Comparison of the technical and clinical performance of the Elecsys HBsAg II assay with the Architect, AxSym, and Advia Centaur HBsAg screening assays.

South East Asia has some of the highest prevalence rates of hepatitis B virus (HBV) infection (>or=8%) in the world, and the emergence of hepatitis B surface antigen (HBsAg) mutant strains is a growing problem. Assays with the highest levels of sensitivity, including mutant detection, should be used for routine HBsAg screening. In this large multicenter study, the clinical and technical performance of the fully automated Elecsys HBsAg II assay was compared with the Architect, AxSYM, and Advia Centaur HBsAg assays for HBsAg screening. Nine laboratories (three each from Thailand, Korea, and Singapore) compared the Elecsys HBsAg II assay with their routine HBsAg screening assay against a range of stored and routine clinical samples, including recombinant mutants. The Elecsys HBsAg II assay demonstrated equivalent sensitivity and specificity to the Architect HBsAg assay. However, the Elecsys HBsAg II assay recognized a native mutant sample (L94S, L97V, L98V, T123A) that the Architect HBsAg assay failed to detect. The AxSYM and Advia Centaur HBsAg assays appeared less sensitive for the detection of early HBV infection and also failed to detect some of the recombinant mutant strains. There was almost complete agreement between the Elecsys HBsAg II assay and comparator assays with respect to routine serum samples. The results of this study demonstrate that the Elecsys HBsAg II assay is a highly sensitive and specific screening assay for HBsAg and detects reliably the most important and clinically relevant HBV mutants and genotypes. It is suitable for routine HBsAg screening in Asia.

NGSP and IFCC-derived NGSP HbA1c can be used interchangeably.

AIM: To evaluate comparability of NGSP-certified method and IFCC-calibrated method. METHODS: HbA1c was measured on two analyzers (n=50). Comparability was tested by Deming regression, bias estimation and Friedman test. RESULTS: A strong correlation and good agreement between two methods was demonstrated. CONCLUSION: NGSP and IFCC-derived NGSP HbA1c can be used interchangeably.

Influence of hemoglobin E on measurement of hemoglobin A1c by immunoassays.

BACKGROUND: Many assays used for HbA1c measurement can be interfered by hemoglobin variants. Hemoglobin E is one of the most common variant. Effect of HbE on high performance liquid chromatography was widely reported but not on immunoassay. OBJECTIVE: To determine the effect of hemoglobin E on HbA1c values by immunoassay methods. MATERIAL AND METHODS: Two immunoassays were used for measurement of HbA1c in samples with hemoglobin type as A2A (normal controls, n=60), EA (heterozygous hemoglobin E, n=151), and EE (homozygous hemoglobin E, n=43). Results within each assay and each hemoglobin typing group were compared. Mann-Whitney U test, Pearson's correlation and linear regression analysis were used. RESULTS: There were significant differences of HbA1c values between normal controls and hemoglobin E-contained samples. Correlation between two assays was worse in the presence of hemoglobin E comparing to normal controls. CONCLUSION: Hemoglobin E can affect the immunoassays used for HbA1c measurement. Further studies are needed to understand the mechanism of interference.

Evaluation of a rapid immunochromatographic test for detection of antibodies to human immunodeficiency virus.

A new immunochromatographic rapid test, Determine HIV-1/2, for the detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 in human whole blood, serum, and plasma was evaluated. Determine HIV-1/2 is a sandwich immunoassay and uses a nitrocellulose strip with a capture site for the patient's results and a procedural control site to confirm the validity of the assay. The results can be read visually, and a positive result is indicated by the formation of a red line within 15 min after sample application. The test showed 100% sensitivity for HIV-1 with 102 whole-blood, 152 serum, and 144 plasma samples obtained from Ramathibodi Hospital, Bangkok, Thailand. The sensitivity of the test for HIV-2 was 100% with 100 serum or plasma samples obtained from Ivory Coast. The sensitivity of the test with 4 anti-HIV-1 seroconversion panels from Boston Biomedica Inc. was equivalent to or better than those of another agglutination assay with serum or plasma and the enzyme immunoassay licensed by the U.S. Food and Drug Administration. The specificity was 100% with 367 sets of whole-blood, serum, and plasma samples from Ramathibodi Hospital. This method had an analytical sensitivity for the detection of HIV-1 equivalent to or better than that of another agglutination assay with serum or plasma. This test had an analytical sensitivity for the detection of HIV-1 better than that of another immunochromatographic test with whole blood. This evaluation demonstrated the excellent performance of this immunochromatographic test with EDTA-anticoagulated whole-blood, serum, and plasma samples. We conclude that this test is suitable for use in emerging countries and is an excellent alternative to HIV antibody testing at remote sites, as well as in traditional laboratories.

