Expression of H5 hemagglutinin vaccine antigen in common duckweed (Lemna minor) protects against H5N1 high pathogenicity avian influenza virus challenge in immunized chickens

Authors: BERTRAN, KATERI - Consultant; THOMAS, COLLEEN - Former ARS Employee; GUO, XUAN - Merial, Ltd; BUBLOT, MICHEL - Merial Sas Research & Development; PRITCHARD, NIKKI - Merial, Ltd; REGAN, JEFFREY - Biolex Therapeutics; COX, KEVIN - Biolex Therapeutics; GASDASKA, JOHN - Biolex Therapeutics; DICKEY, LYNN - Biolex Therapeutics; Kapczynski, Darrell; Swayne, David

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2015
Publication Date: 6/9/2015
Publication URL: http://handle.nal.usda.gov/10113/61345
Citation: Bertran, K., Thomas, C., Guo, X., Bublot, M., Pritchard, N., Regan, J.T., Cox, K.M., Gasdaska, J.R., Dickey, L.F., Kapczynski, D.R., Swayne, D.E. 2015. Expression of H5 hemagglutinin vaccine antigen in common duckweed (Lemna minor) protects against H5N1 high pathogenicity avian influenza virus challenge in immunized chickens. Vaccine. 33(30):3456-3462. doi: 10.1016/j.vaccine.2015.05.076.

Interpretive Summary: The hemagglutinin (HA) gene from an H5N1 highly pathogenic avian influenza (HPAI) virus was expressed in an aquatic plant, duckweed (Lemna minor; rLemna-HA) to produce an advanced biotechnology vaccine for poultry. In experiment studies, vaccinated chicken had excellent protection against the H5N1 HPAI strain used to make the vaccine. However, protection against other H5N1 HPAI challenge viruses was not variable depending on how closely related the challenge virus was to the vaccine. Therefore, biotechnologically advanced duckweed-derived HA could be a good alternative vaccine for poultry against H5N1 HPAI viruses.

Technical Abstract: A synthetic hemagglutinin (HA) gene from the highly pathogenic avian influenza (HPAI) virus A/chicken/Indonesia/7/2003 (H5N1) (Indo/03) was expressed in aquatic plant Lemna minor (rLemna-HA). In Experiment 1, efficacy of rLemna-HA was tested on specific pathogen free (SPF) birds immunized with 0.2 ug or 2.3 ug HA and challenged with 6log10 mean chicken embryo infectious doses (EID50) of homologous virus strain. Both dosages of rLemna-HA conferred clinical protection and dramatically reduced viral shedding. Almost all the birds immunized with either dosage of rLemna-HA elicited hemagglutinin inhibition (HI) antibody titers against Indo/03 antigen, suggesting an association between levels of anti-Indo/03 antibodies and protection. In Experiment 2, efficacy of rLemna-HA was tested on SPF birds immunized with 0.9 ug or 2.2 ug HA and challenged with 6log10 EID50 of heterologous H5N1 virus strains A/chicken/Vietnam/NCVD-421/2010 (VN/10) or A/chicken/West Java/PWT-WIJ/2006 (PWT/06). Birds challenged with VN/10 exhibited 100% survival regardless of immunization dosage, while birds challenged with PWT/06 had 50% and 30% mortality at 0.9 ug HA and 2.2 ug HA, respectively. For each challenge virus, viral shedding titers from 2.2 ug HA vaccinated birds were significantly lower than those from 0.9 ug HA vaccinated birds, and titers from both immunized groups were in turn significantly lower than those from sham vaccinated birds. Even if immunized birds elicited HI titers against the vaccine antigen Indo/03, only the groups challenged with VN/10 developed humoral immunity against the challenge antigen. None (rLemna-HA 0.9 ug HA) and 40% (rLemna-HA 2.2 ug HA) of the immunized birds challenged with PWT/06 elicited pre-challenge antibody titers, respectively. In conclusion, Lemna-expressed HA demonstrated complete protective immunity against homologous challenge and suboptimal protection against heterologous challenge, the latter being similar to results from inactivated whole virus vaccines. Transgenic duckweed-derived HA could be a good alternative for producing high quality antigen for an injectable vaccine against H5N1 HPAI viruses.