For US$16,818.50 would you want a synthetic human virus?

In the media aftermath of the H5N1 transmission debate we've been hearing an awful lot about the possibilities of bringing synthetic biology to the field of virology. In fact, one of the best analyses of this situation is Carl Zimmer's piece in the New York Times. In it, Carl explores the capabilities of DIY, amateur biologists to investigate how viruses infect and cause disease. The pro's and con's of utilizing synthetic DNA to make viruses versus the more traditional methods are looked at briefly but really how easily can it be done? and how different is this new wave of synthetic virology versus earlier methods?





Why do we need genetic technology?

Well, to understand how viruses - or indeed any living systems - behave at the molecular level no technique has provided us a better grasp of this than recombinant DNA technology. Sure we have 'always' (relatively speaking) been able to grow viruses and study how well they replicate and cause disease but the ability to make thousands of copies of a specific piece of DNA from one organism, join these blocks of genes into larger assemblages of similar sequences and insert these genes back into an organism has facilitated an unprecedented appreciation of how life works at the most basic of levels.

It is easy to undervalue this task - the isolation, cloning and analysis of a gene - (it sounds straight forward, right?) but over the last three decades since the invention of the polymerase chain reaction (PCR) in 1983 this has become a somewhat artisan craft taking years to fully master. So what happens when these advances in synthetic DNA technology (sequencing and DNA synthesis) supersedes hard work and training? On one hand it may leave you traditional 'cloner's bitter but on another, this approach could be argued as clearly the far superior craft.

The old fashioned way?

For example: imagine we were interested in how one virus - say measles - enters a human cell. Specifically we thought that amino acid 100 in the viral attachment protein, a lysine, allowed the virus to bind to it's receptor molecule on the cell surface. To test whether this was correct you would want to change the lysine to another amino acid and see if it attached to the receptor as easy as it did when it was a lysine. If removing this lysine seriously impacted virus attachment you would conclude that amino acid 100 was very important to the virus.

Now to do this you would need to grow the virus up (and find some virus in the first place) in tissue culture and once you had enough of it you could go about isolating the viral genes. In this case measles is an RNA virus so you would get the RNA, and make a DNA copy of it through a process called reverse transcription. Once you had measles DNA you would PCR the gene encoding the attachment protein and then mutate that lysine to another amino acid, say alanine. Finally after probably a week or two would be in the position to some experiments.

Increasing complexity

This is a very simple example for one gene, so imagine a more complex experiment with more genes and more organisms involved - imagine constructing an entire viral genome from scratch? You can see it could get very difficult. And also expensive: you need access to the virus (where do you get some measles? or say avian influenza?), you need lab equipment like biosafety cabinets, PCR machines, reagents, primers, enzymes and cells. So what if you could get around all this hassle and order your DNA and genes from any organism (with sequence data available) , in any combination, size etc directly from a company? No longer do you need to invest much time in doing these kinds of experiments.

To see how easy it would be for someone to embark on this kind of work (at least somebody in a university setting) I got in contact with one of the gene synthesis companies out there today. I work on a group of RNA viruses known as the paramyxoviruses - they include human pathogens like measles, mumps, RSV, nipah and hendra. Pretty dangerous stuff. If you wanted to get the entire genome synthesized (about 15,000 base pairs) it would cost you only US$16,818.50. Only. Also with a considerable time delay and no guarantee of delivery. Turns out viral genomes are pretty complicated. And even once you received the viral DNA you would then have to go about turning into a virus, which is not a particularly easy affair.

That being said I doubt that we have anything to worry about in terms of bioterrorism coming from amateur biologists based on the price and practical difficulties (although the monetary hurdle isn't that impressive). However, that didn't stop two research groups using these companies to generate viral genomes to use in these two papers:

Evaluation of Measles Vaccine Virus as a Vector to Deliver Respiratory Syncytial Virus Fusion Protein or Epstein-Barr Virus Glycoprotein gp350.

Rescue of recent virulent and avirulent field strains of bluetongue virus by reverse genetics.

 So perhaps it isn't bioterrorism we should be worried about, it is the intellectual and academic threat that people paying for these synthetic genomes bring to us. Maybe traditional molecular biologists should look towards this field for their everyday experiments.