Study of hematopoietic progenitor cells, hematological values and lymphocyte subsets in cord blood: application for cord blood transplantation.

Hematological values, lymphocyte subsets and hematopoietic progenitor cells from normal term cord blood samples were studied, compared with normal adult blood, and analysed to determine whether a single collection of cord blood is sufficient for transplantation in adults. The parameters were assayed by automatic cells counter, flow cytometry and semisolid cell culture. All of the hematological values except RBC and MCHC were higher than in normal adult blood. Sex had an influence on RBC, Hb, Hct, Plt and reticulocyte counts. For lymphocyte subsets, all of the absolute CD3+, CD4+, CD8+ counts and T helper: suppressor ratio were higher than those of adult blood. All of the hematopoietic progenitor cells in cord blood were also higher than in adult blood. The mean volume of cord blood for each collection was 80.75 +/- 4.81 ml and the mean numbers of nucleated cells, CFU-GM and CD34+ were 13.51 +/- 0.38 x 10(8) cells, 4.33 +/- 0.66 x 10(5) colonies and 42.65 +/- 7.00 x 10(5) cells respectively. This 80 ml of cord blood would contain sufficient marrow repopulating cells for a recipient weighing about 20 kg. Recently developed technology, including ex vivo expansion may even permit transplants in adults.

Serum vitamin A and beta-carotene levels in pregnant women infected with human immunodeficiency virus-1.

OBJECTIVE: To determine if low levels of serum vitamin A and beta-carotene are present in pregnant women with human immunodeficiency virus-1 (HIV-1) infection. METHODS: Serum concentrations of vitamin A and beta-carotene were measured in 74 pregnant women seropositive for HIV-1 infection (17 with CD4 count below 200 cells/microliter) and in 148 pregnant seronegative controls in the first trimester. Comparisons were made between groups stratified by CD4 count. RESULTS: Compared with controls, women with HIV-1 infection and CD4 count below 200 cells/microliter exhibited 37% lower mean serum vitamin A levels (0.820 versus 1.308 micromol/L, P < .001) and 37% lower mean serum beta-carotene levels (1.486 versus 2.362 micromol/L, P < .001). Mean maternal age, parity, gestational age, hemoglobin levels, and body mass index at entry into the study did not differ significantly between the control and HIV-1 infection groups. In addition, serum vitamin A levels correlated significantly with the percentage of CD4 lymphocytes (r = 0.589, P < .001), CD4 count (r = 0.772, P < .001), and CD4 to CD8 ratio (r = 0.593, P < .001). Serum beta-carotene levels correlated with the percentage of CD4 lymphocytes (r = 0.407, P < .001), CD4 count (r = 0.614, P < .001), and CD4 to CD8 ratio (r = 0.434, P < .001). CONCLUSION: Compared with levels in uninfected women, serum vitamin A and beta-carotene are decreased in HIV-1-infected pregnant women in the first trimester with CD4 counts lower than 200 cells/microliter. These micronutrient concentrations also correlate with CD4 count.

Serum ferritin levels in normal and HIV-1 infected pregnant women.

Between May, 1994 and May, 1995 serum ferritin concentrations were measured in 74 pregnant women who were HIV-1 positive (17 with CD4 cell counts below 200 cells/uL) and in 148 HIV-1 negative pregnant controls in first trimester of gestation to determine if a high level of serum ferritin is present in pregnant women with HIV-1 infection. Comparisons were made between groups stratified by CD4 cell counts. Pregnant women with HIV-1 infection had 92% higher mean serum ferritin levels (112.8 versus 58.8 ug/L, p < 0.005) compared to controls, whereas the mean maternal age, parity, gestational age, haemoglobin levels and body mass index at entry into the study did not differ significantly between the control and HIV-1 infection groups. The serum ferritin levels inversely correlated with the percentage of CD4 lymphocytes, CD4 cell counts and the CD4/CD8 ratio. This study suggests that serum ferritin levels can also be used as an immunological marker in HIV-1 infected pregnant women.

Vertical transmission of HIV-1 in mid-trimester gestation.

