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Adenoviruses are common pathogens all over the world. The majority of the population has at some point been infected with an adenovirus. Although severe disease can occur in otherwise healthy individuals an adenovirus infection is most commonly self limited in these cases. For immunocompromised individuals however, adenoviruses can be life-threatening pathogens capable of causing disseminated disease and multiple organ failure. Still there is no approved drug specific for treatment of adenovirus infections. We have addressed this using a unique whole cell viral replication reporter gene assay to screen small organic molecules for anti-adenoviral effect. This RCAd11pGFP-vector based assay allowed screening without any preconceived idea of the mechanism for adenovirus inhibition. As a result of the screening campaign 2-[[2-(benzoylamino)benzoyl]amino]-benzoic acid turned out to be a potent inhibitor of adenoviral replication. To establish a structure-activity relationship a number of analogs were synthesized and evaluated for their anti-adenoviral effect. The carboxylic acid moiety of the molecule was important for efficient inhibition of adenovirus replication.

There are 54 adenovirus types characterized today and these are divided into seven species, A-G. The receptors used by species B and other adenoviruses are not fully characterized. CD46 is a complement regulatory molecule suggested to be used by all species B types and some species D types but this is not established. We have designed a new bioassay for assessment of the interaction between adenoviruses and CD46 and investigated the CD46-binding capacity of adenovirus types indicated to interact with CD46. We concluded that Ad11p, Ad34, Ad35, and Ad50 clearly bind CD46 specifically, whereas Ad3p, Ad7p, Ad14, and Ad37 do not.

CD46 is expressed on all human nucleated cells and serves as a receptor for a number of different bacteria and viruses. Downregulation of CD46 on the cell surface occurs upon binding by some of these pathogens. We show that early in infection Ad11p virions downregulate CD46 upon binding to a much higher extent than the complement regulatory molecules CD55 and CD59.

These findings may lead to a better understanding of the pathogenesis of adenoviruses in general and species B adenoviruses in particular and hopefully we have discovered a molecule that can be the basis for development of new anti-adenoviral drugs.

Small molecule inhibitors of amyloid aggregation have potential as treatment for a variety of conditions. In this issue of Chemistry & Biology, Romero and colleagues use amyloid-dependent B. subtilis biofilm formation to screen for amyloid inhibitors, identifying compounds that not only inhibit B. subtilis biofilm formation but also ones that disrupt preformed biofilms.

Hemagglutination is an established method but has not been used previously to determine the efficacy of virus binding to a specific cellular receptor. Here we have utilized CD46-expressing erythrocytes from a transgenic mouse to establish whether and to what extent the species B adenoviruses (Ads) as well as Ad37 and Ad49 of species D can interact with CD46. A number of different agglutination patterns, and hence CD46 interactions, could be observed for the different adenovirus types. In this system Ad7p, Ad11a, and Ad14 did not agglutinate mouse erythrocytes at all. Hemagglutination of CD46 expressing erythrocytes with high efficiency was observed for the previously established CD46 users Ad11p and Ad35 as well as for the less investigated Ad34. Ad50 agglutinated with moderate efficiency. Ad16, Ad21 and Ad49 gave incomplete agglutination. Ad16 was the only adenovirus that could be eluted. No specific CD46 interaction could be observed for Ad3p or for Ad37.

Adenovirus infections are widespread in society and are occasionally associated with severe, but rarely with life-threatening, disease in otherwise healthy individuals. In contrast, adenovirus infections present a real threat to immunocompromised individuals and can result in disseminated and fatal disease. The number of patients undergoing immunosuppressive therapy for solid organ or hematopoietic stem cell transplantation is steadily increasing, as is the number of AIDS patients, and this makes the problem of adenovirus infections even more urgent to solve. There is no formally approved treatment of adenovirus infections today, and existing antiviral agents evaluated for their anti-adenoviral effect give inconsistent results. We have developed a whole cell-based assay for high-throughput screening of potential anti-adenoviral compounds. The assay is unique in that it is based on a replication competent adenovirus type 11p GFP-expressing vector (RCAd11pGFP). This allows measurement of fluorescence changes as a direct result of RCAd11pGFP genome expression. Using this assay, we have screened 9,800 commercially available small organic compounds. Initially, we observed approximately 400 compounds that inhibited adenovirus expression in vitro by >/= 80% but only 24 were later confirmed as dose-dependent inhibitors of adenovirus. One compound in particular, 2-[[2-(benzoylamino)benzoyl]amino]-benzoic acid, turned out to be a potent inhibitor of adenovirus replication.

