LETHAL TOXIN NEUTRALIZING ANTIBODY RESPONSE INDUCED FOLLOWING ORAL VACCINATION WITH A MICROENCAPSULATED BACILLUS ANTHRACIS STERNE STRAIN 34F2 VACCINE PROOF-OF-CONCEPT STUDY IN WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS).

Improved methods are needed to prevent wildlife deaths from anthrax. Caused by Bacillus anthracis, naturally occurring outbreaks of anthrax are frequent but unpredictable. The commercially available veterinary vaccine is labeled for subcutaneous injection and is impractical for large-scale wildlife vaccination programs; therefore, oral vaccination is the most realistic method to control and prevent these outbreaks. We reported the induction of an anthrax-specific lethal toxin (LeTx) neutralizing antibody response in mice following oral vaccination with alginate microcapsules containing B. anthracis Sterne strain 34F2 spores, coated with poly-L-lysine (PLL) and vitelline protein B (VpB). We continued evaluating our novel vaccine formulation through this proof-of-concept study in white-tailed deer (WTD; Odocoileus virginianus; n = 9). We orally vaccinated WTD via needle-free syringe with three formulations of the encapsulated vaccine: 1) PLL-VpB-coated microcapsules with 107-8 spores/ml (n = 5), 2) PLL-VpB-coated microcapsules with 109-10 spores/ml (n = 2), and 3) PLL-coated microcapsules with 109-10 spores/ml (n = 2). Although the limited sample sizes require continued experimentation, we observed an anthrax-specific antibody response in WTD serum following oral vaccination with PLL-coated microcapsules containing 109 spores/ ml. Furthermore, this antibody response neutralized anthrax LeTx in vitro, suggesting that continued development of this vaccine may allow for realistic wildlife anthrax vaccination programs.

The candidate vaccine strain Brucella ovis ∆abcBA is protective against Brucella melitensis infection in mice.

Brucellosis is a major zoonotic disease, and Brucella melitensis is the species most often associated with human infection. Vaccination is the most efficient tool for controlling animal brucellosis, with a consequent decrease of incidence of human infections. Commercially available live attenuated vaccines provide some degree of protection, but retain residual pathogenicity to human and animals. In this study, Brucella ovis ∆abcBA (Bo∆abcBA), a live attenuated candidate vaccine strain, was tested in two formulations (encapsulated with alginate and alginate plus vitelline protein B [VpB]) to immunize mice against experimental challenge with B. melitensis strain 16M. One week after infection, livers and spleens of immunized mice had reduced numbers of the challenge strain B. melitensis 16M when compared with those of nonimmunized mice, with a reduction of approximately 1-log10 of B. melitensis 16M count in the spleens from immunized mice. Moreover, splenocytes stimulated with B. melitensis antigens in vitro secreted IFN-γ when mice had been immunized with Bo∆abcBA encapsulated with alginate plus VpB, but not with alginate alone. Body and liver weights were similar among groups, although spleens from mice immunized with Bo∆abcBA encapsulated with alginate were larger than those immunized with Bo∆abcBA encapsulated with alginate plus VpB or nonimmunized mice. This study demonstrated that two vaccine formulations containing Bo∆abcBA protected mice against experimental challenge with B. melitensis.

Pathogenesis and immunobiology of brucellosis: review of Brucella-host interactions.

This review of Brucella-host interactions and immunobiology discusses recent discoveries as the basis for pathogenesis-informed rationales to prevent or treat brucellosis. Brucella spp., as animal pathogens, cause human brucellosis, a zoonosis that results in worldwide economic losses, human morbidity, and poverty. Although Brucella spp. infect humans as an incidental host, 500,000 new human infections occur annually, and no patient-friendly treatments or approved human vaccines are reported. Brucellae display strong tissue tropism for lymphoreticular and reproductive systems with an intracellular lifestyle that limits exposure to innate and adaptive immune responses, sequesters the organism from the effects of antibiotics, and drives clinical disease manifestations and pathology. Stealthy brucellae exploit strategies to establish infection, including i) evasion of intracellular destruction by restricting fusion of type IV secretion system-dependent Brucella-containing vacuoles with lysosomal compartments, ii) inhibition of apoptosis of infected mononuclear cells, and iii) prevention of dendritic cell maturation, antigen presentation, and activation of naive T cells, pathogenesis lessons that may be informative for other intracellular pathogens. Data sets of next-generation sequences of Brucella and host time-series global expression fused with proteomics and metabolomics data from in vitro and in vivo experiments now inform interactive cellular pathways and gene regulatory networks enabling full-scale systems biology analysis. The newly identified effector proteins of Brucella may represent targets for improved, safer brucellosis vaccines and therapeutics.

