Anna O'Connell

ANTIBODY TO HEPATITIS-B CORE ANTIGEN IN PATIENTS WITH PRIMARY HEPATIC CARCINOMA

Antibody to hepatitis-B core antigen (anti-HBc) was assayed in the serum of patients with primary hepatic carcinoma (P.H.C.) and controls from Hong Kong, West Africa, and the United States. In each region the prevalence of anti-HBc was higher in P.H.C. patients than in controls, ranging from 70 to 95% in the patients and from 20 to 68% in the controls from Asia and Africa; 24% of P.H.C. patients and 4% of controls from the U.S. had anti-HBc. These data support the hypothesis that chronic infection with hepatitis-B virus is aetiologically related to P.H.C., especially in Asia and Africa, although other factors must also be involved.

Viral antigen expression in the pancreas of DHBV-infected embryos and young ducks

The time course of appearance of viral antigen-positive pancreatic cells was examined in both congenitally duck hepatitis B virus (DHBV)-infected duck embryos and experimentally DHBV-infected posthatch ducks. In the embryos, the earliest detectable viral antigen-positive pancreatic cells were localized to islets and identifiable as endocrine on the basis of hormone expression. Non-islet-associated, viral antigen-positive cells appeared at a late stage of embryogenesis, following the onset of chymotrypsinogen production by exocrine tissue; a number of these viral antigen-positive cells were directly identifiable as exocrine on the basis of chymotrypsinogen expression. By contrast, in the pancreas of experimentally infected posthatch ducks, the appearance of viral antigen-positive exocrine cells (chymotrypsinogen-positive) predated the appearance of antigen-positive islet cells. These results are consistent with the possibility that viral antigen expression in exocrine tissue is dependent on the state of cell maturation.

DNA Polymerase Activity in Human Serum: Studies with Australia Antigen

Summary The presence of DNA polymerase in normal human serum and its possible association with Australia antigen was investigated. DNA polymerase activity was determined in 135 samples of normal serum. Only 3 samples revealed appreciable amounts of activity. The addition of a variety of polynucleotide templates did not stimulate polymerase activity. Australia antigen is a particle associated with hepatitis and is reported to contain RNA. A DNA polymerase, “reverse transcriptase” might be required for replication of this RNA. We found DNA polymerase activity in only one of five preparations of purified Australia antigen. A similar activity was also found to be present in serum from certain normal volunteers. In either case, polymerase activity does not require nor is it stimulated by added polynucleotides suggesting that the enzyme may already be associated with a template such as RNA or DNA. A comparison between the amount of DNA polymerase activity in serum and the presence of Australia antigen in three series of patients with Downs syndrome and hepatitis revealed at most a marginal positive association. Thus, DNA polymerase is probably not a part of Australia antigen and the association observed is probably of an indirect nature. Its presence in occasional normal sera must be considered when using this activity as an index for detection of oncogenic viruses.

The incorporation of radioactive uridine into the hepatitis B antigen of a chimpanzee.

Summary Radioactive (3H) uridine was incorporated into RNA isolated from the HBsAg of a chimpanzee carrier. HBsAg was purified by precipitation as an immune complex with the IgG fraction of chimpanzee anti-HBs. RNA was extracted from the washed complex with buffered phenol precipitated with alcohol and four nucleotides were identified by thin layer chromatography after alkali degradation. We acknowledge with appreciation the time and assistance of Dr. Manfred E. Bayer for the electron microscopic examination of the purified HBsAg—anti HBs complexes. Addendum. After this work was prepared for publication we became aware of the possibility that radioactive uridine could have been incorporated into uridine diphosphoglucose and not RNA. We have since repeated the procedure for the isolation of nucleic acid described in methods but included two additional steps. (1) The chimpanzee plasma was treated with 25 μg/ml of RNAse (4000 units/mg, Worthington, Freehold, NJ) and incubated for 15 min at 37°. A control containing 14C labeled RNA was shown to be completely degraded under the same conditions of treatment. The treated plasma was then extracted with buffered phenol as described in the Materials and methods section. (2) The alcohol precipitated and redissolved RNA was then precipitated with perchloric acid (final concentration 0.2 N). The perchloric acid precipitate, adhering to a fiberglass filter, contained the same radioactive count as the KOH hydrolyzed material originally described under Materials and methods. Uridine diphosphoglucose is not precipitable under these conditions. To further exclude the possibility that the material we were dealing with was not RNA an aliquot of ethanol precipitated material (approx one-fifth of the total yield described in methods) was dissolved in distilled water and treated with 80 μg of RNAse for 15 min at 37°. Perchloric acid was added to a final concentration of 0.2 N.