Intimal lipid accretion and elevated serum cholesterol in Marek's disease virus-inoculated chickens

In our previous studies of the early pathogenesis of the Marek's disease virus (MDV)-associated model of atherosclerosis, the brachiocephalic arteries and ascending aortas of MDV-inoculated chickens failed to develop lipid accretion and intimal/medial proliferation consistent with atherosclerotic lesions, as described in the original reports of this model. The role of cholesterol supplementation in the formation of MDV-associated atherosclerotic lesions was reexamined. At 3 days of age, 40 chicks were inoculated with the CU-2 strain of MDV. Another 40 chicks were sham inoculated. At 15 weeks postinfection, half of the sham- and MDV-inoculated birds received 2% cholesterol supplementation in the diet for the rest of the experimental period. At 30 weeks postinfection, the aortas and brachiocephalic arteries were evaluated. Several observations were different from the original description of the model. None of the chickens among the four experimental groups developed atherosclerotic lesions, regardless of MDV inoculation or cholesterol supplementation. However, intimal thickening and marked oil red O-positive foam cell accumulation were observed in all 11 MDV-inoculated, cholesterol-supplemented chickens. None of the nine MDV-inoculated, unsupplemented chickens manifested arterial lipid accumulation, despite the presence of an intimal cellular infiltrate. Also in contrast to the original model description, both cholesterol-supplemented and unsupplemented MDV-inoculated chickens manifested significant increases in serum cholesterol in comparison with the respective sham-inoculated groups.