Antibody-Dependent Cell-Mediated Cytotoxicity Epitopes on the Hemagglutinin Head Region of Pandemic H1N1 Influenza Virus Play Detrimental Roles in H1N1-Infected Mice

Abstract

Engaging the antibody-dependent cell-mediated cytotoxicity (ADCC) for killing of virus-infected cells and secretion of antiviral cytokines and chemokines was incorporated as one of the important features in the design of universal influenza vaccines. However, investigation of the ADCC epitopes on the highly immunogenic influenza hemagglutinin (HA) head region has been rarely reported. In this study, we determined the ADCC and antiviral activities of two putative ADCC epitopes, designated E1 and E2, on the HA head of a pandemic H1N1 influenza virus in vitro and in a lethal mouse model. Our data demonstrated that sera from the E1-vaccinated mice could induce high ADCC activities. Importantly, the induction of ADCC response modestly decreased viral load in the lungs of H1N1-infected mice. However, the elevated ADCC significantly increased mouse alveolar damage and mortality than that of the PBS-vaccinated group (P < 0.0001). The phenotype was potentially due to an exaggerated inflammatory cell infiltration triggered by ADCC, as an upregulated release of cytotoxic granules (perforin) was observed in the lung tissue of E1-vaccinated mice after H1N1 influenza virus challenge. Overall, our data suggested that ADCC elicited by certain domains of HA head region might have a detrimental rather than protective effect during influenza virus infection. Thus, future design of universal influenza vaccine shall strike a balance between the induction of protective immunity and potential side effects of ADCC.

Natural killer cell activation by respiratory syncytial virus‐specific antibodies is decreased in infants with severe respiratory infections and correlates with Fc‐glycosylation

“…[48][49][50] For influenza, the role of ADCC was shown to be protective in some studies, 51,52 but others point to the involvement of ADCC in exaggeration of the immune response. [53][54][55] Taken together, these examples show that the capacity of pathogenspecific antibodies to engage NK cells can significantly contribute to the outcome of infection. Regarding RSV infection, in mice, NK cells have been shown to be sufficient to eliminate infection 56 and NK cell depletion was found to increase viral titres.…”

“…For HIV, ADCC‐inducing antibodies have been identified as a key correlate of protection in the RV144 HIV vaccine trial . For influenza, the role of ADCC was shown to be protective in some studies, but others point to the involvement of ADCC in exaggeration of the immune response . Taken together, these examples show that the capacity of pathogen‐specific antibodies to engage NK cells can significantly contribute to the outcome of infection.…”

Natural killer cell activation by respiratory syncytial virus-specific antibodies is decreased in infants with severe respiratory infections and correlates with Fc-glycosylation

“…For HIV, ADCC-inducing antibodies have been identified as a key correlate of protection in the RV144 HIV vaccine trial (44-46). For influenza, the role of ADCC was shown to be protective in some studies (47, 48), but others point to the involvement of ADCC in exaggeration of the immune response (49-51). Taken together, these examples show that the capacity of pathogen-specific antibodies to engage NK cells can significantly contribute to the outcome of infection.…”

Influenza A Virus Antibodies with Antibody-Dependent Cellular Cytotoxicity Function

“…Flow cytometry-based ADCC assays are developed to measure ADCC activity by using different fluorescent dyes to differentiate living and dead cells [70,71]. In this assay, PKH-67 is used to label both live and dead target cells while dead target cells and effector cells are labeled with 7-amino actinomycin D (7-AAD).…”

“…The antigen needs to be carefully designed and inclusion of an adjuvant is also critical to protective outcome. Four, there are reports of antibody-dependent enhancement (ADE) in ADCC-mediating antibodies [71,133]. In these studies, ADCC epitopes were identified and these epitope-based vaccines were generated and tested in mice.…”