].

In a prospective, controlled, randomized, multicenter study the immunogenicity of a single (day 0) and two (day 0, 28) booster vaccination against diphtheria were compared in subjects who had received their last diphtheria vaccination more than 10 years ago. Both short-term and long-term immunogenicity was assessed by determining diphtheria antitoxin levels four weeks after vaccination and after one and two years. 102 subjects received the first booster vaccination, and 83 were vaccinated twice. Prior to the first vaccination 27% of the subjects had a diphtheria antitoxin level below 0.01 I.U./ml; after the first booster only 5% were unprotected. The second booster did not show a significant effect, however, in 1 of the 5 subjects who were still unprotected after the first booster the second elicited an antitoxin level of more than 0.01 I.U./ml. After one and two years 7% and 8% of the subjects had diphtheria antitoxin level below 0.01 I.U./ml. A serological effect of a second booster vaccination four weeks after the first one could not be demonstrated neither after one nor after two years.

Adolescent↗
PubMed1999

Frequency of CD8(+) T lymphocytes specific for lytic and latent antigens of Epstein-Barr virus in healthy virus carriers.

We investigated CD8(+) T cell frequencies of five different Epstein-Barr virus-specific cytotoxic T lymphocyte epitopes located within proteins of the replicative cycle and the latent state in healthy long-term virus carriers with IFN-gamma enzyme-linked immunospot assay. Frequencies of the HLA-A3-restricted epitope RVRAYTYSK (RVR) whose minimal length was mapped in this study to amino acid position 148-156 of the immediate-early protein BRLF1 were compared with those of a further known HLA-A3-restricted epitope within EBNA3A, RLRAEAQVK (RLR). Determination of frequencies of CD8(+) T lymphocytes directed against lytic antigen epitope RVR revealed that only one of eight donors recognized this epitope. Frequency was calculated to be 65 RVR-specific CD8(+) T lymphocytes per 10(6) PBMC. None of the HLA-A3-positive donors exhibited IFN-gamma release after antigenic stimulation with the EBNA3A-specific peptide epitope RLR. Furthermore, we chose three known HLA-B8-restricted epitopes, RAKFKQLL (RAK), FLRGRAYGL (FLR), and QAKWRLQTL (QAK), of the lytic protein BZLF1 and the latent protein EBNA3A. Examination of eight HLA-B8-positive virus carriers revealed that the BZLF1-specific epitope RAK was recognized by all donors with a median frequency of 233 RAK-specific CD8(+) T lymphocytes per 10(6) PBMC. Only 50% of these donors reacted against EBNA3A-specific epitope FLR and a minority (25%) reacted against EBNA3A-specific epitope QAK.

CD8-Positive T-Lymphocytes↗
PubMed1999

Diphtheria booster vaccination: one or two injections?

In a prospective, controlled, randomized, multicenter study the immunogenicity and tolerance of a single vaccination (day 0) and two (day 0, 28) booster vaccinations against diphtheria were compared in subjects who had received their last diphtheria vaccination more than 10 years ago. 415 subjects received the first booster vaccination, and 203 were vaccinated twice. The geometric mean diphtheria antitoxin concentration after the first booster (day 28) was 2.354 I.U./ml, and after the second booster (day 56) 2.238 I.U./ml. Prior to the first vaccination 48.9% of the subjects had a diphtheria antitoxin level below 0.1 I.U./m; after the first and second boosters 95.4% and 97.5% of subjects, respectively, showed a level of at least 0.1 I.U./ml. A clear serological effect of a second booster 4 weeks after the first one could not be demonstrated.

Adolescent↗
PubMed1999

A novel deletion mutant of hepatitis B virus surface antigen.