In Vitro Protection and Titer Duration of Anthrax-Specific Antibodies Following Subcutaneous Vaccination of White-tailed Deer (Odocoileus virginianus) with Bacillus anthracis Sterne 34F2 Strain Spores.

Outbreaks of anthrax, caused by the soilborne bacterium Bacillus anthracis, are a continuous threat to free-ranging livestock and wildlife in enzootic regions of the United States, sometimes causing mass mortalities. Injectable anthrax vaccines are commercially available for use in livestock, and although hand injection is not a cost- or time-effective long-term management plan for prevention in wildlife, it may provide a tool for managers to target selectively animals of high conservation or economic value. Vaccine-induced anthrax-specific antibody responses have been reported previously in white-tailed deer (Odocoileus virginianus), but the protective nature was not determined. In this study, five white-tailed deer were subcutaneously vaccinated with one dose (1 mL) of the Anthrax Spore Vaccine. Eight blood collections by jugular venipuncture were conducted over 146 d to measure the anthrax-specific antibody response in each deer's serum over time. Antibodies were first detected by ELISA and later with toxin neutralization assays to estimate in vitro protection. Average peak absorbance by ELISA occurred at 14 d postvaccination, whereas average peak in vitro protection occurred at 28 d postvaccination. Observed in vitro protection on average for white-tailed deer after this single-dose vaccination protocol lasted 42-56 d postvaccination, although three individuals still maintained lethal toxin-neutralizing serum antibody titers out to 112 d postvaccination. Vaccination responses were variable but effective to some degree in all white-tailed deer.

Size discrimination in rat and mouse gastric emptying.

OBJECTIVES: To investigate the relationship between particle size and gastric emptying in rodents using radiolabeled insoluble polymethyl methacrylate (PMMA) microcapsules/beads. METHODS: PMMA microcapsules (50-500 µm) and beads (0.5-3 mm) loaded with technetium-99 m diethylenetriamine pentaacetic acid ((99m) Tc-DTPA) were administered to ICR mice or Sprague Dawley (SD) rats by oral gavage. Gamma scintiscans were acquired initially following administration and then at hourly intervals to 4 hours. RESULTS: Scintiscans revealed that the smallest PMMA microcapsules (50-100 µm) or beads (0.5-1 mm) were impeded in the stomach and emptied slower than large particles in both rodent species. In mice, no significant difference in gastric emptying was found with microcapsules between 100 and 300 µm in diameter (p = 0.25) and particles more than 300 µm could not be administered. In rats, capsules containing 0.5-3 mm beads were stuck to the esophagus (up to 1 hour), this was a limitation of dosing beads of this size because they cannot be suspended in a liquid media for oral gavage purposes. Beads with diameters of 2-3 mm stayed in the stomach for up to 4 hours. CONCLUSIONS: The cut-off emptying size in ICR mice could not be determined, due to the limitation of current available dosing methods. The cut-off emptying size in SD rats was between 1.5 and 2 mm. Therefore, particles with a diameter greater than 2 mm should not be used for gastric emptying studies of intact particles in SD rats, as their emptying is retarded in the stomach.

Evaluation of the safety profile of the vaccine candidate Brucella melitensis 16MΔvjbR strain in goats.

Small ruminant brucellosis is caused by the Gram negative cocci-bacillus Brucella (B.) melitensis, the most virulent Brucella species for humans. In goats and sheep, middle to late-term gestation abortion, stillbirths and the delivery of weak infected offspring are the characteristic clinical signs of the disease. Vaccination with the currently available Rev. 1 vaccine is the best option to prevent and control the disease, although it is far from ideal. In this study, we investigate the safety of the B. melitensis 16MΔvjbR strain during a 15-month period beginning at vaccination of young goats, impregnation, delivery and lactation. Forty, 4 to 6 months old, healthy female crossbreed goats were randomly divided into four groups (n = 10) and immunized subcutaneously with a single vaccine dose containing 1x109 CFU of B. melitensis 16MΔvjbR delivered in alginate microcapsules or non-encapsulated. Controls received empty capsules or the commercially available Rev.1 vaccine. Seven months post-vaccination, when animals were sexually mature, all goats were naturally bred using brucellosis-free males, and allowed to carry pregnancies to term. Blood samples to assess the humoral immune response were collected throughout the study. At two months post-delivery, all dams and their offspring were euthanized and a necropsy was performed to collect samples for bacteriology and histology. Interestingly, none of the animals that received the vaccine candidate regardless of the formulation exhibited any clinical signs associated with vaccination nor shed the vaccine strain through saliva, vagina or the milk. Gross and histopathologic changes in all nannies and offspring were unremarkable with no evidence of tissue colonization or vertical transmission to fetuses. Altogether, these data demonstrate that vaccination with the mutant strain 16MΔvjbR is safe for use in the non-pregnant primary host.

