title: Investigation of novel viral vector-based influenza vaccines for broad mucosal immunity against influenza viruses in human NALT
Creators: name: Puksuriwong, S
Publisher: name: University of Liverpool Repository
Year: 2019

description: Influenza disease has posed a global threat by seasonal epidemics and unforeseen pandemics. The narrow protection of conventional vaccines and the unpredictable outbreaks necessitate novel influenza vaccines that provide broad protection. Since influenza virus infects humans through the nasopharyngeal mucosa, local vaccine delivery that activates cross-reactive mucosal immunity may offer an attractive vaccination strategy against virus infection and control virus transmission. Viral vector-based influenza vaccines have been currently under study and shown good safety and high systemic immunity in animal models and some in human studies. Nevertheless, the data on mucosal immunity of these vaccines in humans are still limited. The study presented here investigates the potential of Pan paniscus adenovirus type3- (PanAd3) and modified Vaccinia Ankara (MVA)-based influenza vaccines to induce broad T and B cell immunity against influenza subtypes in human nasopharyx-associated lymphoid tissue (NALT) using an in vitro cell culture system. Firstly, influenza vaccine antigen expression was detected in adenotonsillar mononuclear cells (MNC), following stimulation by MVA-, but not PanAd3-based vaccines The MNCs, consisting of mainly lymphocytes, appeared to be refractory to PanAd3 virus infection, but susceptible to MVA virus infection. The influenza proteins (NP, M1 and HA) from MVA- NP+M1 and MVA-pdmH1HA were found predominantly in B cells and dendritic cells. Both NP and HA were intracellularly synthesised although HA later appeared to migrate to the cell membrane, whereas NP remained in the cell cytoplasm. Having shown the efficient influenza protein expression in the MNCs, the immune responses in tonsillar MNCs elicited by MVA- NP+M1 and MVA-pdmH1HA were further examined. Designed as a T cell-based vaccine, MVA-NP+M1 activated a marked increase of M1-specific cytotoxic T cell (CTL) response. The vaccine also significantly boosted M158-66-specific CTL responses in older children and adults, in an age-dependent manner. Besides, these cells were polyfunctional as shown by the co-expression of CD107a, IFN-γ and TNF-α in response to recall M158-66 peptide challenge and demonstrated the in vitro specific killing of peptide-pulsed target cells. In addition to MVA-NP+M1, MVA-pdmH1HA elicited cross-reactive HA-specific IgG antibodies that recognised pandemic H1N1 and heterosubtypic influenza strains in HA group1 (seasonal H1, H5 and H9), but not group 2 (H3 and H7). The stronger magnitude and the greater breadth of vaccine-induced antibodies were found in adults compared to children. Using a HAI assay, the MVA-pdmH1HA-induced antibodies were shown to bind to the head HA of pdmH1N1, but not of H5N1. In summary, MVA-NP+M1 and MVA-pdmH1HA have the potential as mucosal vaccines to elicit cross-reactive mucosal T and B cell-mediated immune responses against a range of influenza viruses. These data provide important information for a new vaccination strategy using MVA-vectored universal influenza vaccines in intranasal vaccination against influenza in humans.