Morphogenesis of human cytomegalovirus (HCMV) is

SummaryElectron microscopy (EM) allows visualization of viruses in fixed cells with high resolution. Highpressure freezing for sample fixation in combination with freeze substitution and embedding in resin improves significantly the preservation of cellular structures and specifically of membranes. This advancement allows better visualization of human cytomegalovirus (HCMV) morphogenesis occurring at membranes. To obtain comprehensive information on viral phenotypes from ultrastructural images it is important to also quantify morphological phenotypes. This again can be much refined by three-dimensional visualization after serial sectioning. For elucidation of dynamic processes threedimensional tomography is extremely helpful. We analysed interaction of HCMV particles with host cell membranes during final envelopment. Both wild-type virus and a viral mutant with impaired envelopment were analysed in fibroblasts, but also using in vivo relevant human endothelial cells and macrophages. The quantification of the EM data showed similar ultrastructural phenotypes regarding the envelopment efficiency in the different cell types indicating similar mechanisms in late stages of virus morphogenesis. Furthermore, thorough analysis of the viral assembly complex (AC) -a virus-induced cytosolic structure -by using threedimensional visualization techniques combined with a quantitative analysis revealed that the events of final envelopment are equally distributed within the AC irrespective of different local membrane composition.

Vaccines are one of the best health care advances ever developed, having led to the eradication of smallpox and near eradication of polio and diphtheria. While tremendously successful, traditional vaccines (i.e., whole-killed or live-attenuated) have been associated with some undesirable side effects, including everything from mild injection site inflammation to the autoimmune disease Guillain–Barré syndrome. This has led recent research to focus on developing subunit vaccines (i.e., protein, peptide, or DNA vaccines) since they are inherently safer because they deliver only the bioactive components necessary (i.e., antigens) to produce a protective immune response against the pathogen of interest. However, a major challenge in developing subunit vaccines is overcoming numerous biological barriers to effectively deliver the antigen to the secondary lymphoid organs where adaptive immune responses are orchestrated. Peptide amphiphile micelles are a class of biomaterials that have been shown to possess potent self-adjuvanting vaccine properties, but their optimization capacity and underlying immunostimulatory mechanism are not well understood. The present work investigated the influence of micelle size and charge on the materials’ bioactivity, including lymph node accumulation, cell uptake ability, and immunogenicity. The results generated provide considerable insight into how micelles exert their biological effects, yielding a micellar toolbox that can be exploited to either enhance or diminish host immune responses. This exciting development makes peptide amphiphile micelles an attractive candidate for both immune activation and suppression applications.