American Red Cross experience with routine testing for hepatitis B core antibody

Risk factors of isolated antibody against core antigen of hepatitis B virus: association with HIV infection and age but not hepatitis C virus infection

BACKGROUND

Isolated antibody to hepatitis B core antigen (anti-HBc) is defined as seropositivity for anti-HBc in the absence of hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). It is commonly found in HIV-infected persons or hepatitis C virus (HCV)-infected persons, but the risk factors for isolated anti-HBc remain uncertain, especially in regions that are hyperendemic for hepatitis B virus (HBV) infection.

METHODS

This cross-sectional study included a cohort of 955 nonhemophiliac, HIV-infected patients, diagnosed between 1988 and 2009, and 643 HIV-uninfected injection drug users (IDUs) attending the methadone clinic between August 2007 and May 2009, with available HBV serological data. The medical records were reviewed to identify the risk factors associated with seropositivity of isolated anti-HBc.

RESULTS

The overall seroprevalence of isolated anti-HBc was 12.1% (193 of 1598), in which occult HBV infection accounted for 1.6% (3 of 185) and the majority (91.2 %, 176 of 193) had low titers of anti-HBs (3.6 +/- 2.9 IU/L). Subjects with isolated anti-HBc were significantly older (40.7 +/- 9.3 versus 36.9 +/- 8.0, respectively, P < 0.0001). There was a significantly increasing trend in the prevalence of isolated anti-HBc with age, from 4.0% in those younger than 30 years to 22.5% after 50 years of age (test for trend, P < 0.0001). A significantly higher prevalence of isolated anti-HBc was observed in HIV-infected subjects [14.0% (134 of 955) versus 9.2% (59 of 643), adjusted odds ratio, 1.64; P < 0.01], but not in those with HCV infection (P = 0.18).

CONCLUSIONS

Isolated anti-HBc seropositivity was significantly associated with HIV infection, and older age. HCV infection was not associated with isolated anti-HBc in a country hyperendemic with HBV infection, even in populations with a high prevalence of HCV infection. The majority was not attributable to occult HBV infection, but rather, low level of anti-HBs, suggesting that HBV vaccination may not be required.

High frequency of HCV infection in individuals with isolated antibody to hepatitis B core antigen

Although isolated antibody to hepatitis B core antigen (anti-HBc) is frequently nonspecific or may be the only serological marker of past self-limiting hepatitis B, where antibodies against the surface antigen have disappeared, isolated anti-HBc seropositivity is frequently associated with chronic hepatitis B in HIV- and HCV-infected individuals. Of 5,520 samples that tested positive for anti-HBc (IMx and AxSYM CORE, Abbott, Delkenheim, Germany) at the Institute of Virology, University Clinic Frankfurt during the time interval from January 1994 to February 1996, 643 (11.6%) were isolated anti-HBc-reactive in the IMx and AxSYM CORE assays (inhibition values >90%). There was a statistically significant association between isolated anti-HBc seropositivity and HCV and HIV/HCV coinfection (p < 0.05). A total of 190 samples were available for further testing. Six (3.2%) of 190 isolated anti-HBc-positive samples were considered false-positive since they were only positive in the AxSYM or IMx CORE assay and a linear decrease of the measured signal could not be observed in dilution series. Of 184 serum samples tested with nested PCR using primers of the S genome region, only 6 (3.3%) were HBV DNA-positive. Anti-HBc-IgM antibody could be detected in 3 (1.6 %) of the tested samples using the IMx CORE-M. With the more sensitive VIDAS HBc IgM specific IgM antibody was detected in 15 (8.5%) of 177 samples at concentrations ranging from 10 to >200 Paul Ehrlich Institute U/ml. HIV or HCV coinfection was present in 28.1% and 37.5% of isolated anti-HBc-positive individuals, respectively. We conclude from our observations that only a limited proportion of anti-HBc-isolated individuals are potentially infectious, however anti-HBc-IgM which is detectable in any form of liver disease associated with HBV infection was present in more than 8% of the individuals. Of isolated anti-HBc-positive sera 37% were positive for anti-HCV, suggesting that anti-HCV antibody testing should be performed in isolated anti-HBc-positive individuals.

Hepatitis B core antibody screening in a high prevalence group: comparison of three enzyme immunoassays using receiver operating characteristic analysis

Selected sera from 296 homosexual men were screened by 3 commercially available anti-HBc enzyme immunoassays (EIA). All patients could be classified either as non-immune to hepatitis B, or with current or previous hepatitis B infection. Using the cut-off optical density values (O.D. values) recommended by the respective manufacturers, the results from these three assays were identical for 83% of the serum samples. For anti-HBc reactivity, the ratio (percentage) was calculated using O.D. sample x 100 divided by the O.D. cut-off value. Employing these ratios, sensitivities and specificities for the three assays were compared. All assays performed well when analyzed by receiver operating characteristic curves with area under the curves of 96-97%. A higher specificity, with only a marginal loss of sensitivity could be achieved by lowering the cut-off to 55% for the Enzygost EIA, to 85% for the Enzygost-monoclonal EIA and to 60% for the Corzyme EIA. Using the modified cut-off values, the results with the three assays agreed for 93% of the serum samples.

U.K. multicentre study on blood donors for surrogate markers of non-A non-B hepatitis. Part I: Alanine transferase and anti-HBc testing

Blood samples from 9,215 blood donors in three U.K. centres (North London, Bristol and Manchester) were tested for their alanine aminotransferase (ALT) level and the presence of anti-HBc and anti-HCV. This paper presents the results of the ALT and anti-HBc tests. The prevalence of ALT > 45 IU/l was 3.1% overall (North London 3.06%, Bristol 4.56% and Manchester 1.97%). Manchester results were skewed by the methodology used for ALT measurement, highlighting the need for standard test methods. Anti-HBc was detected using the Wellcome enzyme-immunosorbent assay (EIA) and confirmatory testing was performed using a radioimmunoassay (RIA) and the Corecell haemagglutination assay. Repeat reactive rates were 0.9, 0.79 and 0.94% for North London, Bristol and Manchester, respectively, with an overall rate of 0.9%. The confirmed positive rate was 0.73, 0.53 and 0.65% for the three centres with an overall rate of 0.63%. Donors with an ALT > 45 IU/l, or with confirmed anti-HBc, were interviewed with a medical questionnaire for risk factors. The major contributing factors in donors with a raised ALT were alcohol consumption and obesity.

[The medical interview motivated by the discovery of markers of viral hepatitis permits the identification, in blood donors, of behavior at risk for HIV infection]

From December 1988 to September 1989, 973 blood donors, deferred for anti-HBc reactivity, Ag-HBs positivity, elevated ALT, isolated or associated, but negative for anti-HIV, were interviewed in our blood center in the weeks after donation. Among these 973 donors, 53 (5.4%, 46 males, 7 females) were found at risk for HIV infection: intravenous drug abuse: 24 cases; heterosexuality with multiple partners: 17 cases; homosexuality: 8 cases; sexual relations with persons at risk: 4 cases. These 53 donors did not recognize their risk behaviour during the medical talk before donation. 25 out of these 53 donors were seen afterwards and one of them, homosexual man, seroconverted for anti-HIV seven months after the anti HIV negative but anti-HBc positive blood donation. We conclude that, in our experience, director surrogate viral hepatitis markers help to identify donors at risk for HIV infection, and, in one case, earlier in the course of demonstrated HIV infection than the enzyme immunoassays currently licensed.