THE JOURNAL OF INFECTIOUS DISEASES • VOL. 134, NO.3· SEPTEMBER 1976 © 1976 by the University of Chicago. All rights reserved.

Radioimmunoassay for Antibody to Hepatitis B Surface Antigen Shows Transmission of Hepatitis B Virus among Household Contacts

c. J. Peters, * R. H. PureeD, J. J. Lander, t and K. M. Johnson

From the Middle America Research Unit, Balboa Heights, Canal Zone; and the Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland

In an attempt to understand the mechanisms of HBV transmission in the community, we studied household contacts of patients with hepatitis and of carriers of HB s Ag with use of the sensitive radioimmunoprecipitation test for detection of antibody to HB s Ag (anti-Hb,').

Hepatitis B surface antigen (HB s Ag) has provided a useful marker of infection with one strain of human hepatitis virus, even though the exact relation between viremia and antigenemia is still unclear. The presence of HB s Ag in acute-phase sera from one-quarter of the adults hospitalized with sporadic hepatitis in Panama City, Panama [1] demonstrated active transmission of hepatitis B virus (HBV) , but in many cases it was not possible to implicate household carriers [1], contact with another patient with hepatitis, or recognized parenteral exposure as a source of infection. 1

Materials and Methods

Technical procedures. Sera were separated from blood clots within 48 hr of collection and were stored in coded vials at - 20 C. All sera were tested for HB s Ag by counterelectrophoresis [2] and by CF [3] at the Middle America Research Unit. Radioimmunoprecipitation tests for antiHB s were performed in the Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases [4]. Sera were routinely tested at a 1: 4 dilution with goat antiserum to human y-globulin as a precipitating reagent. Sera with binding of ~ 15 % were considered positive if results were confirmed in repeat tests. Separate aliquots from all apparent seroconversions were retested and were accepted as valid if the first sample had less than 10% binding and the second had ~15%. Drs. Harvey Alter and Paul Holland (Blood Bank, Clinical Center, National Institutes of Health, Bethesda, Md.) performed the radioim-

Received for publication September 22, 1975, and in revised form January 19, 1976. This paper is publication no. 1036 from the Department of Immunopathology, Scripps Clinic and Research Foundation, La Jolla, California. Please address requests for reprints to Dr. R. H. Purcell, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20014. * Present address: Scripps Clinic and Research Foundation, La Jolla, California. t Present address: Washington University Medical School, Department of Medicine, Barnes Hospital Plaza, St. Louis, Missouri. 1 Fifty-eight consecutive HB s Ag-positive patients [1] were queried concerning exposure to jaundiced persons or injections in the previous six months, and 16 (28%) denied either (C. J. Peters, unpublished observations).

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The epidemiology of infections with hepatitis B virus was studied by measurement of serum antibodies to hepatitis B surface antigen (HB s Ag) with the radioimmunoprecipitation test. Prospective studies of household contacts of HB s Ag-positive patients with acute hepatitis demonstrated that four of 41 children and one of 60 adults experienced anicteric seroconversions. Two of the 60 adults also had mild icteric hepatitis and became chronically antigenemic. Neither HB s Ag nor antibody to HB s Ag was detected in follow-up blood samples from 85 seronegative contacts of HB s Ag-negative patients with hepatitis, although seven icteric secondary cases were identified. Household contacts of HB s Ag carriers frequently had serologic evidence of exposure to hepatitis B virus (44% of adults), but the remainder had neither detectable antigen nor antibody.

Transmission of Hepatitis B Virus

Table 1. Characteristics of the index persons who were included in the study. No. of subjects with indicated characteristic

Characteristic

HB s Ag-positive hepatitis

HB s Ag carrier

HB s Ag-negative hepatitis

Age

Radioimmunoassay for antibody to hepatitis B surface antigen shows transmission of hepatitis B virus among household contacts.

THE JOURNAL OF INFECTIOUS DISEASES • VOL. 134, NO.3· SEPTEMBER 1976 © 1976 by the University of Chicago. All rights reserved. Radioimmunoassay for An...
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