Neuraminidase Inhibitor Susceptibility Testing in Human Influenza Viruses: A Laboratory Surveillance Perspective

Neuraminidase inhibitors (NAIs) are vital in managing seasonal and pandemic influenza infections. NAI susceptibilities of virus isolates (n = 5540) collected during the 2008–2009 influenza season were assessed in the chemiluminescent neuraminidase inhibition (NI) assay. Box-and-whisker plot analyses of log-transformed IC50s were performed for each virus type/subtype and NAI to identify outliers which were characterized based on a statistical cutoff of IC50 >3 interquartile ranges (IQR) from the 75th percentile. Among 1533 seasonal H1N1 viruses tested, 1431 (93.3%) were outliers for oseltamivir; they all harbored the H275Y mutation in the neuraminidase (NA) and were reported as oseltamivir-resistant. Only 15 (0.7%) of pandemic 2009 H1N1 viruses tested (n = 2259) were resistant to oseltamivir. All influenza A(H3N2) (n = 834) and B (n = 914) viruses were sensitive to oseltamivir, except for one A(H3N2) and one B virus, with D151V and D197E (D198E in N2 numbering) mutations in the NA, respectively. All viruses tested were sensitive to zanamivir, except for six seasonal A(H1N1) and several A(H3N2) outliers (n = 22) which exhibited cell culture induced mutations at residue D151 of the NA. A subset of viruses (n = 1058) tested for peramivir were sensitive to the drug, with exception of H275Y variants that exhibited reduced susceptibility to this NAI. This study summarizes baseline susceptibility patterns of seasonal and pandemic influenza viruses, and seeks to contribute towards criteria for defining NAI resistance

Predicting average molecular weights and branching level for self-condensing vinyl copolymerization in a CSTR

A continuous stirred-tank reactor (CSTR) model is developed for production of arborescent polyisobutylene (arbPIB, shown in Figure 1), using multidimensional method of moments. ArbPIB is a promising biomaterial, suitable for human implantation, especially for breast reconstruction after cancer surgery.[1,2] To our knowledge, arbPIB has only been produced via carbocationic polymerization in batch and semi-batch reactors, never in a CSTR. ArbPIB is made by copolymerizing IB monomer with an inimer, which is a molecule that contains an initiating group and vinyl group. As such, inimers act both as initiators and monomers, forming T-shaped branching points in the polymer. The CSTR model is used to predict dynamic changes in average branching level and number-average and weight-average molecular weights ( and ). Simulations of this self-condensing vinyl copolymerization (SCVCP) show a tendency toward higher polydispersity and higher branching level compared to batch reactor simulations conducted using the same recipes and residence times.[3] At high inimer feed concentrations and/or long residence times, the model predicts that a CSTR will not reach steady-state operation due to increasing toward infinity. As a result, there is a narrow operating range in which inimer feed concentrations can be adjusted to achieve a desired steady-state . If SCVCP is to be conducted in a CSTR, it will be important to ensure that residence times and inimer feed concentrations are selected within the stable operating window (Figure 2). Please click Additional Files below to see the full abstract

The spirit of light : light is revealed through architecture and architecture through light

There is no abstract available for this thesis.Thesis (B. Arch.)College of Architecture and Plannin

Novel bioinformatic methods for emerging pathogens with applications in influenza diagnostics

With the recent and continued growth of publicly available sequence databases, diagnostic applications of sequence-based techniques such as PCR and DNA microarrays are currently of widespread interest. Efforts are underway to greatly expand global surveillance and pandemic preparedness for influenza, driving the need for rapid, low-cost analytical techniques capable of discriminating between several subtypes of the virus. Low-density oligonucleotide microarrays provide several desirable characteristics, but must be designed carefully to ensure that the limited probe set can detect the widest possible range of viruses in addition to discriminating between virus subtypes. A new microarray probe design protocol was developed to specifically address large, highly variable sequence databases, such as those for influenza genes, using a reductionist approach. Databases were sorted into phylogenetic clusters containing similar viruses, then analyzed to find highly conserved regions of sequence within each cluster. Probe oligos were designed from these conserved regions. Several new pieces of software were written to aid in this design process, most notably ConFind, a tool for identifying conserved regions of sequence data from sequence alignments with missing or ambiguous sequence data. FluChip-55, designed using this methodology, allows three common subtypes of influenza to be distinguished. Further enhancements to the design protocol were developed to aid in developing several diagnostic microarrays, including a microarray for detecting antiviral resistance mutations and the MChip, an influenza subtyping microarray based on pattern recognition. Comparisons of influenza M gene sequences and observed microarray intensity data revealed that the MChip probe oligos do not follow the trends observed for hybridizations in solution-like conditions in cases where the oligo does not perfectly match the influenza gene target. A new position-weighting model for mismatched hybridizations on microarray surfaces was proposed to better model the observed trends. In combination with a method for normalizing single-color microarray fluorescence intensities, the position-weighted mismatch model accurately predicted intensities observed for the MChip oligos by considering only the positions of mismatches between an oligo and the corresponding influenza M gene target

The spirit of light : light is revealed through architecture and architecture through light

There is no abstract available for this thesis.College of Architecture and PlanningThesis (B. Arch.