HBsAg is the most important serological marker for acute or chronic hepatitis B. Nevertheless, there are reports of HBsAg-negative virus carriers, either with anti-HBc as the only marker for hepatitis B virus (HBV) infection or even positive for anti-HBs and anti-HBc. We report isolates from a patient, in which a deletion in the HBs-gene was associated with persisting viremia in the presence of anti-HBs. The 62-year-old female, infected most likely by her husband, had detectable markers of chronic active hepatitis B, such as HBsAg, HBeAg, and anti-HBc-IgM, for 2 years. The patient then seroconverted to anti-HBs, although HBeAg and anti-HBc-IgM remained detectable. At this time, semiquantitative polymerase chain reaction showed about 10(4) viral genomes per milliliter of serum. Direct sequencing of the amplified products revealed a major population of DNA molecules with a deletion of nucleotide 31 of the HBs-gene, which up to now has not been described. This deletion led to a frame-shift and introduced a stop-codon after 21 amino acids of the sHBsAg. We suspect that this deletion, and the resulting HBsAg lacking the major epitopes recognized by specific antibodies, could favor ongoing viral replication, despite the presence of anti-HBs. However, because the reading frame of the polymerase was also severely damaged by this deletion, it is assumed that a minor population of intact genomes was present to help in the formation of virus particles.

Amino Acid Sequence↗
PubMed1999

Prevalence of antibodies against hepatitis C virus in the adult German population.

OBJECTIVE: The prevalence of anti-HCV in Germany has been determined for blood donors and certain risk groups, but the burden of disease in the general population remains unknown. The aim of this study was to determine the prevalence of anti-HCV in a study group representing the normal adult German population. DESIGN: A total of 5312 individuals aged 18-70 years were randomly selected from small, middle-sized and big cities in five different German states. Sera were tested for anti-HCV by enzyme immunoassay and immuno dot assay, as well as for anti-HBc and, in the case of a positive result, for anti-HBs and HBsAg. Serological typing was performed in anti-HCV-positive persons. RESULTS: Thirty-nine individuals were anti-HCV positive; indeterminate results (with antibodies against the viral core protein only) were obtained in 20. There was a tendency to higher prevalence rates with increasing age as well as to a higher prevalence in women. Serological typing revealed the presence of genotype 1 in the vast majority of participants (82%); only a minority showed genotype 3 (7.2%) or other genotypes (7.2%). Markers of HBV were seen in 43.6% of the anti-HCV positive individuals, with nearly one third (29.4%) of the double-infected showing anti-HBc as the only marker for HBV. CONCLUSIONS: According to our data, an anti-HCV prevalence of 0.63% (95% confidence interval, CI, 0.42-0.84%) can be assumed in the general adult German population, with higher values in older people and women. Nearly half of the anti-HCV positive individuals also show markers of hepatitis B virus.

Adolescent↗
PubMed1999

Prevalence of precore mutants in anti-HBe-positive hepatitis B virus carriers in Germany.

Hepatitis B virus (HBV) precore mutants are associated often with highly productive infection in hepatitis B surface antigen (HBsAg) carriers lacking hepatitis B e antigen (HBeAg) but positive for anti-HBe, rendering serological identification of infectious individuals unreliable. Although considered initially to be limited mostly to the Mediterranean area, more recent studies suggest a significant presence of these mutants in northern European countries. The sequence of the precore region was determined and examined for mutations from HBV isolates of 99 German chronic HBsAg carriers positive for HBV-DNA and either HBeAg (n = 15) or anti-HBe (n = 84). In addition, clinical data of individuals carrying wild-type virus and those with precore mutants were compared. HBV precore mutants were found in more than half (44/84) of all HBeAg-negative, anti-HBe-positive virus carriers. There was no difference between carriers of wild-type and precore mutant HBV in the level of viremia or in the clinical course of chronic infection. In conclusion, HBV precore mutants are common in Germany and can therefore present a diagnostic problem for serological testing. However, precore mutants do not appear to have a detrimental effect on the course of chronic HBV infection.

Adult↗
PubMed1998

Novel hepatitis B vaccines.

