The development of recombinant COVID-19 vaccines has resulted from scientific progress made at an unprecedented speed during 2020. The recombinant spike glycoprotein monomer, its trimer, and its recombinant receptor-binding domain (RBD) induce a potent anti-RBD neutralizing antibody response in animals. In COVID-19 convalescent sera, there is a good correlation between the antibody response and potent neutralization. In this review, we summarize with a critical view the molecular aspects associated with the interaction of SARS-CoV-2 RBD with its receptor in human cells, the angiotensin-converting enzyme 2 (ACE2), the epitopes involved in the neutralizing activity, and the impact of virus mutations thereof. Recent trends in RBD-based vaccines are analyzed, providing detailed insights into the role of antigen display and multivalence in the immune response of vaccines under development.

Soberana01 is composed of the SARS-CoV-2 dimeric RBD and Neisseria meningitidis outer membrane vesicles (OMVs) adsorbed on alum. This vaccine induces a potent neutralizing immune response and shows potential against SARS-CoV-2 variants of concern.

Ants are among the most abundant terrestrial invertebrate predators on Earth. To overwhelm their prey, they employ several remarkable behavioral, physiological, and biochemical innovations, including an effective paralytic venom. Ant venoms are thus cocktails of toxins finely tuned to disrupt the physiological systems of insect prey. They have received little attention yet hold great promise for the discovery of novel insecticidal molecules. To identify insect-neurotoxins from ant venoms, we screened the paralytic activity on blowflies of nine synthetic peptides previously characterized in the venom of Tetramorium bicarinatum. We selected peptide U₁₁, a 34-amino acid peptide, for further insecticidal, structural, and pharmacological experiments. Insecticidal assays revealed that U₁₁ is one of the most paralytic peptides ever reported from ant venoms against blowflies and is also capable of paralyzing honeybees. An NMR spectroscopy of U₁₁ uncovered a unique scaffold, featuring a compact triangular ring helix structure stabilized by a single disulfide bond. Pharmacological assays using Drosophila S2 cells demonstrated that U₁₁ is not cytotoxic, but suggest that it may modulate potassium conductance, which structural data seem to corroborate and will be confirmed in a future extended pharmacological investigation. The results described in this paper demonstrate that ant venom is a promising reservoir for the discovery of neuroactive insecticidal peptides.

In Archaea the two major modes of DNA packaging are wrapping by histone proteins or bending by architectural non-histone proteins. To supplement our knowledge about the binding mode of the different DNA-bending proteins observed across the three domains of life, we present here the first model of a complex in which the monomeric Methanogen Chromosomal protein 1 (MC1) from Euryarchaea binds to the concave side of a strongly bent DNA. In laboratory growth conditions MC1 is the most abundant architectural protein present in Methanosarcina thermophila CHTI55. Like most proteins that strongly bend DNA, MC1 is known to bind in the minor groove. Interaction areas for MC1 and DNA were mapped by Nuclear Magnetic Resonance (NMR) data. The polarity of protein binding was determined using paramagnetic probes attached to the DNA. The first structural model of the DNA-MC1 complex we propose here was obtained by two complementary docking approaches and is in good agreement with the experimental data previously provided by electron microscopy and biochemistry. Residues essential to DNA-binding and -bending were highlighted and confirmed by site-directed mutagenesis. It was found that the Arg25 side-chain was essential to neutralize the negative charge of two phosphates that come very close in response to a dramatic curvature of the DNA.