Fig. 4.

Histopathology of IHHN in Litopenaeus stylirostris and L. vannamei is shown in H&E stained sections (a–d) and by ISH with an IHHNV specific DIG-labeled probe (e–h); (a) low magnification photomicrograph of a section through the cuticular epithelium and subcuticular connective tissues of a small juvenile L. stylirostris with severe acute IHHN (unless otherwise noted, the remaining figures are from L. stylirostris). Intranuclear, haloed, eosinophilic Cowdry type A (CAI) inclusion bodies are evident in some infected cells; (b and c) higher magnification photomicrographs of gills (b and insert), hematopoietic nodule (c) and ventral nerve cord (d) showing examples of IHHNV CAIs; and (e–g). IHHNV-infected cell nuclei, some with distinct CIAs, are stained dark blue–black with the IHHNV DIG-labeled probe in the gills (e), hematopoietic nodule (f), and ventral nerve cord of a L. vannamei (g). cytoplasmic accumulations of IHHNV are apparent in the ventral nerve cord (g) and in developing oocytes in the ovary of a L. vannamei (h) where IHHNV appears to be being deposited as yolk. This may be a mechanism by which IHHNV is transmitted vertically. Mayer–Bennett H&E and DIG-labeled probe with Bismarck Brown counter stain.