Using QPCR to assign infectious potencies to adenovirus based vaccines and vectors for gene therapy: toward a universal method for the facile quantitation of virus and vector potency.

Vaccine 23:36 (2005) 4500-4508

Authors:

Fubao Wang, Alan C Puddy, Bill C Mathis, Allison G Montalvo, Anthonise A Louis, Jennifer L McMackin, Jenny Xu, Yuhua Zhang, Charles Y Tan, Timothy L Schofield, Jayanthi J Wolf, John A Lewis

Abstract:

The assignment of infectious potency to test articles of adenovirus has been conducted mainly using classical end-point dilution methods, which rely on virus induced cytopathology to reveal the presence of infectious virus. These assays suffer the disadvantages of labor intensity, duration, throughput restriction and variability. In the course of our development of an Ad5 based HIV vaccine for clinical evaluation, we sought a facile method for the assignment of potency to the numerous test articles generated during the development of bioprocesses for bulk manufacture, downstream purification and formulation. In this paper we describe a quantitative PCR based potency assay (QPA) which uses QPCR to quantitate adenovirus genomes replicated 24h after the inoculation of a test article on 293 cell monolayers, and then relates that mass to potency by interpolation to a standard curve of replicated adenovirus genomes constructed with a reference adenovirus standard to which infectious potency has been previously assigned in the classical end-point dilution assay. The QPA assay for adenovirus is simple and rapid, with a throughput capacity adequate to the potency assay demands of bioprocess development, and with a precision expressed as a root variability of 16.8% R.S.D., allowing for close discriminations of the products of alternative process configurations. The adenovirus QPA principle can be applied to the quantitation of infectious potency of both RNA and DNA viruses and we report briefly on the development of QPA assays for measles and mumps. QPA assays owing to their simplicity and easy automation, rapidity, capacity and precision hold promise to become widely practiced methods for the quantitation of the potency of live virus vaccines and other recombinant virus vectors.

Coarse-graining diblock copolymer solutions: a macromolecular version of the Widom-Rowlinson model

(2005)

Authors:

CI Addison, JP Hansen, V Krakoviack, AA Louis

Composite fermions in a negative effective magnetic field: A Monte Carlo study

Physical Review B - Condensed Matter and Materials Physics 72:4 (2005)

Authors:

G Möller, SH Simon

Abstract:

The method of Jain and Kamilla [J. K. Jain and R. K. Kamilla, Phys. Rev. B 55, R4895 (1997)] allows numerical generation of composite-fermion trial wave functions for large numbers of electrons in high magnetic fields at filling fractions of the form ν=p (2mp+1) with m and p positive integers. In the current paper we generalize this method to the case where the composite fermions are in an effective (mean) field with opposite sign from the actual physical field, i.e., when p is negative. We examine both the ground-state energies and the low-energy neutral excitation spectra of these states. Using particle-hole symmetry we can confirm the correctness of our method by comparing results for the series m=1 with p>0 (previously calculated by others) to our results for the conjugate series m=1 with p<0. Finally, we present similar results for ground-state energies and low-energy neutral excitations for the states with m=2 and p<0, which were not previously addressable, comparing our results to the m=1 case and the p>0, m=2 cases. © 2005 The American Physical Society.

Polymer solutions: from hard monomers to soft polymers

(2005)

Authors:

J-P Hansen, CI Addison, AA Louis

Control of drop positioning using chemical patterning

(2005)

Authors:

A Dupuis, J Leopoldes, DG Bucknall, JM Yeomans