Nine-year follow-up study of a plasma-derived hepatitis B vaccine in a rural African setting.

One hundred and one of 255 recipients of a plasma-derived hepatitis B vaccine were evaluated in 1990, 9 years after the first vaccine dose in a study in Zambia to evaluate the efficacy of one, two, or three doses. In 1983, 2 years after the first vaccine dose, antibody to the hepatitis B surface antigen (anti-HBs) had been detectable in 90 of these 101 participants (89%). In 1990, anti-HBs was still detectable in 72 of 101 (71%), and was present at a protective level (> or = 10 mIU/mL) in 68 of 101 (67%). Although the original vaccine study elicited a protective level of antibody in a greater percentage of children and adolescents than in adults, there were no significant differences among the three groups at 9 years. (In 1990, anti-HBs was still detectable in 52 of 70 [74%] who had had no serologic markers of the hepatitis B virus in 1981, and a protective level was detected in 47 of 70 [67%].) A protective level of anti-HBs was detected in 1990 in 26 of 36 (72%) recipients of three doses and in 23 of 31 (74%) recipients of two doses; the slightly lower prevalence among recipients of one dose (19 of 34 [56%]) was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Varicella vaccine (VARIVAX) in healthy children and adolescents: results from clinical trials, 1987 to 1989.

A total of 3303 healthy children and adolescents, aged 12 months to 17 years, were vaccinated with one of five production lots of a live attenuated varicella vaccine (VARIVAX) containing 1000 to 1625 plaque-forming units per dose. The vaccine was generally well tolerated. Ninety-six percent (2381/2475) of vaccinees responded to vaccination by producing antibody as measured by a glycoprotein-based enzyme-linked immunosorbent assay; 99% (569/576) of those tested maintained antibody at 1 year following vaccination. The incidence of varicella following household exposure in vaccinees was approximately 12%; household contact historically results in 87% infection. Nearly all of the vaccinees who had varicella after vaccination had a clinically modified disease.

Antibody responses of adults, adolescents, and children to a plasma-derived hepatitis B vaccine in a rural African setting.

A field trial of a plasma-derived hepatitis B vaccine in five rural villages in Zambia was analyzed to determine if adults in a rural African setting respond to this vaccine as well as adults in Western countries and to determine the immunogenicity of fewer than the recommended three doses; 255 residents, including 171 who were susceptible to hepatitis B, were vaccinated. Among those who received three vaccine doses, protective levels of antibody to hepatitis B surface antigen (anti-HBs) developed in 67% of adults (ages 21 to 70 years), 87% of adolescents (ages 12 to 19 years), and 100% of children (ages 0 to 11 years). The 67% of vaccinated adults who developed anti-HBs at the protective level was lower than the 96% reported among adults receiving the same vaccine at the same dose and dosage schedule in studies in Western countries. No difference was seen in the response of those receiving two doses compared with those receiving three doses among adults and adolescents, suggesting that a two-dose regimen may be acceptable in these age groups in developing countries to reduce costs and improve compliance. Use of hepatitis B vaccine in a region where prevaccination hepatitis B serologic screening was not available did not appear to increase the number of severity of adverse reactions.

Key issues in the selection of an expression system for vaccine antigens.

Three criteria by which the appropriate host cell is chosen for the expression of a recombinant-derived vaccine antigen are efficacy, safety, and scale-up. Efficacy for a vaccine antigen refers to the ability of the host cell to produce a vaccine antigen capable of eliciting a protective immune response. A concern for safety of a vaccine antigen relates to residual DNA in the final product, especially when derived from continuous mammalian cell lines as opposed to microbial cells. Since tens (or hundreds) of millions of doses of a widely used vaccine might be injected into healthy infants and young children during the lifetime of the product, safety is a critical issue, such that the use of a microbial expression system might be preferable to the use of a continuous cell line in certain circumstances.

Failure of hepatitis B immune globulin to protect against exp infection in chimpanzees.

To study experimentally the protective effect of post-exposure prophylaxis against hepatitis B (HB), a special preparation of hepatitis B immune globulin (HBIG) was injected intravenously (i.v.) into three chimpanzees simultaneously with, or at different time intervals after, intravenous injection of a titred inoculum of hepatitis B virus (HBV). The HBIG was given either simultaneously with the HBV inoculum, at 4 hours after, or at both 4 hours and 4 weeks after the HBV injection. A fourth chimpanzee received a standard preparation of HBIG intramuscularly (i.m.) at both 4 hours and 4 weeks after receiving the HBV injection. A fifth animal received HBIG i.v. 4 hours after the HBV inoculum and at the same time received its first of three HB vaccine injections. All chimpanzees were followed for 1 year. The animals which received HBIG simultaneously with HBV or received HBIG plus vaccine had no serological or biochemical sign of HB during follow-up. The three animals which received HBIG after HBV inoculation all developed HBs-antigenemia and serum aminotransferase (ALT) elevations. HBsAg did however appear in serum several weeks later than expected for the HBV inoculum used. Post-exposure prophylaxis with HBIG did protect the HBV-exposed chimpanzees, only if HBIG was combined with HB-vaccination or if HBIG was given simultaneously with the HBV inoculum.

