Safety and immunogenicity of a modified process hepatitis B vaccine in healthy neonates.

BACKGROUND: A manufacturing process using a modified adjuvant was developed to optimize the consistency and immunogenicity for recombinant hepatitis B vaccine (control: RECOMBIVAX-HB™). This modified process hepatitis B vaccine (mpHBV), which was previously shown to have an acceptable safety and immunogenicity profile in young adults, has now been studied in newborn infants. METHODS: Healthy 1-10-day-old neonates (N=566) received 3 intramuscular doses (5µg hepatitis B surface antigen [HBsAg] per dose) of either mpHBV or control at Day 1, and Months 1 and 6. Serum antibody to HBsAg (anti-HBs) was assayed at Month 7 (1 month Postdose 3). Anti-HBs geometric mean titers (GMTs) and seroprotection rates (SPRs) (% of subjects with an anti-HBs titer ≥10mIU/mL) were compared at Month 7. After each dose, injection-site adverse experiences (AEs) and axillary temperatures were recorded for 5 days; systemic AEs were recorded for Days 1-14. RESULTS: Month 7 SPR was 97.9% for the mpHBV group and 98.9% for the control. The GMT was 843.7mIU/mL for the mpHBV group and 670.1mIU/mL for the control. The GMT ratio (mpHBV/control) was 1.26 (95% confidence interval [CI]: 0.94, 1.69), meeting the prespecified non-inferiority criteria. The percentages of subjects reporting any AE, injection-site AEs, or systemic AEs were similar across the 2 vaccination groups. There were no serious AEs. CONCLUSIONS: The safety profile of mpHBV was comparable to that of the control vaccine. The geometric mean antibody titer for mpHBV was higher than control vaccine in this infant population, but the difference did not meet the predefined statistical criterion for superiority.

Safety and immunogenicity of a modified process hepatitis B vaccine in healthy infants.

BACKGROUND: A modified process hepatitis B vaccine (mpHBV) uses higher phosphate content in the manufacturing process relative to the current product, Recombivax-HB. The higher phosphate is thought to improve antigen presentation, and thereby, increase antibody production. The mpHBV was previously shown to be well tolerated and immunogenic in adults. The current study tested a 2-, 4-, 6-month vaccination schedule and a higher dose formulation (10 µg mpHBV) in healthy infants. METHODS: In a randomized, double-blind study, healthy infants (N = 1718), approximately 2 months of age, received a 0.5-mL intramuscular dose of 5-µg mpHBV, Recombivax-HB (5 µg), 10-µg mpHBV, or Engerix-B (10 µg) at day 1, month 2, and month 4 (2, 4, 6 months of age). Serum antibody to hepatitis B surface antigen (anti-HBs) was analyzed at month 7. The geometric mean titer (GMT) and seroprotection rate (SPR; % subjects with anti-HBs titer ≥ 10 mIU/mL) were determined 1 month after the third dose. RESULTS: Month 7 SPRs were 99.3% (402/405, 95% confidence interval [CI]: 98.3, 100) in the 5 µg mpHBV group, 100.0% (398/398, 95% CI: 99.9, 100) in the 10 µg mpHBV group, 98.5% (400/406, 95% CI: 97.2, 99.8) in the Recombivax-HB group, and 99.5% (398/400, 95% CI: 98.7, 100) in the Engerix-B group. Month 7 GMTs (mIU/mL) were 748.2 (95% CI: 672.0, 833.1) in the 5 µg mpHBV group, 981.5 (95% CI: 891.0, 1081.2) in the 10 µg mpHBV group, 376.8 (95% CI: 331.4, 428.5) in the Recombivax-HB group, and 556.6 (95% CI: 491.8, 629.9) in the Engerix-B group. The percentages of subjects reporting injection-site or systemic adverse events were similar across the vaccination groups. CONCLUSIONS: All 4 hepatitis B vaccines elicited high anti-HBs SPRs. After dose 3, anti-HBs GMT were highest in the 10 µg mpHBV group, but did not meet the predefined criteria for superiority. All vaccines were well tolerated.

Evaluation of a recombinant human gelatin as a substitute for a hydrolyzed porcine gelatin in a refrigerator-stable Oka/Merck live varicella vaccine.

