RHD-specific microRNA for regulation of the DEL blood group: integration of computational and experimental approaches.

OBJECTIVE: The discovery of specific microRNAs (miRNA) mediates a better understanding of molecular mechanisms, diagnosis and prognosis of complex phenotypes. Synthesis of the RhD blood group involves multiple factors causing variation in the expression of RHD antigens. The mechanism underlying the extremely weak expression of RHD antigen associated with the RHD variant called DEL (D-elute) is incompletely understood. Down-regulation of gene expression through miRNA is a guide to the potential involvement of miRNAs in the DEL blood group. In order to determine the association of miRNAs and Rh-DEL blood donors with DEL variant, we investigated the expression level RHD-specific miRNA. METHODS: Blood samples were serologically tested for RhD blood group determination. DNA was analysed using SSP-PCR for the Asian-type DEL allele (RHD 1227 G>A). Bioinformatics analyses were applied for prediction of candidate RHD-specific miRNA. The RHD-specific miRNA expression level was quantitated using a real-time-qPCR approach. The miRNA expression levels of various RhD blood groups were compared and statistically analysed. RESULTS: The bioinformatics tools (n = 3) for prediction of miRNA targeting on RHD identified miR-98 as the miRNA potentially specific for the 3' UTR of RHD. The relative expression levels of miR-98 among D-positive (n = 50), D-negative (n = 49) and DEL (n = 63) subjects showed no statistically significant differences (P-values = 0.58). CONCLUSION: This is the first attempt to determine whether miR-98 is involved in RHD expression using computational and experimental approaches. Further investigations are necessary to fully characterize the miRNA genetics in DEL blood group regulation.

Head-to-head comparison between two screening systems for HBsAG, anti-HBc, anti-HCV and HIV combination immunoassays in an international, multicentre evaluation study.

BACKGROUND: Mandatory screening of blood donations for hepatitis B and hepatitis C viruses and human immunodeficiency viruses 1 and 2 requires assays with exceptional sensitivity and specificity. This study reports the results from a direct head-to-head comparison of the Elecsys HBsAG II, Elecsys Anti-HBc, Elecsys Anti-HCV II and Elecsys HIV combi PT immunoassays with the respective ABBOTT PRISM/Architect instrument immunoassays in a multicentre blood bank evaluation study. STUDY DESIGN AND METHODS: Assay validation was performed in the blood screening laboratories of four blood bank centres in Austria, Germany, Spain and Thailand, where both first-time donor samples (approximately 6000 donors) and repeat donor samples (approximately 14,000 donors) were screened. RESULTS: Of all screened donor samples, 93 (0.46%) were confirmed to be positive using assays from both manufacturers. The specificity of all immunoassays was >99.5% and was comparable between first-time and multiple-time donors. A direct comparison between the assays from Roche and ABBOTT according to Bland and Altman analysis demonstrated equivalent quality. CONCLUSIONS: These results suggest that the Elecsys immunoassays for HBV, HCV and HIV infection, with a comparative sensitivity of 100% and a specificity exceeding the common technical specification threshold of >99.5%, meet the stringent performance criteria stipulated for blood donor screening for these infectious agents. Significant differences in the specificity between first-time and repeat donors were not detectable.

International reference reagents: antihuman globulin. An ISBT/ICSH joint working party report. International Society of Blood Transfusion. International Committee for Standardization in Haematology.

An international working party has conducted a study designed to select a suitable reference reagent for antihuman globulin, to replace those first made available in 1987. The chosen preparation contains levels of anti-IgG and anti-C3 (anti-C3c and anti-C3d) potency that are considered suitable to serve for reference when evaluating either polyspecific antihuman globulin reagents or those containing their separate monospecific components. The reference material is available in 2-ml freeze-dried aliquots from seven assigned distribution centres.

Evolutionary analysis of variants of hepatitis C virus found in South-East Asia: comparison with classifications based upon sequence similarity.

Variants of hepatitis C virus (HCV) have been classified by nucleotide sequence comparisons in different regions of the genome. Many investigators have defined the ranges of sequence similarity values or evolutionary distances corresponding to divisions of HCV into types, subtypes and isolates. Using these criteria, novel variants of HCV from Vietnam, Thailand and Indonesia have been classified as types 7, 8, 9, 10 and 11, many of which can be further subdivided into between two to four subtypes. In this study, this distance-based method of virus classification was compared with phylogenetic analysis and statistical measures to establish the confidence of the groupings. Using bootstrap resampling of phylogenetic trees in several subgenomic regions (core, E1, NS5) and with complete genomic sequences, we found that one set of novel HCV variants ('types 7, 8, 9 and 11') consistently grouped together into a single clade that also contained type 6a, while 'type 10a' grouped with type 3. In contrast, no robust higher-order groupings were observed between any of the other five previously described HCV genotypes (types 1-5). In each subgenomic region, the distribution of pairwise distances between members of the type 6 clade were consistently bi-modal and therefore provided no justification for classification of these variants into the three proposed categories (type, subtype, isolate). Based on these results, we propose that a more useful classification would regard all these variants as subtypes of type 6 or type 3, even though the level of sequence diversity within the clade was greater than observed for other genotypes. Classification by phylogenetic relatedness rules out simple sequence similarity measurements as a method for assigning HCV genotypes, but provides a more appropriate description of the evolutionary and epidemiological history of a virus.