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  • 5/19/2012

Interview with the World's Most Celebrated Virus Hunter: Ian Lipkin

part 2

ian

So you ended up going to work at Scripps. Why did Oldstone think that virus was so important, more so even than HIV?

Oldstone was interested in infections that can persist and cause damage to the greater organism but not the individual cell. LCMV, a cause of meningitis in humans, shuts down the ability of the pituitary gland to make growth hormone. The virus doesn’t kill the cell, ”¨but it suppresses transcription and translation of genes, so the organism as a whole suffers but the individual cell looks OK. My contribution was showing that there were specific effects on neurotransmitters linked to the behavioral manifestations of the ”¨disease. This became a model for understanding how persistent viral infections affect the central nervous system. Oldstone gave me an opportunity with LCMV, but he was a tough guy.

 

In your next project you tracked down a virus that caused both physical and behavioral changes in animals. What happened there?

I was at a meeting in 1986 when Kathy Carbone and Bill Narayan, both from the Johns Hopkins School of Medicine, were presenting their work on Borna disease, a neurological syndrome in some mammals and some birds. They’d been working with rats and had two models for what they said was an infectious disease. One model included an adult infected rat and a neonatally infected rat. The adults had profound inflammation in the brain and movement disorders. Some were massively obese, and many of them died. The neonatally infected rats were smaller than normal rats and more hyperactive, but they didn’t die and they didn’t have movement disorders. And the researchers were like, really? How could the presentation of the disease be so different in neonates and adults?

 

Were you able to solve the mystery of Borna disease?

After my work with LCMV, I knew how to measure neurotransmitter levels. So I did my measurements, and I could see what was different in the adult versus the neonatally infected animals. But I became intrigued by the fact that Bill and several very good people were trying to identify this virus responsible for Borna and couldn’t find it. Oldstone didn’t have the necessary equipment, so he recommended that I talk to other people at Scripps. There was a guy there, Michael Wilson, whose strategy was eliminating as much irrelevant material as possible from a sample until only the virus was left.

 

So you just kept eliminating until you found your virus?

It took me more than two years to get the Borna system up and going. First I had to get brain material from an infected rat. Then I had to get permission to infect living rats with this bug because it’s potentially dangerous, and the USDA was not excited about testing an agent that can kill horses and sheep that’s not native to the United States. By now it’s 1987. I injected healthy rats with brain material from infected animals, then I waited until the rats developed disease. I removed the brains of the rats, cut them in half and studied one half microscopically. If a rat brain showed inflammation, I assumed the animal had Borna disease. And I took the opposite half of the brain, pulled out the hippocampus, which is the area described by researchers as the target for disease, and ground it up, saving the RNA . Eventually I succeeded in making a library of genetic material””single-stranded RNA ””from the hippocampus of an infected animal. I labeled the RNA with radioactive markers so it was “hot.”‌ Then I made another library of RNA from the cerebellum of a normal animal, and this wasn’t hot. I put the RNA from both samples in a tube and mechanically shook it for three days behind plastic shields made from discarded Jack in the Box restaurant signs, because they were free and excellent at blocking radiation.

 

In essence, most of the material from the rat brain bound together, separating out and leaving viral molecules behind. Is that right?

I wound up with a mixture of double-stranded material [because some of the single strands of rat RNA bound together to form a double helix]. The double strands represented material from the rat brain: either the Borna-disease brain, the normal brain, or a combination of the two. I also got single-stranded material””hot material from the Borna brain alone and cold material from the normal brain. All the single-stranded material got separated out on top of a filter, but only the hot Borna brain material appears on film. [Radioactivity exposes photographic film.]

 

So the hot single-stranded material, which did not bind to the brain tissue in your mixture””was that the Borna virus?

Not yet. I had to eliminate more. Now I take the spleen and I take lymph nodes and I take thymus from normal rats and I grind them all up because, theoretically, these organs contain all the transcripts that might represent inflammatory proteins like chemokines and cytokines. Everything hybridized until I was left with just a 38-”¨kilobase protein and a 24-kilobase protein representing viral DNA. I still didn’t have the virus, but I had protein associated with the virus.

You needed many more complex steps, far too elaborate to explain here, to isolate the viral genome and then the virus itself. But when you were done, you had reinvented the field of pathogen discovery with your molecular techniques.

Of all the things I’ve ever done, I am most proud of that. If the Borna virus had been proved to cause a significant human disease, it would have been an even bigger deal.

 

Why do you say it’s not significant? The Borna virus has been implicated in many different diseases.

A group in Berlin reported Borna in AIDS. A Japanese group reported it in chronic fatigue syndrome at very high levels. People were reporting it in brain tumors, in Alzheimer’s disease, in multiple sclerosis. But we could never replicate the findings. Our new blinded, case-controlled study, published in Molecular Psychiatry, finds no association between Borna disease virus and psychiatric disease. People were contaminating tissue cultures. People were contaminating molecular assays.


Source: discovermagazine.com


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