This surprised virologists as the strain had caused never before disease in humans. To date there have been more than 300 clinical cases of H7n9 with a 33 percent mortality rate.
(when a virus jumps from one species to another) of avian flu can be traced back to human contact with domestic poultry.
Although avian flu strain diversity often originates in wild birds it is the mixing of viruses among poultry pigs
and monitor the diversity of all avian flu viruses--not just those known to cause disease.
This snapshot of the world of flu virus diversity in birds is the outcome of many years of ecology
Understanding the natural diversity of viruses is critically important to identifying health risks. But authorities face a challenge both in focusing efforts in the right places
which borrows on approaches used by ecologists to estimate the diversity of flu viruses in a particular location.
With this approach health authorities can design surveillance programs to detect a given percentage of flu virus diversity.
Given that flu viruses can jump from domestic poultry to people ongoing efforts at improving biosecurity at poultry farms
but wastewater carries microorganisms such as viruses bacteria and protozoa that can contaminate food and cause disease.
However normal cooking temperatures and food preservation strategies can reduce the risks posed by microorganisms and viruses.
The probability of rotavirus infection is affected by uncertainty in virus concentration and variation in vegetable consumption.
and regulations for the reuse of wastewater they present only threshold concentrations for bacteria such as E coli not viruses.
or PRRS virus while the other half of the pigs were challenged non. We've known for a long time that plant extracts also called essential oils
After feeding the pigs challenged with the PRRS virus the three plant extracts the researchers observed that the pigs were more efficient in week 1 (55 percent)
When they checked blood samples from the pigs with the PRRS virus they found that the pigs fed plant extracts also had a lower blood viral load (13 percent)
and the PRRS virus. In production animals inflammation is costly. Inflammation reduces feed intake and it diverts nutrients away from growth to the immune system Pettigrew said
However the filter probably cannot trap most viruses which are much smaller in size. Karnik says his group now plans to evaluate the filtering potential of other types of sapwood.
or a busy airport where cold viruses and other germs circulate freely flowers are common gathering places where pollinators such as bees
It showed that deformed wing virus (DWV) and the fungal parasite Nosema ceranae--both of which have major negative impacts on honeybee health--can infect worker bumblebees
One of the novel aspects of our study is that we show that deformed wing virus
honeybees have higher background levels of the virus and the fungus than bumblebees; bumblebee infection is predicted by patterns of honeybee infection;
or virus particle on the flowers that they visit and these may then infect wild bees.
history booksa new study reconstructing the evolutionary tree of flu viruses challenges conventional wisdom and solves some of the mysteries surrounding flu outbreaks of historical significance.
The study published in the journal Nature provides the most comprehensive analysis to date of the evolutionary relationships of influenza virus across different host species over time.
In addition to dissecting how the virus evolves at different rates in different host species the study challenges several tenets of conventional wisdom--for example the notion that the virus moves largely unidirectionally from wild birds to domestic birds rather than with spillover
It also helps resolve the origin of the virus that caused the unprecedentedly severe influenza pandemic of 1918 The new research is likely to change how scientists
and health experts look at the history of influenza virus how it has changed genetically over time
We now have a really clear family tree of theses viruses in all those hosts--including birds humans horses pigs
--and once you have that it changes the picture of how this virus evolved said Michael Worobey a professor of ecology
if you don't account for the fact that the virus evolves at a different rates in each host species you can get nonsense--nonsensical results about
when and from where pandemic viruses emerged. Once you resolve the evolutionary trees for these viruses correctly everything snaps into place
and makes much more sense Worobey said adding that the study originated at his kitchen table.
And I had a glimmer of an idea that this would be important for our public health inferences about where these viruses come from
Using the new family tree of the flu virus as a map showed which species moved to which host species and when.
It revealed that for several of its 8 genomic segments avian influenza virus is not nearly as ancient as often assumed.
What we're finding is that the avian virus has an extremely shallow history in most genes not much older than the invention of the telephone Worobey explained.
which included UA graduate student Guan-Zhu Han and Andrew Rambaut a professor from the University of Edinburgh who is affiliated also with the U s. National institutes of health found a strong signature in the data suggesting that something revolutionary happened to avian influenza virus
Worobey said the timing is provocative because of the correlation of that sudden shift in the flu virus'evolution with historical events in the late nineteenth century.
