Prion diseases such as Creutzfeldt-Jakob disease (CJD) are fatal, neuro-degenerative disorders with no known therapy. A proportion of the UK population has been exposed to a bovine spongiform encephalopathy-like prion strain and are at risk of developing variant CJD. A hallmark of prion disease is the transformation of normal cellular prion protein (PrP(C)) into an infectious disease-associated isoform, PrP(Sc). Recent in vitro studies indicate that anti-PrP monoclonal antibodies with little or no affinity for PrP(Sc) can prevent the incorporation of PrP(C) into propagating prions. We therefore investigated in a murine scrapie model whether anti-PrP monoclonal antibodies show similar inhibitory effects on prion replication in vivo. We found that peripheral PrP(Sc) levels and prion infectivity were markedly reduced, even when the antibodies were first administered at the point of near maximal accumulation of PrP(Sc) in the spleen. Furthermore, animals in which the treatment was continued remained healthy for over 300 days after equivalent untreated animals had succumbed to the disease. These findings indicate that immunotherapeutic strategies for human prion diseases are worth pursuing.

Prion diseases are a group of invariably fatal neurodegenerative disorders that include Creutzfeldt-Jakob disease in humans, scrapie in sheep and goats, and bovine spongiform encephalopathy in cattle. The infectious agent or prion is largely composed of an abnormal isoform (PrPSc) of a host encoded normal cellular protein (PrPc). The conversion of PrPc to PrPSc is a dynamic process and, for reasons that are not clear, the distribution of spongiform change and PrPSc deposition varies among prion strains. An obvious explanation for this would be that the transformation efficiency in any given brain region depends on favourable interactions between conformations of PrPc and the prion strain being propagated within it. However, identification of specific PrPc conformations has until now been hampered by a lack of suitable panels of antibodies that discriminate PrPc subspecies under native conditions. In this study, we show that monoclonal antibodies raised against recombinant human prion protein folded into alpha or beta conformations exhibit striking heterogeneity in their specificity for truncations and glycoforms of mouse brain PrPc. We then show that some of these PrPc isoforms are expressed differentially in certain mouse brain regions. This suggests that variation in the expression of PrPc conformations in different brain regions may dictate the pattern of PrPSc deposition and vacuolation, characteristic for different prion strains.

Oropouche virus (OROV) is an emerging pathogen which causes Oropouche fever and meningitis in humans. Several outbreaks of OROV in South America, especially in Brazil, have changed its status as an emerging disease, but no vaccine or specific drug target is available yet. Our approach was to identify the epitope-based vaccine candidates as well as the ligand-binding pockets through the use of immunoinformatics. In this report, we identified both T-cell and B-cell epitopes of the most antigenic OROV polyprotein with the potential to induce both humoral and cell-mediated immunity. Eighteen highly antigenic and immunogenic CD8+ T-cell epitopes were identified, including three 100% conserved epitopes (TSSWGCEEY, CSMCGLIHY, and LAIDTGCLY) as the potential vaccine candidates. The selected epitopes showed 95.77% coverage for the mixed Brazilian population. The docking simulation ensured the binding interaction with high affinity. A total of five highly conserved and nontoxic linear B-cell epitopes “NQKIDLSQL,” “HPLSTSQIGDRC,” “SHCNLEFTAITADKIMSL,” “PEKIPAKEGWLTFSKEHTSSW,” and “HHYKPTKNLPHVVPRYH” were selected as potential vaccine candidates. The predicted eight conformational B-cell epitopes represent the accessibility for the entered virus. In the posttherapeutic strategy, ten ligand-binding pockets were identified for effective inhibitor design against emerging OROV infection. Collectively, this research provides novel candidates for epitope-based peptide vaccine design against OROV.

