A three-step solid-phase radioimmunoassay, HAVAB-M, was developed for use in clinical labs as an aid to diagnosing hepatitis A. Polystyrene beads were coated with anti-human IgM (mu-chain specific) and were incubated successively with serum specimen, HAV, and anti-HAV 125I. HAVAB-M was used to assay sera from patients with hepatitis A and was found to have high sensitivity for the IgM antibody to HAV. The antibody was detectable within a few days of onset of symptoms of hepatitis, and it reached maximum concentrations within one to three weeks. The test was designed so that most patients' sera would become negative approximately three months after onset. HAVAB-M was shown to be specific for IgM antibody, with virtually no detection of IgG anti-HAV. The test showed no interference fro rheumatoid factor and no cross-reactivity with sera from patients with hepatitis B or other infectious diseases.
The total carbohydrate content of purified hepatitis B antigen (HB Ag) ranged between 3.6 and 6.5% as determined by the phenol-sulfuric acid method. Disc-sodium dodecyl sulfate PAGE of purified HB Ag followed by periodate-Schiff staining revealed one major and two minor glycoproteins with molecular weights of 22,000,27,000 and 32,000 daltons, respectively. Both ad and ay subtypes of HB Ag contained these glycoproteins.
Monolayers of pancreatic p-cells from strains of mice susceptible @IL/J) and resistant (C57BL/&l) to the development of virus-induced diabetes mellitus were inoculated with the M variant of encephalomyocarditis (EMC) virus. Immunofluorescence showed that viral antigens appeared in up to 10 times more /3 cells from susceptible &IL/J mice than from resistant C57BLKJ mice. Infectious center assays revealed that lo-30 times more &IL/J /I cells contained infectious virus than C57BLFJ p cells. Viral attachment experiments showed no difference in the binding of EMC virus when embryonic fibroblasts, pancreatic fibroblasts, and kidney cells from SJLlJ and C57BL/&J mice were compared. However, at least twice as much virus attached to the pancreatic /3 cells from susceptible than from resistant strains of mice. Our data suggest that genetically determined differences in viral receptors on the surface of fi cells may be one of the factors controlling susceptibility to EMC-induced diabetes mellitus. 606
The morphological forms of hepatitis B antigen (HBsAg) present in an HBsAg-positive plasma (15–25 nm spheres, filaments 20–22 nm in diameter and 80–300 nm in length, and 42 nm Dane particles) were isolated and characterized biophysically. The HBsAg in this plasma was fractionated into five distinct populations, containing predominately 15–19 nm spheres, 20–22 nm spheres, 20 × 300 nm filaments, a mixture containing 23–25 nm spheres and rare filaments, and 42 nm Dane particles, respectively. These populations were labeled with 125I and electrofocused in a pH ampholyte gradient. Each population had a distinct isoelectric pH with values ranging from 3.65 to 4.70. Sodium dodecyl sulfate polyacrylamide gel electrophoretic analysis of each of the above labeled populations revealed the presence of 7, 10, 9, 5, and 9 polypeptides, respectively. The population containing predominately 23–25 nm spheres failed to react with antibody specific for HBsAg and probably was composed of inner cores of the Dane particles.
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