Rescue of foot-and-mouth disease viruses that are pathogenic for cattle from preserved viral RNA samples

Background

Foot and mouth disease is an economically important disease of cloven-hoofed animals including cattle, sheep and pigs. It is caused by a picornavirus, foot-and-mouth disease virus (FMDV), which has a positive sense RNA genome which, when introduced into cells, can initiate virus replication.

Principal Findings

A system has been developed to rescue infectious FMDV from RNA preparations generated from clinical samples obtained under experimental conditions and then applied to samples collected in the “field”. Clinical samples from suspect cases of foot-and-mouth disease (FMD) were obtained from within Pakistan and Afghanistan. The samples were treated to preserve the RNA and then transported to National Veterinary Institute, Lindholm, Denmark. Following RNA extraction, FMDV RNA was quantified by real-time RT-PCR and samples containing significant levels of FMDV RNA were introduced into susceptible cells using electroporation. Progeny viruses were amplified in primary bovine thyroid cells and characterized using antigen ELISA and also by RT-PCR plus sequencing. FMD viruses of three different serotypes and multiple lineages have been successfully rescued from the RNA samples. Two of the rescued viruses (of serotype O and Asia 1) were inoculated into bull calves under high containment conditions. Acute clinical disease was observed in each case which spread rapidly from the inoculated calves to in-contact animals. Thus the rescued viruses were highly pathogenic. The availability of the rescued viruses enabled serotyping by antigen ELISA and facilitated genome sequencing.

Conclusions

The procedure described here should improve the characterization of FMDVs circulating in countries where the disease is endemic and thus enhance disease control globally.     

Methionine sulfoxide reductases are essential for virulence of Salmonella typhimurium

Production of reactive oxygen species represents a fundamental innate defense against microbes in a diversity of host organisms. Oxidative stress, amongst others, converts peptidyl and free methionine to a mixture of methionine-S- (Met-S-SO) and methionine-R-sulfoxides (Met-R-SO). To cope with such oxidative damage, methionine sulfoxide reductases MsrA and MsrB are known to reduce MetSOs, the former being specific for the S-form and the latter being specific for the R-form. However, at present the role of methionine sulfoxide reductases in the pathogenesis of intracellular bacterial pathogens has not been fully detailed. Here we show that deletion of msrA in the facultative intracellular pathogen Salmonella (S.) enterica serovar Typhimurium increased susceptibility to exogenous H(2)O(2), and reduced bacterial replication inside activated macrophages, and in mice. In contrast, a ΔmsrB mutant showed the wild type phenotype. Recombinant MsrA was active against free and peptidyl Met-S-SO, whereas recombinant MsrB was only weakly active and specific for peptidyl Met-R-SO. This raised the question of whether an additional Met-R-SO reductase could play a role in the oxidative stress response of S. Typhimurium. MsrC is a methionine sulfoxide reductase previously shown to be specific for free Met-R-SO in Escherichia (E.) coli. We tested a ΔmsrC single mutant and a ΔmsrBΔmsrC double mutant under various stress conditions, and found that MsrC is essential for survival of S. Typhimurium following exposure to H(2)O(2,) as well as for growth in macrophages, and in mice. Hence, this study demonstrates that all three methionine sulfoxide reductases, MsrA, MsrB and MsrC, facilitate growth of a canonical intracellular pathogen during infection. Interestingly MsrC is specific for the repair of free methionine sulfoxide, pointing to an important role of this pathway in the oxidative stress response of Salmonella Typhimurium.     

Kinetics of doubletime kinase-dependent degradation of the Drosophila period protein

Robust circadian oscillations of the proteins PERIOD (PER) and TIMELESS (TIM) are hallmarks of a functional clock in the fruit fly Drosophila melanogaster. Early morning phosphorylation of PER by the kinase Doubletime (DBT) and subsequent PER turnover is an essential step in the functioning of the Drosophila circadian clock. Here using time-lapse fluorescence microscopy we study PER stability in the presence of DBT and its short, long, arrhythmic, and inactive mutants in S2 cells. We observe robust PER degradation in a DBT allele-specific manner. With the exception of doubletime-short (DBT(S)), all mutants produce differential PER degradation profiles that show direct correspondence with their respective Drosophila behavioral phenotypes. The kinetics of PER degradation with DBT(S) in cell culture resembles that with wild-type DBT and posits that, in flies DBT(S) likely does not modulate the clock by simply affecting PER degradation kinetics. For all the other tested DBT alleles, the study provides a simple model in which the changes in Drosophila behavioral rhythms can be explained solely by changes in the rate of PER degradation.     

Ubiquitin Hydrolase UCH-L1 Destabilizes mTOR Complex 1 by Antagonizing DDB1-CUL4-Mediated Ubiquitination of Raptor

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates processes including mRNA translation, proliferation, and survival. By assembling with different cofactors, mTOR forms two complexes with distinct biological functions. Raptor-bound mTOR (mTORC1) governs cap-dependent mRNA translation, whereas mTOR, rictor, and mSin1 (mTORC2) activate the survival and proliferative kinase Akt. How the balance between the competing needs for mTORC1 and -2 is controlled in normal cells and deregulated in disease is poorly understood. Here, we show that the ubiquitin hydrolase UCH-L1 regulates the balance of mTOR signaling by disrupting mTORC1. We find that UCH-L1 impairs mTORC1 activity toward S6 kinase and 4EBP1 while increasing mTORC2 activity toward Akt. These effects are directly attributable to a dramatic rearrangement in mTOR complex assembly. UCH-L1 disrupts a complex between the DDB1-CUL4 ubiquitin ligase complex and raptor and counteracts DDB1-CUL4-mediated raptor ubiquitination. These events lead to mTORC1 dissolution and a secondary increase in mTORC2. Experiments in Uchl1-deficient and transgenic mice suggest that the balance between these pathways is important for preventing neurodegeneration and the development of malignancy. These data establish UCH-L1 as a key regulator of the dichotomy between mTORC1 and mTORC2 signaling.     

