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.
View: Text | PDF
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

×

Figure 2

Identification of viral proteins on the plasma membrane that could prime ADCC.

Options: View larger image (or click on image) Download as PowerPoint
Identification of viral proteins on the plasma membrane that could prime...
(A) Temporal profiles of viral proteins (n = 27) identified previously on the surface of cells infected with HCMV. Proteins were only included in the analysis if detected in experiments PM1 and PM2 and quantified by 2 or more peptides in experiment PM1 or experiment PM2. Data are shown for experiment PM2. Proteins are grouped on the basis of expression kinetics, indicating that greater than 25% of the maximal signal was reached by 24 hours (left), 48 hours (middle), or 72 hours (right). (B) Average total abundance of each surface-expressed viral protein measured using IBAQ. Error bars indicate ranges from experiments PM1 and PM2. (C) Partitioned IBAQ abundance of each surface-expressed viral protein over time. Average IBAQ abundance values in B were multiplied by the fractional abundance at each time point from A. (D) HF-TERTs transfected with the coxsackie-adenovirus receptor (HFFF-hCARs) were transduced with RAds expressing individual viral proteins. An identical vector lacking a transgene was used as a control. Surface-expressed proteins were isolated by aminooxy biotinylation followed by immunoprecipitation with streptavidin beads 48 hours after transduction. Western blots show detection of the C-terminal V5 tags engineered into each protein, with the exception of UL141, which was detected with a UL141-specific Ab. UL141 staining of the gel was performed separately but is overlaid on the same image. (E) Percentage of degranulation of CD56+CD57+ NK cells among PBMCs in the presence of HFFF-hCARs, transduced as in D, and either Cytotect or seronegative IgGs (each at 50 μg/mL). Results are representative of 3 experiments. Data are shown as the mean ± SD of triplicate samples (E). *P < 0.05 and ****P < 0.0001, by 2-way ANOVA. ctrl, control.