Biochemical and functional analysis of smallpox growth factor (SPGF) and anti-SPGF monoclonal antibodies.
Variola, the causative agent of smallpox, is a highly infectious double-stranded DNA virus of the orthopox genus that replicates within the cytoplasm of infected cells. For unknown reasons prominent skin manifestations, including "pox," mark the course of this systemic human disease. Here we characterized smallpox growth factor (SPGF), a protein containing an epidermal growth factor (EGF)-like domain that is conserved among orthopox viral genomes, and investigated its possible mechanistic link. We show that after recombinant expression, refolding, and purification, the EGF domain of SPGF binds exclusively to the broadly expressed cellular receptor, erb-B1 (EGF receptor), with subnanomolar affinity, stimulating the growth of primary human keratinocytes and fibroblasts. High affinity monoclonal antibodies specific for SPGF reveal in vivo immunoprotection in a murine vaccinia pneumonia model by a mechanism distinct from viral neutralization. These findings suggest that blockade of pathogenic factor actions, in general, may be advantageous to the infected host.
Kim
Mikyung
M
Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
Yang
Hailin
H
Kim
Sung-Kwon
SK
Reche
Pedro A
PA
Tirabassi
Rebecca S
RS
Hussey
Rebecca E
RE
Chishti
Yasmin
Y
Rheinwald
James G
JG
Morehead
Tiara J
TJ
Zech
Tobias
T
Damon
Inger K
IK
Welsh
Raymond M
RM
Reinherz
Ellis L
EL
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D002478:Cells, Cultured; D017124:Conserved Sequence; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D006133:Growth Substances / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007371:Interferon-gamma / Q000096:biosynthesis; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D012901:Variola virus / Q000737:chemistry*; D014764:Viral Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*
D000911:Antibodies, Monoclonal; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014764:Viral Proteins; C051087:vaccinia growth factor; D004815:Epidermal Growth Factor; D007371:Interferon-gamma; D066246:ErbB Receptors