Vaccination with hemagglutinin produced in Trichoplusia ni larvae protects chickens against lethal H5N1 challenge

Highly pathogenic avian influenza (HPAI) H5N1 viruses in birds and coincident infections in humans have created demand for a cost-effective vaccine to prevent a pandemic of the disease. We report here that Trichoplusia ni (T. ni) larvae can act as a cost-effective bioreactor to produce recombinant HA5 (rH5HA) proteins as an effective vaccine for chickens. Western blot analysis revealed that the 70 kDa rH5HA protein and partially cleaved products (40 kDa rH5HA1 and 28 kDa rH5HA2) were generated in T. ni larvae infected with recombinant baculovirus carrying the H5HA gene. We demonstrated that a single intramuscular injection of homogenates of T. ni larvae containing rH5HA proteins into chickens could induce the production of antibodies with hemagglutination inhibition (HI) capability and stimulate neutralization activity against a lethal H5N1 influenza virus challenge. Furthermore, each vAc-HA5-infected T. ni larva can vaccinate approximately 20–36 chickens and induce with HI titer values of approximately 5.5 log2 after 7 weeks implied that this single-shot protocol should be economical and provide adequate protection. These data suggest that the baculovirus-larvae recombinant protein expression system could be a cost-effective platform for vaccine production.