From Structural Studies to HCV Vaccine Design.

Hepatitis C virus (HCV) is a serious and growing public health problem despite recent developments of antiviral therapeutics. To achieve global elimination of HCV, an effective cross-genotype vaccine is needed. The failure of previous vaccination trials to elicit an effective cross-reactive immune response demands better vaccine antigens to induce a potent cross-neutralizing response to improve vaccine efficacy. HCV E1 and E2 envelope (Env) glycoproteins are the main targets for neutralizing antibodies (nAbs), which aid in HCV clearance and protection. Therefore, a molecular-level understanding of the nAb responses against HCV is imperative for the rational design of cross-genotype vaccine antigens. Here we summarize the recent advances in structural studies of HCV Env and Env-nAb complexes and how they improve our understanding of immune recognition of HCV. We review the structural data defining HCV neutralization epitopes and conformational plasticity of the Env proteins, and the knowledge applicable to rational vaccine design.

Production and immunological analysis of recombinant hepatitis B vaccine.

The synthesis of the hepatitis B surface antigen (HBsAG) in cells of Saccharomyces cerevisiae and its subsequent isolation, purification and analysis is described. The final, purified HBsAg particle exhibits close structural and biochemical similarities to particles derived from the plasma of chronically infected humans. Particles of yeast and human origin have been found, by chimpanzee efficacy studies and by various in vitro analyses, to be immunologically equivalent. The antigenic expression of a determinant-specific epitopes, as measured by antibody binding to synthetic peptides, has also been shown to be equivalent.

[Detection of antibodies and assessment of an international unit of anti-HBs specific immunoglobulin, HEPAGA]. / Detekce protilátek a stanovení mezinárodní jednotky specifického imunoglobulinu anti-HBs, HEPAGA.

The authors submit information on the presence and titre of antibodies against antigens of the hepatitis B virus [HB] and the Czechoslovak specific anti-HBs immunoglobulin, HEPAGA, and on the presence of the delta-antibody. The presence of the antibody against the surface antigen of the HB virus [HBsAb, anti-HBs] was examined in 32 batches, the antibody against the nucleus of the HB virus [HBcAb] and e-antigen [HBeAb] in a total of 27 batches. HBsAb was positive in the majority of cases still when diluted 1/2,500,000; HBcAb when diluted in the range from 1/25,000 to 1/2,500,000; the positivity of HBcAb ended with the exception of one batch at the dilution of 1/250. The delta antibody was detected only in batches from 1982 and 1983, in a maximum dilution of 1/8. All examinations were made by the radioimmunoassay [RIA] technique. The authors give also an account of the assessment of the international HEPAGA [IU/ml]. The last batch has 170 IU/ml.

[Cytokines in vaccines and interferon preparations]. / Tsitokiny v vaktsinakh i preparatakh interferona.

Virus vaccines prepared on the basis of cells of mammals (rabies, poliomyelitis, measles and hepatitis A vaccines) contain cytokines (IL-1 beta, IL-6, TNF-alpha), whose concentration depends on the kind of the vaccine. Cell lines (green monkey kidney cells, VERO, 4647), used for the preparation of commercial and experimental vaccines, do not produce spontaneously any of the above cytokines. Cell line L-68, used for the manufacture of experimental measles vaccine, is capable of the spontaneous synthesis of IL-6. In Russian and foreign preparations of interferon the presence of IL-1 beta and TNF-alpha has been detected; the content of these cytokines is determined by the specific features of the methods used manufacturing these preparations.

Receptors for polymerized human serum albumin in plasma derived hepatitis B vaccines.

The presence of polymerized human serum albumin receptors (pHSA-R) in two hepatitis B virus (HBV) plasma derived vaccines (HB-Vax, Merck Sharp and Dohme; Hevac-B, Pasteur) was detected by three methods, using pHSA polystyrene coated beads and 125I-anti-HBs (method 1) and polyclonal (method 2) or monoclonal (method 3) peroxidase conjugated anti-HBs. Only a very weak reaction was found for pHSA-R in HB-Vax vaccine when the tests were performed in undiluted vaccine. No reactivity in 1/100 dilution (normally used to test pHSA-R in serum samples) was observed. In contrast, Hevac-B vaccine contained pHSA-R activity in 1/100 dilution as tested by any of the three methods. Furthermore, the level of pHSA-R detected in Hevac-B vaccine is similar to that observed in asymptomatic HBsAg carriers with the same HBsAg concentration. In summary, Hevac-B vaccine contains pHSA-R, whilst HB-Vax shows only weakly reacting pHSA-R, probably insufficient to develop anti-pHSA-R antibodies.

