Vascular endothelial growth factor (VEGF)-like protein from orf virus NZ2 binds to VEGFR2 and neuropilin-1

Vascular endothelial growth factor (VEGF)-like protein from orf virus NZ2 binds to VEGFR2 and neuropilin-1

^*Virus Research Unit, Department of Microbiology, University of Otago, P.O. Box 56, Dunedin, New Zealand; ^†Molecular/Cancer Biology Laboratory, Haartman Institute, University of Helsinki, P.O. Box 21 (Haartmaninkatu 3), SF-00014 Helsinki, Finland; and ^‡Ludwig Institute for Cancer Research, P.O. Box 2008 Royal Melbourne Hospital, Victoria 3050, Australia

Edited by Donald Metcalf, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, and approved January 12, 1999 (received for review November 2, 1998)

Abstract

Orf virus, a member of the poxvirus family, produces a pustular dermatitis in sheep, goats, and humans. The lesions induced after infection with orf virus show extensive proliferation of vascular endothelial cells, dilation of blood vessels and dermal swelling. An explanation for the nature of these lesions may lie in the discovery that orf virus encodes an apparent homolog of the mammalian vascular endothelial growth factor (VEGF) family of molecules. These molecules mediate endothelial cell proliferation, vascular permeability, angiogenesis, and lymphangiogenesis via the endothelial cell receptors VEGFR-1 (Flt1), VEGFR-2 (KDR/Flk1), and VEGFR-3 (Flt4). The VEGF-like protein of orf virus strain NZ2 (ORFV2-VEGF) is most closely related in primary structure to VEGF. In this study we examined the biological activities and receptor specificity of the ORFV2-VEGF protein. ORFV2-VEGF was found to be a disulfide-linked homodimer with a subunit of ≈25 kDa. ORFV2-VEGF showed mitogenic activity on bovine aortic and human microvascular endothelial cells and induced vascular permeability. ORFV2-VEGF was found to bind and induce autophosphorylation of VEGFR-2 and was unable to bind or activate VEGFR-1 and VEGFR-3, but bound the newly identified VEGF₁₆₅ receptor neuropilin-1. These results indicate that, from a functional viewpoint, ORFV2-VEGF is indeed a member of the VEGF family of molecules, but is unique, however, in that it utilizes only VEGFR-2 and neuropilin-1.

Footnotes

↵ § To whom reprint requests should be addressed. e-mail: Steven.stacker{at}ludwig.edu.au.
This paper was submitted directly (Track II) to the Proceedings Office.
ABBREVIATIONS:

KDR human VEGFR2,

NP-1, neuropilin;

NZ2,

New Zealand strain 2;

ORFV2-VEGF,

VEGF-like protein from orf strain NZ2;

PlGF,

placenta growth factor;

VEGF,

vascular endothelial growth factor;

VEGFR,

vascular endothelial growth factor receptor