According to Worobey the newly generated evolutionary trees show a global replacement of the genes in the avian flu virus coinciding closely with the horse flu outbreak
which the analyses also reveal to be the closest relative to the avian virus. Interestingly a previous research paper analyzing old newspaper records reported that in the days following the horse flu outbreak there were repeated outbreaks described at the time as influenza killing chickens
whether the virus jumped from horses to birds or vice versa but a close relationship between the two virus species is clearly there.
With regard to humans the research sheds light on a longstanding mystery. Ever since the influenza pandemic of 1918 it has not been possible to narrow down even to a hemisphere the geographic origins of any of the genes of the pandemic virus. Our study changes that Worobey said.
It is now clear that most of its genome jumped from birds very close to 1918 in the Western hemisphere
The results also challenge the accepted wisdom of wild birds as the major reservoir harboring the flu virus from where it jumps to domestic birds
Instead the genetic diversity across the whole avian virus gene pool in domestic and wild birds often appears to trace back to earlier outbreaks of the virus in domestic birds Worobey explained.
and eggs may be substantially shaping the diversity of these viruses in the wild over time spans of decades.
#RNA sequencing of 750-year-old barley virus sheds new light on the Crusadesscientists have sequenced for the first time an ancient RNA genome--of a barley virus once believed to be only 150 years old--pushing its origin
This new find challenges current beliefs about the age of the BSMV virus which was discovered first in 1950 with the earliest record of symptoms just 100 years ago.
It is important to know as much as we can about virus evolution as emerging infectious plant diseases are a growing threat to global food security
and of those viruses account for almost half. History tells us about the devastation caused by the emergence of disease from wild hosts in disparate countries such as the Central american origin of the oomycete that led to The irish potato famine.
We need to build up an accurate picture of the evolution of different types of virus
however this 750-year-old example of the virus allows us to more accurately estimate its evolution rates and date of origin.
Without the Medieval RNA evidence the virus appears to be much younger than it actually is
It's possible that other viruses that similarly appear to be very recent may in fact have a more ancient origin.
The Seventh crusade of Louis IX in 1234 is the most closely aligned in date to the origin of the virus expansion.
The researchers believe the massive war effort could have caused the virus to spread fuelled by an intensification of farming
This made contact with cultivated barley and wild grass more likely providing opportunities for the virus to'jump'into the crop.
In more recent history the virus appears to have spread to the US from Europe around 120-150 years ago.
That the major causes of annual losses include pests (e g. the Varroa mite) pathogens (e g. viruses that these mites carry) and the need for research and advancements in management techniques available for large-scale apiaries
the toll of agricultural intensification on this semi-free ranging managed species and the confounding pressure of viruses spread through Varroa mites and the burden of these viruses and mites at the individual bee and colony level.
and Dalesbred each showed a lower than average risk of infection to Maidi Visna a virus causing a slow-acting disease affecting millions of sheep worldwide with massive welfare and economic impacts.
These new data provide evidence to support suggestions that the native hill breeds are less susceptible to the virus. Mainstream agriculture is looking to locally adapted breeds of livestock to increase resilience to new pressures from climate change
The routine screening of bees for frequent and rare viruses resulted in the serendipitous detection of Tobacco Ringspot Virus
whether this plant-infecting virus could also cause systemic infection in the bees says Yan Ping Chen from the U s. Department of agriculture's Agricultural research service (ARS) laboratory in Beltsville Maryland an author on the study.
The results of our study provide the first evidence that honeybees exposed to virus-contaminated pollen can also be infected
when they move from flower to flower likely spreading the virus from one plant to another Chen adds.
Notably about 5%of known plant viruses are transmitted pollen and thus potential sources of host-jumping viruses.
As a result viruses such as TRSV generate a flood of variant copies with differing infective properties.
Israel Acute Paralysis Virus (IAPV) Acute Bee Paralysis Virus (ABPV) Chronic Paralysis Virus (CPV) Kashmir Bee Virus (KBV) Deformed Wing
Bee Virus (DWV) Black Queen Cell Virus (BQCV) and Sacbrood Virus (SBV) are known other causes of honeybee viral disease.
or weak TRSV and other viruses were more common in the weak colonies than they were in the strong ones.
TRSV was detected also inside the bodies of Varroa mites a vampire parasite that transmits viruses between bees while feeding on their blood.
