In prion and Alzheimer's diseases, the roles played by amyloid versus nonamyloid deposits in brain damage remain unresolved. In scrapie-infected transgenic mice expressing prion protein (PrP) lacking the glycosylphosphatidylinositol (GPI) membrane anchor, abnormal protease-resistant PrPres was deposited as amyloid plaques, rather than the usual nonamyloid form of PrPres. Although PrPres amyloid plaques induced brain damage reminiscent of Alzheimer's disease, clinical manifestations were minimal. In contrast, combined expression of anchorless and wild-type PrP produced accelerated clinical scrapie. Thus, the PrP GPI anchor may play a role in the pathogenesis of prion diseases.

First identified in 2012, Middle East respiratory syndrome (MERS) is caused by an emerging human coronavirus, which is distinct from the severe acute respiratory syndrome coronavirus (SARS-CoV), and represents a novel member of the lineage C betacoronoviruses. Since its identification, MERS coronavirus (MERS-CoV) has been linked to more than 1372 infections manifesting with severe morbidity and, often, mortality (about 495 deaths) in the Arabian Peninsula, Europe, and, most recently, the United States. Human-to-human transmission has been documented, with nosocomial transmission appearing to be an important route of infection. The recent increase in cases of MERS in the Middle East coupled with the lack of approved antiviral therapies or vaccines to treat or prevent this infection are causes for concern. We report on the development of a synthetic DNA vaccine against MERS-CoV. An optimized DNA vaccine encoding the MERS spike protein induced potent cellular immunity and antigen-specific neutralizing antibodies in mice, macaques, and camels. Vaccinated rhesus macaques seroconverted rapidly and exhibited high levels of virus-neutralizing activity. Upon MERS viral challenge, all of the monkeys in the control-vaccinated group developed characteristic disease, including pneumonia. Vaccinated macaques were protected and failed to demonstrate any clinical or radiographic signs of pneumonia. These studies demonstrate that a consensus MERS spike protein synthetic DNA vaccine can induce protective responses against viral challenge, indicating that this strategy may have value as a possible vaccine modality against this emerging pathogen.

The availability of a robust disease model is essential for the development of countermeasures for Middle East respiratory syndrome coronavirus (MERS-CoV). While a rhesus macaque model of MERS-CoV has been established, the lack of uniform, severe disease in this model complicates the analysis of countermeasure studies. Modeling of the interaction between the MERS-CoV spike glycoprotein and its receptor dipeptidyl peptidase 4 predicted comparable interaction energies in common marmosets and humans. The suitability of the marmoset as a MERS-CoV model was tested by inoculation via combined intratracheal, intranasal, oral and ocular routes. Most of the marmosets developed a progressive severe pneumonia leading to euthanasia of some animals. Extensive lesions were evident in the lungs of all animals necropsied at different time points post inoculation. Some animals were also viremic; high viral loads were detected in the lungs of all infected animals, and total RNAseq demonstrated the induction of immune and inflammatory pathways. This is the first description of a severe, partially lethal, disease model of MERS-CoV, and as such will have a major impact on the ability to assess the efficacy of vaccines and treatment strategies as well as allowing more detailed pathogenesis studies.

Existing mouse models of lethal Ebola virus infection do not reproduce hallmark symptoms of Ebola hemorrhagic fever, neither delayed blood coagulation and disseminated intravascular coagulation, nor death from shock, thus restricting pathogenesis studies to non-human primates. Here we show that mice from the Collaborative Cross exhibit distinct disease phenotypes following mouse-adapted Ebola virus infection. Phenotypes range from complete resistance to lethal disease to severe hemorrhagic fever characterized by prolonged coagulation times and 100% mortality. Inflammatory signaling was associated with vascular permeability and endothelial activation, and resistance to lethal infection arose by induction of lymphocyte differentiation and cellular adhesion, likely mediated by the susceptibility allele Tek. These data indicate that genetic background determines susceptibility to Ebola hemorrhagic fever.

Prion diseases are fatal neurodegenerative diseases of humans and animals characterized by gray matter spongiosis and accumulation of aggregated, misfolded, protease-resistant prion protein (PrPres). PrPres can be deposited in brain in an amyloid-form and/or non-amyloid form, and is derived from host-encoded protease-sensitive PrP (PrPsen), a protein normally anchored to the plasma membrane by glycosylphosphatidylinositol (GPI). Previously, using heterozygous transgenic mice expressing only anchorless PrP, we found that PrP anchoring to the cell membrane was required for typical clinical scrapie. However, in the present experiments, using homozygous transgenic mice expressing two-fold more anchorless PrP, scrapie infection induced a new fatal disease with unique clinical signs and altered neuropathology, compared to non-transgenic mice expressing only anchored PrP. Brain tissue of transgenic mice had high amounts of infectivity, and histopathology showed dense amyloid PrPres plaque deposits without gray matter spongiosis. In contrast, infected non-transgenic mice had diffuse non-amyloid PrPres deposits with significant gray matter spongiosis. Brain graft studies suggested that anchored PrPsen expression was required for gray matter spongiosis during prion infection. Furthermore, electron and light microscopic studies in infected transgenic mice demonstrated several pathogenic processes not seen in typical prion disease, including cerebral amyloid angiopathy and ultrastructural alterations in perivascular neuropil. These findings were similar to certain human familial prion diseases as well as to non-prion human neurodegenerative diseases, such as Alzheimer's disease.

The first influenza pandemic of the new millennium was caused by a newly emerged swine-origin influenza virus (SOIV) (H1N1). This new virus is

Intracytoplasmic protein targeting in mammalian cells is critical for organelle function as well as virus assembly, but the signals that mediate it are poorly defined. We show here that Mason‐Pfizer monkey virus specifically targets Gag precursor proteins to the pericentriolar region of the cytoplasm in a microtubule dependent process through interactions between a short peptide signal, known as the cytoplasmic targeting‐retention signal, and the dynein/dynactin motor complex. The Gag molecules are concentrated in pericentriolar microdomains, where they assemble to form immature capsids. Depletion of Gag from this region by cycloheximide treatment, coupled with the presence of ribosomal clusters that are in close vicinity to the assembling capsids, suggests that the dominant N‐terminal cytoplasmic targeting‐retention signal functions in a cotranslational manner. Transport of the capsids out of the pericentriolar assembly site requires the env‐gene product, and a functional vesicular transport system. A single point mutation that renders the cytoplasmic targeting‐retention signal defective abrogates pericentriolar targeting of Gag molecules. Thus the previously defined cytoplasmic targeting‐retention signal appears to act as a cotranslational intracellular targeting signal that concentrates Gag proteins at the centriole for assembly of capsids.

In the 1990s, Hendra virus and Nipah virus (NiV), two closely related and previously unrecognized paramyxoviruses that cause severe disease and death in humans and a variety of animals, were discovered in Australia and Malaysia, respectively. Outbreaks of disease have occurred nearly every year since NiV was first discovered, with case fatality ranging from 10 to 100%. In the African green monkey (AGM), NiV causes a severe lethal respiratory and/or neurological disease that essentially mirrors fatal human disease. Thus, the AGM represents a reliable disease model for vaccine and therapeutic efficacy testing. We show that vaccination of AGMs with a recombinant subunit vaccine based on the henipavirus attachment G glycoprotein affords complete protection against subsequent NiV infection with no evidence of clinical disease, virus replication, or pathology observed in any challenged subjects. Success of the recombinant subunit vaccine in nonhuman primates provides crucial data in supporting its further preclinical development for potential human use.