The probable ancestral haplotype for human apolipoprotein B (apoB) has been identified through immunological analysis of chimpanzee and gorilla serum and sequence analysis of their DNA. Moreover, the frequency of this ancestral apoB haplotype among different human populations provides strong support for the African origin of Homo sapiens sapiens and their subsequent migration from Africa to Europe and to the Pacific. The approach used here for the identification of the ancestral human apoB haplotype is likely to be applicable to many other genes.The low density lipoproteins (LDL) are the principal carriers of cholesterol in the blood of humans and many higher animals. A single protein is found on the LDL; this protein, named apolipoprotein B (apoB), is composed of 4536 amino acid residues arranged in a single polypeptide chain (1). Allelic variants of apoB are immunogenic, causing antibodies to be produced in the blood of patients who have received multiple transfusions. Immunological studies on these patients eventually identified a group of five immunogenic sites on their LDL; these became known as the "antigen group" (Ag) polymorphism, and the five sites were called Ag(c/g), Ag(a/d), Ag(x/y), Ag(h/i), and Ag(t/z) (2). As shown in Fig.
The significance of indeterminate screening antibody test for human immunodeficiency virus (HIV) serology is still difficult to evaluate, especially in low-risk populations. One hundred twenty-seven blood donors with an initially reactive screening test for HIV antibodies were enrolled in this study. The sera of 95 of these blood donors were reactive on repetition of the test, and none had detectable circulating p24 antigen. Western blot (WB) analysis of the repeatedly reactive sera was as follows: 9 positive, 31 indeterminate, and 55 negative. One of the blood donors with indeterminate WB later presented a seroconversion. On subsequent control 3 to 12 months later, the sera from donors with indeterminate or negative WB did not present any parameters that may indicate a seroconversion. DNA was purified from citrated blood collected from the 127 blood donors at the time of the initial antibody screening. Five micrograms of each DNA sample corresponding to 7 x 10(5) nucleated white blood cells was amplified by polymerase chain reaction (PCR) in the presence of oligonucleotides (primers) corresponding to a highly conserved segment of the pol gene. The detection of amplified DNA was achieved by dot blot and Southern blot using appropriate 32P-labeled oligonucleotides. Ten DNA samples were positive, 9 corresponded to blood donors with a positive HIV serology, and 1 to the blood donor who later presented a seroconversion. These results confirm the sensitivity of the PCR for the diagnosis of HIV infection; they also suggest that repetition of the serology at 3- to 12-month intervals is a valuable procedure for the control of HIV infection status in blood donors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.