New horizons in translational medicine最新文献

Aedes aegypti mosquitoes are the primary vectors transmitting dengue virus (DENV), one of the most aggressive re-emerging pathogens worldwide causing more than 390 million infections per year. The spread of the virus is greatly dependent upon successful replication within both the human host and mosquito vector. Much effort has been placed in understanding the dynamics of virus transmission and replication in both organisms, but little is known about the global impact of DENV on metabolic pathways. Previous studies have demonstrated perturbations in human and Aedes albopictus cellular metabolic environments during DENV infection. Some of these perturbations include increasing the production of membranous lipids that had the capability to induce membrane curvature and permeability, as well as visibly altering both human and mosquito intracellular membrane architecture to support DENV replication. In this study, we have explored metabolic changes in Aedes aegypti midgut and salivary glands upon DENV (serotype 2) infection. We have found several significant fluctuations in the lipid and metabolite repertoire from infected tissues compared to uninfected controls, including differential expression of molecules that function as membrane building blocks, bioactive messengers, energy storage and intermediates in lipid biosynthesis and lipolysis pathways. These results and their relevance to dengue virus infection of its mosquito vector will be discussed.

Members of the genus Phlebovirus (family Bunyaviridae) are new and emerging disease pathogens of humans and animals. Newly identified viruses include Heartland virus (HRTV), Lone Star virus in the USA, and Severe Fever with Thrombocytopenia Syndrome virus in Asia. Assays to support surveillance, epidemiologic studies, and diagnosis of these viruses may also detect related viruses within the genus, confounding interpretation. Rio Grande virus (RGV) was isolated in 1973 from southern plains woodrats (Neotoma micropus) in the United States and has been preliminarily identified as a phlebovirus transmitted by the sand fly Lutzomyia anthophora. RGV is not known to cause disease in humans, but it could be detected by assays designed for HRTV or other phleboviruses. The goal of this study was to determine antigenic cross-reaction between RGV and other phleboviruses. A commercially available ELISA based sand fly fever antigen detection kit was tested for the ability to detect RGV and other New and Old-World phleboviruses, including attenuated Rift valley fever virus (RVFV) strain MP12, Punta Toro virus (PTV), Toscana virus, Aguacate virus, Anhanga virus, Arumowot virus, and Chagres virus. Immunocytochemistry and Western blotting were used to detect cross reactions between RGV, MP12, and PTV using rabbit anti-RVFV nucleocapsid protein and glycoproteins GC and GN, mouse monoclonal anti-PTV, and sheep polyclonal anti-MP12. The ELISA test detected cross reactivity for all phleboviruses excluding RGV, but Western blotting detected the presumed RGV nucleocapsid protein (N) using rabbit anti-RVFV-N serum, RGV-infected cells were also identified when labeled with this antibody. Our findings demonstrate assay specific antigenic cross reactivity between these phleboviruses, thus further characterization of the molecular targets of the cross-reaction is required for proper interpretation of serological assays.

Varicella zoster virus (VZV) is a ubiquitous neurotropic alphaherpesvirus that typically causes childhood varicella (chickenpox) on primary infection and zoster (shingles) after reactivation. During latency most of the ~70 virus genes are transcriptionally silent; however, analysis of latent VZV gene transcription in its natural setting requires analysis of human ganglia removed at autopsy. Recognizing the problems associated with such samples, we have observed that as the post-mortem time interval increases, so do the number of VZV genes transcribed. Based on our data and recent similar findings concerning reactivation of HSV-1, we propose an interesting testable model to describe epigenetic control of neurotropic alphaherpesvirus gene transcription during latency and early reactivation.

In humans only a single prion-forming protein named PrP^c (for “cellular prion protein”) is currently known, yet many more neurodegenerative disorders involve aberrant protein aggregation. The classical model for these diseases has involved cell-autonomous aggregation, assuming that aggregation occurs independently in each cell within a diseased patient. However, more recent models have proposed a non-cell-autonomous progression of disease in which aggregates formed in one cell may be transmitted to neighboring cells. These aggregate seeds then cause aggregation of the soluble protein in the “infected” cells, similar to the prion diseases. Within the past few years, a number of proteins that exhibit prion-like aggregation and spread to neighboring tissues have been discovered in patients with Amyotrophic Lateral Sclerosis (ALS). Although ALS has been studied for a number of decades, these proteins were only recently linked to ALS by chance. This demonstrates a clear need for an accurate method to systematically identify additional proteins that may play a pathological role in neurodegenerative disorders. Taking advantage of the compositional similarity of these proteins to the known yeast prions, I plan to use the prion prediction methodology that our lab has pioneered to develop an entirely new algorithm specifically suited for this class of neuronal proteins.

Varicella-zoster virus (VZV) is a herpesvirus that causes a characteristic vesicular exanthem in humans with primary infection (varicella) or reactivation (zoster). We have previously observed that vesicular cells are filled with autophagosomes that are easily detectable by confocal microscopy after immunolabeling for the LC3 protein. Through a 3D imaging software program called Imaris we have quantitated autophagosomes as greater than 100 per cell. Similarly, we have assessed autophagy in VZV-infected monolayers after inoculation by the traditional method with infected cells at a ratio of one infected to 8 uninfected cells. Again, autophagosomes are easily detected, but their count is lower than that observed in human skin cells. As an additional control, we enumerated the autophagosomes in the Severe Combined Immuno-Deficient (SCID) Mouse model of VZV infection. In this model, human skin is inserted under the skin of the mouse and subsequently inoculated with VZV-infected cells. Again, autophagy was abundant in the VZV-infected skin and minimal in the mock-infected skin sample. Subsequently, we investigated autophagy following infection with sonically prepared cell free virus in cultured cells. After cell free virus inoculation, autophagy was detected in a majority of infected cells at all time points, but was less than that seen after an infected-cell inoculum. Finally, we investigated VZV-induced autophagic flux by two different methods (radiolabeling proteins and a dual-colored LC3 plasmid); both showed no evidence of a block in autophagy. Overall, therefore, autophagy within a VZV-infected cell was remarkably different from autophagy within an HSV-infected cell, whose genome contains two modifiers of autophagy, ICP34.5 and US11, not present in VZV.

