Coexpression of soluble and membrane-bound avian influenza virus H5 by recombinant Newcastle disease virus leads to an increase in antigen levels

Development and Scalable Production of Newcastle Disease Virus-Vectored Vaccines for Human and Veterinary Use

“…NDV constructs bearing genes encoding the SARS-CoV S protein [ 28 ] and the SARS-CoV-2 S protein [ 27 ], both around 3.8 kb in size, have been successfully generated, demonstrating this vector’s capacity for inserts in this size range. NDV has also been shown to tolerate multiple transgenes [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ] using different co-expression strategies [ 59 ]. Each foreign gene must be flanked by untranslated regions (UTRs) of NDV genes called gene start (GS) and gene end (GE) sequences ( Figure 1 ).…”

“…Similar to vaccine candidates for human use, several NDV vaccines expressing multiple antigens have been developed for veterinary use either by co-expressing the antigens within the same vector [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ] or by inoculating different vectors, each expressing a different antigen, in the same formulation [ 71 , 86 , 93 , 94 ]. For the latter, two studies have found that a formulation with only one vector/antigen yielded better results and sufficient protection [ 86 , 93 ], while another study found adequate immune responses regardless of inoculating one or multiple vectors [ 71 ].…”

“Antigen Camouflage and Decoy” Strategy to Overcome Interference From Maternally Derived Antibody With Newcastle Disease Virus-Vectored Vaccines: More Than a Simple Combination

“…However, recent results verified that modification of GOI expression pattern is an effective means to overcome the inhibition by GOI MDA. Soluble and membrane-bound H5 HAs were coexpressed in a recombinant NDV (rNDVsolH5_H5), resulting in a significant increase in antigen levels (Murr et al, 2020b). They speculated that elevated antigen levels may enhance antigenicity of HA, which may overwhelm the interference of AIV-MDA.…”

“…Sufficient amounts of the antigens in these two forms are required to absorb high proportions of MDA and to stimulate protective antibody immune response, respectively. In Murr's work, the soluble and FL HA were inserted between the P-M and F-HN genes, which resulted in 5.25-fold increase in total HA expression level (Murr et al, 2020b). Other combinations of the insertion sites in NDV genome for the GOI should be further evaluated.…”

“…Therefore, protein trimerization signals are needed to restore the natural conformation of the GOI when the transmembrane domain is deleted to make the soluble protein. The truncated HA of H5N1 AIV was expressed in trimer in NDV vectors through adding an isoleucine-zipper trimerization motif GCN4 to the C-terminal (Cornelissen et al, 2012;Murr et al, 2020b). In addition, NDV-vectored vaccines have tissue tropism mainly in the respiratory tract and the soluble proteins secreted into the extracellular space cross the mucosal barrier to enter systematic circulation inefficiently due partly to the physical properties of the epithelial cells.…”