Funding for this research was provided by:
Sixth Framework Programme (SUPASALVAC)
Biotechnology and Biological Sciences Research Council (BB/M028399/1)
Received: 15 August 2019
Accepted: 23 June 2020
First Online: 9 July 2020
: The current work approval and licence (30/2069) was granted by the UK Home Office under the Animals (Scientific Procedures) Act 1986 and following local ethical approval.
: Not applicable.
: The authors declare that they have no competing interests.