Abstract:
Newcastle disease (ND) is a highly contagious viral respiratory and neurological
disease that has a severe impact on poultry production worldwide. In the present
study, an expression platform was established for the transient production in
N.bethamiana of ND virus-like particles (VLPs) for use as vaccines against ND.
The expression of the ND Fusion (F) and/or Hemagglutinin-neuraminidase (HN)
proteins of a genotype VII.2 strain formed ND VLPs in planta as visualized under the
transmission electron microscope, and HN-containing VLPs agglutinated chicken
erythrocytes with hemagglutination (HA) titres of up to 13 log2.The
immunogenicity of the partially-purified ND VLPs was confirmed in specificpathogen-
free White leghorn chickens. Birds receiving a single intramuscular
immunization with 1024 HA units (10 log2) of the F/HN ND VLPs administered
with 20% [v/v] Emulsigen®-P adjuvant, seroconverted after 14 days with F- and
HN-specific antibodies at ELISA titres of 5705.17 and HI geometric mean titres
(GMTs) of 6.2 log2, respectively. Furthermore, these ND-specific antibodies
successfully inhibited viral replication in vitro of two antigenically closely-related
ND virus isolates, with virus-neutralization test GMTs of 3.47 and 3.4, respectively.
Plant-produced ND VLPs have great potential as antigen-matched vaccines for
poultry and other avian species that are highly immunogenic, cost-effective, and
facilitate prompt updating to ensure improved protection against emerging ND
field viruses.
