Investigation into the infectivity and neutralisation profiles of diverse lyssaviruses using a pseudotyped virus system

Rabies is an encephalitic disease with a mortality rate that approaches 100% in the absence of treatment. The World Health Organisation recognises rabies as a neglected tropical disease due to its disproportionate impact on poor and vulnerable populations in developing countries. Whilst vaccines exist to help prevent and control rabies, these are not always available or accessible to those at high risk. Rabies currently can only be treated effectively prior to the onset of symptoms and as immunoglobulin treatments are expensive and in short supply, and current vaccines require multiple doses to reach full efficacy, full courses of post-exposure prophylaxis may not be completed, leaving vulnerable individuals at risk. Rabies is a zoonotic viral disease that is predominantly caused by the rabies virus. The rabies virus has a broad host range and is capable of infecting most mammalian species, though its main reservoir, and the source of most human infections, are canids, particularly dogs. Rabies can also be caused by non-rabies lyssaviruses, a group of viruses related to rabies virus that are mainly found in bats. Lyssaviruses have been isolated globally and whilst there are very few reports of rabies encephalitis caused by non-rabies lyssavirus species in humans, the general lack of awareness of lyssaviruses in bats can lead to delays in seeking treatment and increase the risks of developing rabies once exposed. Current vaccines are highly effective against rabies virus, but display less effectiveness against other lyssavirus species, with little to no protection provided against the more diverse lyssaviruses. In this project, a lyssavirus pseudotype panel was generated using a range of lyssavirus species. This pseudotype panel was then used to investigate the neutralisation and tropism profiles of the lyssaviruses in question. In developing the pseudotype panel, it was identified that the choice of glycoprotein expression plasmid was vital for the generation of highly infectious pseudotype particles, and that the pI.18 plasmid was superior to pcDNA3.1. A novel chimp adenovirus-based rabies vaccine was compared to a current human rabies vaccine for its capacity to elicit rabies-neutralising antibodies. A single dose of the novel vaccine was revealed to produce a comparable antibody response to that produced by the human vaccine following a full three-dose schedule. Finally, the lyssavirus pseudotype panel was used to infect several animal cell lines to determine whether the viruses displayed any evidence of host adaptation. Some of the lyssavirus species showed increased infectivity in cells corresponding to their original host species, relative to a lab-adapted rabies virus strain.