Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stolen gene allows insect virus to enter cells

04.07.2005


A gene enabling an insect virus to enter new cells was likely stolen from a host cell and adapted for the virus’s use, researchers at Boyce Thompson Institute (BTI) at Cornell University report.



Virologists have long thought of baculoviruses, a group of viruses that can liquefy their insect hosts in a matter of days but don’t induce so much as a sneeze in mammals, as potential pesticides. But the viruses would require tweaking to be effective since they kill insects more slowly than chemical insecticides. Studying baculoviruses also yields insights into general viral behavior. The current study examined how baculoviruses took the evolutionary leap needed to become the nasty bugs they are today.

In the study, reported in the July 1 issue of the Journal of Virology, BTI researchers Gary Blissard and Oliver Lung investigated whether a fruit fly gene, called an f gene, had originally moved from an insect to a virus or the other way around. (Retroviruses, such as HIV, insert their own genes into their hosts’ DNA in order to replicate, and remnants of these invaders can be passed to descendants.) In viruses, an f gene codes for a fusion (F) protein, which enables the virus to penetrate the host cell’s membrane and infect it. Scientists had shown that some other viral genes were probably copied from host cells, but the origin of so-called fusion proteins, like F, has remained a mystery.


"The gigantic step was when the Drosophila melanogaster [fruit fly] genome was published," Blissard says. "The first thing was to ask whether the gene was turned on or not, to validate whether it’s a bona fide gene."

Blissard and Lung found messenger RNA (mRNA) copies of the gene in fruit fly cells, as well as F proteins--both products unlikely to arise if f were a piece of "junk DNA" left over from a long-departed retrovirus. The researchers then looked for evidence that the fruit fly regulates the f gene, switching it on and off as needed. Indeed, they found that the f gene stays quiet until the third and final stage of a maggot’s development, then begins to produce F proteins, which persist into adulthood. "f seems to be developmentally regulated, like a lot of Drosophila genes," says Blissard. Exactly what role the F protein plays in fruit flies remains to be answered.

At some point, perhaps after retroviruses had sprinkled host genomes with multiple copies of the f gene, a baculovirus picked it up through recombination. Unlike retroviruses, baculoviruses don’t insert their genes into their hosts’ genomes. They do steal genes, however, by mixing host DNA with their own. "The way they generate diversity in their genome is by recombination," Blissard says.

No matter how the original f gene moved from the fruit fly into viruses, it had to change a lot to win its current starring role in infectivity, Blissard says. He and Lung found that while viral F proteins naturally migrate to the surface of a host cell, F proteins native to the cell appear to stay on the inside. "Membrane fusion goes on all over the place inside the cell," Blissard says. "But fusion in cells is regulated by fairly large complexes of proteins. Viruses can accomplish membrane fusion with a one-protein machine." The F in fruit flies may not even be a fusion protein.

If the F protein is so important, how did baculoviruses get along without it? These viruses actually generate two types of infectious particles, Blissard explains: one type specialized to infect gut cells, and another that spreads infection in other parts of the insect. The latter type uses F to enter cells. An ancestor of today’s baculoviruses "might have just existed as a diarrheal-type virus, reproducing itself at a low level in the gut, letting the host survive," Blissard hypothesizes. "Picking up the f gene may have caused a radical change in the pathology of this virus, because a virus that co-exists nicely with its host will function a lot differently than one that’s trying to use all the tissues of the animal." In other words, it might have been a host’s own gene that turned baculoviruses into the lean, mean killing machines they are today.

The study was funded by the National Institutes of Health and the Boyce Thompson Institute for Plant Research.

Shawna Williams | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Life Sciences:

nachricht Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society

nachricht 127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>