BackgroundChronic HBV infects 350 million people causing cancer and liver failure. We
aimed to assess the safety and efficacy of plasmid DNA (pSG2.HBs) vaccine,
followed by recombinant modified vaccinia virus Ankara (MVA.HBs), encoding
the surface antigen of HBV as therapy for chronic HBV. A secondary goal was
to characterize the immune responses.MethodsFirstly 32 HBV e antigen negative (eAg–) participants were
randomly assigned to one of four groups: to receive vaccines alone,
lamivudine (3TC) alone, both, or neither. Later 16 eAg+
volunteers in two groups received either 3TC alone or both 3TC and vaccines.
Finally, 12 eAg– and 12 eAg+ subjects were
enrolled into higher-dose treatment groups. Healthy but chronically
HBV-infected males between the ages of 15 – 25 who lived in the
western part of The Gambia were eligible. Participants in some groups
received 1 mg or 2 mg of pSG2.HBs intramuscularly twice followed by
5×107 pfu or 1.5×108 pfu of MVA.HBs
intradermally at 3-weekly intervals with or without concomitant 3TC for
11–14 weeks. Intradermal rabies vaccine was administered to a negative
control group. Safety was assessed clinically and biochemically. The primary
measure of efficacy was a quantitative PCR assay of plasma HBV. Immunity was
assessed by IFN-γ ELISpot and intracellular cytokine staining.ResultsMild local and systemic adverse events were observed following the vaccines.
A small shiny scar was observed in some cases after MVA.HBs. There were no
significant changes in AST or ALT. HBeAg was lost in one participant in the
higher-dose group. As expected, the 3TC therapy reduced viraemia levels
during therapy, but the prime-boost vaccine regimen did not reduce the
viraemia. The immune responses were variable. The majority of IFN-γ was
made by antigen non-specific CD16+ cells (both
CD3+ and CD3–).ConclusionsThe vaccines were well tolerated but did not control HBV infection.Trial RegistrationISRCTN ISRCTN67270384
Background/Aim: The study aimed at developing a real-time quantitative PCR assay to monitor HBV serum virus load of chronic carriers enrolled in therapeutic trials.
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