Talk delivered in the Clinical Virology workshop
Offered paper: Utilisation of chimeric haemagglutinin bearing lentiviral pseudotypes to dissect head and stalk directed antibody responses
Abstract
As universal vaccines against conserved epitopes of the influenza virus are developed and tested in clinical trials, the need for assays detecting the neutralising antibodies elicited is paramount. We have employed a system utilising chimeric haemagglutinin (cHA) bearing lentiviral pseudotypes (PV) in order to dissect neutralising antibodies targeting the stalk-region from those targeting the hyper-variable head region of the influenza HA glycoprotein. This system compares antibody titres generated against this cHA, composed of an H1 influenza stalk (A/California/7/2009) and H11 head (A/duck/Memphis/546/1974) alongside each parental strain, allowing the user to determine whether broadly neutralising stalk-directed neutralising antibodies are present in serum. A panel of human sera spanning before and after the 2009 influenza pandemic was tested using this system, confirming that stalk-directed, broadly neutralising antibodies increase in abundance after the pandemic. We also show highly significant correlation between this HA data and NA directed antibody responses using a PV ELLA assay. Furthermore, we have employed PV to test for heterosubtypic antibody responses by traditional PV methods against human seasonal (H1, H3) as well as exotic subtypes (H5, H7) of influenza, finding a subset of patients with sera able to neutralise all strains tested. These results suggest that the cHA bearing PV system is an excellent candidate assay for the evaluation of universal vaccine immunogenicity and that the data generated can be employed alone or in concert with other sero-assays in a comparative serology framework.