Application of the primer in situ DNA synthesis (PRINS) technique to titer recombinant virus and evaluation of the efficiency of viral transduction

[From the conception of the PRINS to its coronation]

As a non-isotopic molecular cytogenetic technique, the primed in situ (PRINS) labelling reaction represents a major technological progress achieved in the past decade. It has become a routine technique for the microscopic visualization of specific DNA sequences in cells and nuclei and constitutes a good alternative to the fluorescence in situ hybridization (FISH) procedure. Among the multiple advantages that characterize the PRINS technique, specificity, rapidity, reliability, reproducibility, and cost-effectiveness can be mentioned. PRINS can be in addition associated with other techniques like FISH, indirect immunofluorescence, and nick translation. The most recent developments show the great potential of this technique. Now PRINS can be used to study single-copy genes and, consequently, can be routinely used to investigate deletions associated with microdeletion syndromes. Therefore, the PRINS technique has the potential to become a widely used molecular cytogenetic tool in clinics and research. This short review presents how the PRINS technique contributed to further the understanding of biological phenomena and describes the different possibilities and applications of the PRINS method in several biological and clinical fields (pre-implantation testing, prenatal, constitutional and oncologic genetic diagnosis).

Rapid enumeration of respiratory viruses

Virus detection and enumeration has become increasingly important in fields ranging from medicine and biotechnology to environmental science. Although there are a wide variety of techniques that can be used to count viruses, there is demand for a rapid and more accurate means for virus enumeration. In this work, the performance of a flow cytometer that was designed and custom-built specifically for rapid detection of single viruses was evaluated. The instrument, designated a single nanometric particle enumerator (SNaPE), was characterized and calibrated using fluorescent polystyrene nanospheres. The reliability of the instrument with respect to virus enumeration was demonstrated for three medically relevant viruses, adenovirus-5, respiratory syncytial virus, and influenza A, treated with a fluorescent nucleotide stain. In each case, the SNaPE yielded a virus particle concentration consistent with, but slightly lower than, transmission electron microscopy (TEM) results, as expected. In addition, on the basis of calibration of signal intensity, the average peak height for a given virus was correlated with genome size, as expected. In contrast to time-consuming analyses such as TEM and plaque titers, SNaPE analysis of pure virus samples (including sample handling, data collection, and data processing) can be completed within 1 h.