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. 2019 Nov;12(11):1790-1796.
doi: 10.14202/vetworld.2019.1790-1796. Epub 2019 Nov 18.

Endotheliotropic herpesvirus infection in Asian elephants (Elephas maximus) of Assam, India

G Mahato  1 , K K Sarma  2 , D C Pathak  3 , N N Barman  4 , P Gogoi  5 , M Dutta  6 , P Basumatary  7
Affiliations

Endotheliotropic herpesvirus infection in Asian elephants (Elephas maximus) of Assam, India

G Mahato et al. Vet World. 2019 Nov.

Abstract

Background and aim: Elephant endotheliotropic herpesvirus (EEHV) is an emerging disease of elephant. Therefore, a study was conducted to know the actual status of the disease in Assam State of India.

Materials and methods: A total of 289 Asian elephants of Assam were screened during 2 years of study from April 2017 to March 2019. The clinical symptoms of diseased as well as gross and histopathological changes of dead elephants were recorded for the diagnosis of the disease. Virus involved in the occurrence of the disease was confirmed by polymerase chain reaction (PCR).

Results: In the present study, a total of three elephant calves out of 22 were found positive to EEHV1A. On the other hand, three adult asymptomatic elephants were also found positive for EEHV1 on screening 267 captive Asian elephants of Assam. The amplified PCR product showed band size of 520, 600, and 930 bp. The PCR amplified product with size 600 bp had shown the gene sequence for EEHV1U77/HEL. Gross lesions include congested blood vessels of the liver and intestinal mucosa, foci of petechiae in the spleen, and heart and focal ulceration in the dorsal surface of the tongue. Microscopically, the kidneys showed intertubular edema and focal areas of degeneration associated with coagulative necrosis of the tubular epithelium. The liver showed hydropic degeneration and fatty changes of the hepatocytes. There was a massive proliferation of fibroblasts in the interlobular spaces which penetrated the necrosed areas of the hepatic lobules.

Conclusion: A total of three wild rescued elephant calves and three asymptomatic adults were found positive for EEHV1A during the 2 years of study. The PCR amplified product with size 600 bp had shown the gene sequence for EEHV1U77/HEL.

Keywords: amplicons; amplification; elephant endotheliotropic herpesvirus; phylogenetic; polymerase chain reaction.

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Figures

Figure-1
Figure-1
Swollen head.
Figure-2
Figure-2
Edematous swelling with vesicles in tongue.
Figure-3
Figure-3
Inflamed mandibles.
Figure-4
Figure-4
Lateral recumbency.
Figure-5
Figure-5
Congested blood vessels of liver.
Figure-6
Figure-6
Petechial hemorrhage in spleen.
Figure-7
Figure-7
Congested serosal surface of stomach.
Figure-8
Figure-8
Congested mucosa of cecum.
Figure-9
Figure-9
Severe intertubular edema in kidneys.
Figure-10
Figure-10
Proliferation of fibroblast cells replacing the necrotic hepatocytes in liver.
Figure-11
Figure-11
Blood vessels showing loss of endothelium.
Figure-12
Figure-12
Depletion of lymphoid cells in the germinal center of the lymphoid follicles of the spleen.
Figure-13
Figure-13
Phylogenetic tree of elephant endotheliotropic herpesvirus (EEHV) isolated from elephant of Assam based on helicase (U77) gene. The tree was constructed in MEGAX software by neighbor-joining method and substitution model used was Tamura 3-parameter as estimated to be the best fit model in MEGAX software on the basis of Bayesian information criterion (BIC). Different EEHV strains are represented in the figure. Numbers along the branches refer to the bootstrapping value (percentage of confidence). The partial helicase gene sequence (520 bp) of EEHV used in this study is highlighted with red solid circle and found to be clustered with EEHV1A group. EEHV1A was detected in three wild rescued elephant calves and three asymptomatic adult elephants of Assam during 2 years of study.
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