Characterization of a 70-kDa, EBV gp350/220-binding protein on HSB-2 T cells.
EBV binds and infects HSB-2 T cells via a receptor distinct from CD21. To further study this novel EBV receptor, we expressed the first 470 amino acids of the EBV-gp350/220 using the baculovirus expression system. The recombinant gp350/220(1-470) has a m.w. of 95 kDa, reacts with anti-gp350/220 Abs, and binds CD21 in ELISA. Radiolabeled gp350/220(1-470) binds both HSB-2 and Raji cells. The gp350/220(1-470) protein also inhibits EBV binding to both HSB-2 and Raji, detected by flow cytometry. Lysates of HSB-2 cells compete with CD21 for binding to gp350/220(1-470), suggesting that the two receptors bind related epitopes on the recombinant protein. Scatchard analysis reveals that gp350/220(1-470) binds to 34,000 high affinity sites/HSB-2 cell (Kd = 0.92 x 10(-8) M) compared with the 97,000 high affinity sites bound/Raji cell (Kd = 1.78 x 10(-8) M). Utilizing a gp350/220(1-470)-affinity matrix, we identify a 70-kDa (55-kDa nonreduced) protein on the surfaces of 125I-labeled HSB-2 cells. Binding of this protein to the matrix is inhibited by anti-gp350/220 Ab 72A1. In summary, we characterize a novel EBV-binding molecule on HSB-2 cells, compare its reactivity with gp350/220 to that of CD21, and provide evidence of a gp350/220-reactive, 70-kDa protein on the surfaces of HSB-2 cells. In view of previous evidence of HSB-2 infectivity by EBV, we propose that the 70 kDa protein represents the novel EBV receptor.
Department of Biology, San Diego State University, CA 92182.
J A
JA
Hedrick
Z
Z
Lao
S G
SG
Lipps
Y
Y
Wang
S C
SC
Todd
J D
JD
Lambris
C D
CD
Tsoukas
D000818:Animals; D000956:Antigens, Viral / Q000378:metabolism*; D001483:Base Sequence; D001667:Binding, Competitive; D002144:Callithrix; D002460:Cell Line; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017464:Receptors, Complement 3d / Q000378:metabolism; D011991:Receptors, Virus / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000378:metabolism*
D000956:Antigens, Viral; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D017464:Receptors, Complement 3d; D011991:Receptors, Virus; D011994:Recombinant Proteins; D014763:Viral Matrix Proteins