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Forget mosquito bites. Volunteers let researchers inject them with the dengue virus in the name of science - and an experimental vaccine protected them. Next up, scientists plan to use this same strategy against dengue's cousin, the Zika virus. It's called a human challenge, a little-known but increasing type of research where healthy people agree to be deliberately infected in the quest for new or improved vaccines against a variety of health threats, from flu to malaria. Wednesday's dengue study offered more evidence that what sounds bizarre not only can be done safely, it can offer important clues for how well a shot might work. "What we're trying to do is accelerate vaccine research," said senior author Dr. Anna Durbin of Johns Hopkins University's school of public health. It may be the best way "to know if you have a stinker before you try to test it in thousands or tens of thousands of people." The dengue candidate proved highly promising, researchers reported in the journal Science Translational Medicine. Dengue fever may have slipped from the headlines as the related Zika virus sweeps through Latin America, but every year mosquito-borne dengue causes devastating outbreaks throughout the tropics and subtropics. While most people survive dengue with few or even no symptoms, more than 2 million a year suffer serious illness and about 25,000 die. Creating a vaccine has been tough. It must work against four separate strains of dengue, and a shot that's only partially protective might backfire. That's because people who survive one type of dengue can suffer worse symptoms if they're later infected with another strain. Enter an experimental vaccine created at the National Institutes of Health, made from four live but weakened dengue strains. Initial studies had suggested the shots were safe and promising. But, "we really wanted to have an early clue that it was go to work," especially against the hard-to-prevent dengue serotype 2, said Dr. Stephen Whitehead of NIH's National Institute of Allergy and Infectious Diseases, who led the vaccine development. Researchers at Hopkins and the University of Vermont gave 41 healthy people who'd never been exposed to dengue either a single dose of the vaccine or a dummy shot. Six months later, those volunteers were challenged - injected with a weakened version of that dengue-2 strain. The results were striking: All 21 people who'd gotten the real vaccine were completely protected - while all 20 who'd gotten a placebo had dengue virus in their bloodstream and either a mild rash or a temporary drop in white blood cell count, researchers reported Wednesday. This kind of study mimics "the closest that it can be to what may happen in natural infection," said Dr. Nikos Vasilakis, a virologist at the University of Texas Medical Branch in Galveston, who wasn't involved in the new work but calls the NIH shot "one of the better vaccine candidates." Based in part on the findings, the Butantan Institute in Brazil last month began recruiting 17,000 people, ages 2 to 59, for the final testing needed to prove how well the NIH vaccine works against dengue in real-world conditions, when it is spread by mosquitoes. A competing vaccine, made by Sanofi Pasteur, recently was approved by Brazilian regulators for ages 9 to 45. What about Zika, the dengue relative that's been linked to babies born with unusually small heads? Already, researchers are planning similar challenge studies that could start even before there's a vaccine candidate, Durbin said. "We see a Zika challenge model as really beneficial for not only vaccine development but also to learn more about Zika itself," she explained. "We know very little about Zika right now," including how long it stays in blood and other parts of the body. Key to these challenge studies: Scientists must modify a virus strain in the laboratory so that it doesn't make volunteers openly ill but still is strong enough to spark a mild infection, what Whitehead called "that perfect in-between." Plus, that mimics what happens with both dengue and Zika, where most people who become infected never report symptoms. Before deliberately infecting someone, "you have to know that it's a completely controllable situation, that it's a mild and controlled infection," said Dr. Beth Kirkpatrick, who directs the University of Vermont Vaccine Testing Center that tested the dengue model.

Qiao J.,China Agricultural University | Rao Z.,Testing Center | Dong B.,China Agricultural University | Cao Y.,China Agricultural University
Applied Biochemistry and Biotechnology | Year: 2010

The 1014 nucleotides long gene-encoding β-mannanase from Bacillus subtilis strain MA139 was cloned using PCR. To obtain high expression levels in Pichia pastoris, the β-mannanase gene was optimized according to the codon usage bias of P. pastoris and fused downstream of GAP promoter. The reconstituted plasmid pGAP-mann was transformed into P. pastoris X-33 strain to constitutively express β-mannanase. When cultured at 28∈°C for 3 days protein yields up to 2.7 mg/mL was obtained with the enzyme activity of up to 230 U/mL. In comparison, wild-type gene product yielded 1.9 mg/mL and 170 U/mL, respectively indicating that the protein yield and enzyme activity were significantly improved by codon modification. After purification, the enzyme properties were characterized. The optimal activity was at pH 6.0 and 50∈°C. In the pH range of 3.0 to 9.0, β-mannanase showed above 60% of its peak activity. Among the numerous ions tested copper significantly inhibited the enzyme activity. These results suggested that codon-optimized β-mannanase expressed in P. pastoris could potentially be used as an additive in the feed for monogastric animals. © 2009 Humana Press. Source