Between July, 1994 and March, 1995, 23 heart blood samples from fresh abortuses of HIV-1 seropositive pregnant women after elective termination of pregnancy between 18 and 25 weeks of gestation by prostaglandin E1 analogue vaginal administration were examined for polymerase chain reaction (PCR) of HIV-1 genome and p24 antigen to investigate the transplacental transfer of HIV-1 infection. All samples of fetal heart blood were positive for HIV-1 antibody (ELISA), but negative for PCR and HIV-1 p24 antigen assay. These negative results could be due to the lack of the virus in the peripheral blood or to a viral load low enough to be undetectable by PCR method at mid-trimester gestation and suggest that HIV-1 vertical transmission occurs mostly during the last trimester of pregnancy and/or at delivery.

Intradermal hepatitis B virus immunization: immunogenicity and reactogenicity.

Mass immunization of hepatitis B virus (HBV) vaccine in adults is frequently demanded. However the high cost of conventional immunization is an obstacle to the provision of this vaccine. We investigated the serological response and adverse reactions following administration of a low-dose (1 or 2 micrograms of yeast-derived HBV vaccine (HB-VAX II, Merck, Sharp and Dohme) intradermally in young adults. Each 1 ml dose of the vaccine contained 10 micrograms of HBsAg protein. The study population included 58 female volunteers, aged 20-33 years, who were serologically-negative for HBV. They were alternately allocated to 1 microgram or 2 micrograms intradermal dose given by 2 experienced nurses as one or two 0.1 ml injections. Doses were given at 0, 1, and 6 months. Anti-HBs concentration was tested by enzyme-immunoassay on their sera obtained at 1, 6, and 7 months after the first dose. Positive seroconversion (anti-HBs greater than 10 IU/1) at 7 months was found in 90% (95% CL 79%, 100%) of the 1 microgram group and 96% (95% CL 89%, 100%) of the 2 micrograms group. Local reaction, a transient pigmented macule with an underlying nodule, was found in most volunteers but did not bother them. Intradermal HBV immunization could be an alternative strategy for mass immunization in young adults.

Gold blot for detection of immunoglobulin M (IgM)- and IgG-specific antibodies for rapid serodiagnosis of melioidosis.

Gold blot tests for rapid serodiagnosis of melioidosis were developed and evaluated with sera from 40 melioidosis patients and 159 normal controls. The sensitivity and specificity were 87.5 and 88%, respectively, for the immunoglobulin M (IgM) test and 100 and 91%, respectively, for the protein A test for IgG. Combination of the IgM gold blot and protein A gold blot yielded 97.5% sensitivity and 94.3% specificity. The tests were rapid and simple.

Enzyme-linked immunosorbent assay for immunoglobulin M specific antibody for the diagnosis of melioidosis.

Indirect hemagglutination (IHA) is commonly used for serodiagnosis of melioidosis. However, in endemic areas, high background titers in normal populations and occasional low titers in patients with septicemic melioidosis prompted a search for a more sensitive and more specific method of serodiagnosis. An indirect fluorescent-antibody test for immunoglobulin M (IgM) specific antibody to Pseudomonas pseudomallei was more sensitive and more specific, but fluorescence microscopes are rarely available in the endemic areas. An enzyme-linked immunosorbent assay (ELISA) for IgM antibody is an attractive alternative. An indirect ELISA for IgM antibody (IgM ELISA) and an IgM antibody capture ELISA for melioidosis were developed. Both tests, together with IHA, were evaluated for 153 serum specimens from blood donors and 16 serum specimens from 16 melioidosis patients. It was found that IHA, the IgM ELISA, and the IgM antibody capture ELISA had sensitivities of 88, 88, and 75%, respectively, with specificities of 97.4, 92.2, and 91.5%, respectively. When IHA was combined with IgM ELISA, a sensitivity of 100% and a specificity of 95.4% were obtained. The IgM ELISA and IHA should be used in combination for serodiagnosis of melioidosis.

HBsAg carrier rate among institutionalised children from Phyathai Institute.

To identify the evidence supporting the horizontal transmission of hepatitis B virus, HBsAg carrier rate among institutionalised children is determined and compared to children of the same age-group from the well baby clinic, Ramathibodi hospital. The results of this study show that HBsAg is detected four times more frequently in institutionalised children than in children from a well baby clinic. The chance of becoming an HBsAg carrier increases with age and duration of stay in the institution. Repeated study one year later shows that the HBsAg carrier rate among the same group of institutionalised children had increased by 35 per cent. The evidence supports the hypothesis that hepatitis B virus can be transmitted nonparenterally. To prevent this mode of transmission in both institutions and the community, hepatitis B vaccine should be given to these children.

A passive hemagglutination test for leprosy using a synthetic disaccharide antigen.

