Fox minute virus-like particle.

Abstract

Morphological investagations were carried out on basophilic intranuclear and cytoplasmic inclusion bodies in epithelial cells of the hair bulbs of anagen hair follicles in wild foxes affected with an abnormal hair coat condition. The inclusions , which were DNA-positive, contained numerous minute virus-like particles ("FMVP"). The particles, having a diameter of approximately 13 nm, had an arrangement of caps orner-like subunits of approximately 2-3 nm in diameter and were nonenveloped. The striking resemblance to icosahedral virus was crystallographically and morphologically demonstrated. INTRODUCTION Wild foxes, Vulpes vulpes sckrencki KISHIDA, 1924, which in winter have an abnormal hair coat condition consisting of leucotrichia, hypotrichosis and incomplete shedding of the primary hairs, have been noted in northern Hokkaido, Japan, in recent years. Fifty three fox~s affected with the condition, including 136 that were killed in the Soya district of northern Hokkaido in 1981, have been recorded. The present paper describes some of the morphological characteristics of "fox minute virus-like particle", which made up the intranuclear and cytoplasmic inclusion bodies seen in hair follicles from the affected foxes. MATERIALS AND METHODS Thirteen foxes affected with the abnormal hair coat condition, weighing 4-7kg, were shot dead in the winters of 1981-1983 and examined pathologically. Light microscopy Examinations were performed in various regions of the skin throughout the whole body and in all of the segments from the cervical to the lumbar parts of the spinal cord in all 13 animals. Section preparations were stained with hematoxylin-eosin, luxol fast blue, Bodian stain and Feulgen reaction. Electron microscopy Tissue specimens from various regions of the skin thoughout the whole body of 5 randomly selected animals were fixed in 3%-glutaraldehyde in O.lM-phosphate buffer and 1 %-OS04 in O.lM-phosphate buffer. The specimens were embedded in Quetol-812 mixture. Ultra thin sections were stained with uranyl acetate and lead citrate. RESULTS Light microscopy Almost all of the hair follicles of the 13 animals were in the telogen stage, although there were a few anagen follicles. Epithelial cells of the hair bulbs, especially the matrices of the anagen follicles, often showed hydropic degenera-tion or pyknosis and decrease or lack of melanin granules. These regressively changed epithelial cells often had basophilic inclusion bodies that were intranuclear in 7 animals and cytoplasmic in all 13 animals (Fig. 1). The intranuclear inclusions were either homogeneous or granular. The cytoplasmic inclusions were homogenous, with occasional fine vesicles, and they varied in shape, size and number. Both …