Multicentric evaluation of the DiaMed enzyme-linked immunosorbent assay malaria antibody test for screening of blood donors for malaria

BACKGROUND

The risk of malaria transmission by blood transfusion is critical due to extensive travel from endemic areas to non-endemic areas. An enzyme-linked immunosorbent assay (ELISA) malaria antibody test has been developed that is claimed to perform better than the immunofluorescence assay test (IFAT). The assay contains antigens to both Plasmodium falciparum and Plasmodium vivax. A multicentre study was performed to evaluate the appropriateness of replacing the IFAT by the new ELISA test.

MATERIAL AND METHODS

Nine French blood banks participated in this multicentre study. Two panels of samples were evaluated. The first included 4163 samples from healthy donors and was used to calculate clinical specificity of the assay. The second involved 10,995 samples, either collected retrospectively or prospectively from malaria-risk donors , was used to assess the comparative performance of the ELISA and IFAT. Discordant samples were further tested using an in-house IFAT and also tested for presence of Plasmodium DNA by polymerase chain reaction.

RESULTS

The ELISA showed a clinical specificity of 99.02%. In the malaria-risk blood donors groups, the retrospective group showed a concordance rate of 92.6% (k = 0.90), while the prospective group showed a concordance rate of 97% (k = 0.46). After confirming the discordant sample results by an in-house IFAT, the k index increased to 0.81. None of the discordant samples was shown to contain Plasmodium DNA.

CONCLUSION

The performance of the ELISA test in this study has confirmed its potential as a new screening test for use in blood banks, as an alternative to the IFAT in prevention of transfusion-transmitted malaria in non-endemic countries.

Differential influence of the E4 adenoviral genes on viral and cellular promoters

BACKGROUND

Strong and stable transgene expression is fundamental to the success of recombinant adenovirus vectors in human gene therapy. However, control of transgene expression is a complex process, involving both viral and cellular factors. In this study, the influence of the E4 adenoviral region on the activity of various promoters was investigated in vitro and in vivo.

METHODS

Pairs of isogenic E1o and E1oE4o vectors were generated and compared. Levels of transgene expression were determined by Northern blot, ELISA and FACS analysis. Initiation of transcription was studied by nuclear run-on assays.

RESULTS

Similar to the viral CMV and RSV promoters, the activity of the ubiquitous cellular PGK promoter required the presence of the E4 genes in vitro and in vivo. In contrast, transgene expression from selected liver- and tumor-specific promoters did not require E4 functions.

CONCLUSION

Together with the reported low liver toxicity of E1oE4o vectors, the independence of E4 of liver-specific promoters renders such vectors interesting alternatives to the use of gutless vectors.