Chimaeric VP2 proteins from infectious bursal disease virus containing the N-terminal M2e of H9 subtype avian influenza virus induce neutralizing antibody responses to both viruses

Abstract

Subunit vaccines capable of inducing antibody against both infectious bursal disease virus (IBDV) and H9 subtype avian influenza virus (AIV) were developed. The VP2 protein of IBDV was used as a cargo protein to display a 12-amino-acid immunodominant epitope derived from the N-terminal M2 extracellular domain (nM2e) of the H9 subtype AIV. Two chimaeric proteins were constructed by insertion of one copy of the nM2e into the PBC region (VP2BCnM2e(H9)) or by fusing four copies of nM2e to the carboxyl terminal (VP2-4nM2e(H9)) of VP2. Genes that encoded the VP2 chimaeras were subsequently cloned into a baculovirus vector and expressed in Spodoptera frugiperda cells. The recombinant proteins were used to vaccinate chickens at day 0 and again after 4 weeks. Blood was collected at 2-week intervals after primary and secondary vaccination to detect the antibody titre against VP2 or the nM2e via indirect enzyme-linked immunosorbent assay. Virus neutralization tests were also performed to measure anti-IBDV or anti-H9 AIV neutralizing antibodies in chick embryo fibroblasts. Oropharyngeal and cloacal swabs were collected 3, 5 and 7 days post H9 subtype AIV infection for virus isolation. Vaccination with VP2-4nM2e(H9) induced higher levels of antibody responses against IBDV or H9 subtype AIV, and provided better protection against an IBDV virulent challenge compared with vaccination with VP2BCnM2e(H9) vaccine, the wild-type VP2 subunit vaccine or the IBDV subunit commercial vaccines. Both chimaeric VP2 vaccines showed poor efficacy in inhibiting H9 virus replication post challenge. In summary, chimaeric proteins that contain the nM2e epitope were able to induce both IBDV and H9 subtype AIV-neutralizing antibody responses.

Single Dose of Consensus Hemagglutinin-Based Virus-Like Particles Vaccine Protects Chickens against Divergent H5 Subtype Influenza Viruses

“…The consensus rHA VLPs based vaccines elicited protective immune responses similar to those of the inactivated whole-virus vaccine, and could be applied to the assessment criteria of commercial inactivated virus vaccine, the index including serum HI titers and protective efficacy PC. We have also tested the efficacy of a single copy of the M2 ectodomain (M2e) as a broad-spectrum influenza vaccine candidate in chickens ( 22 ). Nevertheless, its further application was restricted by the lack of an appropriate method to evaluate the immune response elicited by the M2e antigens in chickens.…”

“…Serum antibody levels were titrated by hemagglutinin inhibition (HI) assay or serum-neutralization (SN) assay in DF-1 cell (ATCC, CRL-12203) ( 19 , 22 ). The SN assay was performed as following described.…”

Immunogenicity and protective efficacy of the norovirus P particle-M2e chimeric vaccine in chickens

“…The Lactococcus lactis expressing M2e on the surface also showed minimal protective efficacy against H5N2 HPAI virus challenge [23]. Infectious bursal disease virus (IBDV) was used to incorporate M2e into the VP2 of the virus, and the chimeric vaccine showed poor efficacy in inhibiting H9 virus replication post challenge [24]. A novel platform utilizing a self-assembling polypeptide nanoparticle was used to present M2e in either monomeric or tetrameric forms.…”

Antigen-Sparing and Enhanced Efficacy of Multivalent Vaccines Adjuvanted with Immunopotentiators in Chickens

“…Serum antibody levels were titrated by HI assay for EDSV, IBV, and NDV, or by SN test for IBDV with DF-1 cell line (Tang et al, 2013). The cytokine levels of IFNγ (Invitrogen, CA) and IL-4 (USCN, Wuhan, China) in chickens serum of pooled samples were detected by commercially available ELISA kit following the manufacturer's instructions and with reference to our previous report (Lu et al, 2016).…”