Protective effect of a synthetic peptide comprising the complete preS2 region of the hepatitis B virus surface protein.

A peptide was synthesized containing the entire 55 amino acid residue sequence of the hepatitis B virus (HBV) surface antigen preS2 region (ad subtype). The unconjugated peptide was inoculated into four chimpanzees. Following multiple injections, all of the animals developed specific antipeptide antibodies that reacted with intact surface antigen particles bearing the preS2 moiety. All four peptide-inoculated animals were found to be protected from infection after intravenous challenge with live HBV of either the ad or ay subtypes.

Successful postexposure vaccination against hepatitis B in chimpanzees.

To study the effect of postexposure vaccination, four chimpanzees were vaccinated with hepatitis B (HB) vaccine 4, 8, 48, and 72 hr, respectively, after intravenous injection of an infectious hepatitis B virus (HBV) inoculum. The second and third vaccine inoculations were given 2 and 6 weeks later, i.e., at considerably shorter intervals than recommended either for ordinary prophylactic vaccination or for postexposure vaccination in combination with hepatitis B immune globulin (HBIG). The chimpanzees were followed for 1 year. None showed HBs-antigenemia, liver enzyme elevation (ALT), or histopathological alterations in liver biopsies. Late appearance of anti-HBc was observed only in the serum of the animal whose series of vaccination started 72 hr after HBV inoculation. An unvaccinated control chimpanzee, which received the HBV inoculum only, developed clinical hepatitis B with ALT-elevations and HBs-antigenemia within 2 months of the experimental HBV inoculation. These results indicate that postexposure vaccination against hepatitis B begun within 48 hr after HBV exposure, with short intervals between the vaccine injections, can protect against hepatitis B infection also when concomitant HBIG-prophylaxis is not given.

Chromatographic removal of hepatitis B virus from a factor IX concentrate. Experimental studies in chimpanzees.

Non-A, non-B hepatitis virus can be removed from a factor IX concentrate by a hydrophobic chromatographic step added to the ordinary fractionation process. The efficacy of this procedure for removal of hepatitis B virus (HBV) was evaluated in chimpanzees. A well-defined hepatitis B virus (HBV) inoculum was added to a factor IX preparation and this preparation was subjected to chromatography with octanohydrazide-Sepharose 4B at a high salt concentration and then injected intravenously into two chimpanzees. A control chimpanzee was inoculated with the part of the factor IX/HBV preparation that had not been chromatographed. The two chimpanzees that received the treated material remained free of any serologic or biochemical evidence of hepatitis B infection during a 12-month follow-up, whereas the control chimpanzee had hepatitis B. After a later HBV challenge, the two healthy animals also had hepatitis B. The hydrophobic binding procedure seems to be useful for the adsorption of viral agents in blood components.

New findings in live, attenuated hepatitis A vaccine development.

Strain CR326F of hepatitis A virus, derived from a fecal specimen of Costa Rican patient 033-03, was passed 15 times in fetal rhesus monkey kidney (FRhK6) cell cultures plus eight times in human diploid lung (MRC5) cell cultures to yield variant F and 16 times in MRC5 cell cultures to yield variant F'. Both variants were purified by limit dilution passages. Virulence for marmosets was assessed at six different passage levels, including variants F and F'. There was a gradual loss of virulence with in vitro passage. Variant F retained slight virulence for marmosets; variant F' showed no evidence of virulence. Both variants induced hepatitis A antibody in most marmosets that received them, and the animals were immune to infection when challenged. Variants F and F' were also assessed in chimpanzees. As in marmosets, F retained slight virulence but F' did not. Experimental vaccines made from variants F and F' were then inoculated parenterally into adult human volunteers. A portion of recipients of variant F showed brief, low-order enzyme elevations; none was seen in recipients of F', although their occurrence could not be totally ruled out. As in the animal models, F' appeared more attenuated than F. Most persons developed hepatitis A antibody, indicating the feasibility of developing a live, attenuated hepatitis A vaccine for human beings.

