Background: The Arctic-like rabies viruses (AL RABV) constitute a lineage of RABV circulating in the Middle East and Asia with distinct antigenic and genetic characteristics. As with all lyssaviruses, AL RABV cause an invariably fatal disease of mammals with zoonotic implications. A RABV glycoprotein (G) lentiviral pseudotyped virus (PV) has shown to be a highly sensitive and specific surrogate to live virus in neutralisation assays. However, using wildtype AL RABV G failed to generate infectious PV.
Objective: To generate AL RABV PV with chimeric G and compare titres achieved with PVs bearing wildtype G. Undertake serology studies to determine the efficacy of current vaccines and antivirals against this RABV subset.
Methods: Chimeras were constructed by splicing the ecto- and transmembrane domains of four AL RABV G strains with the cytoplasmic domains of vesicular stomatitis virus (VSV) G or RABV challenge virus standard-11 (CVS-11) G. PV generation followed a three plasmid transfection protocol and neutralisation assays (IC100) were undertaken using a panel of sera.
Results: Comparison of PV expressing wildtype or chimeric G revealed chimeric AL RABV with a VSV G cytoplasmic domain significantly increased PV titres (22-2200 fold). When comparing wildtype and VSV G based chimeric G PVs the latter showed neutralisation occurred within a single doubling serum dilution. AL RABV chimeric PV were neutralised by a range of the serum samples tested.
Conclusion: Infectious PV titre is effectively improved for AL RABV through the generation of chimeric G with a VSV G cytoplasmic domain. Comparison of chimeric and wildtype G PV shows switching the cytoplasmic domain does not affect the neutralisation profile. AL RABV are neutralised by responses to existing vaccines and therapeutics. On-going serological studies will fully evaluate the efficacy of current vaccines and antivirals against these viruses.