Gene-based vaccination with a mismatched envelope protects against simian immunodeficiency virus infection in nonhuman primates

The RV144 trial demonstrated that an experimental AIDS vaccine can prevent human immunodeficiency virus type 1 (HIV-1) infection in humans. Because of its limited efficacy, further understanding of the mechanisms of preventive AIDS vaccines remains a priority, and nonhuman primate (NHP) models of lentiviral infection provide an opportunity to define immunogens, vectors, and correlates of immunity. In this study, we show that prime-boost vaccination with a mismatched SIV envelope (Env) gene, derived from simian immunodeficiency virus SIVmac239, prevents infection by SIVsmE660 intrarectally. Analysis of different gene-based prime-boost immunization regimens revealed that recombinant adenovirus type 5 (rAd5) prime followed by replication-defective lymphocytic choriomeningitis virus (rLCMV) boost elicited robust CD4 and CD8 T-cell and humoral immune responses. This vaccine protected against infection after repetitive mucosal challenge with efficacies of 82% per exposure and 62% cumulatively. No effect was seen on viremia in infected vaccinated monkeys compared to controls. Protection correlated with the presence of neutralizing antibodies to the challenge viruses tested in peripheral blood mononuclear cells. These data indicate that a vaccine expressing a mismatched Env gene alone can prevent SIV infection in NHPs and identifies an immune correlate that may guide immunogen selection and immune monitoring for clinical efficacy trials.     

Evolutionary dynamics of local pandemic H1N1/2009 influenza virus lineages revealed by whole-genome analysis

Virus gene sequencing and phylogenetics can be used to study the epidemiological dynamics of rapidly evolving viruses. With complete genome data, it becomes possible to identify and trace individual transmission chains of viruses such as influenza virus during the course of an epidemic. Here we sequenced 153 pandemic influenza H1N1/09 virus genomes from United Kingdom isolates from the first (127 isolates) and second (26 isolates) waves of the 2009 pandemic and used their sequences, dates of isolation, and geographical locations to infer the genetic epidemiology of the epidemic in the United Kingdom. We demonstrate that the epidemic in the United Kingdom was composed of many cocirculating lineages, among which at least 13 were exclusively or predominantly United Kingdom clusters. The estimated divergence times of two of the clusters predate the detection of pandemic H1N1/09 virus in the United Kingdom, suggesting that the pandemic H1N1/09 virus was already circulating in the United Kingdom before the first clinical case. Crucially, three clusters contain isolates from the second wave of infections in the United Kingdom, two of which represent chains of transmission that appear to have persisted within the United Kingdom between the first and second waves. This demonstrates that whole-genome analysis can track in fine detail the behavior of individual influenza virus lineages during the course of a single epidemic or pandemic.     

Lipophosphonate/lipophosphoramidates: a family of synthetic vectors efficient for gene delivery

Lipophophoramidates constitute a class of synthetic vectors which were especially designed for gene delivery. In this family of compounds, the phosphorus functional group links two lipid chains to a spacer ended by a polar headgroup. Such vectors, which can readily be obtained, offer an alternative to the numerous examples of glycerolipid-based vectors that have been more exhaustively studied. Since the pioneering work describing this series of synthetic vectors, several chemical modifications have been proposed with the aim of correlating the molecular structure with the gene transfection efficacy. It has indeed been observed that some modifications which may be considered as minor at first glance, actually have important consequences on both the transfection efficacy and cytotoxic side effects. We herein discuss the modification of the structure of lipophosphoramidates, in particular of their lipidic part and of the nature of the cationic polar head which may be constituted by a trimethylammonium, trimethylphosphonium or trimethylarsonium motif. We also report that, as well as the in vitro transfection efficacy which governs the selection of the most promising vectors for in vivo studies, other aspects related to the synthetic pathway must be also considered for the development of new synthetic vectors (such as modularity of the synthesis, scaling-up).     

The endogenous melatonin (MT) signal facilitates reentrainment of the circadian system to light-induced phase advances by acting upon MT2 receptors

