Detection of pathogenic elephant endotheliotropic herpesvirus in routine trunk washes from healthy adult Asian elephants (Elephas maximus) by use of a quantitative real-time polymerase chain reaction assay

Author(s): Jeffrey J. Stanton, DVM; Jian-Chao Zong, PhD; Erin Latimer, BS; Jie Tan, BS; Alan Herron, DVM; Gary S. Hayward, PhD; Paul D. Ling, PhD

Publication: American Journal of Veterinary Research

Publication Date: August 2010

Abstract: Elephant endotheliotropic herpesviruses can cause acute hemorrhagic disease in endangered Asian and African (Loxodonta africana) elephants, resulting in considerable illness, reproductive loss, and death in captive elephant populations.1–8 This herpesvirus-associated disease primarily affects juvenile Asian elephants and results in rapid-onset endotheliolytic disease with a mortality rate of 85% in elephants that have positive results for the disease as indicated by semiquantitative conventional PCR-assay blood tests.9 After the origiDetection of pathogenic elephant endotheliotropic herpesvirus in routine trunk washes from healthy adult Asian elephants (Elephas maximus) by use of a quantitative real-time polymerase chain reaction assay Jeffrey J. Stanton, DVM; Jian-Chao Zong, PhD; Erin Latimer, BS; Jie Tan, BS; Alan Herron, DVM; Gary S. Hayward, PhD; Paul D. Ling, PhD Objective—To investigate the pathogenesis and transmission of elephant endotheliotropic herpesvirus (EEHV1) by analyzing various elephant fluid samples with a novel EEHV1-specific real-time PCR assay. Animals—5 apparently healthy captive Asian elephants (Elephas maximus) from the same herd. Procedures—A real-time PCR assay was developed that specifically detects EEHV1. The assay was used to evaluate paired whole blood and trunk-wash samples obtained from the 5 elephants during a 15-week period. Deoxyribonucleic acid sequencing and viral gene subtyping analysis were performed on trunk-wash DNA preparations that had positive results for EEHV1. Viral gene subtypes were compared with those associated with past fatal cases of herpesvirus-associated disease within the herd. Results—The PCR assay detected viral DNA to a level of 1,200 copies/mL of whole blood. It was used to detect EEHV1 in trunk secretions of 3 of the 5 elephants surveyed during the 15-week period. Viral gene subtyping analysis identified 2 distinct elephant herpesviruses, 1 of which was identical to a previous fatal case of herpesvirus-associated disease within the herd. Conclusions and Clinical Relevance—EEHV1 was shed in the trunk secretions of healthy Asian elephants. Trunk secretions may provide a mode of transmission for this virus. Results of this study may be useful for the diagnosis, treatment, and management of EEHV1- associated disease and the overall management of captive elephant populations. (Am J Vet Res 2010;71:1025–1033) nal report of EEHV in 1999,2 > 60 cases of systemic herpesvirus-associated hemorrhagic disease have been identified worldwide, with most disease developing in captive-born juvenile Asian elephants.

 

VIEW and DOWNLOAD