Bird flu spread mutations among humans identified
An international team of scientists has identified several genetic mutations that, should they arise, could potentially allow the avian influenza strain H7N9 to spread between humans. The findings are published in PLOS Pathogens.
H7N9 is a strain of flu virus that normally infects birds but has spread to at least 779 humans in a number of outbreaks related to poultry markets. The virus is not currently capable of spreading sustainably from human to human, but scientists are concerned that it could potentially mutate into a form that can.
To investigate this possibility, James Paulson of The Scripps Research Institute, California, and colleagues analyzed mutations that could occur in H7N9's genome. They focused on a gene that codes for the H7 hemagglutanin, a protein found on the surface of flu viruses. This protein allows flu viruses to latch onto host cells.
Flu strains that circulate in avian viruses have different subtypes of hemagglutanin, called H1-H16. So far only three subtypes have been found in human flu viruses (H1, H2 and H3). Like other avian flu viruses, H7N9 has is specific for receptors on bird cells, but not receptors on human cells. However, a transition to human specificity could enable H7N9 to circulate among humans, just like other human flu strains that have caused pandemics in the past.
The research team used molecular modeling and knowledge of hemagglutanin's structure to identify mutations that would change the protein's amino acid sequence and cause a switch to human specificity. Then, they produced the hemagglutanin with different combinations of these mutations in an experimental cell line (testing the mutations in H7N9 viruses themselves could be dangerous).
The scientists harvested the mutant hemagglutanin proteins from the cells and tested how strongly they bound to human-type and bird-type receptors. Several forms with mutations in three amino acids bound far more strongly to human receptors; they had switched specificity from bird to human. These triple-mutant H7 hemagglutinins also successfully latched onto cells in samples of human trachea tissue.
Safety regulations prohibit introducing these mutations to actual H7N9 viruses, limiting scientists' ability to test their effects in animals. Nonetheless, the research team suggests that keeping an eye out for the development of these mutations in humans infected with H7N9 could help trigger a timely response to prevent potential spread.
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Journal Reference:
de Vries RP, Peng W, Grant OC, Thompson AJ, Zhu X, Bouwman KM, et al. Three mutations switch H7N9 influenza to human-type receptor specificity. PLoS Pathog, 2017 DOI: 10.1371/journal.ppat.1006390 ... See MoreSee Less
1 week ago ·
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It’s time! Once again UN Environment seeks to make the biggest global call and mobilization for action on 5 June, 2017 in arranging World Environment Day (WED).
World Environment Day is the biggest annual event for positive environmental action and takes place every 5 June. This year’s host country Canada got to choose the theme and will be at the centre of celebrations around the planet.
World Environment Day is a day for everyone, everywhere. Since it began in 1972, global citizens have organized many thousands of events, from neighbourhood clean-ups, to action against wildlife crime, to replanting forests.
"Connecting People to Nature", the theme for World Environment Day 2017, implores us to get outdoors and into nature, to appreciate its beauty and its importance, and to take forward the call to protect the Earth that we share. This year’s theme invites you to think about how we are part of nature and how intimately we depend on it. It challenges us to find fun and exciting ways to experience and cherish this vital relationship.
Background
The year 1972 marked a turning point in the development of international environmental politics: the first major conference on environmental issues, convened under the auspices of the United Nations, was held from June 5-16 in Stockholm (Sweden). Known as the Conference on the Human Environment, or the Stockholm Conference, its goal was to forge a basic common outlook on how to address the challenge of preserving and enhancing the human environment.
Later that year, on 15 December, the General Assembly adopted a resolution (A/RES/2994 (XXVII)) designating June 5 as World Environment Day and urging “Governments and the organizations in the United Nations system to undertake on that day every year world-wide activities reaffirming their concern for the preservation and enhancement of the environment, with a view to deepening environmental awareness and to pursuing the determination expressed at the Conference.” The date coincides with the first day of the landmark Conference.
