Safety and Immunogenicity of H5N1 Influenza Vaccine Based on Baculovirus Surface Display System of Bombyx mori

Avian influenza virus (H5N1) has caused serious infections in human beings. This virus has the potential to emerge as a pandemic threat in humans. Effective vaccines against H5N1 virus are needed. A recombinant Bombyx mori baculovirus, Bmg64HA, was constructed for the expression of HA protein of H5N1 influenza virus displaying on the viral envelope surface. The HA protein accounted for approximately 3% of the total viral proteins in silkworm pupae infected with the recombinant virus. Using a series of separation and purification methods, pure Bmgp64HA virus was isolated from these silkworm pupae bioreactors. Aluminum hydroxide adjuvant was used for an H5N1 influenza vaccine. Immunization with this vaccine at doses of 2 mg/kg and 0.67 mg/kg was carried out to induce the production of neutralizing antibodies, which protected monkeys against influenza virus infection. At these doses, the vaccine induced 1:40 antibody titers in 50% and 67% of the monkeys, respectively. The results of safety evaluation indicated that the vaccine did not cause any toxicity at the dosage as large as 3.2 mg/kg in cynomolgus monkeys and 1.6 mg/kg in mice. The results of dose safety evaluation of vaccine indicated that the safe dose of the vaccine were higher than 0.375 mg/kg in rats and 3.2 mg/kg in cynomolgus monkeys. Our work showed the vaccine may be a candidate for a highly effective, cheap, and safe influenza vaccine for use in humans

The expression of a 45 kD HA protein of influenza by recombinant Bmgp64HA.

<p>The recombinant baculovirus was purified from pupae by four steps centrifugation. Lane M. Protein molecular weight marker. Lane 1. The purified recombinant baculovirus. Lane 3. HA protein expression detected by western blotting.</p

An ideograph of HA/gp64-fusion recombinant baculovirus

<p>An ideograph of HA/gp64-fusion recombinant baculovirus</p

Summary of neutralizing antibody titers of monkey following viral challenge after immunization.

<p>Each of the groups had 4 monkeys.</p

Summary of RT-PCR results for viral detection in throat swab samples of monkeys following viral challenge after immunization with the vaccine.

<p>Each of the groups had 4 monkeys.</p

The antibody titers of the rhesus monkeys were measured by ELISA.

<p>The numbers of seropositive monkeys were shown.</p><p>Each of the groups had 4 monkeys.</p

The weight change in a long-term experiment in monkeys immunized with the influenza vaccine.

<p>‘−1’ refers to 1 week before the vaccine immunization. Vaccine immunizations occurred during weeks 1 to 10. Weeks ‘11 to 14’ refered to the time post-immunization.</p

The ecombinant baculovirus Bmgp64HA was detected by 2-D electrophoresis.

<p>45 kD HA protein was expressed in recombinant baculovirus.</p