Chlamydia trachomatis is a global health burden due to its prevalence as a sexually transmitted disease and as the causative agent of the eye infection trachoma. We recently discovered 3-amido thiazolino 2-pyridones which attenuated C. trachomatis infectivity without affecting host cell or commensal bacteria viability. We present here the synthesis and evaluation of nonhydrolyzable amide isosteres based on this class, leading to highly potent 1,2,3-triazole based infectivity inhibitors (EC₅₀ ≤ 20 nM).

Adenovirus 11 prototype (Ad11p), belonging to species B, uses CD46 as an attachment receptor. CD46, a complement regulatory molecule, is expressed on all human nucleated cells. We show here that Ad11p virions downregulate CD46 on the surface of K562 cells as early as 5min p.i. Specific binding to CD46 by the Ad11p fiber knob was required to mediate downregulation. The complement regulatory factors CD55 and CD59 were also reduced to a significant extent as a consequence of Ad11p binding to K562 cells. In contrast, binding of Ad7p did not result in downregulation of CD46 early in infection. Thus, the presumed interaction between Ad7p and CD46 did not have the same consequences as the Ad11p-CD46 interaction, the latter virus (Ad11p) being a promising gene therapy vector candidate. These findings may lead to a better understanding of the pathogenesis of species B adenovirus infections.

Small organic molecules that inhibit functional bacterial amyloid fibers, curli, are promising new antibiotics. Here we investigated the mechanism by which the ring-fused 2-pyridone FN075 inhibits fibrillation of the curli protein CsgA. Using a variety of biophysical techniques, we found that FN075 promotes CsgA to form off-pathway, non-amyloidogenic oligomeric species. In light of the generic properties of amyloids, we tested whether FN075 would also affect the fibrillation reaction of human α-synuclein, an amyloid-forming protein involved in Parkinson's disease. Surprisingly, FN075 stimulates α-synuclein amyloid fiber formation as measured by thioflavin T emission, electron microscopy (EM), and atomic force microscopy (AFM). NMR data on (15)N-labeled α-synuclein show that upon FN075 addition, α-synuclein oligomers with 7 nm radius form in which the C-terminal 40 residues remain disordered and solvent exposed. The polypeptides in these oligomers contain β-like secondary structure, and the oligomers are detectable by AFM, EM, and size-exclusion chromatography (SEC). Taken together, FN075 triggers oligomer formation of both proteins: in the case of CsgA, the oligomers do not proceed to fibers, whereas for α-synuclein, the oligomers are poised to rapidly form fibers. We conclude that there is a fine balance between small-molecule inhibition and templation that depends on protein chemistry.

Chlamydia trachomatis infections are a global health problem and new approaches to treat C. trachomatis with drugs of high specificity would be valuable. A library of substituted ring fused 2-pyridones has been synthesized and evaluated for their ability to attenuate C. trachomatis infectivity. In vivo pharmacokinetic studies were performed, with the best candidates demonstrating that a C8-methylsulfonamide substituent improved pharmacokinetic properties important for oral administration. C8-Methyl sulfonamide analogue 30 inhibited C. trachomatis infectivity in low micromolar concentrations. Further pharmacokinetic evaluation at an oral dose of 10 mg kg(-1) showed an apparent bioavailability of 41%, compared to C8-cyclopropyl and -methoxy analogues which had negligible oral uptake. In vitro ADME (absorption, distribution, metabolism and excretion) testing of solubility and Caco-2 cell permeability revealed that both solubility and permeability is greatly improved with the C8-methyl sulfonamide 30, effectively moving it from BCS (Biopharmaceutical Classification System) class IV to II.