Distribution and load of elephant endotheliotropic herpesviruses in tissues from associated fatalities of Asian elephants

•Elephant Endotheliotropic Herpesviruses (EEHVs) cause fatality in juvenile elephants.•Distribution and burden of the viruses within the organs of fatal cases are unknown.•Real time qPCRs detected EEHV-1 and 5 DNA in all the tissues examined.•The examined tissues revealed substantial differences in viral DNA load.•The highest virus loads were in liver (EEHV-1A) and heart (EEHV-1B and 5).

Elephant Endotheliotropic Herpesviruses (EEHVs) are the cause of a highly fatal haemorrhagic disease in elephants primarily affecting young Asian elephants (Elephas maximus) in both captivity and in the wild. The viruses have emerged as a significant threat to Asian elephant conservation, critically affecting overall sustainability of their population. So far insight into the pathogenesis of EEHV infections has been restricted to examination of EEHV-infected tissues. However, little is known about distribution and burden of the viruses within the organs of fatal cases, crucial elements in the understanding of the virus pathogenesis. This study was therefore undertaken to assess the extent of organ and cell involvement in fatal cases of EEHV-1A, 1B and 5 using a quantitative real-time PCR. EEHV-1 and 5 DNA were detectable in all the tissues examined, albeit with substantial differences in the viral DNA load. The highest EEHV-1A DNA load was observed in the liver, followed by the heart, thymus and tongue. EEHV-1B and 5 showed the highest DNA load in the heart, followed by tongue and liver. This study provides new insights into EEHV pathogenicity and has implications in choice of sample type for disease investigation and virus isolation.