Hepatitis B virus type 2.

The worldwide consensus of the minimum protective anti-HBs level against HBV infection is 10 mIU/mL on assays standardized by the World Health Organization (WHO) reference preparations. To investigate whether this value could be applied to recipients of yeast-derived recombinant HB vaccine containing the major surface protein of subtype adr (Bimmugen, Astellas Pharmaceutical, Tokyo), we compared anti-HBs measurements between chemiluminescent immunoassay (CLIA) (Architect Ausab, Abbott Japan, Tokyo) and chemiluminescent enzyme immunoassay (CLEIA) (Lumipulse Forte, Fujirebio, Tokyo) in given serum samples obtained from the vaccinees. The vaccine and the two assay methods are currently in a wide use in Japan. The study included 300 medical students who completed a standard vaccination course (0, 1 and 6 months). Serum samples obtained 1 month or 13 months after completing the vaccination were simultaneously tested for anti-HBs by CLIA and CLEIA. In 147 samples with quantifiable values on both CLIA and CLEIA (10 to 1000 mIU/mL) the geometric mean titer on CLEIA (225.0 mIU/mL) was significantly higher than that on CLIA (94.5 mIU/mL) (p < 0.0001). Of 26 subjects with CLIA measurements below 10 mIU/mL, 15 samples (57.7%) showed CLEIA measurements more than 10 mIU/mL. Thus, in the subtype adr-vaccinees CLEIA demonstrated considerably high serum anti-HBs measurements compared to CLIA and discordance in determining critical anti-HBs level of 10 mIU/mL was observed in more than half the samples. This suggests that the minimum HBV-protective anti HBs titer of 10 mIU/mL is difficult to be introduced to Japan where subtype adr-HB vaccines or -HBV infection are prevalent, unless characteristics of assay methods are carefully evaluated.

Hepatitis B Antibodies↗

PubMed2004

[Hepatitis B virus surface antigen reactivity in the absence of antibodies to core antigen: an atypical serological pattern having diverse significance].

BACKGROUND: Reactivity for hepatitis B virus (HBV) surface antigen (HBsAg) in samples lacking antibody to the HBV core antigen (anti-HBc) may be due to either non-specific reactions or sample contamination, but it can also reflect other situations that may present clinical relevance. In Spain, the frequency described for this atypical pattern of HBV markers ranged from 0.05 to 1.3% in different series, so that it can be considered as moderately frequent. METHODS: Confirmatory assays for HBsAg and tests for detecting total and IgM anti-HBc, HBV "e" antigen and viral DNA were performed on serum samples taken from 96 patients who showed reactivity for HBsAg in absence of total anti-HBc on routine studies. These samples were collected between January, 2001 and May, 2002 and were sent for study from different Spanish laboratories. Follow-up samples were also studied from selected cases. RESULTS: Presence of HBsAg was excluded in 70 cases (72.9%) and total anti-HBc was detected in two additional patients, so that the original results were confirmed in 24 patients (25.0%). After further investigations, two early phases of the window period of the acute HBV infection were identified, as well as a further case of chronic HBV carriage in absence of antibody response. A single case could be confirmed as due to a contamination of the aliquot of sample studied. The pattern of HBV markers and its evolution on the follow-up were the characteristic of the phenomenon known as "hepatitis B virus type 2 infection" in eight patients. No conclusions could be drawn from the remainder 12 cases, since no follow-up samples were available for study. CONCLUSIONS: Besides most cases respond to non-specific reactions or reflect situations of low clinical relevance, the reactivity for HBsAg in samples lacking anti-HBc should be taken into consideration and routinely investigated, since this atypical pattern can also reflect unusual, but clinically relevant facts of the HBV infection that must be noticed.

Hepatitis B Antibodies↗