The increasing prevalence of TRSV in conjunction with other bee viruses is associated with a gradual decline of host populations
but the usual suspects (viruses and bacterial infections) didn't have anything to do with the poor health of the trees.
You are known for your groundbreaking research on developing virus-resistant plants through biotechnology. What are some of the ways biotechnology can be used today?
or to fight a virus, do you stop growing the crop? It s been largely the purview of the agrochemical companies.
including the Lyme spirochete, West Nile virus, and Hanta viruses. Recent studies suggest that contact with nature can have positive effects on our mental health.
if pesticides or viruses or something else is the cause for the colony decline. Even if you don't like honey,
and a mix of a parasite and a virus. Montana's ecologist Colin Henderson said to the Washington post:
but in Hong kong, a frightening outbreak of the SARS virus 10 years ago awakened an interest in living more healthfully.
the flu virus can be controlled. Here again the potato blight offers some clues. Nearly three-quarters of the blight's genome consists of junk DNA,
Or what warranted a vaccine for this particular virus? This is one of the big problems.
Trying to predict which of these viruses we ought to be worried most about. In the animal population there is a whole soup of flu viruses.
We are not good at determining which of those are most likely to jump into humans.
This particular virus had concerned features that us. There are specific mutations in its genome that we associate with an increased ability to grow in mammals.
And our laboratory studies found an elevated ability of this virus, as compared to most other avian viruses,
to transmit. Was there any overt indication that this strain of flu was more of a risk?
Well, we know that there are genetic elements of a virus associated with growth in mammals.
This particular virus had some of those. Also, the hemagglutinin (H) protein in this virus attaches the virus to the host cell.
We saw some significant changes in that protein that looked like it might be able to bind to a human host cell.
what viruses bind to. So there are signatures that avian viruses have that are associated with binding to those avian cells.
This virus is primarily avian still but it did have some signatures that we associate with mammalian virus. Where does this virus rank among the flu viruses we know about already?
I think it is more infectious than H5. It's probably more infectious than H9
which is another virus we sporadically see in humans. But if we rank it highest amongst the avian flu viruses,
what does that mean? The next leap is: Does it have a ten percent chance of being able to go human-to-human?
Is it one percent or less? We really don't know. I think the chances are still most likely that it is going to remain a chicken virus that will spread human infections.
But flu viruses do change. If you give them enough opportunity they will adapt to a new host.
So it may have the ability to turn into a real bona fide human pathogen. That is why we continue to monitor this in the bird populations,
So we have quite a bit of immunity to the human flu viruses. And that probably stunts a lot of the ability of that virus to cause disease.
It can still get in and make you a little bit sick. It can still transmit but the severity is limited by your immunity.
The H-type is the most variable part of that virus. That is why we call them H1, H3,
We group flu viruses into pathogenic types. Highly pathogenic or low pathogenic. Some viruses of the H5n7 type fall into a very virulent form.
And we know how they do this. They accumulate additional amino acids in their H protein. The H5n1 is one of these highly virulent forms.
this particular virus does not have that extra bit. So that is a good thing? No.
and you know the virus is there. With the H7 you cannot tell just by looking at the chickens.
Isn't that the case with most viruses? With any flu viruses there is a period
when you're infectious before you start to get clinical signs. With the H5 you eventually see sick birds.
But if you look at the pandemics we've seen they have all been from viruses of the H1, H2 and H3 type.
If we find viruses like the H7 that we perceive as high-risk then we start making viable vaccine strains.
but essentially you are protected only from a portion of these H1 viruses. And you are protected not against the H5 or H7.
There is some hope that perhaps we can target other parts of the virus. There is a lot of work toward creating a universal flu vaccine.
But what about viruses? The computer metaphor, though, is a reminder that there is no shortage of fools
and criminals ready to construct viruses and other harmful computer programs. If such people got interested in the biological world,
Modern herbal treatments with Astragalus membranaceus root (often in concert with other herbs) are partly based on clinical trials showing benefits in strengthening immune function during viral (e g. chronic hepatitis)
But, while it may take decades to transmit something as complicated as a virus or a single molecule of DNA,
and viruses were amenable to the technology and within reach of a startup. According to Hessel, individualized drugs could lower the cost of drug development across the entire spectrum of the development chain.
< Back - Next >
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011