Currently available hepatitis B vaccines are immunogenic, efficacious and safe. There is no doubt that their consistent use makes the elimination of hepatitis B in most countries possible. Nevertheless, there are still aspects of these vaccines which could be improved: three doses are needed for a full course of vaccination (which is sometimes difficult to achieve because of poor compliance or difficult logistic situations in some regions), there is a comparably high rate of non-responders to the vaccine (about 5% in adults) and, finally, it is not impossible that there are strains of HBV showing mutations of HBsAg which could escape the immunity induced by present vaccines. Work is underway to overcome these problems. Combined vaccines such as those providing protection against diphtheria, pertussis, tetanus, Haemophilus influenzae type b hepatitis B and poliomyelitis are an important step in simplifying hepatitis B vaccination of infants. Combined vaccines are already in use under clinical evaluation. In an effort to reduce the number of injections, two dose schedules with vaccines of higher dosages are being examined and single-dose vaccines encapsulated in degradable micro-particles of biopolymers (called slow-release vaccines) have been successfully tested in animals. Intense research is being conducted to enhance the immunogenicity of present vaccines. One possibility under investigation is the development of recombinant vaccines containing the complete preS1 and preS2 regions of HBsAg or immunogenic epitopes of these regions in addition to the small surface protein; several of such vaccines have already been tested in clinical trials. Future developments include expression of HBsAg determinants in bacteria, e.g., Salmonella, for oral vaccination or DNA vaccines against hepatitis B.

Animals↗
PubMed1998

Immediate-early transactivator Rta of Epstein-Barr virus (EBV) shows multiple epitopes recognized by EBV-specific cytotoxic T lymphocytes.

We analyzed the immediate-early transactivator Rta of Epstein-Barr virus (EBV) for its role as a target for specific cytotoxic T lymphocytes (CTL). Panels of overlapping peptides covering the entire amino acid sequence of Rta were synthesized and used to induce and analyze specific CTL responses in EBV-positive donors. Using peptide-pulsed target cells, we found nine different CTL epitopes that are distributed over the entire protein sequence. One epitope restricted by HLA-A24 could be mapped to the decameric sequence DYCNVLNKEF between amino acid positions 28 and 37 of the Rta protein. A second epitope could be assigned to the same region of Rta (residues 25 to 39) and was shown to be restricted by HLA-B18. Another, minimal epitope could be mapped to the nonameric sequence ATIGTAMYK between amino acid positions 134 and 142; this peptide was restricted by HLA-A11. Another four epitopes were proven to be restricted by HLA-A2, -A3, -B61, and -Cw4 and were located between Rta residues 225 and 239, 145 and 159, 529 and 543, and 393 and 407, respectively. For two other epitopes, only the location within the Rta protein is known so far (residues 121 to 135 and 441 to 455); their exact HLA restriction patterns have not yet been identified. Using target cells infected with recombinant vaccinia virus containing the gene for Rta, we showed that six of eight Rta-specific CTL lines recognized the corresponding peptides also after endogenous processing. These data suggest that Rta comprises an important target for EBV-specific cellular cytotoxicity. Together with recent findings of other immediate-early and early proteins also acting as CTL targets, they reveal the role of proteins of the lytic cycle in the immune recognition of EBV-infected cells.

Amino Acid Sequence↗
PubMed1997

[Hepatitis B vaccination of children and adolescents].

In the 14 years that have passed since its introduction, the hepatitis B vaccine has proved to be highly immunogenic, effective and very well tolerated. The vaccination, previously performed only in persons at high risk of contracting hepatitis B, in particular medical personnel, has appreciably reduced the incidence of hepatitis B in this group. The incidence of the disease in the general population, however, has been reduced only marginally. Thus, the sole possibility of resolving the hepatitis B problem is to introduce general vaccination. To this end, the The Ständige Impfkommission (STIKO) has included hepatitis B vaccination in the catalog of vaccinations for children and adolescents. The greatest importance must probably attach to vaccination of young children, in whom hepatitis B vaccination is carried out along the same lines as the diphtheria, pertussis and tetanus vaccination, within the framework of which it can therefore be administered, thus making possible a wide application. However, the 12-15 year-old age group should also be involved in the vaccination program, for this is the group on the threshold of the periods of greatest danger of infection, which begins with the initiation of first sexual relationships.

