Background The worst Ebola virus disease (EVD) outbreak in history has resulted in more than 28,000 cases and 11,000 deaths. We present the final results of two phase 1 trials of an attenuated, replication-competent, recombinant vesicular stomatitis virus (rVSV)–based vaccine candidate designed to prevent EVD. Methods We conducted two phase 1, placebo-controlled, double-blind, dose-escalation trials of an rVSV-based vaccine candidate expressing the glycoprotein of a Zaire strain of Ebola virus (ZEBOV). A total of 39 adults at each site (78 participants in all) were consecutively enrolled into groups of 13. At each site, volunteers received one of three doses of the rVSV-ZEBOV vaccine (3 million plaque-forming units [PFU], 20 million PFU, or 100 million PFU) or placebo. Volunteers at one of the sites received a second dose at day 28. Safety and immunogenicity were assessed. Results The most common adverse events were injection-site pain, fatigue, myalgia, and headache. Transient rVSV viremia was noted in all the vaccine recipients after dose 1. The rates of adverse events and viremia were lower after the second dose than after the first dose. By day 28, all the vaccine recipients had seroconversion as assessed by an enzyme-linked immunosorbent assay (ELISA) against the glycoprotein of the ZEBOV-Kikwit strain. At day 28, geometric mean titers of antibodies against ZEBOV glycoprotein were higher in the groups that received 20 million PFU or 100 million PFU than in the group that received 3 million PFU, as assessed by ELISA and by pseudovirion neutralization assay. A second dose at 28 days after dose 1 significantly increased antibody titers at day 56, but the effect was diminished at 6 months. Conclusions This Ebola vaccine candidate elicited anti-Ebola antibody responses. After vaccination, rVSV viremia occurred frequently but was transient. These results support further evaluation of the vaccine dose of 20 million PFU for preexposure prophylaxis and suggest that a second dose may boost antibody responses. (Funded by the National Institutes of Health and others; rVSVΔG-ZEBOV-GP ClinicalTrials.gov numbers, NCT02269423 and NCT02280408.)

Alzheimer's disease (AD) is an age-related neurodegenerative pathology in which defects in proteolytic clearance of amyloid β peptide (Aβ) likely contribute to the progressive nature of the disorder. Lysosomal proteases of the cathepsin family exhibit up-regulation in response to accumulating proteins including Aβ1–42. Here, the lysosomal modulator Z-Phe-Ala-diazomethylketone (PADK) was used to test whether proteolytic activity can be enhanced to reduce the accumulation events in AD mouse models expressing different levels of Aβ pathology. Systemic PADK injections in APPSwInd and APPswe/PS1ΔE9 mice caused 3- to 8-fold increases in cathepsin B protein levels and 3- to 10-fold increases in the enzyme's activity in lysosomal fractions, while neprilysin and insulin-degrading enzyme remained unchanged. Biochemical analyses indicated the modulation predominantly targeted the active mature forms of cathepsin B and markedly changed Rab proteins but not LAMP1, suggesting the involvement of enhanced trafficking. The modulated lysosomal system led to reductions in both Aβ immunostaining as well as Aβx-42 sandwich ELISA measures in APPSwInd mice of 10–11 months. More extensive Aβ deposition in 20-22-month APPswe/PS1ΔE9 mice was also reduced by PADK. Selective ELISAs found that a corresponding production of the less pathogenic Aβ1–38 occurs as Aβ1–42 levels decrease in the mouse models, indicating that PADK treatment leads to Aβ truncation. Associated with Aβ clearance was the elimination of behavioral and synaptic protein deficits evident in the two transgenic models. These findings indicate that pharmacologically-controlled lysosomal modulation reduces Aβ1–42 accumulation, possibly through intracellular truncation that also influences extracellular deposition, and in turn offsets the defects in synaptic composition and cognitive functions. The selective modulation promotes clearance at different levels of Aβ pathology and provides proof-of-principle for small molecule therapeutic development for AD and possibly other protein accumulation disorders.

Surveillance of Ebola virus disease flare-ups uncovers a reduced rate of Ebola virus evolution during persistent infections.

