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 Nerves control the body’s bacterial community
26.09.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Ageless ears? Elderly barn owls do not become hard of hearing
26.09.2017 | Carl von Ossietzky-Universität Oldenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>