W. Coussement

In vivo morphogenesis of a new porcine enteric coronavirus, CV 777

SummaryThe morphogenesis of a new porcine enteric coronavirus, CV777, in intestinal epithelial cells of experimentally infected newborn piglets is described. The virus shows a morphogenetic pattern characteristic for members of the Coronaviridae family. It is formed by budding through membranes of the endoplasmic reticulum. Some specific aspects of this morphogenesis are discussed.

Pathology of Experimental CV777 Coronavirus Enteritis in Piglets. I. Histological and Histochemical Study

Sixteen cesarean-derived colostrum-deprived piglets were infected oronasally with CV777 coronavirus on the second or third day of life. Two uninfected piglets were controls. They were killed at 96 and 120 hours after birth. After an incubation period of 22 to 36 hours, all principals showed severe diarrhea. The principals were killed between 12 and 120 hours after infection. Exfoliation of enterocytes was seen first in the piglet killed 24 hours after infection (two hours after the diarrhea began). From that time on, shortening and fusion of villi was present in all small intestinal parts. Affected cells showed vacuolation. The histochemical study showed that infected piglets had decreased activity of all four enzymes studied. The light microscope showed no lesions in the absorptive colonic epithelium. The significance of the lesions in relation to intestinal dysfunction is discussed, and lesions are compared to those of transmissible gastroenteritis and porcine rotavirus infection.

Pathology of Experimental CV777 Coronavirus Enteritis in Piglets. II. Electron Microscopic Study

Sixteen cesarean-derived, colostrum-deprived piglets were infected oronasally with CV777 coronavirus on the second or third day of life. Two uninfected piglets were controls. After an incubation period of 22 hours to 36 hours, all principals showed severe diarrhea. The piglets were killed at different time intervals. Viral particles were found in the jejunal villous epithelial cells from 18 hours after infection until four days after the beginning of diarrhea. In the colonic epithelial cells, viral particles and degenerative lesions were found only in the piglet killed 36 hours after onset of diarrhea. Degenerative lesions in the enterocytes began at 18 hours after infection and were most pronounced in the jejunum at the onset of clinical signs. From 24 hours on after the onset of clinical signs, three cell types were found: degenerated virus-containing enterocytes; cuboidal cells; and columnar, highly vacuolated cells containing lipid droplets.

Sequential Pathological Study of Experimental Porcine Adenovirus Enteritis

The sequential enteric lesions of experimental porcine adenovirus strain 6618 infection were studied in 18 hysterotomy-derived, colostrum-deprived piglets, by histology, transmission electron microscopy, and an immunoperoxidase technique. Viral particles could be seen in altered epithelial cells of the lower small intestine from 24 hours until 16 days after inoculation. With the immunoperoxidase technique, viral antigen could be found in epithelial cells at 45 days after challenge. Destruction of epithelial cells and shortening of villi could be related directly to the presence of the virus. Histology of the lower jejunum and ileum, which demonstrates intranuclear inclusion bodies, is proposed as a useful diagnostic technique.

Spontaneous and experimental myofibrillar hypoplasia and its relation to splayleg in newborn pigs

Abstract The relation of myofibrillar hypoplasia to clinical splayleg was studied. A strain of Belgian Landrace sows was selected for this study because they produced pigs which had no myfibrillar hypoplasia. Myofibrillar hypoplasia could nevertheless by induced experimentally in these animals by dexamethasone treatment of the sows during late pregnancy. The lesion was observed without clinical signs and was compared to the myofibrillar hypoplasia in clinical cases of splayleg. The differences between these 2 groups may account for the appearance of clinical signs. These differences included the maturity of the myofibrils and the degree of autophagosomal glycogen breakdown.

Malacoplakia-like lesion in the lymph node of a pig.

Abstract Among 112 mandibular and mesenteric lymph nodes with tuberculosis-like lesions from slaughtered pigs, one tuberculous lymph node had a malacoplakia-like granulomatous lesion; no similar lesion has been recorded before in animals.

Dual adenovirus and distemper virus pneumonia in a dog

A case of simultaneous infection of the lungs of a dog with canine distemper virus (CDV) and canine adenovirus (CAV) is described. The techniques employed are histological stains, immunoperoxidase technique, and transmission electron microscopy. Two viruses are shown to infect the same cells. The significance of dual infection of the same cells is discussed in comparison with literature data on in vitro experiments.

Replication of porcine enteric adenovirusesin vivo

SummaryThe replication of an enteropathogenic porcine adenovirus in the intestinal epithelial cells of naturally and experimentally piglets has been studied by transmission electron microscopy (TEM) and by immunoperoxidase (Ip) staining of paraffin sections.Three types of intranuclear inclusion bodies were observed. Viral particles appeared to be assembled from electron dense crescents which seemed to originate from type II intranuclear inclusion bodies. Virus accumulated in the nucleus of infected cells. It formed paracrystalline arrays in the electron dense centre of the nucleus but was dispersed in the peripheral electron translucent zone. Virus was released from the cells after rupture of the nuclear and plasma membranes.The results are compared with published data on the replication of adenoviruses in cell cultures.