Monovalent single-chain Fv fragments and bivalent miniantibodies bound to vesicular stomatitis virus protect against lethal infection.
Several antibody-dependent mechanisms have been postulated to mediate neutralization of different animal viruses, including blocking of docking to receptors, induction of conformational changes in the virus coat, and Fc-dependent opsonization. We have studied the molecular requirements for antibody-mediated neutralization of vesicular stomatitis virus (VSV) in vitro and protection against lethal disease in vivo with a single-chain Fv fragment (scFv) and the corresponding bivalent miniantibody (scFv-dHLX) generated from a VSV-neutralizing monoclonal antibody. Both monovalent scFv and bivalent scFv-dHLX miniantibodies were able to neutralize VSV in vitro and to protect interferon-alphabeta receptor-deficient (IFN-alphabeta R-/-) mice against lethal disease after intravenous injection of 50 plaque-forming units (pfu) VSV pre-incubated with the scFv reagents. Similarly, severe-combined immunodeficient (SCID) mice infected with immune complexes of 10(8) pfu VSV and bivalent scFv-dHLX were protected against lethal disease; however, mice infected with immune complexes of 10(8) pfu VSV and monovalent scFv were not. Although repeated scFv-dHLX treatment reduced virus quantities in the blood, neither SCID nor IFN-alphabeta R-/- mice were protected against lethal disease after passive immunization and subsequent VSV infection. This was due to the short half-life of 17 min of scFv-dHLX in the circulation. These data demonstrate that neutralization of VSV and protection against lethal disease do not require Fc-mediated mechanisms and that cross-linking is not crucial for protection against physiologically relevant virus doses in vivo.
Kalinke
U
U
Institute of Experimental Immunology, Department of Pathology, University of Zürich, Switzerland. ukalinke@usz.unizh.ch
Krebber
A
A
Krebber
C
C
Bucher
E
E
Plückthun
A
A
Zinkernagel
R M
RM
Hengartner
H
H
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology*; D001667:Binding, Competitive / Q000276:immunology; D007128:Immunoglobulin Fragments / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D008969:Molecular Sequence Data; D018353:Rhabdoviridae Infections / Q000401:mortality* / Q000517:prevention & control*; D014721:Vesicular stomatitis Indiana virus / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D007128:Immunoglobulin Fragments; D007135:Immunoglobulin Variable Region