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Human endogenous retroviruses (HERVs) can be divided into distinct families of tens to thousands of paralogous loci. The expression of HERV elements has been detected in all tissues tested to date, particularly germ cells, embryonic tissues and neoplastic tissues. Hence, the study of HERV expression could represent added value in cancer diagnosis. We developed a quantitative assay combining a multiplex degenerate PCR (MD-PCR) amplification, based on the relative conservation of the pol genes, and a colorimetric Oligo Sorbent Array (OLISA). Nine HERV families were selected and amplification primers and capture probes were designed for each family. The features required to achieve efficient amplification of most of the elements of each HERV family and balanced co-amplification of all HERV families were analyzed. We found that MD-PCR reliability, i.e. equivalence of amplification and dose-effect relationship, relied on the adjustment of three critical parameters: the primer degeneracy, the relative concentration of each primer and the total amount of primers in the amplification mixture. The analysis of tumoral versus normal tissues suggests that this assay could prove useful in tumor phenotyping.

The occurrence of beta-glucuronidase activity, a main characteristic of Escherichia coli and the presence of the uid chromosomal region of E. coli, coding for this enzyme, were tested on representative members of enteric bacteria. DNA hybridization techniques using uid probes and amplification experiments of uidA gene by the polymerase chain reaction (PCR) confirmed the specificity of uid genes for E. coli and Shigella spp. (i.e., S. boydii, S. dysenteriae, S. flexneri and S. sonnei), independent of the beta-glucuronidase phenotype of bacterial strains. This specificity seemed to be conserved when studies were extended to a wide range of bacteria. It was not possible to distinguish E. coli from Shigella spp. The detection sensitivity using double stranded DNA radiolabeled probes was 3 x 10(4) bacteria and could be brought down to 8 bacteria by PCR. Thus, the uid genes appeared to be ideal candidates for DNA probes technology to detect E. coli-Shigella species.