Interactions between fungal hyaluronic acid and host CD44 promote internalization by recruiting host autophagy proteins to forming phagosomes.

Phagocytosis and autophagy play critical roles in immune defense. The human fungal pathogen Cryptococcus neoformans (Cn) subverts host autophagy-initiation complex (AIC)-related proteins, to promote its phagocytosis and intracellular parasitism of host cells. The mechanisms by which the pathogen engages host AIC-related proteins remain obscure. Here, we show that the recruitment of host AIC proteins to forming phagosomes is dependent upon the activity of CD44, a host cell surface receptor that engages fungal hyaluronic acid (HA). This interaction elevates intracellular Ca2+ concentrations and activates CaMKKß and its downstream target AMPKα, which results in activation of ULK1 and the recruitment of AIC components. Moreover, we demonstrate that HA-coated beads efficiently recruit AIC components to phagosomes and CD44 interacts with AIC components. Taken together, these findings show that fungal HA plays a critical role in directing the internalization and productive intracellular membrane trafficking of a fungal pathogen of global importance.

Case Report: Paucisymptomatic College-Age Population as a Reservoir for Potentially Neutralization-Resistant Severe Acute Respiratory Syndrome Coronavirus 2 Variants.

To better understand the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant lineage distribution in a college campus population, we carried out viral genome surveillance over a 7-week period from January to March 2021. Among the sequences were three novel viral variants: BV-1 with a B.1.1.7/20I genetic background and an additional spike mutation Q493R, associated with a mild but longer-than-usual COVID-19 case in a college-age person, BV-2 with a T478K mutation on a 20B genetic background, and BV-3, an apparent recombinant lineage. This work highlights the potential of an undervaccinated younger population as a reservoir for the spread and generation of novel variants. This also demonstrates the value of whole genome sequencing as a routine disease surveillance tool.

Protective antibody response following oral vaccination with microencapsulated Bacillus Anthracis Sterne strain 34F2 spores.

An oral vaccine against anthrax (Bacillus anthracis) is urgently needed to prevent annual anthrax outbreaks that are causing catastrophic losses in free-ranging livestock and wildlife worldwide. The Sterne vaccine, the current injectable livestock vaccine, is a suspension of live attenuated B. anthracis Sterne strain 34F2 spores (Sterne spores) in saponin. It is not effective when administered orally and individual subcutaneous injections are not a practical method of vaccination for wildlife. In this study, we report the development of a microencapsulated oral vaccine against anthrax. Evaluating Sterne spore stability at varying pH's in vitro revealed that spore exposure to pH 2 results in spore death, confirming that protection from the gastric environment is of main concern when producing an oral vaccine. Therefore, Sterne spores were encapsulated in alginate and coated with a protein shell containing poly-L-lysine (PLL) and vitelline protein B (VpB), a non-immunogenic, proteolysis resistant protein isolated from Fasciola hepatica. Capsule exposure to pH 2 demonstrated enhanced acid gel character suggesting that alginate microcapsules provided the necessary protection for spores to survive the gastric environment. Post vaccination IgG levels in BALBc/J mouse serum samples indicated that encapsulated spores induced anti-anthrax specific responses in both the subcutaneous and the oral vaccination groups. Furthermore, the antibody responses from both vaccination routes were protective against anthrax lethal toxin in vitro, suggesting that further optimization of this vaccine formulation may result in a reliable oral vaccine that will conveniently and effectively prevent anthrax in wildlife populations.

A Tractable Drosophila Cell System Enables Rapid Identification of Acinetobacter baumannii Host Factors.

