ABSTRACT
BACKGROUND: Epstein-Barr virus (EBV) spreads through bodily fluids, especially saliva, and can cause infectious mononucleosis. EBV immunity and infection status can be assessed by testing EBV viral capsid antigen and nuclear antigen (EBNA) antibodies in blood. In this study, we investigated the seroprevalence and force of infection (FOI) of EBV antibodies among children and young people in 3 ethnic groups in Singapore. METHODS: Eight hundred ninety-six residual serum samples at a tertiary hospital were tested for viral capsid antigen (IgG and IgM) and EBNA IgG antibodies using Abbott Architect assays. We calculated the EBV seroprevalence using catalytic models to estimate the EBV force of infection from age-stratified seroprevalence data, both overall and by ethnic group. RESULTS: Overall seropositivity was 68.3% (n = 612). Seropositivity was higher in Malays (81.8%) compared with both Chinese (64.2%) and Indians (58.4%). EBV FOI was consistently higher in Malays, with an estimated annual rate of seroconversion of 25% in children 1 year, of age compared with 14% among Chinese and Indians at the same age. CONCLUSIONS: The seroprevalence patterns of EBV antibodies in the Chinese and Indian, but not Malay children in Singapore by 19 years of age resemble those previously reported in developed countries. Ideally, any future EBV vaccination strategy would need to target infants <1 year of age for maximum population benefit.
Subject(s)
Antibodies, Viral/blood , Epstein-Barr Virus Infections/ethnology , Adolescent , Child , Child, Preschool , China/ethnology , Cohort Studies , Epstein-Barr Virus Infections/immunology , Female , Herpesvirus 4, Human , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , India/ethnology , Infant , Malaysia/ethnology , Male , Seroepidemiologic Studies , Singapore/epidemiology , Tertiary Care Centers/statistics & numerical data , Young AdultABSTRACT
Background The measurement of hemoglobin A1c (HbA1c) is important for diagnosing diabetes mellitus as well as assessing glycemic control in diabetic patients. Commutable whole blood certified reference materials (CRMs) are needed in the measurement of HbA1c for method validation and/or as quality controls. Methods We developed three levels of hemolyzed whole blood CRMs for HbA1c. The certified values were determined using liquid chromatography-isotope dilution tandem mass spectrometry method (LC-IDMS/MS) where two "signature" hexapeptides of HbA1c and hemoglobin A0 (HbA0) were used as the calibration standards. The concentrations of the hexapeptide solutions were determined by amino acid analysis by the LC-IDMS/MS method using amino acid CRMs as the calibration standards. The commutability study was conducted by measuring 25 patient specimens and the whole blood CRMs by both LC-IDMS/MS method and various routine methods using six different clinical analyzers. Results The certified values were determined to be 35.1±2.0, 50.3±1.9 and 65.8±2.6 mmol/mol, respectively. These CRMs showed good commutability on five of the six clinical analyzers but showed poor commutability on one of the clinical analyzers that used similar method as two other analyzers where good commutability was observed. Conclusions With certified target values based on metrological traceability and good commutability on most of the clinical analyzers, the developed whole blood CRMs can be used for method validation or as quality control materials in the measurement of HbA1c. The commutability study results also underscored the need of commutability testing of clinical CRMs using various clinical analyzers.
