Trunkloads of viruses

Abstract

Elephant populations are under intense pressure internationally from habitat destruction and poaching for ivory and meat. They also face pressure from infectious agents, including elephant endotheliotropic herpesvirus 1 (EEHV1), which kills ~20% of Asian elephants (Elephas maximus) born in zoos and causes disease in the wild. EEHV1 is one of at least six distinct EEHV in a phylogenetic lineage that appears to represent an ancient but newly recognized subfamily (the Deltaherpesvirinae) in the family Herpesviridae.

FIG 1

EEHV phylogeny and taxonomy. (A) EEHV lines of descent in the context of established herpesvirus taxonomy. With the exception of the EEHV, the taxonomic relationships shown are based on current herpesvirus taxonomy (http://ictvonline.org/). The proposed (indicated with a blue asterisk) Deltaherpesvirinae (δ) subfamily branches from between the Betaherpesvirinae (β) and Gammaherpesvirinae (γ) lineages. In constructing the diagram, it is assumed that the Proboscivirus genus would be retained in the proposed new subfamily, and the diagram indicates the possibility of establishing a new genus for the GC-rich viruses that are shown in panel B. (B) Relationships among the EEHV. AT- and GC-rich branches are shown, as well as the host species for each virus. The host species were Asian elephants (As) or African elephants (Af). This figure was adapted from reference .

FIG 2

EEHV1 genomic architecture. The 180-kb genome consists of a unique segment bounded by a pair of direct terminal repeats. The locations of the six blocks of core genes conserved among members of the Herpesviridae are shown, along with the orientations of these regions characteristic of the alpha-, beta-, and gammaherpesvirus subfamilies. The conserved core region is flanked by genes not found in other herpesviruses. This figure is based on information in references , , , , and . The genomic orientation shown is reversed from the depictions in references and .