Elephant Genomes Elucidate Disease Defenses and Other Traits

Abstract

Disease susceptibility and defense are important factors in conservation, particularly for elephants. We report that in addition to endotheliotropic herpesvirus and tuberculosis, Asian elephants are also more susceptible to cancer than African elephants. To determine mechanisms underlying elephant traits including disease resistance, we analyzed genomic datasets from multiple individuals and species. We report a draft genome assembly for the Asian elephant and an improved African elephant assembly. We found 862 and 1,017 potential regulatory elements in Asian and African elephants, respectively, that are enriched near 5,034 differentially expressed genes in peripheral blood mononuclear cells between the two species.These genes are enriched in immunity pathways, including tumor-necrosis factor which plays a role in the elephant response to endotheliotropic herpesvirus. Some elephant TP53 retrogenes are being maintained by purifying selection and may contribute to cancer resistance in elephants. Positive selection scans revealed genes that may control tusk development, memory, and somatic maintenance. Our study provides an example of how genomics can inform functional immunological studies, which may improve conservation and medical care for elephants and translate into human therapies.

Epigenetic clock and methylation studies in elephants

“…Recent findings suggest there are marked inter‐specific differences in rates of benign and malignant tumorigenesis between these species, at least among African savanna and Asian elephants housed at zoos in North America (Tollis et al, 2020). Despite these differences, our elephant clocks apply to both species.…”