Submitted to: Veterinary Pathology
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/1997
Publication Date: N/A
Technical Abstract: Recent unusually severe abortion storms in swine associated with PRRSV infection have been characterized by 10-50% of the herd aborting in a 1-5 week period and 5-10% sow mortality. Sows in 4 affected herds exhibited hepatitis characterized by hepatocellular swelling, multifocal hepatocyte apoptosis, and portal and sinusoidal infiltrates of mononuclear inflammatory cells, a lesion not previously associated with PRRSV infection. Four groups of 26-day old cesarean-derived, colostrum-deprived pigs (7/group) were inoculated oronasally and intravenously with one of 4 liver filtrates from sows with hepatitis from four different herds experiencing severe abortion storms. Two other groups received cell culture propagated PRRSV isolates from two of the herds. PRRSV was isolated from serum, bronchoalveolar lavage fluid, and livers from experimental pigs necropsied at 7, 14, 28, 35, and 42 dpi. Necrotizing hepatitis, hyperbilirubinemia, and increases in serum AST and GGT were induced in pigs in 2/4 liver filtrate (2/5 pigs each) and in 1/2 virus (1/5 pigs) groups between 14 and 42 dpi. We conclude that some highly virulent strains of PRRSV sporadically induce necrotizing hepatitis or that a coinfection with another virus has occurred.