Ikoma Lyssavirus, Highly Divergent Novel Lyssavirus in an African Civet¹

Denise A. Marston, Daniel L. Horton, Chanasa Ngeleja, Katie Hampson, Lorraine M. McElhinney, Ashley C. Banyard, Daniel Haydon, Sarah Cleaveland, Charles E. Rupprecht, Machunde Bigambo, Anthony R. Fooks

, and Tiziana Lembo

Author affiliations: Animal Health and Veterinary Laboratories Agency, Addlestone, UK (D.A. Marston, D.L. Horton, L.M. McElhinney, A.C. Banyard, A.R. Fooks); Central Veterinary Laboratory, Dar es Salaam, Tanzania (C. Ngeleja); University of Glasgow, Glasgow, Scotland, UK (K. Hampson, D. Haydon, S. Cleaveland, T. Lembo); National Consortium for Zoonosis Research, Neston, UK (L.M. McElhinney, A. R. Fooks); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (C.E. Rupprecht); Lincoln Park Zoo Tanzania Program, Arusha, Tanzania (M. Bigambo)

Abstract

Evidence in support of a novel lyssavirus was obtained from brain samples of an African civet in Tanzania. Results of phylogenetic analysis of nucleoprotein gene sequences from representative Lyssavirus species and this novel lyssavirus provided strong empirical evidence that this is a new lyssavirus species, designated Ikoma lyssavirus.

Eleven Lyssavirus species have been classified: Rabies virus (RABV), Lagos bat virus (LBV), Mokola virus (MOKV), Duvenhage virus (DUVV), European bat lyssavirus types -1 and -2, Australian bat lyssavirus, Aravan virus, Khujand virus, Irkut virus, and West Caucasian bat virus (WCBV) (1). All these viruses except MOKV have been detected in bats. Two newly identified lyssaviruses, Shimoni bat virus (SHIBV) (2) and Bokeloh bat lyssavirus (3), both detected in bats, have not yet been classified. The presence of numerous lyssaviruses in bat species has led to increasing research efforts toward lyssavirus discovery in bat populations globally. However, lyssavirus surveillance in terrestrial mammals remains limited across most of Africa.
Of the 13 lyssaviruses, 5 circulate in Africa (RABV, LBV, MOKV, DUVV, and SHIBV). LBV, MOKV, DUVV, and SHIBV are detected exclusively in Africa, whereas RABV is detected worldwide. The predominant RABV variants circulating in Africa are the mongoose and canine biotypes. In South Africa, canine RABV is considered to have been introduced in the eastern Cape Province after importation of an infected dog from England in 1892 and subsequently spread, infecting domestic and wild carnivores (4). Separate introductions of canine RABV (particularly in northern Africa) have been suggested (5). In addition, molecular clock analysis indicates that mongoose RABV was present in southern Africa ≈200 years before the introduction of canine RABV (6).
In Tanzania, canine RABV is endemic and widespread throughout the country. In the Serengeti ecosystem, detailed studies have shown a single variant of canine RABV circulating in multiple host species (7). However, annual mass rabies vaccination campaigns have been conducted for dogs in villages surrounding Serengeti National Park since 2003, and rabies has not been detected in the park since 2000 (8). Enhanced laboratory-based surveillance in support of this canine rabies elimination program has been running concurrently in the region.