Analyses of the endotheliotropic herpesvirus of elephants and establishment of a method for surveillance
Endotheliotropic elephant herpesvirus (EEHV) poses an acute threat for elephants. During recent years, a number of elephants in zoos worldwide as well as in the wild died from EEHV, among other three Asian elephants in Switzerland. At present, the virus cannot be serially passaged in cell cultures but genomic analyses have revealed that at least 7 different types of EEHV exist (Ling et al., 2013; Wilkie et al., 2013; Pellet, 2014), five of which can cause the lethal syndrome, termed elephant hemorrhagic disease (EHD).
Our goal is to improve the diagnostic, therapeutic, and, eventually, the prophylactic tools against EHD.
For this purpose, we initiated a trunkwash-screening program, which identified three members of one of our Swill elephant families as frequent shedders of EEHV1. Interestingly, no member of this family ever succumbed yet to EHD, whereas our three EHD victims all originated from rare-shedder families . As often times the trunk wash samples provided invalid results, we are presently comparing EEHV-shedding by the trunk as opposed to shedding by saliva.
Moreover, we constructed several mutant herpes simplex viruses, which express particular EEHV1-genes, i.e ETk and ECPK, in order to test their potential for activating antiviral drugs that are presently being used for the treatment of EHD, though without proof of their suitability. It seems that ECPK is able to phosphorylate ganciclovir, one of the drugs currently in use for elephant treatment upon an outbreak of EHD (manuscript in preparation).
1. Ackermann M, Hatt JM, Schetle N, Steinmetz H. Identification of shedders of elephant endotheliotropic herpesviruses among Asian elephants (Elephas maximus) in Switzerland. PloS one. 2017;12(5):e0176891. Epub 2017/05/04. doi: 10.1371/journal.pone.0176891. PubMed PMID: 28467495; PubMed Central PMCID: PMCPMC5415103.