Arctic and Arctic-like rabies viruses: distribution, phylogeny and evolutionary history

Abstract

Forty-one newly sequenced isolates of Arctic and Arctic-like rabies viruses, were genetically compared to each other and to those available from GenBank. Four phylogenetic lineages of Arctic viruses were identified. Arctic-1 viruses circulate in Ontario, Arctic-2 viruses circulate in Siberia and Alaska, Arctic-3 viruses circulate circumpolarly, and a newly described lineage Arctic-4 circulates locally in Alaska. The oldest available isolates from Siberia (between 1950 and 1960) belong to the Arctic-2 and Arctic-3 lineages and share 98.6-99.2% N gene identity with contemporary viruses. Two lineages of Arctic-like viruses were identified in southern Asia and the Middle East (Arctic-like-1) and eastern Asia (Arctic-like-2). A time-scaled tree demonstrates that the time of the most recent common ancestor (TMRCA) of Arctic and Arctic-like viruses is dated between 1255 and 1786. Evolution of the Arctic viruses has occurred through a northerly spread. The Arctic-like-2 lineage diverged first, whereas Arctic viruses share a TMRCA with Arctic-like-1 viruses.

Fig. 1

Neighbour-joining phylogenetic tree of Arctic and Arctic-like rabies viruses (entire N gene) used in the present study (with a European fox virus RV1590 as outgroup). Bootstrap support for 1000 replicates is provided for nodes. Branch lengths are drawn to scale.

Fig. 2

Isolation points of Arctic-2 (●), Arctic-3 (■) and Arctic-4 (▲) rabies viruses in Alaska during 2005–2007.

Fig. 3

Time-scaled phylogenetic tree of the rabies virus N gene dataset estimated using a relaxed molecular clock.