Eat me.
Poxvirus (in green) may enter its host cell (in red) by sporting a "garbage" tag that prompts the cell to swallow it.
Credit: Jason Mercer/Swiss Federal Institute of Technology
Posted on 05/03/2008 9:44:44 PM PDT by neverdem
Eat me.
Poxvirus (in green) may enter its host cell (in red) by sporting a "garbage" tag that prompts the cell to swallow it.
Credit: Jason Mercer/Swiss Federal Institute of Technology
It might not be the most elegant entrance, but poxviruses have engineered a way to sneak into cells through the garbage chute. According to a new study, the virus disguises itself as junk so that it will be gobbled by cells cleaning up floating debris. The discovery could explain how the virus that causes smallpox infects its hosts.
In order to replicate, viruses must find some way of getting their DNA into host cells. Once there, the DNA takes over the cellular machinery, effectively turning the cell into a virus factory. Most viruses stage this coup by fusing with the cell membrane to insert their DNA or entering the cell whole via small membrane vessels. Poxviruses have been seen both fused with and inside cells, but scientists have been unclear about exactly how they gain entry.
Using a light microscope, researchers at the Swiss Federal Institute of Technology in Zürich watched fluorescently tagged vaccinia virus--a more benign cousin of smallpox virus--migrate toward target cells. The virus seemed to trigger and enter through a balloonlike structure, or bleb, on the cell surface, which normally only forms during cell movement, division, or death. The researchers found that they could block blebbing and infection by disrupting the cell's "drinking" process, by which cells take up fluids via membrane vessels. The results suggest that the virus relies on this process to enter the cell, the first time such an entry mode has been shown, says cell biologist and lead author Jason Mercer. The virus may employ this strategy because it's too big to fit into the smaller vessels that other viruses typically travel in, the authors report today in Science.
Because most cells also use their "drinking" mechanism to suck up the remains of old cells, the team wondered if the virus was playing dead. They found that the virus's surface was studded with phosphatidylserine, a lipid that also flags dead cells as garbage. Removing lipids from the virus's surface stopped infection, and recoating the virus with phosphatidylserine restarted it. The results suggest that the virus is "more clever than originally thought" because it exploits a garbage-collection process found in almost all cells, says Mercer.
The study clears up some of the mystery around poxvirus infection, says Grant McFadden, a virologist at the University of Florida, Gainesville. It shows that the virus is "hijacking some fundamental machinery from the cell," he says, although which cell proteins are critical for virus entry remains to be worked out. But Jacomine Krijnse-Locker, a cell biologist at the European Molecular Biology Laboratory in Heidelberg, Germany, says that the evidence is "too indirect" to support the study's conclusions. To make a more convincing case, she says, scientists need to observe the virus's path into the cell with higher resolution techniques like electron microscopy. Mercer says the team has since done electron microscopy experiments that show the virus moving into the cell through membrane indentations, although these data were not part of the published study.
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Pox virus (how it works?) ping...
“They found that the virus’s surface was studded with phosphatidylserine, a lipid that also flags dead cells as garbage.”
Wonder if researchers have mistaken other viruses with cellular garbage at other times?
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus
That was quick, Joe.
bump & a micro ping
IIRC, The genetic code can be DNA or RNA, and it can be either double or single stranded. They also come with a specific glycoprotein exterior that determines which cells they hijack. I know that they can thrive in animals, plants and bacteria. I don't know if they use fungi and various other parasites.
The virus is the most poorly understood organism and yet its also one of the most complex.
Prion diseases, e.g. mad cow disease, are the least understood, IMHO.
Exercise Your Brain, or Else You’ll ... Uh ...
FReepmail me if you want on or off my health and science ping list.
PING - smallpox
interesting
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