The central nervous systems of piglets experimentally infected with hog cholera virus strain were examined by light microscope (LM) and electron microscope (EM) at 3, and 10 days post infection (P1). Nonsuppurative encephalomyelitis was the principal lesion observed in this study under LM. And the changes of nerve cells could only be of chromatin, swelling of rough endoplasmic reticulum and mitochondria, and dilatation of myelin sheath were noticed at 3 days P1. At 7 and 10 days P1 dilatation of nuclear membran and clumping or marginating of Chromatin were found in most of nerve cells.
Characteristic microtubular structure exhibiting irregular arrangement was seen in the nucleus of some nerve cells. Some degenerating small lymphocytes wee seen in the areas of gliosis. Frequently, glia cells were found to contain special bodies that could be the autophagosomes or secondary lysosomes at 10 days P1. The changes of swelling and vacuolation were found in both cytoplasm and nucleus of endothelia and its mitochondsia. Folding of endothelia membrance was seen in any stages. No virus particle could be found in any thin section in this study