Effective protection against influenza after vaccination with subunit vaccine.

Immunization with an influenza subunit vaccine given in one dose about 1 month to 2 months before onset of an epidemic of influenza afforded from 80% to 90% protection in a double-blind clinical trial which was supported by isolation of virus and serological studies. In the vaccinated group, 20% failed to develop antibodies to the vaccine. Either serology tests or attempted isolation of virus alone would have failed to detect some of the cases.

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.

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 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.

A prospective study of acute viral hepatitis with particular reference to hepatitis A.

In order to investigate the relationship of hepatitis A antigen to viral hepatitis, a prospective study was carried out on 97 patients admitted to Fairfield Hospital, Melbourne, with suspected viral hepatitis, and 3 of their family contacts. Evidence of infection with hepatitis A virus was obtained by detecting hepatitis A antigen in stools, and/or antibody to it in sera, by immune electron microscopy. Infection with hepatitis B virus was determined by testing for hepatitis B surface antigen and antibody in serum, by solid phase radioimmunoassay. Sixteen patients were found to have diseases other than viral hepatitis and 2 patients (child contacts) suffered no illness. There was clinical and/or biochemical evidence compatible with viral hepatitis in 82 patients, of whom 35 were confirmed as having hepatitis A and 31 as having hepatitis B infections. In the remaining 16 patients there was no evidence of infection with either hepatitis A or B virus. It is possible that some of these patients may have been infected with viral agents as yet unidentified.