Effects of between and within herd moves on the shedding of recrudescent elephant endotheliotropic herpesvirus (EEHV) in captive Asian elephants (Elephas maximus)

Titus, Sanna; Patterson, Stuart; Prince-Wright, Joanna; Dastjerdi, Akbar; Molenaar, Fieke

Abstract

Haemorrhagic disease associated with elephant endotheliotropic herpesvirus (Elephantid her-pesvirus, EEHV) infections is the leading cause of death for Asian elephant (Elephas maximus) calves. This study assessed the effect of captive herd management on EEHV shedding, as evi-dence of latent infection reactivation, focusing on: (1) the influence of social change on the odds of recrudescence; (2) the respective effects of between and within herd moves; and (3) character-istics of recrudescent viral shedding. Trunk and conjunctival swabs (n=165) were obtained from six elephants at an EAZA-accredited zoo, collected during a period of social stability, and at times of social change. Longitudinal sampling took place at times of moving two bulls out of the collection and one new bull into an adjacent enclosure to the cow herd (between herd moves), and during a period of mixing this new bull with the cow herd to facilitate mating (within herd moves). Quantitative PCR was employed to detect EEHV 1a/b, 4a/b, and EF-1-ɑ (housekeeping gene). Generalised estimating equations determined EEHV recrudescence odds ratios (OR) and relative viral DNA. Sixteen EEHV 1a/b shedding events occurred and no EEHV 4a/b was detect-ed. All management-derived social changes promoted recrudescence (social change OR=3.27, 95% CI=0.412-26, p=0.262; between herd moves OR=1.6, 95% CI=0.178-14.4, p=0.675), though within herd movements posed the most significant increase of EEHV reactivation odds (OR=6.86, 95% CI=0.823-57.1, p=0.075) and demonstrated the strongest relative influence (post hoc Tukey test p=0.0425). Shedding onset and magnitude ranged from six to 54 days and from 3.59 to 11.09 ΔCts, revealing comparable shedding characteristics to primary infections. Differing challenges are associated with between and within herd movements, which can promote recrudescence and should be considered an exposure risk to naïve elephants.

Citation

Titus, S., Patterson, S., Prince-Wright, J., Dastjerdi, A., & Molenaar, F. (2022). Effects of between and within herd moves on the shedding of recrudescent elephant endotheliotropic herpesvirus (EEHV) in captive Asian elephants (Elephas maximus). Viruses, https://doi.org/10.3390/v14020229

• Journal Article Type: Article
• Acceptance Date: Jan 18, 2022
• Publication Date: Jan 24, 2022
• Deposit Date: Oct 12, 2021
• Publicly Available Date: Feb 10, 2022
• Journal: Viruses
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.3390/v14020229
• Public URL: https://rvc-repository.worktribe.com/output/1551608