Evaluation of the purity of a purified, inactivated hepatitis A vaccine (VAQTA).

Manufacture of VAQTA, an inactivated hepatitis A virus vaccine, includes extensive purification of the intact virus particle to remove endogenous components from the host cell culture lysate as well as compounds introduced in the upstream purification process. Analysis of the final purified hepatitis A virus product by SDS-PAGE prior to inactivation shows that greater than 95% of the protein in the preparation is found in four protein bands, which have been confirmed to be hepatitis A virus capsid proteins VP0, VP1, VP2 and VP3 based on Western blot and mass spectrometry analyses. Validation of the manufacturing process and direct analysis of the final product were used to demonstrate that no other specific host cell-derived components are detected and that process residuals are all below the limits of detection of the assays used. Establishment of a rigorous standard of high purity for this product was pursued to minimize the impact of impurities during clinical development of this product and will facilitate the incorporation of this product into combination vaccines.

Preparation and immunogenicity of an inactivated hepatitis A vaccine.

A hepatitis A vaccine was prepared by formaldehyde inactivation of purified hepatitis A virus (HAV) LSH/S strain grown on human diploid MRC-5 cells. The vaccine was devoid of residual infectivity in vitro and failed to induce in marmoset monkeys any pathological features or variations of haematological and clinical chemistry values. Infectious HAV particles were not detected in faeces and sera of the vaccinated primates by ELISA or after passages in MRC-5 cells. The immunogenicity of the vaccine was evaluated by injecting guinea-pigs with 0.8, 0.2 or 0.05 micrograms of HAV antigen adsorbed onto 0.5 and 1 mg of Al (OH)3 or 0.3 mg of AlPO4. The antibody response, measured by a competitive radioimmunoassay, was dose- and adjuvant-dependent. One injection of 0.2 micrograms of AlPO4-adsorbed HAV antigen induced seroconversion in 100% of animals and high levels of specific and neutralizing serum antibodies. A further increase of antibody titres was observed after the second and third inoculations. These results show that this vaccine formulation is safe and immunogenic in animal models, and suggest that it should be evaluated further by human clinical studies.

[Clinical and immunological studies of an experimental series of vaccines against hepatitis B]. / Klinicheskie i immunologicheskie issledovaniia éksperimental'nykh serii vaktsiny protiv gepatita B.

Two experimental lots of hepatitis B vaccine were prepared by purification of HBsAg from human plasma, inactivation at 100 degrees C for 2 min and at 37 degrees C for 72 hours with formalin in a concentration of 1:4000. The former lot comprises purified HBsAg (40 mg/ml) adsorbed with 0.32 mg % Al(OH)3, the latter consists of purified HBsAg stabilized with 0.1% human albumin and adsorbed with 1 mg% Al(OH)3. The immune response after vaccination with the first lot was observed in 54.54% of the vaccinees. The second vaccine after 3 administrations of 80 micrograms/ml each produced a very good primary and a very good secondary immune response. Both vaccines are nonreactogenic and well tolerated by the vaccinees.