Clinical Application of a Real-Time Quantitative PCR Assay to Detect Elephant Endotheliotropic Herpesvirus Infection in Asian Elephants (Elephas maximus)
Elephant endotheliotropic herpesvirus (EEHV) hemorrhagic disease accounts for approximately half of all Asian elephant deaths that occur in captivity.2 Survival from EEHV-associated disease depends on rapid diagnosis and treatment of affected elephants. We have recently described a novel real-time quantitative PCR (qPCR) assay that detects EEHV1A and B, which are most commonly associated with mortality in captive Asian elephants in North America.1 Using this assay we also determined that many healthy Asian elephants have been previously infected with EEHV1 and they frequently shed virus in trunk secretions.1 Management of clinically ill animals would benefit with the availability of data describing viral loads and shedding in nasal secretions during the course of clinical disease. To address this issue, we monitored the kinetics of EEHV1 viremia and shedding in the nasal secretions and urine of both subclinical and clinically ill captive-born Asian elephants during the course of infection and treatment. We found that peak viral loads were reached between 4–21 days following appearance of clinical symptoms. Detectable viremia persisted for up to 90 days for some animals. Virus was detectable in nasal secretions with slightly delayed kinetics relative to viremia in the blood and was still detectable at the end of the time period for collecting nasal secretions, which was several weeks following recovery Low levels of viral DNA could also be found in some urine samples, which is a novel finding. This work is of significance for all veterinarians and elephant managers involved in the care of Asian elephants.
The authors would like to thank the veterinarians and elephant teams at the Houston Zoo, St. Louis Zoo, and Ringling Brothers and Barnum and Bailey Circus for providing biological materials used in this study. Support for these studies was provided by the Houston zoo, the Elephant Managers Association, and NIH training grant T32-AI-07471.
1. Stanton, J.J., J.C. Zong, E. Latimer, J. Tan, A. Herron, G.S. Hayward, and P.D. Ling. 2010. Detection of pathogenic elephant endotheliotropic herpesvirus in routine trunk washes from healthy adult Asian elephants (Elephas maximus) by use of a novel quantitative real-time PCR assay. Am. J. Vet. Res. (In Press).
2. Zong, J.C., E. Latimer, S. Heaggans, L.K. Richman, and G.S. Hayward. 2007. Pathogenesis and molecular epidemiology of fatal elephant endotheliotropic disease associated with the expanding proboscivirus genus of the Betaherpesvirinae. Proceedings of the 2007 International Elephant Conservation and Research Symposium, Florida, USA. 23–35.