Final Report Summary - MAJARVISCIG (A Single Dose, Cytomegalovirus-based Vaccine to Induce Heterosubtypic Protective Immunity to Influenza A Virus) This project uses a novel immunogenic vector called cytomegalovirus (CMV), which is biased towards induction of cytotoxic T lymphocytes (CTLs), as a means to induce cross-reactive immunity against multiple influenza A virus (IA) serotypes. IA 'pandemics' with high mortality result from introduction of IA with a new surface IA serotype into an immunologically naïve population. Currently there is no commercial vaccine for pandemic IA. We hypothesized that by using CMV to focus the CTL response on more conserved internal regions of IA, the resultant immunity will protect against pandemic IA. In the initial component we used state-of-the-art bacterial artificial chromosome (BAC)-based technology to construct a panel of murine CMV (MCMV) recombinants each expressing a different region of conserved internal IA proteins known to induce CTLs in mice. These CTL epitopes were derived from the conserved internal IA proteins: nucleoprotein (NP), polymerase acidic protein (PA) – a subunit of the IA polymerase complex, and the nonstructural protein 2 (NS2), a protein involved in nuclear export. In the initial reporting period, MCMV-IA recombinants expressing these epitopes (MCMV-IANP, MCMV-IAPA and MCMV-IANS2) were constructed and completely characterized. This panel of MCMV-IA recombinants was then used to test immunogenicity and efficacy induced by these vectors in the C57BL/6 flu mouse model. For efficacy testing we determined the ability to protect mice against challenge using both a low-pathogenic completely homologous IA virus (PR8; H1N1) and high-pathogenic heterologous IA virus (Avian Viet04; H5N1). Notably, when administered as a mixture of the 3 MCMV-IA recombinants, the T cell responses induced against the IA CTL epitopes were substantially reduced (10-fold) compared to responses normally observed for similar MCMV recombinants. They were also non-protective. In the final reporting period, this phenomenon was examined in more detail, which required construction of an additional panel of MCMV-IA recombinants. Importantly, these new studies showed that normal levels of T cell responses are restored by using the MCMV-IA recombinants singly rather than as a mixture. Although the effect on protection is not yet known, this finding has impact both at the level of basic immunological mechanisms associated with CMV infection, as well as in terms of the translational development of this vaccine platform. Within the final reporting period, we also further developed the idea of conditionally-attenuation for inexpensive production of safe vaccines suited for production in low and middle income countries (LMICs). In terms of career development, results from this CIG-funded project have substantially increased my integration within the European scientific research community by providing critical preliminary data to support funded grant applications. By providing the environment for creation of the idea of conditional attenuation, the CIG also provided the conceptual framework that has served as the basis for multiple additional projects, both funded and currently under review. These projects together with the CIG have served to further increase my profile in the area of herpesvirus vaccine development resulting in my further integration (more information regarding these collaborations as well as outreach activities can be obtained at www.thejarvislab.com). The CIG also contributed to the funding of a PhD student who successfully completed their degree in 2017 and training of a post-doctoral fellow. The impact of this project has been further increased by the recent spin-out of a commercial entity (The Vaccine Group; TVG), which has the goal of commercial development of herpesvirus-based vaccines (see: http://www.thejarvislab.com/research/). This company is underpinned by four patent applications which were submitted during the CIG funding period.
