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 4

Human anti-UL16 and anti-UL141 mAbs activate ADCC efficiently against adenovirally expressed UL16 and UL141.

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Human anti-UL16 and anti-UL141 mAbs activate ADCC efficiently against ad...
(A–D) HFFF-hCARs were transduced with RAds expressing wild-type UL16 or UL141. An identical vector lacking a transgene was used as a control. (A) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of transduced HFFF-hCARs and Cytotect (40 μg/mL), seronegative IgGs (40 μg/mL), or UL16-specific mAbs (each at 30 μg/mL). All 4 mAbs were included at equimolar concentrations in the mixture. (B) As in A for UL141. Five mAbs were included at equimolar concentrations in 1 mixture (B2, D3, G3, G4, and G11), and 8 mAbs were included at equimolar concentrations in another mixture (B2, C3, D3, E5, G2, G3, G4, and G11). (C) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of transduced HFFF-hCARs and different concentrations of the tetravalent UL16-specific mAb mixture. (D) As in C for the pentavalent UL141-specific mAb mixture. (E and F) HF-TERTs were infected with HCMV strain Merlin. Mock-infected HF-TERTs were included as controls. (E) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of infected HF-TERTs and Cytotect, seronegative IgGs, or the UL16-specific mAb mixture (each at 30 μg/mL). (F) As in E for UL141. Results are representative of at least 3 experiments. Data are shown as the mean ± SD of triplicate samples (A–F). All experiments were performed 48 hours after transduction (A–D) or infection (E and F). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 2-way ANOVA.