Also on 15 December, the General Assembly adopted another resolution (A/RES/3000 (XXVII)) that led to the creation of the United Nations Environment Programme (UNEP), the specialized agency on environmental issues.
Since the first celebration in 1974, the World Environment Day has helped UNEP to raise awareness and generate political momentum around growing concerns such as the depletion of the ozone layer, toxic chemicals, desertification and global warming. The Day has developed into a global platform for taking action on urgent environmental issues. Millions of people have taken part over the years, helping drive change in our consumption habits, as well as in national and international environmental policy.
Green Living Association is arranging special activities to raise the significance of the day in motivating people to save our Environment. ... See MoreSee Less
3 weeks ago ·
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West Antarctic Glaciers are Melting at a High Pace
Researchers with the University of California (UC), Irvine, and NASA have completed a pair of studies documenting the pace of glacier melt in West Antarctica. Their findings show that the melting there is occurring at a rate never before observed.
The studies examined three neighboring glaciers that are melting and retreating at different rates. The Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea embayment in West Antarctica, the part of the continent with the largest decline in ice.
One, led by a UC Irvine researcher, looked at satellite records in its approach. Scientists compared radar measurements from the European Space Agency’s Sentinel-1 mission and data from the earlier ERS-1 and ERS-2 satellites to identify changes in each glacier’s grounding line. That is the boundary where it loses contact with bedrock and begins to float on the ocean.
The analysis revealed that the Smith Glacier’s grounding line had retreated 1.24 miles each year since 1996. The Pope Glacier’s grounding line receded more slowly, at 0.31 miles annually since 1996. And the Kohler Glacier’s grounding line, which had gradually retreated over time, re-advanced 1.24 miles since 2011.
The second study, led by NASA scientists, relied on data from the space agency’s Operation IceBridge and other airborne campaigns. These include measurements radar and laser altimetry instruments.
Data from the sensors showed stunning rates of ice loss from the glaciers’ undersides on the ocean sides of their grounding lines. The fastest-melting glacier, Smith, lost between 984 and 1,607 feet in thickness between 2002 and 2009 near its grounding line, or up to 230 feet per year.
Results of both studies will likely aid in ongoing efforts to predict the future loss of West Antarctica ice. One is published in the journal Geophysical Research Letters. The one led by NASA can be found in Nature Communications.
(Credit: NASA Jet Propulsion Lab / Public Domain) ... See MoreSee Less
4 months ago ·
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Germany decided to go nuclear-free by 2022
A CO2-emission-free electricity supply system based on intermittent sources, such as wind and solar -- or photovoltaic (PV) -- power could replace nuclear power. However, these sources depend on the weather conditions. In a new study published in EPJ Plus, Fritz Wagner from the Max Planck Institute for Plasma Physics in Germany analysed weather conditions using 2010, 2012, 2013 and 2015 data derived from the electricity supply system itself, instead of relying on meteorological data. By scaling existing data up to a 100% supply from intermittent renewable energy sources, the author demonstrates that an average 325 GW wind and PV power are required to meet the 100% renewable energy target. This study shows the complexity of replacing the present primary energy supply with electricity from intermittent renewable sources, which would inevitably need to be supplemented by other forms of CO2-free energy production.
Intermittent sources are, by definition, unsteady. Therefore, a back-up system capable of providing power at a level of 89% of peak load would be needed. This requires creating an oversised power system to produce large amounts of surplus energy. A day storage to handle surplus is ineffective because of the day-night correlation of surplus power in the winter. A seasonal storage system loses its character when transformation losses are considered; indeed, it only contributes to the power supply after periods with excessive surplus production.
The option of an oversized, intermittent renewable-energy-sources system to feed the storage is also ineffective. This is because, in this case, energy can be taken directly from the large intermittent supply, making storage superfluous. In addition, the impact on land use and the transformation of landscape by an unprecedented density of wind convertors and transmission lines needs to be taken into consideration. He also warns of the risk that it will intensify social resistance.
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4 months ago ·
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