Fan R.,Wuhan University | Zhao L.,Testing Center | Zong R.,Wuhan University | Gong Y.,Wuhan University
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2015

The flysch trace fossils of western Junggar, Xinjiang, NW China are mainly distributed in the Upper Devonian-Lower Carboniferous Ta'erbahatai Formation and Baogutu, Tailegula and Hala'alate formations of the Carboniferous. Characteristic trace fossils include Phycosiphon, Nereites, Megagrapton, Glockerichnus, Cochlichnus, Lophoctenium, Gordia, Chondrites, Zoophycos, Scolicia, Thalassinoides, forming two characteristic trace fossil assemblages of the Nereites ichnofacies: the Phycosiphon-Nereites and Megagrapton-Glockerichnus-Cochlichnus ichnoassemblages. The Baogutu and Tailegula formations represent the medial-distal submarine fan fringe-basin plain environments, while the Hala'alate and Ta'erbahatai formations are chiefly medial-distal submarine fan lobe deposits. The distribution of flysch trace fossils in western Junggar is closely linked to the thickness of the Bouma sequences. In millimetre to centimetre Bouma sequences, there are only scarce and blur traces of Phycosiphon or Nereites, while in centimetre to decimetre Bouma sequences, Phycosiphon and Nereites of various diametres and transitional morphologies occur, which might be produced by conspecific trace makers in an ontogenetic series. The thickness of a single Bouma sequence in submarine fan related environments determines if there is enough time for a mature benthic fauna to develop (with a series of young and old individuals). ©, 2015, China University of Geosciences. All right reserved. Source

Liu C.,Soochow University of China | Jiang J.,Soochow University of China | Gao L.,Soochow University of China | Gao L.,Red Cross | And 6 more authors.
International Journal of Genomics | Year: 2014

Objective. Programmed cell death 1 (PD-1) induces negative signals to T cells during interaction with its ligands and is therefore a candidate gene in the development of autoimmune diseases such as rheumatoid arthritis (RA). Herein, we investigate the association of PDCD-1 polymorphisms with the risk of RA among Chinese patients and healthy controls. Methods. Using the PCR-direct sequencing analysis, 4 PDCD-1 SNPs (rs36084323, rs11568821, rs2227982, and rs2227981) were genotyped in 320 RA patients and 309 matched healthy controls. Expression of PD-1 was determined in peripheral blood lymphocytes by flow cytometry and quantitative real-time reverse transcriptase polymerase chain reaction. Results. We observed that the GG genotype of rs36084323 was associated with a increased risk for developing RA (OR 1.70, 95% 1.11-2.61, P = 0.049). Patients carrying G/G genotype displayed an increased mRNA level of PD-1 (P = 0.04) compared with A/A genotype and healthy controls. Meanwhile, patients homozygous for rs36084323 had induced basal PD-1 expression on activated CD4+ T cells. Conclusion. The PDCD-1 polymorphism rs36084323 was significantly associated with RA risk in Han Chinese population. This SNP, which effectively influenced the expression of PD-1, may be a biomarker of early diagnosis of RA and a suitable indicator of utilizing PD-1 inhibitor for treatment of RA. © 2014 CuiPing Liu et al. Source

Zhou M.,Soochow University of China | Qin S.,Soochow University of China | Chu Y.,Soochow University of China | Wang F.,Testing Center | And 2 more authors.
International Journal of Clinical and Experimental Pathology | Year: 2014

Matrix metalloproteinase (MMP)-2 and MMP-9, two important members of the matrix metalloproteinase family, have been shown critical contributions in intra-tumor angiogenesis and invasion of tumor progression, and they might also play important roles in the angiogenesis as well as the pannus formation of rheumatoid arthritis (RA). In the present study, we used the immunohistochemistry, the immunofluorescence staining and the con-focal scanning methods to characterize the immunolocalization of MMP-2 and MMP-9 in RA synovium tissues. Our results showed that both MMP-2 and MMP-9 immunostaining could be found in synoviocytes and vascular endothelial cells. Moreover, our con-focal scanning also showed that MMP-2 could be found in infiltrating CD14+ monocytes and CD68+ macrophages, and MMP-9 could be found in infiltrating CD68+ macrophages in RA synovium tissues, while weak or negative staining of these two MMPs could be found in infiltrating CD20+B cells and CD3+T cells in RA synovium. Thus, our finding suggests that both MMP-2 and MMP-9 expressed by synoviocytes as well as certain infiltrating immune cells role importantly in the angiogenesis in RA progression. Source

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