Kane J P, Hardman D A, Dimpfl J C, Levy J A
Proc Natl Acad Sci U S A. 1979 Nov;76(11):5957-61. doi: 10.1073/pnas.76.11.5957.
We have shown that the circulating lipoproteins of the mouse contain a potent inhibitor of infectivity of the xenotropic type C virus. This virus neutralization does not involve immunoglobulins or complement. After fractionation of the lipoproteins on the basis of particle size, flotation properties, and electrostatic charge, virus neutralizing activity is found primarily in the triglyceride-rich lipoproteins (predominantly the chylomicrons) and in the HDL(2) subfraction of the high density lipoproteins. In fasted animals, activity resides chiefly in the high density lipoproteins. Neutralization titers increase strikingly during alimentary lipemia in both the lipoproteins of the rho < 1.006 g/cm(3) fraction and the high density lipoproteins. Increased activity persists in the high density lipoproteins after the lipemia recedes. Virus neutralizing activity is completely eliminated in all fractions by antiserum against high density lipoproteins and, in the triglyceride-rich fractions, by antiserum to murine apolipoprotein B. Complete removal of lipids markedly reduces the neutralizing activity of both classes of lipoproteins. Apolipoproteins delipidated with tetramethylurea retain some activity, which is enhanced by binding to a phospholipid-stabilized triglyceride emulsion and which is abolished by proteolytic digestion. We have demonstrated in vitro transfer of activity between high density and very low density lipoproteins of the mouse. These data indicate that xenotropic virus neutralization by normal mouse serum depends upon a protein that transfers among lipoprotein particles in a fashion analogous to the C apolipoproteins of other mammalian species.
我们已经证明，小鼠的循环脂蛋白含有一种对嗜异性C型病毒感染力有强大抑制作用的物质。这种病毒中和作用不涉及免疫球蛋白或补体。根据颗粒大小、漂浮特性和静电荷对脂蛋白进行分级分离后，发现病毒中和活性主要存在于富含甘油三酯的脂蛋白（主要是乳糜微粒）以及高密度脂蛋白的HDL(2)亚组分中。在禁食动物中，活性主要存在于高密度脂蛋白中。在食后脂血症期间，ρ<1.006 g/cm(3)组分的脂蛋白和高密度脂蛋白中的中和滴度均显著增加。脂血症消退后，高密度脂蛋白中的活性仍然持续升高。用抗高密度脂蛋白抗血清可使所有组分中的病毒中和活性完全消除，而在富含甘油三酯的组分中，用抗小鼠载脂蛋白B抗血清也可使其消除。完全去除脂质会显著降低这两类脂蛋白的中和活性。用四甲基脲脱脂的载脂蛋白保留了一些活性，这种活性通过与磷脂稳定的甘油三酯乳剂结合而增强，并可被蛋白水解消化消除。我们已经在体外证明了小鼠高密度脂蛋白和极低密度脂蛋白之间的活性转移。这些数据表明，正常小鼠血清对嗜异性病毒的中和作用取决于一种以类似于其他哺乳动物物种载脂蛋白C的方式在脂蛋白颗粒之间转移的蛋白质。