BACKGROUND: The labile nature of live, attenuated varicella-zoster virus (Oka/Merck) requires robust stabilization during virus bulk preparation and vaccine manufacturing in order to preserve potency through storage and administration. One stabilizing ingredient used in a varicella-zoster virus (VZV) vaccine is hydrolyzed porcine gelatin which represents the major protein/peptide-based excipient in the vaccine formulation. METHODS: In this comparative study, a recombinant human gelatin fragment (8.5 kD) was assessed as a potential replacement for hydrolyzed porcine gelatin in an experimental live, attenuated VZV (Oka/Merck) vaccine. VZV (Oka/Merck) was harvested in two formulations prepared with either a hydrolyzed porcine gelatin or a recombinant human gelatin. Moreover, the viral stability in the experimental VZV (Oka/Merck) vaccines was evaluated under accelerated and real-time conditions in a comparative study. RESULTS AND DISCUSSION: The stabilizing effect of recombinant human gelatin on VZV (Oka/Merck) potency change during vaccine lyophilization was similar to the experimental vaccine containing porcine-derived gelatin. Vaccine viral potency changes were comparable in stabilized VZV (Oka/Merck) formulations containing either hydrolyzed porcine gelatin or recombinant human gelatin. No statistically significant difference in potency stability was observed between the vaccine formulations stored at any of the temperatures tested. CONCLUSION: The recombinant human gelatin demonstrated similar ability to stabilize the live attenuated VZV (Oka/Merck) in an experimental, refrigerator-stable varicella vaccine when compared to the vaccine preparation formulated with hydrolyzed porcine gelatin used in currently marketed varicella vaccine.

Convergent evolution of SIV env after independent inoculation of rhesus macaques with infectious proviral DNA.

The env gene of three simian immunodeficiency virus (SIV) variants developed convergent mutations during disease progression in six rhesus macaques. The monkeys had been inoculated with supercoiled plasmids encoding infectious proviruses of SIVmac239 (a pathogenic, wild-type strain), SIVdelta3 (the live attenuated vaccine strain derived from SIVmac239), or SIVdelta3+ (a pathogenic progeny virus that had evolved from SIVdelta3). All six monkeys developed immunodeficiency and progressed to fatal disease. Although many divergent mutations arose in env among the different hosts, three regions consistently mutated in all monkeys studied; these similar mutations developed independently even though the animals had received only a single infectious molecular clone rather than standard viral inocula that contain viral quasispecies. Together, these data indicate that the env genes of SIVmac239, SIVdelta3, and SIVdelta3+, in the context of different proviral backbones, evolve similarly in different hosts during disease progression.

Truncated forms of human and simian immunodeficiency virus in infected individuals and rhesus macaques are unique or rare quasispecies.

Truncated proviruses of variable sizes are present in peripheral blood mononuclear cells (PBMC) of human immunodeficiency virus type 1 (HIV-1)-infected persons and simian immunodeficiency virus (SIV)-infected rhesus macaques. Here, we investigated whether the highly deleted HIV and SIV proviruses are present in infected organisms as multiple copies or whether each truncated provirus is unique. Using end-point dilution, multiple long-distance (LD) DNA PCR assays were run in parallel using DNA extracted from PBMC of seropositive, treatment-naive persons and from lymph nodes of a rhesus monkey inoculated with cloned, full-length SIVmac239 DNA. The PCR products were titrated and mapped. Most truncated proviruses were present in the DNA samples tested as single, nonintegrated molecules that differed from one another in size and/or nucleotide sequence. These results indicate that truncated primate lentiviral sequences found in infected tissues are unique or rare quasispecies that do not replicate significantly.

Rev-independent simian immunodeficiency virus strains are nonpathogenic in neonatal macaques.

The viral protein Rev is essential for the export of the subset of unspliced and partially spliced lentiviral mRNAs and the production of structural proteins. Rev and its RNA binding site RRE can be replaced in both human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) by the constitutive RNA transport element CTE of the simian type D retroviruses. We used neonatal macaques as a sensitive animal model to evaluate the pathogenicity of a pair of SIV mutant strains generated from Rev-independent molecular clones of SIVmac239 which differ only in the presence of the nef open reading frame. After high primary viremia, all animals remained persistently infected at levels below the threshold of detection. All macaques infected as neonates developed normally, and none showed any signs of immune dysfunction or disease during follow-up ranging from 2.3 to 4 years. Therefore, the Rev-RRE regulatory mechanism plays a key role in the maintenance of high levels of virus propagation, which is independent of the presence of nef. These data demonstrate that Rev regulation plays an important role in the pathogenicity of SIV. Replacement of Rev-RRE by the CTE provides a novel approach to dramatically lower the virulence of a pathogenic lentivirus. These data further suggest that antiretroviral strategies leading to even a partial block of Rev function may modulate disease progression in HIV-infected individuals.