Acute Hepatitis in a Piglet Experimentally Inoculated with Tissue Homogenates from Pigs with Postweaning Multisystemic Wasting Syndrome

Abstract

ABSTRACT. Five 2 day-old colostrum-deprived piglets were inoculated with tissue homogenates from pigs with postweaning multisystemic wasting syndrome. One of the five piglets developed icterus and died 23 days post-inoculation. Histologic examination revealed acute hepatitis. Porcine circovirus type 2 (PCV-2) antigen and nucleic acid were detected in hepatocytes and phagocytic cells. Ultrastructurally, hepatocytes and phagocytic cells had large numbers of cytoplasmic inclusions, which were composed of electron-dense paracrystalline arrays of small non-enveloped viral particles approximately 17 nm in diameter. Apoptotic hepatocytes were confirmed by the TUNEL method and electron microscopic examination. These findings may indicate that hepatocellular necrosis is associated with replication of PCV-2. Apoptosis of hepatocytes also contributes to the pathogenesis of hepatic lesions in this case. KEY WORDS: hepatitis, PCV-2, PMWS.

Occurrence of Swine Salmonellosis in Postweaning Multisystemic Wasting Syndrome (PMWS) Affected Pigs Concurrently Infected with Porcine Reproduction and Respiratory Syndrome Virus (PRRSV)

“…PCV2 immunolabelling in the apoptotic hepatocytes has been already reported by Rosell et al [20] and Hirai et al [8]. PCV2 antigens were also found in the degenerated cells which were phagocytosed by histocytes or multinuclear giant cells in the nodules, being analogous to "paratyphoid" nodules in one case.…”

Infectivity of Porcine Circovirus 1 and Circovirus 2 in Primary Porcine Hepatocyte and Kidney Cell Cultures

“…During fetal life, cardiomyocytes, hepatocytes and macrophages were main target cells of PCV2 [12]. In our previous study, we reproduced lymphadenitis and hepatitis in a piglet experimentally inoculated with tissue homogenates from pigs with PMWS [5]. The aim of this study was to confirm if PCV2 can infect primary porcine hepatocyte cultures as observed in the liver of PMWSaffected pigs.…”

“…In many cases of PMWS, lymphadenitis and hepatitis are the commonly observed lesions. Since hepatic necrosis and/or apoptosis have been detected in the hepatic lesions of PMWS [4,5,7,9,10], hepatocytes also seem to be a target cell for PCV2 infection [5,10]. During fetal life, cardiomyocytes, hepatocytes and macrophages were main target cells of PCV2 [12].…”

“…The PCV2 inoculum used in this study was the same as reported previously [5]. Briefly, the inoculum (10 3.0 TCID 50 /ml) was derived from lymphoid tissue homogenates of pigs diagnosed as PMWS.…”

“…For immunohistochemistry (IHC), hyperimmune swine sera raised against PCV1 or PCV2 was used. The procedures of IHC and in situ hybridization (ISH) were similar to those previously described [5,6]. PCV-positive cells were counted in the dishes of hepatocyte and kidney cell cultures at the indicated time points after infection.…”