Lassa Virus Targeting of Anterior Uvea and Endothelium of Cornea and Conjunctiva in Eye of Guinea Pig Model

Abstract

Lassa virus (LASV), a hemorrhagic fever virus endemic to West Africa, causes conjunctivitis in patients with acute disease. To examine ocular manifestations of LASV, we histologically examined eyes from infected guinea pigs. In fatal disease, LASV immunostaining was most prominent in the anterior uvea, especially in the filtration angle, ciliary body, and iris and in and around vessels in the bulbar conjunctiva and peripheral cornea, where it co-localized with an endothelial marker (platelet endothelial cell adhesion molecule). Antigen was primarily associated with infiltration of T-lymphocytes around vessels in the anterior uvea and with new vessel formation at the peripheral cornea. In animals that exhibited clinical signs but survived infection, eyes had little to no inflammation and no LASV immunostaining 6 weeks after infection. Overall, in this model, LASV antigen was restricted to the anterior uvea and was associated with mild chronic inflammation in animals with severe disease but was not detected in survivors.

Keywords: Lassa fever; Lassa virus; anterior uvea; endothelial cells; eye; guinea pig; ocular; viral hemorrhagic fever; viruses; zoonoses.

Figure 1

Lassa virus (LASV) localization in guinea pigs that died of or survived infection with LASV-Josiah in study of LASV targeting of anterior uvea and endothelium of cornea and conjunctiva in eye. Primary diagram at top shows major structures of the eye; smaller diagrams detail the general regions in which LASV antigen (red circles) was detected in the eye of each animal by immunohistochemical analysis. All animals were euthanized because of disease (14–23 days postinfection) except Jos-2, which did not exhibit overt clinical signs (no weight loss or elevated body temperature) and was euthanized at study completion (41 days postinfection).

Figure 2

Detection of Lassa virus (LASV) antigen in the anterior uvea and endothelium within the eye of guinea pigs infected with LASV-Josiah and in the epithelium of structures adjacent to the eye in study of LASV targeting of anterior uvea and endothelium of cornea and conjunctiva in eye. A) Anterior uvea with LASV antigen immunolabeled (red) within the peripheral CO and CJ vessels, the FA, CB, and I. Original magnification ×4. B) Immunohistochemical (IHC) staining in the endothelium and adjacent stroma of the corneal margin (asterisk) and in the endothelium deep to Descemet’s membrane (arrowhead). Original magnification ×20 with 1.25 Optivar. C) Perivascular and endothelial staining in the bulbar conjunctiva. Original magnification ×63. D) IHC staining in the filtration angle. Original magnification ×20. E) Photomicrograph of the ciliary body highlighting the labeling in the pigmented epithelium (arrowheads) and stroma. Original magnification ×30. F) Photomicrograph of the iris showing IHC staining of LASV antigen in the stroma, smooth muscle (dilator muscle, white asterisk), and posterior pigmented epithelium (arrowheads). Original magnification ×40. G) IHC staining in eyelid epithelium (asterisk) and dermal vessels in the eyelid. Representative animal Jos-9. Original magnification ×15. H) IHC staining for LASV antigen in the acini of the lacrimal gland (asterisks). Representative animal Jos-9. Original magnification ×5. Representative animals: A–F, Jos-4; F, G, Jos-9. CB, ciliary body; CJ, conjunctival; CO, corneal; FA, filtration angle; I, iris; IHC, immunohistochemical.

Figure 3

Mild mononuclear anterior uveitis in eyes of guinea pigs infected with Lassa virus (LASV) Josiah by hematoxylin and eosin stain in study of LASV targeting of anterior uvea and endothelium of cornea and conjunctiva in eye. A) Anterior uvea, conjunctiva, and cornea highlighting the mild inflammation and new vessel formation in the peripheral cornea. Original magnification ×4. B) New vessel formation of the peripheral cornea. Original magnification ×12. C) New vessel formation within the cornea highlighting the endothelial swelling and mixed inflammation. Original magnification ×20. D) The ciliary body, filtration angle, peripheral cornea, and a portion of the conjunctiva with mixed, mild, primarily lymphocytic inflammation in the filtration angle and around vessels in the conjunctiva, peripheral cornea, and sclera. Representative animal Jos-1. Original magnification ×6. E) Inflammation around conjunctival vessels at the margin of the cornea. Original magnification ×20. F) Mononuclear inflammation in the filtration angle and at the base of the ciliary body. Original magnification ×20. Representative animals: A–C, Jos-3; D–F, Jos-1.

Figure 4

Lassa virus (LASV) targeting endothelial cells in the eye in study of LASV targeting of anterior uvea and endothelium of cornea and conjunctiva in eye. Co-staining for LASV antigen (red) and platelet endothelial cell adhesion molecule (an endothelial marker, brown) in vessels at the margin of the cornea and within the conjunctiva show co-localization of LASV and endothelial antigens (arrowheads). Original magnification ×10; insets enlarged to ×63.

Figure 5

T-lymphocyte inflammation predominant in the eyes of animals that died of Lassa virus (LASV) infection >17 days postinfection in study of LASV targeting of anterior uvea and endothelium of cornea and conjunctiva in eye. CD3+ (left) and CD79a+ (right) lymphocyte antigens targeted by immunohistochemical (IHC) analysis are stained red. A) Inflamed filtration angle and sclera highlighting CD3+ T-lymphocytes. Original magnification ×10. B) Inflamed filtration angle and sclera highlighting the predominant population of CD79a+ B-lymphocytes. Original magnification ×10. C) Mildly inflamed filtration angle and sclera showing the predominance of CD3+ T-lymphocytes within the region. Original magnification ×10. D) Absence of CD79a+ B-lymphocytes. Original magnification ×10. E) New vessel formation at the margin of the cornea, indicating scattered CD3+ T-lymphocytes. Original magnification ×20. F) Minimal CD79a+ B-lymphocytes. Original magnification ×20. Representative animals: A, B, Jos-1; C–F, Jos-5.