Adolescent↗
PubMed1997

Booster immunization of low- and non-responders after a standard three dose hepatitis B vaccine schedule--results of a post-marketing surveillance.

Seventy-nine low-responders and 83 non-responders after a previous three-dose hepatitis B (HB) vaccine course at 0.1, and 6 months were enrolled to receive additional 20 micrograms recombinant HB vaccine doses every 2 months until all had anti-HBs levels > or = 100 mIU ml-1. After the first booster, 65.4% had anti-HBs levels > or = 100 mIU ml-1, 17.9% were low-responders (10-99 mIU ml-1), and 16.7% remained non-responders (< 10 mIU ml-1). All complying non-responders developed anti-HBs levels > or = 100 mIU ml-1 after the third booster at the latest, whereas all low-responders reached this level after the second booster. Although body mass index affected the response to the first hepatitis B booster, when full compliance to regular revaccination was ensured, all non- and low-responders eventually reached sufficient anti-HBs levels.

Adolescent↗
PubMed1997

Long-term persistence of anti-HAV antibodies following active immunization with hepatitis A vaccine.

Seventy-one anti-hepatitis A virus (HAV) negative volunteers were immunized against hepatitis A. An inactivated hepatitis A vaccine (HAVRIX, SmithKline Beecham), derived from tissue cell cultures, at single doses of 720 ELISA units was used following a schedule of vaccinations at month 0.1 and 6. The vaccines were tested for the presence of HAV antibodies 1 month after each vaccination and then after 2, 3, 4 and 5 years. The annual decrease of anti-HAV titres was 25%. Five years after vaccination a protective antibody titre, varying between 20 and 5200 mIU ml-1, could be demonstrated in all 47 retested volunteers with a geometric mean titre (GMT) of 442 mIU ml-1. Levels of anti-HAV-antibodies following active immunization were significantly higher in female volunteers. This could be consistently demonstrated throughout the observation period. Based on these data the antibody persistence was calculated over time. GMTs at protective levels higher than 20 mIU ml-1 can be expected to persist for at least 15 years.

Adult↗
PubMed1997

[High percentage of isolated anti-HBc-positive persons among prisoners].

PURPOSE: Is the result "isolated Anti-HBc" higher among prisoners than in the normal population and can testing for HBV-DNA clarify the results? PATIENTS AND METHODS: In Berlin, 519 prisoners were serologically tested in 1994 for hepatitis-B and -C because of intravenous drug abuse and alcohol disease or signs of hepatitis. Beside virus antigen and antibodies, HBV-DNA was also measured by hybridisation technique or PCR. RESULTS: 50.3% of all individuals showed markers of hepatitis-B and 36.8% of hepatitis-C. 19.2% of persons with hepatitis B markers were positive for anti HBc only, i.e. more than twice as many than in the normal population. 90% of the isolated anti-HBc-positive Persons were also anti-HCV positive, which is nearly double the number of individuals with other patterns of HBV markers. Half of them were tested for HBV-DNA. Whereas the hybridisation technique failed to detect HBV-DNA, 36% of sera were found positive by HBV-PCR. CONCLUSION: This study shows again that the result "anti-HBc alone" is relatively frequent especially among prisoners. This pattern often seems associated with concurrent HCV-infection and in one third of the cases correlated with a chronic hepatitis-B. The result of an isolated anti-HBc should therefore always lead to further testing of anti-HCV and HBV-DNA by PCR.

Berlin↗