[en] Conventional fragments of fluorescent proteins used in bimolecular fluorescence complementation technique (BiFC), form light-emitting species only when they are kept in close proximity by interacting proteins of interest. By contrast, certain fluorescent protein fragments complement spontaneously, namely those corresponding to the 1st to 10th beta-strands (GFP1-10) and the 11th beta-strand of superfolder GFP (GFP11). They were designed as folding reporters for high throughput expression and structure biology. Besides, for light microscopy, self-associating fluorescent protein fragments constitute a valuable and sometimes unique tool. The GFP11 tag is very advantageous when a full-length fluorescent protein cannot be fused to a protein of interest, namely for live imaging of certain pathogens. Self-associating GFP fragments enable live labelling of specific synapses, visualization of proteins topology and their exposure to particular subcellular compartments. Present review aims to attract attention of scientific community to these tools and to inspire their further development and applications. (topical review)

[en] Highlights: • Focused library screen identifies bacteriostatics of many pathogens. • Staphylococcus aureus' growth is inhibited at IC₅₀ = 30–150 μM. • Proteus mirabilis is killed by similar compound chemical structures of compounds are different from known antibacterials. Staphylococcus aureus is a human pathogen rapidly becoming a serious health problem due to ease of acquiring antibiotic resistance. To help identify potential new drug candidates effective against the pathogen, a small focused library was screened for inhibition of bacterial growth against several pathogens, including S. aureus. At least one of the compounds, Compound 10, was capable of blocking bacterial growth of S. aureus in a test tube with IC₅₀ = 140 ± 30 μM. Another inhibitor, Compound 7, was bacteriostatic against S. aureus with IC₅₀ ranging from 33 to 150 μM against 3 different strains. However, only Compound 7 was bactericidal against P. mirabilis as examined by electron microscopy. Human cell line toxicity studies suggested that both compounds had small effect on cell growth at 100 μM concentration as examined by MTT assay. Analysis of compounds’ structures showed lack of similarity to any known antibiotics and bacteriostatics, potentially offering the inhibitors as an alternative to existing solutions in controlling bacterial infections for selected pathogens.

[en] Non-typeable Haemophilus influenzae (NTHi) is a human-adapted bacterial pathogen, responsible for infections of the human respiratory tract. This pathogen expresses a range of adhesins that mediate binding to host cells. Most NTHi strains can express the related adhesins HMW1 and HMW2. Expression of HMW proteins is phase-variable: changes in the length of simple-sequence repeats located in the encoding genes promoter regions results in changes in expression levels of these adhesins. HMW expression is also controlled by epigenetic regulation. HMW1 has been previously demonstrated to bind α 2–3 sialyl-lactosamine, but affinity of this interaction has not been investigated. The host receptor(s) for HMW2 is currently unknown. We hypothesized that host glycans may act as receptors for HMW2-mediated adherence. We examined the glycan-binding activity of HMW2 using glycan arrays and Surface Plasmon Resonance (SPR). These studies demonstrate that HMW2 binds 2–6 linked N-acetylneuraminic acid with high affinity. HMW2 did not bind glycan structures containing the non-human form of sialic acid, N-glycolylneuraminic acid. Thus, the specificity of HMW1 and HMW2 have complementary lectin activities that may allow NTHi distinct niches in the human host.

[en] Highlights: • A SARS-CoV sister clade member, Betacoronavirus EPI1, found in Western Europe. • Betacoronavirus EPI1 circulates in Rhinolophus ferrumequinum bat in Western Europe. • 9 alphacoronaviruses species found in Vespertillionidae and Miniopteridae bats. • Rhinolophus ferrumequinum hosts Betacov EPI1 and Alphacov EPI4, EPI6 and EPI7. • Alphacoronavirus EPI6 is strictly associated with Rhinolophus ferrumequinum. The emergence of SARS-CoV and MERS-CoV, triggered the discovery of a high diversity of coronaviruses in bats. Studies from Europe have shown that coronaviruses circulate in bats in France but this reflects only a fraction of the whole diversity. In the current study the diversity of coronaviruses circulating in western Europe was extensively explored. Ten alphacoronaviruses in eleven bat species belonging to the Miniopteridae, Vespertilionidae and Rhinolophidae families and, a SARS-CoV-related Betacoronavirus in Rhinolophus ferrumequinum were identified. The diversity and prevalence of bat coronaviruses presently reported from western Europe is much higher than previously described and includes a SARS-CoV sister group. This diversity demonstrates the dynamic evolution and circulation of coronaviruses in this species. That said, the identified coronaviruses were consistently associated with a particular bat species or genus, and these relationships were maintained no matter the geographic location. The observed phylogenetic grouping of coronaviruses from the same species in Europe and Asia, emphasizes the role of host/pathogen coevolution in this group.