The safety of the hepatitis B vaccine. Inactivation of the AIDS virus during routine vaccine manufacture.

In the United States, one hepatitis B vaccine (Heptavax-B) has been licensed for the prevention of hepatitis B virus infections. Even though this vaccine has been shown to be highly effective and well tolerated in controlled trials and has been recommended for use in those at risk for acquiring infection by hepatitis B virus, many individuals have been reluctant to be immunized for fear of contracting acquired immunodeficiency syndrome (AIDS). In this study, we demonstrate that each of the three inactivation steps used in the manufacture of Heptavax-B independently will inactivate the infectivity of high-titered preparations of the AIDS virus; recipients of the hepatitis B vaccine do not develop antibodies to the AIDS virus; the hepatitis B vaccine does not contain detectable levels of nucleic acids related to the AIDS virus. These observations clearly demonstrate that vaccination with the currently available hepatitis B vaccine poses no demonstrable risk for acquiring AIDS.

Immunogenicity of hepatitis B surface antigen derived from the baculovirus expression vector system: a mouse potency study.

A standard mouse potency test was performed to evaluate the immunogenicity of recombinant hepatitis B surface antigen (HBsAg) produced in the baculovirus/insect cell expression system. Groups of NIH Swiss mice were immunized with serial four-fold amounts of either baculovirus-derived HBsAg adsorbed to aluminum sulfate or a commercially available yeast-derived recombinant HBsAg vaccine preparation. Results from these experiments showed that the effective dose of baculovirus- and yeast-derived HBsAg vaccine preparations necessary to seroconvert 50% of the animals were similar. The duration of the antibody response to HBsAg was studied in mice immunized with the highest doses of the two recombinant vaccine preparations 3 and 6 months after injection. No decrease in the anti-HBs response was observed 6 months after injection. No decrease in the anti-HBs response was observed 6 months after immunization with either of the two vaccine preparations. These results indicate that the baculovirus-derived recombinant HBsAg could serve as an alternative vaccine candidate for hepatitis B virus.

AIDS in children: a review of the clinical, epidemiologic and public health aspects.

A high level of suspicion by every provider is very important to ensure diagnosis and complete reporting. Such active surveillance will enable effective national monitoring of the occurrence of the disease, the definition of new risk groups and the identification of unusual cases for further study. Physicians and health care workers should report all children and adults suspected of having AIDS to their state health departments who, in turn, report to the CDC. It is clear that the number of cases of AIDS in children and adolescents is increasing because of either increased occurrence, increased diagnosis and/or increased surveillance. Pediatric health care personnel, especially those in high prevalence areas and those caring for high risk populations, need to be aware of AIDS and the problem encountered in caring for these children.

Hepatitis B vaccination of newborn infants: clinical study of new vaccine formulation and dose regimen.

To investigate the efficacy in anti-HBsAg response with half the recommended adult dose in a standard vaccination schedule or with a full dose in reduced number of vaccination schedule, 201 healthy newborn infants were randomized to receive either 2.5 micrograms Hevac B vaccine at birth [1, 2 and 14 months in Group I (101)] or 5 micrograms at birth [2 and 14 months in Group II (100)]. Anti-HBsAg responses in the two groups were compared. Passively acquired anti-HBsAg positivity rates at birth were 51.5 and 45.0% in Groups I and II, respectively. Cumulative anti-HBsAg seroconversion rates in Group I were 12.2, 76.6, 82.6 and 86.4% at 2, 4, 14 and 16 months, while the rates in Group II were 2.5, 62.5, 73.7 and 91.0%, showing no significant difference (p greater than 0.05). Significant difference in seroconversion rates at the 2-month follow-up stage between passively acquired anti-HBsAg-negative and -positive groups was observed (11.9 vs. 2.6%). Significant rise in anti-HBsAg titer at 16 months following the booster at 14 months was noted: 36.4 mIU per ml before, 546.4 mIU per ml after in Group I and 25.3 mIU per ml before, 782.6 mIU per ml after in Group II. The booster, 12 months after the primary vaccination series, is therefore considered imperative for maximum effectiveness of hepatitis B active immunization.(ABSTRACT TRUNCATED AT 250 WORDS)