BackgroundAn early event in the neuropathology of prion and Alzheimer's diseases is the loss of synapses and a corresponding reduction in the level of synaptophysin, a pre-synaptic membrane protein essential for neurotransmission. The molecular mechanisms involved in synapse degeneration in these diseases are poorly understood. In this study the process of synapse degeneration was investigated by measuring the synaptophysin content of cultured neurones incubated with the prion derived peptide (PrP82-146) or with Aβ1-42, a peptide thought to trigger pathogenesis in Alzheimer's disease. A pharmacological approach was used to screen cell signalling pathways involved in synapse degeneration.ResultsPre-treatment with phospholipase A2 inhibitors (AACOCF3, MAFP and aristolochic acids) protected against synapse degeneration in cultured cortical and hippocampal neurones incubated with PrP82-146 or Aβ1-42. Synapse degeneration was also observed following the addition of a specific phospholipase A2 activating peptide (PLAP) and the addition of PrP82-146 or Aβ1-42 activated cytoplasmic phospholipase A2 within synapses. Activation of phospholipase A2 is the first step in the generation of platelet-activating factor (PAF) and PAF receptor antagonists (ginkgolide B, Hexa-PAF and CV6029) protected against synapse degeneration induced by PrP82-146, Aβ1-42 and PLAP. PAF facilitated the production of prostaglandin E2, which also caused synapse degeneration and pre-treatment with the prostanoid E receptor antagonist AH13205 protected against PrP82-146, Aβ1-42 and PAF induced synapse degeneration.ConclusionsOur results are consistent with the hypothesis that PrP82-146 and Aβ1-42trigger abnormal activation of cytoplasmic phospholipase A2 resident within synapses, resulting in elevated levels of PAF and prostaglandin E2that cause synapse degeneration. Inhibitors of this pathway that can cross the blood brain barrier may protect against the synapse degeneration seen during Alzheimer's or prion diseases.

In prion diseases, such as variant Creutzfeldt-Jakob disease normal cellular prion protein (PrPC), a largely α-helical structure is converted to an abnormal conformational isoform (PrPSc) that shows an increase in β-sheet content. Similarly, the recombinant form of PrPC (rα-PrP) can be converted to a conformation dominated by β-sheet (rβ-PrP) by reduction and mild acidification in vitro, a process that may mimic in vivo conversion following PrPC internalization during recycling. Despite PrPSc accumulation and prion propagation in the lymphoreticular system before detectable neuroinvasion, no Ab response to PrP has been detected, probably due to immune tolerance. To investigate how the immune system may respond to α- and β-PrP, we immunized Prnp0/0 mice that are not tolerant of PrP with rα-PrP and rβ-PrP. In this study, we show that although T cells stimulated by these differently folded conformers PrP recognize similar immunodominant epitopes (residues 111–130 and 191–210) the cytokine profile in response to rα- and rβ-PrP was different. Challenge with rα-PrP elicited a strong response of IL-5 and IL-10, whereas rβ-PrP led to an early increased production of IFN-γ. In addition, immunization with rα-PrP led to production of predominantly IgG1 isotype Ab in the sera, whereas after immunization with rβ-PrP, IgG2b was significantly produced. Thus, both humoral and cellular responses to these differently folded isoforms of the same protein are different, indicating a possible involvement of Th1 and Th2 pathway activation. These differences may be exploitable diagnostically and therapeutically for prion diseases, such as variant Creutzfeldt-Jakob disease.

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Background: The early stages of Alzheimer's disease (AD) are closely associated with the production of the Aβ 1-42 peptide, loss of synapses and gradual cognitive decline. Since some epidemiological studies showed that EGb 761, an extract from the leaves of the Ginkgo biloba tree, had a beneficial effect on mild forms of AD, the effects of some of the major components of the EGb 761 extract (ginkgolides A and B, myricetin and quercetin) on synapse damage in response to Aβ 1-42 were examined.

Background: The transmissible spongiform encephalopathies (TSEs), otherwise known as the prion diseases, occur following the conversion of the normal cellular prion protein (PrP C ) to an alternatively folded isoform (PrP Sc ). The accumulation of PrP Sc within the brain leads to neurodegeneration through an unidentified mechanism. Since many neurodegenerative disorders including prion, Parkinson's and Alzheimer's diseases may be modified by cholesterol synthesis inhibitors, the effects of prion infection on the cholesterol balance within neuronal cells were examined.