The indolamine melatonin is an important rhythmic endocrine signal in the circadian system. Exogenous melatonin can entrain circadian rhythms in physiology and behavior, but the role of endogenous melatonin and the two membrane-bound melatonin receptor types, MT1 and MT2, in reentrainment of daily rhythms to light-induced phase shifts is not understood. The present study analyzed locomotor activity rhythms and clock protein levels in the suprachiasmatic nuclei (SCN) of melatonin-deficient (C57BL/6J) and melatonin-proficient (C3H/HeN) mice, as well as in melatonin-proficient (C3H/HeN) mice with targeted deletion of the MT1, MT2, or both receptors, to determine effects associated with phase delays or phase advances of the light/dark (LD) cycle. In all mouse strains and genotypes, reentrainment of locomotor activity rhythms was significantly faster after a 6-h phase delay than a 6-h phase advance. Reentrainment after the phase advance was, however, significantly slower than in melatonin-deficient animals and in mice lacking functional MT2 receptors than melatonin-proficient animals with intact MT2 receptors. To investigate whether these behavioral differences coincide with differences in reentrainment of clock protein levels in the SCN, mPER1, mCRY1 immunoreactions were compared between control mice kept under the original LD cycle and killed at zeitgeber time 04 (ZT04) or at ZT10, respectively, and experimental mice subjected to a 6-h phase advance of the LD cycle and sacrificed at ZT10 on the third day after phase advance. This ZT corresponds to ZT04 of the original LD cycle. Under the original LD cycle, the numbers of mPER1- and mCRY1-immunoreactive cell nuclei were low at ZT04 and high at ZT10 in the SCN of all mouse strains and genotypes investigated. Notably, mouse strains with intact melatonin signaling and functional MT2 receptors showed a significant increase in the number of mPER1- and mCRY1-immunoreactive cell nuclei at the new ZT10 as compared to the former ZT04. These data suggest the endogenous melatonin signal facilitates reentrainment of the circadian system to phase advances on the level of the SCN molecular clockwork by acting upon MT2 receptors.     

Spectral trends in the fluorescence of single bacterial light-harvesting complexes: experiments and modified redfield simulations

In this work we present and discuss the single-molecule fluorescence spectra of a variety of species of light-harvesting complexes: LH2 of Rhodopseudomonas acidophila, Rhodobacter sphaeroides, and Rhodospirillum molischianum and LH1 of Rhodobacter sphaeroides. The emission spectrum of these complexes varies as a function of time as was described in earlier work. For each type of complex, we observe a pronounced and well-reproducible characteristic relationship between the fluorescence spectral parameters of the peak wavelength, width, and asymmetry. This dependence for the LH2 complexes can be quantitatively explained on the basis of a disordered exciton model by varying the static disorder and phonon coupling parameters. In addition, a correlation of the pigment site energies has to be assumed to interpret the behavior of the LH1 complex.     

Multiple resistance traits control Plum pox virus infection in Arabidopsis thaliana

Twelve Arabidopsis accessions were challenged with Plum pox potyvirus (PPV) isolates representative of the four PPV strains. Each accession supported local and systemic infection by at least some of the PPV isolates, but high variability was observed in the behavior of the five PPV isolates or the 12 Arabidopsis accessions. Resistance to local infection or long-distance movement occurred in about 40% of all the accession-isolate combinations analyzed. Except for Nd-1, all accessions showed resistance to local infection by PPV-SoC; in the Landsberg erecta (Ler) accession, this resistance was compromised by sgt1 and rar1 mutations, suggesting that it could be controlled by an R gene-mediated resistance pathway. While most of the susceptible accessions were symptomless, PPV induced severe symptoms on inflorescences in C24, Ler, and Bay-0 as early as 15 days after inoculation. Genetic analyses indicated that these interaction phenotypes are controlled by different genetic systems. The restriction of long-distance movement of PPV-El Amar and of another member of genus Potyvirus, Lettuce mosaic virus, in Col-0 requires the RTM genes, indicating for the first time that the RTM system may provide a broad range, potyvirus-specific protection against systemic infection. The restriction to PPV-PS long-distance movement in Cvi-1 is controlled by a single recessive gene, designated rpv1, which was mapped to chromosome 1. The nuclear inclusion polymerase b-capsid protein region of the viral genome appears to be responsible for the ability of PPV-R to overcome rpv1-mediated resistance.     

Remodelling of arabinoxylan in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) endosperm cell walls during grain filling

Previous studies using spectroscopic imaging have allowed the spatial distribution of structural components in wheat endosperm cell walls to be determined. FT-IR microspectroscopy showed differing changes in arabinoxylan (AX) structure, during grain development under cool/wet and hot/dry growing conditions, for differing cultivars (Toole et al. in Planta 225:1393–1403, 2007). These studies have been extended using Raman microspectroscopy, providing more details of the impact of environment on the polysaccharide and phenolic components of the cell walls. NMR studies provide complementary information on the types and levels of AX branching both early in development and at maturity. Raman microspectroscopy has allowed the arabinose:xylose (A/X) ratio in the cell wall AX to be determined, and the addition of ferulic acid and related phenolic acids to be followed. The changes in the A/X ratio during grain development were affected by the environmental conditions, with the A/X ratio generally being slightly lower for samples grown under cool/wet conditions than for those from hot/dry conditions. The degree of esterification of the endosperm cell walls with ferulic acid was also affected by the environment, being lower under hot/dry conditions. The results support earlier suggestions that AX is either delivered to the cell wall in a highly substituted form and is remodelled through the action of arabinoxylan arabinofuranohydrolases or arabinofuranosidases, or that low level substituted AX are incorporated into the wall late in cell wall development, reducing the average degree of substitution, and that the rate of this remodelling is influenced by the environment. ¹H NMR provided a unique insight into the chemical structure of intact wheat endosperm cell walls, providing qualitative information on the proportions of mono- and disubstituted AX and the levels of branching of adjacent units. The A/X ratio did not change greatly with either the development stage or the growth conditions, but the ratio of mono- to disubstituted Xylp residues increased markedly (by about fourfold) in the more mature samples, confirming the changes in branching levels determined using FT-IR. To the best of our knowledge, this is the first time that intact endosperm cell walls have been studied by ¹H NMR.     

