Infecting mice with recombinant Ad5-BPI₂₃-Fcγ1 virus protects against systemic Escherichia coli challenge

Infections caused by Gram-negative bacteria (GNB) are increasingly common and can result in significant mortality rates due to the development of sepsis. To examine the potential usage of a recombinant Ad5-BPI(23)-Fcγ1 virus as a biological treatment against systemic infection by GNB, a construct containing the human bactericidal/permeability increasing protein (BPI) gene, encoding the functional N terminus (amino acid residues 1-199) of human BPI, and the Fcγ1 gene, encoding the Fc segment of human immunoglobulin G1, was inserted into an adenovirus serotype 5 (Ad5) chromosome to produce a recombinant Ad5-BPI(23)-Fcγ1 virus. Human A549 cells in culture and BALB/c mice were infected with the recombinant Ad5-BPI(23)-Fcγ1 virus and BPI(23)-Fcγ1 expression was confirmed by Western blot analysis and ELISA. The concentrations of BPI(23)-Fcγ1 protein were 5.59 µg ml(-1) in vitro and 21.37 ng ml(-1) in vivo and it was observed that these concentrations were sufficient to decrease endotoxin concentrations while enhancing bactericidal activity. In addition, mice treated with the recombinant Ad5-BPI(23)-Fcγ1 virus had decreased levels of IL-1β and TNF-α and were protected from an E. coli O111 : B4 challenge. Our data support the concept that Ad5-mediated BPI(23)-Fcγ1 gene delivery could be used as an ancillary biological treatment in the management of infection caused by GNB.