Antibody fragments, expressed by a fowl adenovirus vector, are able to neutralize infectious bursal disease virus.
Single-chain variable fragments (scFv) contain the heavy and light chain variable domains of immunoglobulin, joined by a short peptide linker. Previously, our laboratory has produced neutralizing scFv to epitopes of infectious bursal disease virus (IBDV). The in vitro delivery and expression of one of these scFv with and without the C(H)2-C(H)4 Fc domain of chicken IgY attached (scFv-Fc) by a serotype 8 fowl adenovirus (FAdV-8) vector was investigated in the present study. A panel of FAdV-8 vectors was constructed, each containing a different transgene (scFv or scFv-Fc), a different promoter to drive scFv and scFv-Fc transcription (CMVie or the fowl adenovirus major late promoter), and a different sized, right-hand end genomic deletion (52 bp or 2.3 kb). This panel was used to establish what effect these variables had on protein production, viral replication and scFv transcription, as measured by enzyme-linked imunosorbent assay and real-time polymerase chain reaction. Our results showed that, using a FAdV-8 vector containing the optimal CMVie promoter/2.3 kb deletion combination, we successfully expressed a secreted form of both scFv and scFv-Fc that were able to neutralize IBDV both in vitro and in ovo. These studies indicate that the FAdV-8 vector may be a promising candidate to deliver and express therapeutic molecules such as scFv and scFv-Fc in vivo in poultry.
CSIRO Australian Animal Health Laboratory, Victoria, Australia. sameer.greenall@monash.edu
Sameer A
SA
Greenall
Scott G
SG
Tyack
Michael A
MA
Johnson
Sandra I
SI
Sapats
D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology* / Q000378:metabolism; D000259:Aviadenovirus / Q000276:immunology*; D002460:Cell Line; D002645:Chickens; D004797:Enzyme-Linked Immunosorbent Assay; D017353:Gene Deletion; D005822:Genetic Vectors; D007128:Immunoglobulin Fragments / Q000235:genetics / Q000276:immunology*; D007243:Infectious bursal disease virus / Q000276:immunology*; D010957:Plasmids; D014779:Virus Replication
D000914:Antibodies, Viral; D007128:Immunoglobulin Fragments