Evaluation of the highly sensitive chemiluminescent enzyme immunoassay "Lumipulse HBsAg-HQ" for hepatitis B virus screening.

BACKGROUND: Ongoing efforts in the development of HBsAg detection kits are focused on improving sensitivity and specificity. The purpose of this study was to evaluate an improved, highly sensitive quantitative assay, "Lumipulse HBsAg-HQ", a chemiluminescent enzyme immunoassay designed for a fully automated instrument, the "Lumipulse G1200". METHODS: Serum samples for reproducibility, dilution, correlation, sensitivity, and specificity studies were obtained from patients at the Osaka University Hospital. Seroconversion and sensitivity panels were purchased from a commercial vender. Subtype, sensitivity panels, and HBsAg recombinant proteins with one or two amino acid substitutions were prepared in-house. RESULTS: The coefficients of variation for the low, medium, and high concentration samples ranged from 1.93 to 2.55%. The HBsAg-HQ reagent for dilution testing showed good linearity in the 0.005-150 HBsAg IU/mL range and no prozone phenomenon. All 102 HBV carrier samples were positive by HBsAg-HQ, while other commercial reagents showed one or more to be negative. In the seroconversion panel, the 14-day blood sample was positive. The sensitivity against HBsAg-HQ "ad" and "ay" subtypes was 0.025 ng/mL. Comparisons among the HBsAg-HQ, HISCL, and Architect HBsAg reagents were performed using the Bland-Altman plot. Specificity for 1000 seronegative individuals was 99.7%. HBsAg-HQ detected 29 positive serum among 12 231 routinely obtained serum samples, which showed concentrations of 0.005-0.05 HBsAg IU/mL. CONCLUSIONS: According to these results, the Lumipulse HBsAg-HQ assay, with a highly sensitive limit of detection of 0.005 IU/mL, may facilitate the development of a better management strategy for a considerable proportion of infected patients.

Seroprevalence survey of measles, rubella, varicella, and mumps antibodies in health care workers and evaluation of a vaccination program in a tertiary care hospital in Japan.

Vaccine-preventable viral infections in health care workers (HCWs) have been on the rise for the past 10 years in Japan. To reduce the viral infections and the burden of exposure follow-up surveys at a tertiary care hospital in Osaka, Japan, a seroprevalence survey was conducted, and free vaccinations for measles, rubella, varicella, and mumps were offered to newly hired HCWs (199 physicians and 72 nurses and nursing assistants) who had negative serologic results for antibodies against these viruses. Negative antibody titers were obtained from 7.4% of the newly hired HCWs for measles, 12.5% for rubella, 4.1% for varicella, and 15.9% for mumps. The vaccination program for HCWs improved the vaccine-preventable infection rates and resulted in fewer exposure follow-up surveys, fewer lost work days, and fewer HCWs requiring hospitalization for these viral infections compared with those counted for the previous year. These data indicate that all HCWs should be strongly recommended to be vaccinated against (or have documented immunity to) these viruses in Japan, as is the case in the United States.

[Comparison of eight screening tests for ant-HCV antibody].

We compared eight HCV screening tests for detection of anti-HCV antibody; Ortho Quick Chaser HCV Ab (QC), Ortho HCV Ab ELISA III (ELISA), Ortho HVC Ab PA test III (PA), Lumipulse II Ortho HCV (LUMI), IMx HCV.DAINAPACKII (IMx), ARCHITECT HCV (ARCH), Immucheck.F-HCV C50 Ab (Immu), RANREAM HCV Ab Ex II (RAN). Sera from six hundred patients were examined by these eight screening tests. The positive rates of the eight screening tests were from 9.0% to 13.2%. Forty-five sera showed discrepant results between the eight screening tests, and about half of them showed weak positive reaction and/or false positive. Twenty-five of the forty-five sera were negative for ant-HCV antibody in the CHIRON RIBA III confirmatory test, and forty-four of them were negative for HCV-RNA in the PCR method. The agreement rates between the two reagents were from 95.5% to 99.2%, but were not always high between the two reagents that used similar antigen. The specificities and sensitivities evaluated by using the RIBA III confirmatory test were excellent in ELISA, LUMI, IMx, ARCH and Immu. Three BBI seroconversion panels were used to compare the positive readings in the initial stage of HCV infection by eight screening tests. ELISA and ARCH showed the earliest positive readings, and then IMx, LUMI = RAN, PA, QC and Immu in this order. These findings indicate that ELISA and ARCH were the most excellent in the sensitivity, specificity and early diagnosis of HCV infection. However, we must pay attention to the weak positive reaction in the screening tests, because there is a possibility of "false positive".

[Clinical evaluation of polymerase chain reaction (PCR) method for the detection of hepatitis B virus (HBV)-DNA].

It is important to monitor the quantity of hepatitis B virus (HBV)-DNA for the evaluation of the therapeutic effect of lamivudine on patients with chronic HBV infection. Using 174 samples from HBV-infected patients, in this study, we compared two methods for the detection of HBV-DNA; AMPLICOR HBV MONITOR Test (PCR method; Roche Diagnostics) and QUANTIPLEX HBV DNA Assay (bDNA) (probe method; Daiichi Pure Chemicals CO.). In all 174 samples, the detection rate of HBV-DNA was higher in the PCR method (75.9%) than in the probe method (39.1%) (p < 0.001). Furthermore, both in 103 samples from patients who were negative for HBe antigen (Ag) and positive for anti-HBe antibody (Ab) and in 48 samples from patients who were undergoing lamivudine therapy, the detection rates of HBV-DNA were also higher in the PCR method (71.8% and 47.9%, respectively) than in the probe method (19.4% and 6.3%, respectively) (p < 0.001, respectively). Data from the two methods were significantly correlated in 68 samples that were positive in both methods (r = 0.988, p < 0.001, y = 0.913x + 0.184). These data indicate that the PCR method is more suitable for the detection of HBV-DNA in long-term follow-up patients with negative for HBe Ag and positive for anti-HBe Ab, and in patients with lamivudine therapy for HBV infection.