Comparison of three luminescent assays combined with a sandwich hybridization for the measurement of PCR-amplified human cytomegalovirus DNA

Bacillus anthracis: toxicology, epidemiology and current rapid-detection methods

B. anthracis, the causative agent for anthrax, has been well studied for over 150 years. Due to the genetic similarities among various Bacillus species, as well as its existence in both a spore form and a vegetative state, the detection and specific identification of B. anthracis have been proven to require complex techniques and/or laborious methods. With the heightened interest in the organism as a potential biological threat agent, a large number of interesting detection technologies have recently been developed, including methods involving immunological and nucleic acid-based assay formats. The technologies range from culture-based methods to portable Total Analysis Systems based on real-time PCR. This review with 170 references provides a brief background on the toxicology and epidemiology of B. anthracis, discusses challenges associated with its detection related to genetic similarities to other species, and reviews immunological and, with greater emphasis, nucleic acid-based detection systems.

Comparison between microwell and bead supports for the detection of human cytomegalovirus amplicons by sandwich hybridization

In this study, we compared the efficiency of capture DNA probes covalently bound onto magnetic beads or microplates for their hybridization with target human cytomegalovirus (HCMV) DNA amplicons. Polystyrene supports were first aminated by wet chemistry to allow covalent grafting of the capture probes. The level of amines grafted was three times higher on beads than on microwells. Increasingly higher sizes of capture probes were fixed on both supports and the best reaction yield ranged from 300 to 500 fmol. The sizes of the capture and detection probes were optimized in order to obtain high target DNA hybridization yield. Long capture probes were more accessible than short ones to the target, with faster kinetics of hybridization obtained on beads than on microplates. Sensitivity of the hybridization assay was then determined with a nonisotopic method and the detection limit found was 30 amol of HCMV amplicons on both supports. HCMV DNA extracted from clinical samples were amplified by PCR. The resulting amplicons were then analyzed using the optimized sandwich hybridization assay discussed here. The results perfectly fitted with the qualitative conclusions obtained after a nested PCR analyzed on agarose gel.