[en] Highlights: • We generated a novel antibody specific to an immunodominant decoy epitope of PCV2. • Using this novel antibody, we measured levels of decoy epitope in PCV2 vaccine. • Decoy epitope in PCV2 vaccine affected the neutralizing antibody titer induction. Viral pathogens have evolved a wide range of tactics to evade host immune responses and thus propagate effectively. One efficient tactic is to divert host immune responses toward an immunodominant decoy epitope and to induce non-neutralizing antibodies toward this epitope. Therefore, it is expected that the amount of decoy epitope in a subunit vaccine can affect the level of neutralizing antibody in an immunized animal. In this study, we tested this hypothesis by generating an antibody specific to the decoy epitope on the capsid protein of porcine circovirus type 2 (PCV2). Using this antibody, we found that two commercial vaccines contained statistically different amounts of the decoy epitope. The vaccine with lower levels of decoy epitope induced a significantly higher level of neutralizing antibody after immunization. This antibody can be used as an analytical tool to monitor the quality of a vaccine from batch to batch.

[en] Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel β-methoxy acrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, ¹H nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbicular, Botrytis cinerea Pers and Protoporphyria caps ici Leon ian at the concentration of 50 μg/mL. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial stilbenetriol fungicide azoxystrobin

[en] Using a dynamic model we study the adaptive immune response to a sequence of two infections. We incorporate lymphocyte diversity by modeling populations as continuous distributions in a multi-dimensional space. As expected, memory cells generated by the primary infection invoke a rapid response when the secondary infection is identical (homologous). When the secondary infection is different (heterologous), the memory cells have a positive effect or no effect at all depending on the similarity of the infections. This model displays ‘original antigenic sin’ where the average effector affinity for the heterologous infection is lower than it would be for a naive response, but in cases with original antigenic sin we see a reduction in pathogen density. We model pathology resulting from the immune system itself (immunopathology) but find that in cases of original antigenic sin, immunopathology is still reduced. Average effector affinity is not an accurate measure of the quality of an immune response. The effectivity, which is the total pathogen killing rate, provides a direct measure of quality. This quantity takes both affinity and magnitude into account. (paper)

[en] IL-22 is an IL-10 family cytokine that initiates innate immune responses against bacterial pathogens and contributes to immune disease. IL-22 biological activity is initiated by binding to a cell-surface complex composed of IL-22R1 and IL-10R2 receptor chains and further regulated by interactions with a soluble binding protein, IL-22BP, which shares sequence similarity with an extracellular region of IL-22R1 (sIL-22R1). IL-22R1 also pairs with the IL-20R2 chain to induce IL-20 and IL-24 signaling. To define the molecular basis of these diverse interactions, we have determined the structure of the IL-22/sIL-22R1 complex. The structure, combined with homology modeling and surface plasmon resonance studies, defines the molecular basis for the distinct affinities and specificities of IL-22 and IL-10 receptor chains that regulate cellular targeting and signal transduction to elicit effective immune responses.

[en] RxLR genes are a prominent class of effectors in oomycetes, and almost half of these proteins contain a conserved sequence motif termed the WY domain, that may exist singly, or as divergent tandem repeats in different effectors. Here we describe the crystal structure of PcRxLR12 (63-488) from Phytophthora capsici at 3.0 Å resolution. The structure consists of five tandemly arrayed WY-domains linked to each other by short connecting helices. Superposition of the WY-2 domain on the other four domains of PcRxLR12, show that the first α-helix termed the K motif, and Loop 3 which connects α₃ and α₄ are the key regions of structural divergence between the WY domains. A similar pattern was observed when WY-2 was superposed on the 11 WY domains from other oomycete effectors. We also note that an added connecting helix between WY domains in some RXLR effectors, ensures that the WY domains are oriented in the same direction.

[en] The template synthesis of copper(II) and nickel(II) complexes derived from 2,6-diformyl-4-methylphenol with diethylenetriamine or 1,2-bis(3-amino propylamino)ethane produce the 12-membered N₃O and 17-membered N₄O macrocyclic complexes, respectively. The geometry of the complexes has been determined with the help of electronic and EPR spectroscopic values and found to be five coordinated square pyramidal and, six coordinated distorted tetragonal for 12-membered and 17-membered macrocyclic complexes, respectively. Electrochemical studies of the mononuclear N₃O and N₄O copper(II) complexes show one irreversible one electron reduction wave at E^pc = .1.35 and .1.15 V respectively, and the corresponding nickel(II) complexes show irreversible one-electron reduction wave at E^pc = .1.25 and .1.22 V, respectively. The nickel(II) complexes show irreversible one-electron oxidation wave at Epa = +0.84 and +0.82 V, respectively. All the complexes were evaluated for in vitro antimicrobial activity against the human pathogenic bacteria and fungi