Inositol‐requiring enzyme‐1 regulates phosphoinositide signaling lipids and macrophage growth

The ER‐bound kinase/endoribonuclease (RNase), inositol‐requiring enzyme‐1 (IRE1), regulates the phylogenetically most conserved arm of the unfolded protein response (UPR). However, the complex biology and pathology regulated by mammalian IRE1 cannot be fully explained by IRE1’s one known, specific RNA target, X box‐binding protein‐1 (XBP1) or the RNA substrates of IRE1‐dependent RNA degradation (RIDD) activity. Investigating other specific substrates of IRE1 kinase and RNase activities may illuminate how it performs these diverse functions in mammalian cells. We report that macrophage IRE1 plays an unprecedented role in regulating phosphatidylinositide‐derived signaling lipid metabolites and has profound impact on the downstream signaling mediated by the mammalian target of rapamycin (mTOR). This cross‐talk between UPR and mTOR pathways occurs through the unconventional maturation of microRNA (miR) 2137 by IRE1’s RNase activity. Furthermore, phosphatidylinositol (3,4,5) phosphate (PI(3,4,5)P₃) 5‐phosphatase‐2 (INPPL1) is a direct target of miR‐2137, which controls PI(3,4,5)P₃ levels in macrophages. The modulation of cellular PI(3,4,5)P₃/PIP₂ ratio and anabolic mTOR signaling by the IRE1‐induced miR‐2137 demonstrates how the ER can provide a critical input into cell growth decisions.     

(99m)Tc(CO)(3)-Ibritumomab tiuxetan; a novel radioimmunoimaging (RII) agent of B cell non-Hodgkin's lymphoma (NHL)

To exploit the B-lymphocyte antigen-CD20 binding capacity of the Ibritumomab tiuxetan (IBTN) monoclonal antibody (mAb) for imaging, the over-expression of B cells in non-Hodgkin's lymphoma (NHL) (a myeloproliferative disorder of the lymphatic system) was investigated. In the current investigation, we present the labeling of the IBTN with technetium-99m ((99m)Tc) through [(99m)Tc(CO)(3)](+) precursor for radioimmunoimaging (RII) of the tumor prior to its treatment with (90)Y labeled IBTN. Labeled IBTN was radiobiologically characterized in terms of radiochemical purity, in vitro stability in human plasma, immunoreactivity, binding with Raji and Ramos cells and biodistribution in a female nude mouse (FNM) model. It was observed that the reduced IBTN (rIBTN) showed more promising radiobiologic characteristics than the nonreduced IBTN. Significantly higher transchelation was seen in excess cysteine compared with histidine. The radioconjugate showed higher saturated binding affinity with CD20 antigen. Significantly higher target (tumor) to background ratios were observed 1 h post-injection (p.i.). Based on radiochemical purity, in vitro stability, immunoreactivity, binding and biodistrubtion in the FNM model, we recommend the radiolabeling of the rIBTN using tricarbonyl technique as a potential RII agent.     

Allelopathic suppression of wheat and mustard byRumex dentatus ssp.klotzschianus

Laboratory studies were conducted to see the allelopathic suppression of wheat and mustard byRumex dentatus ssp.klotzschianus (Meissn) Rech. It was observed that aqueous extracts, rain leachates and litter from dried and fresh shoot and roots invariably inhibited the germination and seedling growth of both the crop species. Soil collected from beneathRumex dentatus also proved harmful for the germination and seedling growth. It is suggested thatRumex dentatus ssp.klotzschianus exhibits allelopathy against wheat and mustard.     

Human Parechovirus Genotypes -10, -13 and -15 in Pakistani Children with Acute Dehydrating Gastroenteritis

Human parechoviruses are known to cause asymptomatic to severe clinical illness predominantly respiratory and gastroenetric infections. Despite their global prevalence, epidemiological studies have not been performed in Pakistan. In this study, we retrospectively analyzed 110 fecal specimen and found 26 (24%) positive for viral RNA with HPeV-10 (n = 3, 23%), HPeV-13 (n = 4, 31%) and HPeV-15 (n = 6, 46%) genotypes. Clinical features of patients with different HPeV genotypes were compared. All HPeV positive children were aged ≤4 years (mean 13.92 months). The male-to-female ratio was 1: 1.17 (46.2 vs 53.8%) with significant association (p = .031) to HPeV infectivity. HPeV-10 and -13 were found during summer while HPeV-15 was only detected during late winter season. Disease symptoms were more severe in children infected with HPeV-10 and -13 as compared to HPeV-15. Fever and vomiting were observed in 100% cases of HPeV-10 and -13 while only 17% patients of HPeV-15 had these complaints. Phylogenetic analyses showed that HPeV-10, -13 and -15 strains found in this study have 9–13%, 16.8% and 21.8% nucleotide divergence respectively from the prototype strains and were clustered to distinct genetic lineages. This is the first report of HPeV-15 infection in humans although first identified in rhesus macaques. The arginine-glycine-aspartic acid (RGD) motif present at the C-terminal of VP1 responsible for the viral attachment to cellular integrins was not found in all of these strains. In conclusion, these findings enhance our knowledge related to the epidemiology and genetic diversity of the HPeV in Pakistan and support the need for continued laboratory based surveillance programs especially in infants and neonatal clinical settings. Further, the parechovirus pathogenesis, cross-species transmission and disease reservoirs must be ascertained to adopt better prevention measures.