Acinetobacter baumannii is an important causative agent of nosocomial infections worldwide. The pathogen also readily acquires resistance to antibiotics, and pan-resistant strains have been reported. A. baumannii is widely regarded as an extracellular bacterial pathogen. However, accumulating evidence demonstrates that the pathogen can invade, survive or persist in infected mammalian cells. Unfortunately, the molecular mechanisms controlling these processes remain poorly understood. Here, we show that Drosophila S2 cells provide several attractive advantages as a model system for investigating the intracellular lifestyle of the pathogen, including susceptibility to bacterial intracellular replication and limited infection-induced host cell death. We also show that the Drosophila system can be used to rapidly identify host factors, including MAP kinase proteins, which confer susceptibility to intracellular parasitism. Finally, analysis of the Drosophila system suggested that host proteins that regulate organelle biogenesis and membrane trafficking contribute to regulating the intracellular lifestyle of the pathogen. Taken together, these findings establish a novel model system for elucidating interactions between A. baumannii and host cells, define new factors that regulate bacterial invasion or intracellular persistence, and identify subcellular compartments in host cells that interact with the pathogen.

Enhanced immune response of red deer (Cervus elaphus) to live rb51 vaccine strain using composite microspheres.

Brucellosis is an important zoonotic disease of nearly worldwide distribution. The occurrence of the infection in humans is largely dependent on the prevalence of brucellosis in animal reservoirs, including wildlife. The current vaccine used for cattle Brucella abortus strain RB51, has proven ineffective in protecting bison (Bison bison) and elk (Cervus nelsoni) from infection and abortion. To test possible improvements in vaccine efficacy, a novel approach of immunization was examined from April 2004 to November 2006 using alginate composite microspheres containing a nonimmunogenic, eggshell-precursor protein of the parasite Fasciola hepatica (Vitelline protein B, VpB) to deliver live vaccine strain RB51. Red deer (Cervus elaphus), used as a model for elk, were vaccinated orally (PO) or subcutaneously (SC) with 1.5x10(10) viable organisms per animal. Humoral responses postvaccination (immunoglobulin G [IgG] levels), assessed at different time points, indicated that capsules containing live RB51 elicited an anti-Brucella specific IgG response. Furthermore, the encapsulated vaccine elicited a cell-mediated response that the nonencapsulated vaccinates failed to produce. Finally, red deer were challenged with B. abortus strain 19 by conjunctival exposure. Only animals that received encapsulated RB51 vaccine by either route exhibited a significant reduction in bacterial counts in their spleens. These data suggest that alginate-VpB microspheres provide a method to enhance the RB51 vaccine performance in elk.

Vaccine safety studies of Brucella abortus S19 and S19ΔvjbR in pregnant swine.

Brucellosis in swine is caused by Brucella suis, a bacterial infection of nearly worldwide distribution. Brucella suis is also transmissible to humans, dogs and cattle and is considered a reemerging disease of public health concern. To date, there is no effective vaccine for swine. This prompted us to investigate the potential use of the commercially available vaccine for cattle or the live attenuated vaccine candidate S19ΔvjbR. As the first step, we sought to study the safety of the vaccine candidates when administered in pregnant sows, since one of the major drawbacks associated with vaccination using Live Attenuated Vaccines (LAV) is the induction of abortions when administered in pregnant animals. Fifteen pregnant gilts at mid-gestation were divided into four groups and subsequently vaccinated subcutaneously using different formulations containing 2.0 ±â€¯0.508 × 109 CFU of either S19 or S19ΔvjbR. Vaccination in pregnant animals with the vaccine candidates did not induce abortion, stillbirths or a reduction in litter size. Multiple tissues in the gilts and piglets were examined at the time of delivery to assess bacterial colonization and histopathological changes. There was no evidence of vaccine persistence in the gilts or bacterial colonization in the fetuses. Altogether, these data suggest that both vaccine candidates are safe for use in pregnant swine. Analysis of the humoral responses, specifically anti-Brucella IgG levels measured in serum, demonstrated a robust response induced by either vaccine, but of shorter duration (4-6 weeks post-inoculation) compared to that observed in cattle or experimentally infected mice. Such a transient humoral response may prove to be beneficial in cases where the vaccine is used in eradication campaigns and in the differentiation of vaccinated from infected animals. This study provides evidence to support future efficacy studies of both vaccine candidates in swine.

Immunization with a single dose of a microencapsulated Brucella melitensis mutant enhances protection against wild-type challenge.

