Meningoencephalitis in a Polar Bear Caused by Equine Herpesvirus 9 (EHV-9)

Donovan, Taryn A.; Schrenzel, Mark D.; Tucker, Tammy A.; Pessier, Allan P.; Bicknese, B.; Busch, M. D.M.; Wise, Annabel G.; Maes, Roger K.; Kiupel, Matti; McKnight, Courtney; Nordhausen, Robert W.

doi:10.1354/vp.09-vp-0007-d-cr

Cited by 45 publications

(36 citation statements)

References 30 publications

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“…Recently, it has been reported that the host range of EHV-9 has expanded to include Grevy's zebras (Equus grevysi) and polar bears (Ursus maritimus), 7,31 as well as a giraffe (Giraffa camelopardalis reticulata).…”

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confidence: 99%

An Ocular Infection Model Using Suckling Hamsters Inoculated With Equine Herpesvirus 9 (EHV-9)

et al. 2012

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By using a new member of the neurotropic equine herpesviruses, EHV-9, which induced encephalitis in various species via various routes, an ocular infection model was developed in suckling hamsters. The suckling hamsters were inoculated with EHV-9 via the conjunctival route and were sacrificed after 6,12,24,36, 48, 72, 96, 120, and 144 hours (h) post inoculation (PI). Three horizontal sections of the brains, including the eyes and cranial cavity, were examined histologically to assess the viral kinetics and time-course neuropathological alterations using a panoramic view. At 6 to 24 h PI, there were various degrees of necrosis in the conjunctival epithelial cells, as well as frequent mononuclear cell infiltrations in the lamina propria and the tarsus of the eyelid, and frequent myositis of the eyelid muscles. At 96 h PI, encephalitis was observed in the brainstem at the level of the pons and cerebellum. EHV-9 antigen immunoreactivity was detected in the macrophages circulating in the eyelid and around the fine nerve endings supplying the eyelid, the nerves of the extraocular muscles, and the lacrimal glands from 6 h to 144 h PI. At 96 h PI, the viral antigen immunoreactivity was detected in the brainstem at the level of the pons and cerebellum. These results suggest that EHV-9 invaded the brain via the trigeminal nerve in addition to the abducent, oculomotor, and facial nerves. This conjunctival EHV-9 suckling hamster model may be useful in assessing the neuronal spread of neuropathogenic viruses via the eyes to the brain. Keywords EHV-9, eye, suckling hamsters, neuropathogenesis EHV-9, the newest member of the equine herpesvirus family, is a highly neurotropic herpesvirus first isolated in an outbreak of encephalitis in a herd of Thomson's gazelles (Gazella thomsoni) kept at a zoological garden. 13,36 Although the natural host of EHV-9 and the complete host range are still unknown, a member of the equidae is suspected to be a natural host of EHV-9, as domestic horses (Equus caballus) inoculated intranasally with EHV-9 exhibited only mild encephalitis and there were no resulting deaths. 34 In addition, a high seroprevalence for EHV-9 without any signs was detected among Burchell's zebras (Equus burchelli) in Serengeti National Park in Tanzania. 2 Recently, it has been reported that the host range of EHV-9 has expanded to include Grevy's zebras (Equus grevysi) and polar bears (Ursus maritimus), 7,31 as well as a giraffe (Giraffa camelopardalis reticulata).18 EHV-9 is most closely related to the recently re-emergent neurotropic pathogen, EHV-1; however, cleavage by restriction enzymes showed that the DNA fingerprint of EHV-9 is different from that of EHV-1 and other equine herpesviruses. 13Emerging EHV-9 infections are of special interest because there is a wide range of susceptible hosts, which includes mice and rats, 13 hamsters, 12 goats, 35 pigs, 26 dogs and cats, 37,38 and common marmosets. 21 Recently, EHV-9 was used to induce encephalitis in hamsters by different routes of inoculation, including th...