Influence of dietary fibre level and pelleting on the digestibility of energy and nutrients in growing pigs and adult sows

Two experiments were carried out to investigate the effect of pelleting on the apparent total tract digestibility (ATTD) of energy and nutrients according to the dietary fibre (DF) level in growing pigs (experiment 1) and in adult sows (experiment 2). Four diets based on wheat, barley, maize and soybean meal and supplemented with increased contents of a mixture of wheat bran, maize bran, soybean hulls and sugar beet pulp (116, 192, 268 and 344 g NDF/kg dry matter (DM) in diets 1 to 4) were tested. In experiment 1, 32 growing pigs (62 kg average BW), in two replicates and according to a factorial design, were fed one of the four diets, either as mash or as pellets. The digestibility of energy, organic matter (OM) and all nutrients decreased with DF increasing for both feed forms; the reduction was about 1% for each 1% NDF increase in the diet (P < 0.001). Pelleting improved moderately the digestibility of energy and OM (+1.5% and +1.0%, respectively; P < 0.05) in connection with greater DF (+5%; P < 0.05) and fat digestibility (+25%). Thus, pelleting improved the digestible energy content of diets on average by 0.3 MJ/kg of feed DM (P < 0.01). In experiment 2, four adult dry sows (235 kg average BW) were used in a 4 × 4 Latin square design and fed the four diets used in experiment 1 as pellets. The digestibility of energy, OM and macronutrients also decreased with DF increase (P < 0.001; -0.4% per 1% increase of dietary NDF for energy) while the digestibility of DF (i.e. crude fibre (CF) or ADF) increased (P < 0.001) or remained at a high level. In conclusion, increasing DF in diets decreases the digestibility of nutrients and energy in pigs and in sows. Although positive, the pelleting impact is minor on the energy and nutrients digestibility of fibre-rich diets in growing pigs, even in high-DF diets.     

Temporal and spatial changes in cell wall composition in developing grains of wheat cv. Hereward

A combination of enzyme mapping, FT-IR microscopy and NMR spectroscopy was used to study temporal and spatial aspects of endosperm cell wall synthesis and deposition in developing grain of bread wheat cv. Hereward. This confirmed previous reports that changes in the proportions of the two major groups of cell wall polysaccharides occur, with β-glucan accumulating earlier in development than arabinoxylan. Changes in the structure of the arabinoxylan occurred, with decreased proportions of disubstituted xylose residues and increased proportions of monosubstituted xylose residues. These are likely to result, at least in part, from arabinoxylan restructuring catalysed by enzymes such as arabinoxylan arabinofurano hydrolase and lead to changes in cell wall mechanical properties which may be required to withstand stresses during grain maturation and desiccation.     

Sex differences in auditory filters of brown-headed cowbirds (Molothrus ater)

Receiver sensory abilities can be influenced by a number of factors, including habitat, phylogeny and the selective pressure to acquire information about conspecifics or heterospecifics. It has been hypothesized that brood-parasitic brown-headed cowbird (Molothrus ater) females may locate or determine the quality of potential hosts by eavesdropping on their sexual signals. This is expected to produce different sex-specific pressures on the auditory system to detect conspecific and heterospecific acoustic signals. Here, we examined auditory filter shape and efficiency, which influence the ability to resolve spectral and temporal information, in males and females at center frequencies of 2, 3 and 4 kHz. We found that overall, cowbirds had relatively wide filters (lsmean ± SE: 619.8 ± 41.6 Hz). Moreover, females had narrower filters (females: 491.4 ± 66.8, males: 713.8 ± 67.3 Hz) and greater filter efficiency (females: 59.0 ± 2.0, males: 69.8 ± 1.9 dB) than males. Our results suggest that the filters of female cowbirds may allow them to extract spectral information from heterospecific vocalizations. The broader auditory filters of males may reflect limited spectral energy in conspecific vocalizations in this frequency range, and hence, weaker selection for high resolution of frequency in the range of 2–4 kHz.