The relationships between West Nile and Kunjin viruses.

Jacqueline H Scherret,Vincent Deubel,Annette K Broom,John S Mackenzie,Thomas Briese,Michael Poidinger,Ernest A Gould,W Ian Lipkin,Roy A Hall

doi:10.3201/eid0704.010418

Abstract

Until recently, West Nile (WN) and Kunjin (KUN) viruses were classified as distinct types in the Flavivirus genus. However, genetic and antigenic studies on isolates of these two viruses indicate that the relationship between them is more complex. To better define this relationship, we performed sequence analyses on 32 isolates of KUN virus and 28 isolates of WN virus from different geographic areas, including a WN isolate from the recent outbreak in New York. Sequence comparisons showed that the KUN virus isolates from Australia were tightly grouped but that the WN virus isolates exhibited substantial divergence and could be differentiated into four distinct groups. KUN virus isolates from Australia were antigenically homologous and distinct from the WN isolates and a Malaysian KUN virus. Our results suggest that KUN and WN viruses comprise a group of closely related viruses that can be differentiated into subgroups on the basis of genetic and antigenic analyses.

Highlights

Kunjin (KUN) and West Nile (WN) viruses belong to the Japanese encephalitis (JE) antigenic complex of the Flavivirus genus in the family Flaviviridae [1]
The lineage I viruses were further separated into three clusters: the Australian KUN isolates; the Indian WN viruses; and WN isolates from Africa, the Middle East, Europe, and North America
High bootstrap confidence levels (100%) for the sequences of the NS5/3'UTR support the separation of the two lineages and the branching of the NY99 cluster of WN viruses with the Australian KUN viruses in lineage I, rather than with the WN group of viruses in lineage II

Summary

Introduction

Kunjin (KUN) and West Nile (WN) viruses belong to the Japanese encephalitis (JE) antigenic complex of the Flavivirus genus in the family Flaviviridae [1]. Cross-neutralization studies with polyclonal antisera raised to single strains of WN and KUN viruses revealed that these viruses shared a close relationship but were antigenically distinct [7,8,9]. Genetic studies have shown that KUN virus exists in Australia as a single topotype with

Methods

Results

Conclusion