Background:The early oligomer states of A␤ are the primary therapeutic target for AD. Results: PADK binds to A␤ directly and inhibits and reverses the formation of dodecamer of A␤42. Conclusion: PADK disrupts and remodels the early oligomerization of A␤42. Significance: The study of PADK and A␤42 provides an example of small molecule therapeutic development for AD and other amyloid diseases.The oligomerization of the amyloid-␤ protein (A␤) is an important event in Alzheimer disease (AD) pathology. Developing small molecules that disrupt formation of early oligomeric states of A␤ and thereby reduce the effective amount of toxic oligomers is a promising therapeutic strategy for AD. Here, mass spectrometry and ion mobility spectrometry were used to investigate the effects of a small molecule, Z-Phe-Ala-diazomethylketone (PADK), on the A␤42 form of the protein. The mass spectrum of a mixture of PADK and A␤42 clearly shows that PADK binds directly to A␤42 monomers and small oligomers. Ion mobility results indicate that PADK not only inhibits the formation of A␤42 dodecamers, but also removes preformed A␤42 dodecamers from the solution. Electron microscopy images show that PADK inhibits A␤42 fibril formation in the solution. These results are consistent with a previous study that found that PADK has protective effects in an AD transgenic mouse model. The study of PADK and A␤42 provides an example of small molecule therapeutic development for AD and other amyloid diseases. Alzheimer disease (AD)2 is the leading cause of late life dementia and is characterized as a progressive brain disorder that damages synapses and eventually destroys brain cells (1, 2). The aggregation of amyloid-␤ protein (A␤) into soluble oligomeric species has been implicated as a key step in AD pathogenesis (3). Among the A␤ peptides that exist in vivo, the 42-amino acid A␤42 has been found to be the primary component of amyloid deposits that are a hallmark of AD (4). Recently, increasing evidence shows that the early oligomeric states rather than the later stage fibrillization of A␤42 are implicated in the onset of AD (5-8). A␤42 monomers form small oligomers in solution, as well as paranuclei (pentamers and hexamers) that self-assemble to form decamers and dodecamers (9 -14). An in vivo study identified a 56-kDa A␤ species (corresponding to a dodecamer) as the cause of memory disruption in affected mice (15). Because of their role in neuronal pathology, early oligomers of A␤42 are a primary therapeutic target for AD.A critical aspect of AD treatment and prevention is the clearance of A␤ proteins and protein aggregates from the brain (16). This clearance can be accomplished by directly disrupting the aggregation of A␤ proteins or by the degradation of A␤ proteins by proteases. Numerous natural proteins, peptides, and small molecules have been found to interfere with A␤ and disrupt the aggregation pathway (17). Small molecules are particularly attractive as a direct therapeutic strategy for the treatment of amyloidosis (18 -20). They include know...

Lysosomes are involved in degrading and recycling cellular ingredients, and their disruption with age may contribute to amyloidogenesis, paired helical filaments (PHFs), and a-synuclein and mutant huntingtin aggregation. Lysosomal cathepsins are upregulated by accumulating proteins and more so by the modulator ZPhe-Ala-diazomethylketone (PADK). Such positive modulators of the lysosomal system have been studied in the well-characterized hippocampal slice model of protein accumulation that exhibits the pathogenic cascade of tau aggregation, tubulin breakdown, microtubule destabilization, transport failure, and synaptic decline. Active cathepsins were upregulated by PADK; Rab proteins were modified as well, indicating enhanced trafficking, whereas lysosome-associated membrane protein and proteasome markers were unchanged. Lysosomal modulation reduced the pre-existing PHF deposits, restored tubulin structure and transport, and recovered synaptic components. Further proof-of-principle studies used Alzheimer disease mouse models. It was recently reported that systemic PADK administration caused dramatic increases in cathepsin B protein and activity levels, whereas neprilysin, insulin-degrading enzyme, a-secretase, and b-secretase were unaffected by PADK. In the transgenic models, PADK treatment resulted in clearance of intracellular amyloid beta (Ab) peptide and concomitant reduction of extracellular deposits. Production of the less pathogenic Ab 1-38 peptide corresponded with decreased levels of Ab 1-42 , supporting the lysosome's antiamyloidogenic role through intracellular truncation. Amelioration of synaptic and behavioral deficits also indicates a neuroprotective function of the lysosomal system, identifying lysosomal modulation as an avenue for disease-modifying therapies. From the in vitro and in vivo findings, unique lysosomal modulators represent a minimally invasive, pharmacologically controlled strategy against protein accumulation disorders to enhance protein clearance, promote synaptic integrity, and slow the progression of dementia.