The host exosome pathway underpins biogenesis of the human cytomegalovirus virion.

Human Cytomegalovirus (HCMV) infects over half the world's population, is a leading cause of congenital birth defects, and poses serious risks for immuno-compromised individuals. To expand the molecular knowledge governing virion maturation, we analysed HCMV virions using proteomics, and identified a significant proportion of host exosome constituents. To validate this acquisition, we characterized exosomes released from uninfected cells, and demonstrated that over 99% of the protein cargo was subsequently incorporated into HCMV virions during infection. This suggested a common membrane origin, and utilization of host exosome machinery for virion assembly and egress. Thus, we selected a panel of exosome proteins for knock down, and confirmed that loss of 7/9 caused significantly less HCMV production. Saliently, we report that VAMP3 is essential for viral trafficking and release of infectious progeny, in various HCMV strains and cell types. Therefore, we establish that the host exosome pathway is intrinsic for HCMV maturation, and reveal new host regulators involved in viral trafficking, virion envelopment, and release. Our findings underpin future investigation of host exosome proteins as important modulators of HCMV replication with antiviral potential.

Effect of Mo on the catalytic activity of Ni-based self-organizing catalysts for processing of dichloroethane into segmented carbon nanomaterials.

A series of micro-disperse Ni-Mo alloys with the sponge-like structure was prepared by a simultaneous precipitation method followed by sintering of the sediment in H2 atmosphere at 800 °C. According to XRD data, the formation of single-phase solid solution Ni1-xMox took place for the samples with Mo content of 0.6-8.3 wt.%. Synthesized samples were studied in a process of the catalytic CVD of C2H4Cl2 at 550-700 °C. In situ kinetic studies of carbon deposition process were carried out in a flow gravimetric setup equipped with McBain balances. An interaction of Ni-Mo alloys with C2H4Cl2 is accompanied by their rapid disintegration with formation of disperse active particles catalyzing the growth of carbon nanomaterials (CNM). The strong boosting effect of Mo on the catalytic performance of Ni was revealed. The maximum yield of CNM product (8.3 wt.% Mo, 600 °C, 120 min) was as high as 45 g/gM. The study on effect of the reaction temperature on the CNM yield allowed one to define an optimal temperature regime. The impact of Mo concentration upon the morphology, structural features and textural properties of the produced carbon fibers was investigated by means of SEM, TEM, Raman spectroscopy and low-temperature nitrogen adsorption. The role of chemisorbed chlorine species in a pulse-to-pulse regime of the segmented carbon filaments formation was discussed.

Force-induced globule-coil transition in laminin binding protein and its role for viral-cell membrane fusion.

The specific interactions of the pairs laminin binding protein (LBP)-purified tick-borne encephalitis viral surface protein E and certain recombinant fragments of this protein, as well as West Nile viral surface protein E and certain recombinant fragments of that protein, are studied by combined methods of single-molecule dynamic force spectroscopy (SMDFS), enzyme immunoassay and optical surface waves-based biosensor measurements. The experiments were performed at neutral pH (7.4) and acid pH (5.3) conditions. The data obtained confirm the role of LBP as a cell receptor for two typical viral species of the Flavivirus genus. A comparison of these data with similar data obtained for another cell receptor of this family, namely human αVß3 integrin, reveals that both these receptors are very important. Studying the specific interaction between the cell receptors in question and specially prepared monoclonal antibodies against them, we could show that both interaction sites involved in the process of virus-cell interaction remain intact at pH 5.3. At the same time, for these acid conditions characteristic for an endosome during flavivirus-cell membrane fusion, SMDFS data reveal the existence of a force-induced (effective already for forces as small as 30-70 pN) sharp globule-coil transition for LBP and LBP-fragments of protein E complexes. We argue that this conformational transformation, being an analog of abrupt first-order phase transition and having similarity with the famous Rayleigh hydrodynamic instability, might be indispensable for the flavivirus-cell membrane fusion process.