There is a need for a simple, sensitive, and specific test for the serodiagnosis of leprosy. A passive hemagglutination (PHA) test for leprosy was developed to meet these requirements. A synthetic disaccharide, conjugated to bovine serum albumin and specific for the phenolic glycolipid of Mycobacterium leprae, was sensitized to aldehyde preserved and tanned sheep erythrocytes (SRBC). The sensitized SRBC were used for testing sera from leprosy and tuberculosis cases and normal controls at 1: 64 and 1:128 serum dilutions. It was found that if the hemagglutination reaction at greater than or equal to 1: 128 is considered positive, the test was positive in 84.2% of 38 cases of multibacillary leprosy, 16.7% of 24 cases of paucibacillary leprosy, 16.7% of 6 contacts of multibacillary leprosy, 11.8% of 51 cases of tuberculosis, and 3.7% of 54 blood donors. If the cutoff value used was 1:64, the test was more sensitive but less specific. The results are similar to that of an ELISA for IgM antibody to the same synthetic antigen. The present PHA test is simple and sensitive, but moderately specific. Its simplicity and sensitivity make it highly suitable for large-scale screening of contacts in leprosy-endemic areas.

A new solid phase passive hemagglutination test for IgM antibody to hepatitis B core antigen.

There is a need for a simple, sensitive, specific, and inexpensive test for immunoglobulin M antibody to hepatitis B core antigen (anti-HBc IgM). A solid phase passive hemagglutination test (SP-PHA) was developed for this purpose and compared with the enzyme-linked immunosorbent assay (ELISA) test. Hepatitis B core antigen (HBcAg) used in PHA and SP-PHA was synthesized in Escherichia coli. Human IgM was captured to a microtiter plate coated with anti-human IgM, and the presence of anti-HBc IgM was demonstrated by the adherence of HBcAg-sensitized erythrocytes to the bottom of a U-shaped microtiter plate. ELISA and SP-PHA were made at 1:100 and 1:1,000 serum dilution, respectively. Both were positive in 100% of 36 cases of acute hepatitis B, 68.18% of 22 cases of chronic hepatitis B, and 20% of 75 healthy carriers of hepatitis B surface antigen (HBsAg) but none in 65 anti-HBc-positive blood donors that had negative results for HBsAg. Results of both tests were identical but were false positive because rheumatoid factor was found only in ELISA. End-point titration by SP-PHA and PHA was also found useful for the differentiation of acute hepatitis B from chronic hepatitis B and HBsAg carriers.

Passive hemagglutination test for antibody to hepatitis B core antigen.

Available tests for antibody to hepatitis B core antigen (anti-HBc) are complicated. A passive hemagglutination assay for anti-HBc was developed by sensitizing sheep erythrocytes with hepatitis B core antigen synthesized by a recombinant DNA technique. It was compared with a commercial passive hemagglutination assay and an enzyme-linked immunosorbent assay for anti-HBc and showed good agreement with both. It is rapid, simple, and sensitive.

Application of indirect hemagglutination test and indirect fluorescent antibody test for IgM antibody for diagnosis of melioidosis in Thailand.

In hyperendemic areas such as Thailand, rapid diagnosis of melioidosis depends upon both bacteriological culture and serological methods. However, interpretation of indirect hemagglutination (IHA) for melioidosis which is the only test available, is seriously hampered by increased IHA titers present in one-third to one-half of the population. In order to get the best results from the available tests, IHA and indirect fluorescent antibody for IgM (IFA-IgM) were evaluated in controls and patients in Thailand. IHA titers of greater than or equal to 1:40 were considered remote or recent exposure to P. pseudomallei. IHA titers of this level were found in 47.1% of 227 blood donors and 29.5% of 210 sera submitted for other tests, while IFA-IgM was positive in only one donor who had an IHA titer of 1:1,280. IHA was positive in eight out of nine patients with melioidosis with IHA titers of less than 1:20 to 1:2,560. IFA-IgM was positive in six out of seven melioidosis patients whose sera were available for this test including a serum with IHA titer of less than 1:20. Six patients were predisposed by diabetes mellitus. Among sera serologically tested for melioidosis, 33 had IHA titers of 1:80-1:1,280, 10 of which were positive for IFA-IgM. This study demonstrates high background IHA titers among IHA titers among Thai people which greatly limits its use for serodiagnosis of melioidosis. In sharp contrast, serodiagnosis by IFA-IgM was more successful. Positive IFA-IgM among healthy Thais did exist indicating that serologic tests for melioidosis at best are only supplementary to bacteriological culture and clinical awareness.