STUDIES ON EASTERN EQUINE ENCEPHALOMYELITIS : III. INTRAOCULAR INFECTION WITH FIXED VIRUS IN THE GUINEA PIG

Ocular histopathology in Eastern equine encephalitis: A case report

Purpose

To describe the ophthalmic symptoms and histopathological findings in a human case of Eastern equine encephalitis (EEE).

Observations

The patient was a septuagenarian male whose presentation and clinical course were thought to be most consistent with viral meningoencephalitis. ELISA suggested recent infection with EEE virus. Microscopic analysis of the brain demonstrated perivascular lymphohistiocytic cuffing which was consistent with viral type encephalitis. Similarly, both eyes manifested a lymphohistiocytic infiltrate in the retina and optic nerve and a reduced number of ganglion cells.

Conclusions and importance

To our knowledge, this is the first report of ophthalmological and ocular pathology observations in an EEE patient. Interestingly, the inflammatory findings in the retina are reminiscent of the central nervous system effects of EEE virus. These findings are relevant given the recent epidemic of microcephaly and ophthalmic complications secondary to another arboviral virus, the Zika virus.

Human-like antibodies neutralizing Western equine encephalitis virus

This study describes the development of the first neutralizing antibodies against Western equine encephalitis virus (WEEV), a member of the genus Alphavirus. WEEV is transmitted by mosquitoes and can spread to the human central nervous system, causing symptoms ranging from mild febrile reactions to life-threatening encephalitis. WEEV has been classified as a biological warfare agent by the US Centers for Disease Control and Prevention. No anti-WEEV drugs are currently commercially available. Neutralizing antibodies are useful for the pre- and post-exposure treatment of WEEV infections. In this study, two immune antibody gene libraries were constructed from two macaques immunized with inactivated WEEV. Four antibodies were selected from these libraries and recloned as scFv-Fc, with a human Fc part. These antibodies bound WEEV specifically in ELISA with little or no cross-reaction with other alphaviruses. They were further analyzed by immunohistochemistry. All binders were suitable for the intracellular detection of WEEV particles. Neutralizing activity was determined in vitro. Three of the four antibodies were found to be neutralizing; about 1 ng/mL of the best antibody (ToR69–3A2) neutralized 50% of 5x10⁴ TCID₅₀/mL. Due to its human-like nature with a germinality index of 89% (VH) and 91% (VL), the ToR69–3A2 antibody is a promising candidate for future passive vaccine development.