Molecular Dynamics Simulations on the Behaviors of Hydrophilic/Hydrophobic Cyclic Peptide Nanotubes at the Water/Hexane Interface

In this work, nine kinds of amino acid residues, i.e., alanine (A), leucine (L), valine (V), isoleucine (I), tryptophan (W), glutamine (Q), threonine (T), serine (S), and cysteine (C), were selected to construct seven cyclic peptide nanotubes (CPNTs) with diverse hydrophilic/hydrophobic external surfaces, which were further separately inserted at the water/hexane interface to investigate their microstructures and interfacial properties. Molecular dynamics (MD) simulations reveal that all the CPNTs except the QT- and VL-CPNTs have different degrees of tilt, fracture, and shedding at the interface. The end-CPs are more susceptible to the effect of the surroundings than the mid-CPs. The interactions of individual CP subunits with the neighborings disclose the firmness of the mid-CPs and the dissociation of the end-CPs. The results indicate that a hydrophobic CPNT is prone to stay at the interface, while a hydrophilic CPNT easily enters the water phase, resulting in many H-bonds with water. Results in this work enrich the dynamic properties of a hydrophilic/hydrophobic CPNT at the biphase interface at the atomic level

Enhanced immunity against SARS-CoV-2 in returning Chinese individuals

Global COVID-19 vaccination programs effectively contained the fast spread of SARS-CoV-2. Characterizing the immunity status of returned populations will favor understanding the achievement of herd immunity and long-term management of COVID-19 in China. Individuals were recruited from 7 quarantine stations in Guangzhou, China. Blood and throat swab specimens were collected from participants, and their immunity status was determined through competitive ELISA, microneutralization assay and enzyme-linked FluoroSpot assay. A total of 272 subjects were involved in the questionnaire survey, of whom 235 (86.4%) were returning Chinese individuals and 37 (13.6%) were foreigners. Blood and throat swab specimens were collected from 108 returning Chinese individuals. Neutralizing antibodies against SARS-CoV-2 were detected in ~90% of returning Chinese individuals, either in the primary or the homologous and heterologous booster vaccination group. The serum NAb titers were significantly decreased against SARS-CoV-2 Omicron BA.5, BF.7, BQ.1 and XBB.1 compared with the prototype virus. However, memory T-cell responses, including specific IFN-γ and IL-2 responses, were not different in either group. Smoking, alcohol consumption, SARS-CoV-2 infection, COVID-19 vaccination, and the time interval between last vaccination and sampling were independent influencing factors for NAb titers against prototype SARS-CoV-2 and variants of concern. The vaccine dose was the unique common influencing factor for Omicron subvariants. Enhanced immunity against SARS-CoV-2 was established in returning Chinese individuals who were exposed to reinfection and vaccination. Domestic residents will benefit from booster homologous or heterologous COVID-19 vaccination after reopening of China, which is also useful against breakthrough infection.</p