Mechanism for neutralizing activity by the anti-CMV gH/gL monoclonal antibody MSL-109.
Cytomegalovirus (CMV) is a widespread opportunistic pathogen that causes birth defects when transmitted transplacentally and severe systemic illness in immunocompromised individuals. MSL-109, a human monoclonal IgG isolated from a CMV seropositive individual, binds to the essential CMV entry glycoprotein H (gH) and prevents infection of cells. Here, we suggest a mechanism for neutralization activity by MSL-109. We define a genetic basis for resistance to MSL-109 and have generated a structural model of gH that reveals the epitope of this neutralizing antibody. Using surface-based, time-resolved FRET, we demonstrate that gH/gL interacts with glycoprotein B (gB). Additionally, we detect homodimers of soluble gH/gL heterodimers and confirm this novel oligomeric assembly on full-length gH/gL expressed on the cell surface. We show that MSL-109 perturbs the dimerization of gH/gL:gH/gL, suggesting that dimerization of gH/gL may be required for infectivity. gH/gL homodimerization may be conserved between alpha- and betaherpesviruses, because both CMV and HSV gH/gL demonstrate self-association in the FRET system. This study provides evidence for a novel mechanism of action for MSL-109 and reveals a previously undescribed aspect of viral entry that may be susceptible to therapeutic intervention.
Departments of Infectious Diseases.
Ashley E
AE
Fouts
Protein Chemistry.
Laëtitia
L
Comps-Agrar
Structural Biology,Early Discovery Biochemistry, and.
Katharina F
KF
Stengel
Protein Chemistry.
Diego
D
Ellerman
Early Discovery Biochemistry, and.
Allyn J
AJ
Schoeffler
Molecular Biology, Genentech Inc., South San Francisco, CA 94080.
Søren
S
Warming
Protein Chemistry.
Dan L
DL
Eaton
Departments of Infectious Diseases, becketf@gene.com.
Becket
B
Feierbach
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D057134:Antibodies, Neutralizing / Q000276:immunology* / Q000494:pharmacology; D000914:Antibodies, Viral / Q000276:immunology / Q000494:pharmacology; D001483:Base Sequence; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D003412:Cricetulus; D003587:Cytomegalovirus / Q000276:immunology*; D003586:Cytomegalovirus Infections / Q000188:drug therapy* / Q000276:immunology*; D019281:Dimerization; D024882:Drug Resistance, Viral / Q000276:immunology; D018604:Epitope Mapping; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008969:Molecular Sequence Data; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D014759:Viral Envelope Proteins; C071440:glycoprotein H, Cytomegalovirus; C409204:sevirumab