Monoclonal antibodies targeting nonstructural viral antigens can activate ADCC against human cytomegalovirus
Virginia-Maria Vlahava, … , Eddie C.Y. Wang, Richard J. Stanton
Virginia-Maria Vlahava, … , Eddie C.Y. Wang, Richard J. Stanton
Published February 15, 2021
Citation Information: J Clin Invest. 2021;131(4):e139296. https://doi.org/10.1172/JCI139296.
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Research Article Immunology Virology

Monoclonal antibodies targeting nonstructural viral antigens can activate ADCC against human cytomegalovirus

Abstract

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that causes severe disease following congenital infection and in immunocompromised individuals. No vaccines are licensed, and there are limited treatment options. We now show that the addition of anti-HCMV antibodies (Abs) can activate NK cells prior to the production of new virions, through Ab-dependent cellular cytotoxicity (ADCC), overcoming viral immune evasins. Quantitative proteomics defined the most abundant HCMV proteins on the cell surface, and we screened these targets to identify the viral antigens responsible for activating ADCC. Surprisingly, these were not structural glycoproteins; instead, the immune evasins US28, RL11, UL5, UL141, and UL16 each individually primed ADCC. We isolated human monoclonal Abs (mAbs) specific for UL16 or UL141 from a seropositive donor and optimized them for ADCC. Cloned Abs targeting a single antigen (UL141) were sufficient to mediate ADCC against HCMV-infected cells, even at low concentrations. Collectively, these findings validated an unbiased methodological approach to the identification of immunodominant viral antigens, providing a pathway toward an immunotherapeutic strategy against HCMV and potentially other pathogens.

Authors

Virginia-Maria Vlahava, Isa Murrell, Lihui Zhuang, Rebecca J. Aicheler, Eleanor Lim, Kelly L. Miners, Kristin Ladell, Nicolás M. Suárez, David A. Price, Andrew J. Davison, Gavin W.G. Wilkinson, Mark R. Wills, Michael P. Weekes, Eddie C.Y. Wang, Richard J. Stanton

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Figure 1

Characterization of ADCC-mediated NK cell activation against HCMV-infected fibroblasts.

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Characterization of ADCC-mediated NK cell activation against HCMV-infect...
HFFFs immortalized with hTERT or similarly immortalized autologous SFs were infected with HCMV strain Merlin. Mock-infected HF-TERTs or SFs were included as controls. (A and B) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of HF-TERTs infected for 48 hours with HCMV and different concentrations of either Cytotect or seronegative IgGs (Neg IgG). PBMCs were either untreated (A) or pretreated for 18 hours with IFN-α (B). (C and D) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of HF-TERTs infected for 24 hours, 48 hours, or 72 hours with HCMV and either Cytotect or seronegative IgGs (each at 50 μg/mL). PBMCs were either untreated (C) or pretreated for 18 hours with IFN-α (D). (E and F) Percentage of degranulation of CD56+CD57+NKG2C+ NK cells among PBMCs in the presence of HF-TERTs (E) or SFs (F) infected for 48 hours with HCMV and either Cytotect or seronegative IgGs (each at 50 μg/mL). Results are representative of at least 3 experiments. All data are shown as the mean ± SD of triplicate samples. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 2-way ANOVA.