Detection of Quiescent Infections with Multiple Elephant Endotheliotropic Herpesviruses (EEHVs), Including EEHV2, EEHV3, EEHV6, and EEHV7, within Lymphoid Lung Nodules or Lung and Spleen Tissue Samples from Five Asymptomatic Adult African Elephants.

Abstract

More than 80 cases of lethal hemorrhagic disease associated with elephant endotheliotropic herpesviruses (EEHVs) have been identified in young Asian elephants worldwide. Diagnostic PCR tests detected six types of EEHV in blood of elephants with acute disease, although EEHV1A is the predominant pathogenic type. Previously, the presence of herpesvirus virions within benign lung and skin nodules from healthy African elephants led to suggestions that African elephants may be the source of EEHV disease in Asian elephants. Here, we used direct PCR-based DNA sequencing to detect EEHV genomes in necropsy tissue from five healthy adult African elephants. Two large lung nodules collected from culled wild South African elephants contained high levels of either EEHV3 alone or both EEHV2 and EEHV3. Similarly, a euthanized U.S. elephant proved to harbor multiple EEHV types distributed nonuniformly across four small lung nodules, including high levels of EEHV6, lower levels of EEHV3 and EEHV2, and a new GC-rich branch type, EEHV7. Several of the same EEHV types were also detected in random lung and spleen samples from two other elephants. Sanger PCR DNA sequence data comprising 100 kb were obtained from a total of 15 different strains identified, with (except for a few hypervariable genes) the EEHV2, EEHV3, and EEHV6 strains all being closely related to known genotypes from cases of acute disease, whereas the seven loci (4.0 kb) obtained from EEHV7 averaged 18% divergence from their nearest relative, EEHV3. Overall, we conclude that these four EEHV species, but probably not EEHV1, occur commonly as quiescent infections in African elephants.