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.

A glycoprotein associated with the non-A, non-B hepatitis agent(s): isolation and immunoreactivity.

A glycoprotein was isolated and purified to homogeneity from the serum of a patient with chronic non-A, non-B hepatitis. NaDodSO4/PAGE of the glycoprotein revealed a single major band at Mr approximately 77,000. Antibodies to this glycoprotein were shown to possess the following immunoreactivity: (i) they reacted by radioimmunoassay with sera obtained at the time of diagnosis from 17 of 42 patients with non-A, non-B hepatitis and with only 2 of 58 sera from either matched controls or patients with hepatitis A or hepatitis B, (ii) they reacted with sucrose gradient fractions from a proven infectious non-A, non-B hepatitis serum at a peak density of 1.14 g/ml and in the soluble protein fractions on top of the gradient, and (iii) they reacted in ELISA with disrupted human T-cell lymphocytotropic virus type III (HTLV-III), and (iv) they reacted in immunoblots with a protein of Mr 74,000 derived from HTLV-III.

Retrovirus-like particles in hepatocytes of patients with transfusion-acquired non-A, non-B hepatitis.

Retrovirus-like particles 60-85 nm in diameter were observed in the cytoplasm of hepatocytes in liver biopsies obtained during the acute and chronic phases of non-A, non-B hepatitis (NANBH) in three patients with transfusion-acquired disease. The particles appeared in dilated endoplasmic reticulum cisternae as well as in enlarged Golgi vesicles. No such particles were seen in hepatocytes in liver biopsies similarly obtained during the acute or chronic phases of NANBH from 11 additional patients with NANBH who did not acquire their disease following blood transfusion. Particle-associated reverse transcriptase activity (peak activity at a density of 1.14 gm/ml) was present in the sera of all three "particle-positive" patients and also in 42% of the "particle-negative" patients. The retrovirus-like particles described here were apparently unrelated to the previously described human T cell lymphocytotropic retroviruses (HTLV), since none of the 14 patients studied had antibodies in their serum directed against antigens of any of the three known HTLVs.

Neutralization of hepatitis B virus infectivity by a murine monoclonal antibody: an experimental study in the chimpanzee.

Two study chimpanzees were inoculated intravenously with approximately 1,000 chimpanzee infectious doses of hepatitis B virus (HBV), one with subtype adr and one with subtype ayw, each previously incubated with 0.1 ml of a murine monoclonal antibody (IgG 1(K) class) directed against a single epitope on hepatitis B surface antigen common to most or all HBV. Two control chimpanzees received identical doses of HBV not incubated with the murine anti-HBs. Neither study chimpanzee developed HBV infection during 12 months of follow-up as judged by normal serum aminotransferase activity, normal liver biopsies, and negative serological tests for HBV-associated antigens and antibodies. In contrast, both control chimpanzees became infected by HBV as evidenced by elevated serum aminotransferase activity, liver biopsy changes characteristic of viral hepatitis, and the appearance of hepatitis B surface antigen (HBsAg) in their sera. Both study chimpanzees were shown to be fully susceptible to infection with these same HBV inocula when challenged 15 months after the initial inoculations at a time when passively administered anti-HBs was no longer detectable. Prior to challenge with HBV, one of the two study chimpanzees received a second injection of the same volume of the murine monoclonal anti-HBs. The survival of this anti-HBs in serum was reduced from six weeks (after the initial injection) to approximately two weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Serologic markers of hepatitis A and B in the population of Bali, Indonesia.

A total of 343 sera from Balinese subjects in different age groups and geographic locations were tested by radioimmunoassay (RIA) for serum antibodies to hepatitis B surface antigen (anti-HBs) and hepatitis B core antigen (anti-HBc); most sera were also tested for hepatitis B surface antigen (HBsAg), and for antibody to hepatitis A virus (anti-HAV). One hundred percent of the adult population was found to have anti-HAV, with antibody acquisition beginning in early childhood and reaching a level of 95% by the age of 10 years. Antibodies to hepatitis B virus were also frequent in young children, rapidly peaking to near 80% in older children and adolescents, then declining to a plateau that fluctuated between 40% and 60% throughout adult life. Overall, anti-HBc (49%) was detected slightly more often than anti-HBs (45%), but the relative frequencies of the 2 antibodies varied considerably from group to group. Despite these high antibody prevalences, HBsAg was detected in only 1.5% of the general population, and in no woman of child-bearing age. In utero infection is thus far less likely to account for the early acquisition of antibody to hepatitis B virus than inapparent percutaneous transmission occurring under conditions of close personal contact.