Noreen I. Lehmann

The antibody response following hepatitis A infection.

A specific IgM response to hepatitis A virus was detected in sera from patients suffering acute hepatitis A infection. The presence of virus-specific IgM in 19S components of acute and early convalescent phase sera was detected by immune electron microscopy and solid-phase radioimmunoassay. The presence of virus-specific IgM in whole serum specimens was demonstrated by indirect immunoferritin labeling. Following acute infection, however, the major immunoglobulin response appears to be IgG, since titers of specific 7S and whole serum antibody were very similar.

Comparison of electron microscopy, enzyme-linked immunosorbent assay, solid-phase radioimmunoassay, and indirect immunofluorescence for detection of human rotavirus antigen in faeces.

Four techniques were compared for their practicability, speed, and sensitivity for the detection of human rotavirus. Radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) were found to be the most sensitive means of identifying rotavirus, and, once processed, up to 40 specimens could be examined daily. Electron microscopy, although less sensitive than these techniques, had the advantage of being able to detect other viral agents present in faecal extracts. Indirect immunofluorescence failed to detect rotavirus as often as the other three methods. In laboratories where routine examination of faecal specimens from patients with gastroenteritis is required, ELISA and RIA are useful alternatives to electron microscopy.

The polypeptides of hepatitis A virus.

Hepatitis A virus was purified from fecal specimens obtained from 3 patients with naturally acquired hepatitis A, by a process of differential centrifugation, chloroform extraction, column chromatography, and isopycnic ultracentrifugation. Analysis of purified virus by discontinuous SDS-PAGE revealed three major polypeptides with molecular weights of 34,000, 25,500, and 23,000 daltons. These polypeptides appear to be specific for hepatitis A virus and have similar molecular weights to three of the four major polypeptides reported for members of the genus Enterovirus within the family Picornaviridae.

The Detection of Hepatitis B Surface Antigen by Radioimmunoassay

Summary A comparative study was performed to assess the sensitivity and specificity of counterimmunoelectrophoresis (CIEP) and radioimmunoassay (RIA) for the detection of hepatitis B surface antigen. The 8,823 sera examined included selected reference panels and sera collected from populations with low, moderate and high rates of chronic antigen carriage. Overall, hepatitis B surface antigen was detected in 265 sera by CIEP and in 376 by RIA. As well as detecting 46.4% additional positives, the RIA test detected all CIEP‐positive sera; i.e., there were no false negative results. However, 150 sera (1.8% of the total tested) gave a positive result by RIA which was not repeatable on retesting. The explanation for this phenomenon appeared to lie in inadequate washing of the antibody‐coated tubes.

Purification of hepatitis A virus from human feces.

Hepatitis A virus was purified fecal specimens obtained from 2 patients with naturally acquired hepatitis A. The purification procedure involved differential centrifugation, organic solvent extraction, agarose gel filtration, ion-exchange chromatography, and isopycnic ultracentrifugation in cesium chloride. Using immune electron microscopy and discontinuous SDS-PAGE, this procedure was found to be effective in removing extraneous material from hepatitis A virus. There was significant recovery of virus as judged by immune electron microscopy and solid-phase radioimmunoassay. Using this protocol, it has been possible to obtain virus preparations of sufficient purity and high enough titer to enable biochemical studies to proceed.

An evaluation of the use of sensitized latex particles for the detection of the hepatitis-associated antigen

Summary The sensitivity and specificity of a latex agglutination test for the detection of hepatitis‐associated antigen has been compared with three other serological techniques in general use. The sensitivity of latex agglutination was intermediate between cross‐over Immunoelectrophoresis and complement fixation, but a considerable number of false positive results were encountered.