THE JOURNAL OF I:-.IFECTIOUS DISEASES. VOL. 134, NO.5. NOVEMBER 1976
© 1976 by the University of Chicago. All rights reserved.
From the Center for Disease Control
The visualization by immune electron microscopy (IEM) of 27-nm virus-like particles in specimens of human stool obtained before and in the early acute phase of hepatitis A [1, 2] provided the initial basis for identification of a particulate antigen (HA Ag) closely associated with hepatitis A. It was recognized that HA Ag could be used in IEM for detection of homologous serum antibody (anti-HA). Subsequent studies in both chimpanzees [3, 4] and marmosets [5, 6] provided substantial evidence that the 27-nm particles are probably the virus that causes type A hepatitis. The recent adaptation of a microtiter solidphase immunoradiometric assay technique (micro-SPIRA) for detection of HA Ag [7] has enabled us to monitor and recover this antigen on a continuing basis from stools of chimpanzees experimentally infected with hepatitis A virus. U sing purified HA Ag derived from such chimpanzee stools in a modified, double-antibody, micro-SPIRA procedure for measurement of antiHA [8], we collected preliminary data on prevalence of this antibody in a human population. We examined 538 sera from a stratified random sample of the population of Corpus Christi, Please address requests for reprints to Dr. James E. Maynard, Phoenix Laboratories Division, Center for Disease Control, Phoenix, Arizona 85014.
Table 1. Frequency of antibody to hepatitis A virus according to age and socioeconomic class of 538 randomly selected persons in Corpus Christi, Texas. Socioeconomic class" Upper Age (years)
0-4 5-14 15-29 30-49 ~50
Total "Upper
No. tested
Middle
Percentage positive
No. tested
Lower
Percentage positive
No. tested
Combined
Percentage positive
No. tested
Percentage positive
6 36 29 47 30
0 3 17 49 70
19 90 58 73 23
5 20 57 78 83
13 51 21 20 22
31 24 48 80 77
38 177 108 140 75
13 18 44 69 76
148
34
263
49
127
46
538
44
= Hollingshead category
1; middle
= Hollingshead category 2,3, and 4; 528
and lower = Hollingshead category 5 [9].
Downloaded from http://jid.oxfordjournals.org/ at University of New South Wales on September 11, 2015
Texas. These samples were collected in 1967 as part of a survey for arboviruses and were stored in the Center for Disease Control (CDC) serum bank (Atlanta, Ga.). For each participant in the survey, information on age, sex, and socioeconomic level was derived from census tract data and individual household classification according to the Hollingshead index [9J. For use in the double-antibody, micro-SPIRA procedure, HA Ag derived from chimpanzee stool was purified in a three-stage process consisting of initial polyethylene glycol precipitation followed by isopycnic banding on CcCI and separation by Sepharose'" column chromatography. As previously described [8], purified HA Ag was added to micro titer wells that had been precoated with dilutions of the serum to be tested. After incubation and washing, 125I-labeled anti-HA was added to the wells, and residual cpm were ascertained after incubation and rewashing. A positive test for anti-HA consisted of a residual cpm greater than or equal to twice the mean cpm of negative control samples. We detected anti-HA in 237 (44%) of the 538 specimens tested. A somewhat higher prevalence of antibody in females (122 of 258; 47%) was not significantly different from that found in males (114 of 280; 41%). As shown in table 1, there was a significant association between prevalence of anti-HA seropositivity and age (P
© 1976 by the University of Chicago. All rights reserved.
From the Center for Disease Control
The visualization by immune electron microscopy (IEM) of 27-nm virus-like particles in specimens of human stool obtained before and in the early acute phase of hepatitis A [1, 2] provided the initial basis for identification of a particulate antigen (HA Ag) closely associated with hepatitis A. It was recognized that HA Ag could be used in IEM for detection of homologous serum antibody (anti-HA). Subsequent studies in both chimpanzees [3, 4] and marmosets [5, 6] provided substantial evidence that the 27-nm particles are probably the virus that causes type A hepatitis. The recent adaptation of a microtiter solidphase immunoradiometric assay technique (micro-SPIRA) for detection of HA Ag [7] has enabled us to monitor and recover this antigen on a continuing basis from stools of chimpanzees experimentally infected with hepatitis A virus. U sing purified HA Ag derived from such chimpanzee stools in a modified, double-antibody, micro-SPIRA procedure for measurement of antiHA [8], we collected preliminary data on prevalence of this antibody in a human population. We examined 538 sera from a stratified random sample of the population of Corpus Christi, Please address requests for reprints to Dr. James E. Maynard, Phoenix Laboratories Division, Center for Disease Control, Phoenix, Arizona 85014.
Table 1. Frequency of antibody to hepatitis A virus according to age and socioeconomic class of 538 randomly selected persons in Corpus Christi, Texas. Socioeconomic class" Upper Age (years)
0-4 5-14 15-29 30-49 ~50
Total "Upper
No. tested
Middle
Percentage positive
No. tested
Lower
Percentage positive
No. tested
Combined
Percentage positive
No. tested
Percentage positive
6 36 29 47 30
0 3 17 49 70
19 90 58 73 23
5 20 57 78 83
13 51 21 20 22
31 24 48 80 77
38 177 108 140 75
13 18 44 69 76
148
34
263
49
127
46
538
44
= Hollingshead category
1; middle
= Hollingshead category 2,3, and 4; 528
and lower = Hollingshead category 5 [9].
Downloaded from http://jid.oxfordjournals.org/ at University of New South Wales on September 11, 2015
Texas. These samples were collected in 1967 as part of a survey for arboviruses and were stored in the Center for Disease Control (CDC) serum bank (Atlanta, Ga.). For each participant in the survey, information on age, sex, and socioeconomic level was derived from census tract data and individual household classification according to the Hollingshead index [9J. For use in the double-antibody, micro-SPIRA procedure, HA Ag derived from chimpanzee stool was purified in a three-stage process consisting of initial polyethylene glycol precipitation followed by isopycnic banding on CcCI and separation by Sepharose'" column chromatography. As previously described [8], purified HA Ag was added to micro titer wells that had been precoated with dilutions of the serum to be tested. After incubation and washing, 125I-labeled anti-HA was added to the wells, and residual cpm were ascertained after incubation and rewashing. A positive test for anti-HA consisted of a residual cpm greater than or equal to twice the mean cpm of negative control samples. We detected anti-HA in 237 (44%) of the 538 specimens tested. A somewhat higher prevalence of antibody in females (122 of 258; 47%) was not significantly different from that found in males (114 of 280; 41%). As shown in table 1, there was a significant association between prevalence of anti-HA seropositivity and age (P