Prions are infectious proteins capable of self-propagating and transmitting between organisms. Even though there is no homolog to the mammalian prion protein in yeast, several soluble proteins can form heritable aggregates de novo. These proteins provide a model system to investigate the nucleation, aggregation and propagation steps involved in the formation of a prion fibril. Several prion prediction algorithms have been developed to predict yeast proteins that have the propensity to form prions. One of these algorithms was previously developed in our laboratory (Prion Aggregation Prediction Algorithm, PAPA, Toombs et al., 2012). Therefore, we used PAPA to scan the yeast proteome to extract proteins that contain domains predicted to have prion activity (prion-like domains). These prion-like domains will be tested in four prion activity assays to assess their activity in vivo as well as in vitro. Here we provide preliminary evidence that we are successful at predicting yeast proteins that present prion activity in vivo. Following characterization of these prion-like domains, we will test the respective full-length proteins for prion activity using microscopy as well as developing phenotypic assays. Ultimately, we may identify new prion candidates in yeast, which will contribute information about the parameters necessary for prion formation and insight into the functions prions play in yeast. In addition, by confirming PAPA’s ability to predict prion proteins from the yeast proteome, it allows the possibility to apply this methodology to other proteomes.

Three major vaccine manufacturers in the United States currently sell multivalent vaccines containing modified live bovine herpesvirus 1 (BoHV-1) for use in pregnant cattle. The first of these products entered the US market in 2003. Yet it has been known since the early 1960 s that vaccinal BoHV-1 causes abortion in cattle. The products became popular as they can be used year-round, regardless of pregnancy status in herds. Abortifacient effects have been considered to be minimal, provided initial vaccination is done during the previous 12 months using specific vaccine products and in accordance with label directions. Single nucleotide polymorphisms (SNPs) in BoHV-1 can be used to resolve whether post-vaccination outbreaks of abortion in cattle herds are iatrogenic (Fulton et al.; Vaccine. 2013; 31(11):1471-1479). We tested tissues from 10 abortion episodes (2010–2014) where an apparent association existed between recent use of modified live BoHV-1 and abortion 1–3 months later. Products were used on or off label in individual outbreaks. All 10 episodes had SNP patterns consistent with those of commonly-used modified live BoHV-1 strains (O’Toole et al.; Vet Pathol. 2014, In press). In spite of this, it is likely such products will remain on the market. This is due the absence of meaningful post-marketing surveillance of suspect adverse reactions in animals by the USDA, compounded by the courts’ interpretation of the Virus-Serum-Toxin Act of 1913 [Lynnbrook Farms v. SmithKline Beecham Corp., 79 F.3d 620 (7th Cir.)]. Interesting differences exists between the handling of adverse vaccinal reactions in human patients through the National Vaccine Injury Compensation Program (VICP), and similar reactions in animals following use of federally licensed vaccines.

Previous studies have reported that domestic cats can be naturally infected with bovine herpesvirus 4 (BHV4), and experimental inoculations have been linked to feline urolithiasis. It has been difficult to recapitulate initial diagnostic and experimental observations, thus here we have initiated a study to evaluate BHV4 presence in a large cohort of cats at risk for exposure to circulating feline viruses using a sensitive and specific assay. Domestic cat blood DNA samples (n=101) collected from California, Colorado, and Florida were screened for BHV4 using sensitive real time PCR. In contrast to BHV4 containing tissue culture extracts, all domestic cat blood samples were negative for BHV4. Samples were shown to contain intact DNA and to be infected with other horizontally-transmitted feline infections. We conclude that BHV4 is unlikely to be a common pathogen of domestic cats.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) and is the most common disabling neurological disease of young adults. Although the cause of MS is unknown, genetic and epidemiological studies indicate that MS may be triggered by an environmental agent. The presence of intrathecally produced antibodies, which produce oligoclonal Ig bands in the CNS of MS patients, provides tools for investigating the target of the inflammatory response. In most of the CNS conditions with oligoclonal bands the target is known and the antibody is directed against an infectious, causative agent. For example, in subacute sclerosing panencephalitis, a measles virus (MV) infection of the brain, the oligoclonal bands and intrathecal antibodies are primarily directed against MV. In earlier studies of MS, we demonstrated that the intrathecal antibody response in MS brain does not react to varicella zoster or Epstein-Barr virus. The current study investigates the reactivity of the intrathecal antibody response in MS brain to MV. We isolated individual CD38(+) plasma cells from MS brain to produce recombinant antibodies (rAbs). These rAbs likely represent oligoclonal bands and were used to immunostain MV-infected or uninfected monkey kidney (Vero) cells. Although many of the rAbs from MS brain reacted against auto-antigens in several mouse and human tissues, none of fifteen MS rAbs reacted against MV-infected cells. These results indicate that measles virus is not a disease-relevant antigen in MS.

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