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An Ocular Infection Model Using Suckling Hamsters Inoculated With Equine Herpesvirus 9 (EHV-9)

et al. 2012

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“…However, other neurotropic herpesviruses such as herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV) are known to infect glial cells as well as neurons (Johnson, 1998). Astrocytes infection of EHV-9 was described in the cases of a giraffe and a polar bear (Donovan et al, 2009;Hoenerhoff et al, 2006). Immunohistochemistry demonstrated the presence of EHV-9 antigen in the neurons and neuronal fibers including the axons and dendrites in the brain of the goat and the naturally infected bear which indicate a trans-synaptic spread of EHV-9 from neuron to neuron via the neuronal fibers (Taniguchi et al, 2000b;Donovan et al, 2009).…”

Section: Conclusion: Ehv-9 Infection As a Model Of Cross-species Viramentioning

confidence: 98%

“…A 12-year-old female polar bear (Ursus maritimus) developed a sudden onset of neurological symptoms in 2007 (Schrenzel et al, 2008;Donovan et al, 2009). Nonsuppurative pleocytosis of cerebrospinal fluid was observed.…”

Section: Meningoencephalitis In a Polar Bearmentioning

confidence: 99%

“…EHV-9 can be also propagated in neural cells derived from a fetal equine brain as well as a fetal murine brain. EHV-9 has been isolated from Thomson's gazelles, zebras (Borchers et al, 2008;Schrenzel et al, 2008), giraffes (Samy et al, 2009), polar bears (Schrenzel et al, 2008;Donovan et al, 2009) and onager (Schrenzel et al, 2008) as described in Section 1. Epizootiologically all of the cases in zoo animals associated with the presence of zebras.…”

Section: Virus Genomementioning

confidence: 99%

“…Multifocal neuronal necrosis was most evident in the ventral portion of the cerebral hemispheres, and areas of neuronal necrosis were occasionally associated with characteristic herpetic eosinophilic intranuclear inclusions in neurons and astrocytes. Donovan et al (2009) described as follows. The polar bear was in good body condition The meninges of the brain and spinal cord were diffusely congested.…”

Section: Giraffementioning

confidence: 99%

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Virology and Pathology of Encephalitis in Alien Hosts by Neurotropic Equine Herpesvirus 9

Fukushi¹,

Yanai²

2011

Non-Flavivirus Encephalitis

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A Review of Infectious Agents in Polar Bears (Ursus maritimus) and Their Long-Term Ecological Relevance

et al. 2015

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Disease was a listing criterion for the polar bear (Ursus maritimus) as threatened under the Endangered Species Act in 2008; it is therefore important to evaluate the current state of knowledge and identify any information gaps pertaining to diseases in polar bears. We conducted a systematic literature review focused on infectious agents and associated health impacts identified in polar bears. Overall, the majority of reports in free-ranging bears concerned serosurveys or fecal examinations with little to no information on associated health effects. In contrast, most reports documenting illness or pathology referenced captive animals and diseases caused by etiologic agents not representative of exposure opportunities in wild bears. As such, most of the available infectious disease literature has limited utility as a basis for development of future health assessment and management plans. Given that ecological change is a considerable risk facing polar bear populations, future work should focus on cumulative effects of multiple stressors that could impact polar bear population dynamics.

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Meningoencephalitis in a Polar Bear Caused by Equine Herpesvirus 9 (EHV-9)

Cited by 45 publications

References 30 publications

An Ocular Infection Model Using Suckling Hamsters Inoculated With Equine Herpesvirus 9 (EHV-9)

An Ocular Infection Model Using Suckling Hamsters Inoculated With Equine Herpesvirus 9 (EHV-9)

Virology and Pathology of Encephalitis in Alien Hosts by Neurotropic Equine Herpesvirus 9

A Review of Infectious Agents in Polar Bears (Ursus maritimus) and Their Long-Term Ecological Relevance

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