The development of safe and efficacious immunization systems to prevent brucellosis is needed to overcome the disadvantages of the currently licensed vaccine strains that restrict their use in humans. Alginate microspheres coated with a protein of the parasite Fasciola hepatica (vitelline protein B [VpB]) and containing live Brucella melitensis attenuated mutant vjbR::Tn5 (BMEII1116) were evaluated for vaccine efficacy and immunogenicity in mice. A single immunization dose in BALB/c mice with the encapsulated vjbR mutant improved protection against wild-type B. melitensis 16M challenge compared to the nonencapsulated vaccine strain (P < 0.05). The encapsulated mutant was also shown to induce a sustained elevation of Immunoglobulin G levels. Cytokine secretion from spleen cells of mice vaccinated with the encapsulated vjbR::Tn5 revealed elevated secretion of gamma interferon and interleukin-12, but no interleukin-4, suggesting an induction of a T helper 1 response reflecting the enhanced immunity associated with microencapsulation. Together, these results suggest that microencapsulation of live attenuated organisms offers the ability to increase the efficacy of vaccine candidates.

Activation of Host IRE1α-Dependent Signaling Axis Contributes the Intracellular Parasitism of Brucella melitensis.

Brucella spp. are intracellular vacuolar pathogens that causes brucellosis, a worldwide zoonosis of profound importance. We previously demonstrated that the activity of host unfolded protein response (UPR) sensor IRE1α (inositol-requiring enzyme 1) and ER-associated autophagy confer susceptibility to Brucella melitensis and Brucella abortus intracellular replication. However, the mechanism by which host IRE1α regulates the pathogen intracellular lifestyle remains elusive. In this study, by employing a diverse array of molecular approaches, including biochemical analyses, fluorescence microscopy imaging, and infection assays using primary cells derived from Ern1 (encoding IRE1) conditional knockout mice, we address this gap in our understanding by demonstrating that a novel IRE1α to ULK1, an important component for autophagy initiation, signaling axis confers susceptibility to Brucella intracellular parasitism. Importantly, deletion or inactivation of key signaling components along this axis, including IRE1α, BAK/BAX, ASK1, and JNK as well as components of the host autophagy system ULK1, Atg9a, and Beclin 1, resulted in striking disruption of Brucella intracellular trafficking and replication. Host kinases in the IRE1α-ULK1 axis, including IRE1α, ASK1, JNK1, and/or AMPKα as well as ULK1, were also coordinately phosphorylated in an IRE1α-dependent fashion upon the pathogen infection. Taken together, our findings demonstrate that the IRE1α-ULK1 signaling axis is subverted by the bacterium to promote intracellular parasitism, and provide new insight into our understanding of the molecular mechanisms of intracellular lifestyle of Brucella.

Analysis of stress responsive genes induced by single-walled carbon nanotubes in BJ Foreskin cells.

Nanotechnology is finding its use as a potential technology in consumer products, defense, electronics, and medical applications by exploiting the properties of nanomaterials. Single-walled carbon nanotubes are novel forms of these nanomaterials with potential for large applications. However, the toxicity studies on this material are not explored in detail and therefore limiting its use. It has been earlier reported that single-walled carbon nanotubes induces oxidative stress and also dictates activation of specific signaling pathway in keratinocytes. The present study explores the effect of single-walled carbon nanotubes on stress genes in human BJ Foreskin cells. The results show induction of oxidative stress in BJ Foreskin cells by single-walled carbon nanotubes and increase in stress responsive genes. The genes included inducible genes like HMOX1, HMOX2, and Cyp1B1. In addition we validated increase for four genes by SWCNT, namely ATM, CCNC, DNAJB4, and GADD45A by RT-PCR. Moreover results of the altered stress related genes have been discussed and that partially explains some of the toxic responses induced by single-walled carbon nanotubes.

Global Reprogramming of Host Kinase Signaling in Response to Fungal Infection.

Cryptococcus neoformans (Cn) is a deadly fungal pathogen whose intracellular lifestyle is important for virulence. Host mechanisms controlling fungal phagocytosis and replication remain obscure. Here, we perform a global phosphoproteomic analysis of the host response to Cryptococcus infection. Our analysis reveals numerous and diverse host proteins that are differentially phosphorylated following fungal ingestion by macrophages, thereby indicating global reprogramming of host kinase signaling. Notably, phagocytosis of the pathogen activates the host autophagy initiation complex (AIC) and the upstream regulatory components LKB1 and AMPKα, which regulate autophagy induction through their kinase activities. Deletion of Prkaa1, the gene encoding AMPKα1, in monocytes results in resistance to fungal colonization of mice. Finally, the recruitment of AIC components to nascent Cryptococcus-containing vacuoles (CnCVs) regulates the intracellular trafficking and replication of the pathogen. These findings demonstrate that host AIC regulatory networks confer susceptibility to infection and establish a proteomic resource for elucidating host mechanisms that regulate fungal intracellular parasitism.

