August 16, 1991) ABSTRACT Recombinant soluble CD4 (rsCD4) has potent antiviral activity against cell line-adapted isolates of the human immunodeficiency virus type 1 (iHV-1) but low activity toward H1V-1 primary isolates from patients. A simple hypothesis proposed to explain this discrepancy, which questions the therapeutic utility of soluble CD4-based approaches, is that the major envelope glycoprotein, gpl20, of patient virus has lower

Two novel, distinct truncated forms of apolipoprotein B (apo B) designated as apo B-90 and apo B-40 were found in five members of a kindred with hypobetalipoproteinemia. Sodium dodecyl sulfate gels and immunoblots of plasma or low density llpoproteln (LOL) (d=1.019 to 1.063 g/ml) of the affected members demonstrated the presence of one or both of the truncated apo B bands. Employing four monoclonal antl-LDL antibodies with defined regional specificities, we demonstrated that amlno terminal epttopes of the truncated apo Bs were Intact, but that 10% and 60%, respectively, of the carboxyl terminal regions were absent Tnrombln digestion of apo B-90 generated an abnormally small T2 fragment, confirming that approximately 550 amlno acids had been deleted from the carboxyl terminus of apo B-100. A polipoprotein B (apo B) is important in lipoprotein metabolism. Under normal conditions, human apo B is secreted in two forms, one with apparent A^=550 Kd (apo B-100) from liver in association with very low density lipoprotein (VLDL) and another with apparent M r =246 Kd (apo B-48) from intestine in association with chylomicrons. Hepatic VLDL are converted to intermediate density lipoprotein (IDL) and low density lipoprotein (LDL), which are removed from circulation via LDL receptormediated endocytosis, and apo B-100 serves as the ligand for lipoprotein recognition in this case.Familial hypobetalipoproteinemia (HBL), is characterized in the homozygous state by symptoms that resemble abetalipoproteinemia (ABL).

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