Figure 3.

Henipavirus-induced syncytia in vivo. (a–f) Histological sections of lungs of animals experimentally infected with henipaviruses. Slides were stained with haematoxylin and eosin (a,c,e) and by immunohistochemistry for henipavirus nucleoprotein antigen (b,d,f) (brown color). Horse lungs (a,b, magnification x40) show syncytia of the blood vessel endothelium (black arrowheads) and associated with the alveolar walls (white arrowhead). Ferret lungs (c,d, magnification x20) show syncytia of the blood vessel endothelium (black arrowheads); in these images, the endothelium has fused with attenuation and sloughing, leaving regions of the vessel wall denuded. Virus has also infected the endothelium of lymphatic vessels (white arrowheads). Ferret bronchi (e,f, magnification x20) show syncytia of the bronchial epithelium (black arrowheads), some of which form into stalked structures; in these images, the bronchus is filled with inflammatory and cellular debris, transferred from elsewhere in the airways. These pictures were prepared specifically for this review from material taken from past studies ((a,b) [90]; (c,f) [91]).