A novel 78-kDa fatty acyl-CoA synthetase (ACS1) of Babesia bovis stimulates memory CD4+ T lymphocyte responses in B. bovis-immune cattle.

Antigen-specific CD4+ T lymphocyte responses contribute to protective immunity against Babesia bovis, however the antigens that induce these responses remain largely unknown. A proteomic approach was used to identify novel B. bovis antigens recognized by memory CD4+ T cells from immune cattle. Fractions obtained from merozoites separated by continuous-flow electrophoresis (CFE) that contained proteins ranging from 20 to 83 kDa were previously shown to stimulate memory CD4+ lymphocyte responses in B. bovis-immune cattle. Expression library screening with rabbit antiserum raised against an immunostimulatory CFE fraction identified a clone encoding a predicted 78 kDa protein. BLAST analysis revealed sequence identity of this B. bovis protein with Plasmodium falciparum fatty acyl coenzyme A synthetase (ACS) family members (PfACS1-PfACS11), and the protein was designated B. bovis acyl-CoA synthetase 1 (ACS1). Southern blot analysis indicated that B. bovis ACS1 is encoded by a single gene, although BLAST analysis of the preliminary B. bovis genome sequence identified two additional family members, ACS2 and ACS3. Peripheral blood lymphocytes and CD4+ T cell lines from B. bovis-immune cattle proliferated significantly against recombinant ACS1 protein, consistent with its predicted involvement in protective immunity. However, immune sera from cattle recovered from B. bovis infection did not react with ACS1, indicating that epitopes may be conformationally dependent.

The Case for Live Attenuated Vaccines against the Neglected Zoonotic Diseases Brucellosis and Bovine Tuberculosis.

Vaccination of humans and animals with live attenuated organisms has proven to be an effective means of combatting some important infectious diseases. In fact, the 20th century witnessed tremendous improvements in human and animal health worldwide as a consequence of large-scale vaccination programs with live attenuated vaccines (LAVs). Here, we use the neglected zoonotic diseases brucellosis and bovine tuberculosis (BTb) caused by Brucella spp. and Mycobacterium bovis (M. bovis), respectively, as comparative models to outline the merits of LAV platforms with emphasis on molecular strategies that have been pursued to generate LAVs with enhanced vaccine safety and efficacy profiles. Finally, we discuss the prospects of LAV platforms in the fight against brucellosis and BTb and outline new avenues for future research towards developing effective vaccines using LAV platforms.

Hsp20, a novel alpha-crystallin, prevents Abeta fibril formation and toxicity.

Beta-amyloid (Abeta) is a major protein component of senile plaques in Alzheimer's disease, and is neurotoxic when aggregated. The size of aggregated Abeta responsible for the observed neurotoxicity and the mechanism of aggregation are still under investigation; however, prevention of Abeta aggregation still holds promise as a means to reduce Abeta neurotoxicity. In research presented here, we show that Hsp20, a novel alpha-crystallin isolated from the bovine erythrocyte parasite Babesia bovis, was able to prevent aggregation of denatured alcohol dehydrogenase when the two proteins are present at near equimolar levels. We then examined the ability of Hsp20 produced as two different fusion proteins to prevent Abeta amyloid formation as indicated by Congo Red binding; we found that not only was Hsp20 able to dramatically reduce Congo Red binding, but it was able to do so at molar ratios of Hsp20 to Abeta of 1 to 1000. Electron microscopy confirmed that Hsp20 does prevent Abeta fibril formation. Hsp20 was also able to significantly reduce Abeta toxicity to both SH-SY5Y and PC12 neuronal cells at similar molar ratios. At high concentrations of Hsp20, the protein no longer displays its aggregation inhibition and toxicity attenuation properties. Size exclusion chromatography indicated that Hsp20 was active at low concentrations in which dimer was present. Loss of activity at high concentrations was associated with the presence of higher oligomers of Hsp20. This work could contribute to the development of a novel aggregation inhibitor for prevention of Abeta toxicity.