MadSci Network: Genetics

Re: Re: Re: human firefly virus on the wild

Date: Mon Feb 27 15:08:52 2006
Posted By: Jeff Buzby,
Area of science: Genetics
ID: 1137976272.Ge

Dear Tiago:

Your question is very timely & represents a justifiable concern for both the general public and those working in the genetic engineering & gene therapy fields.

Transmission of genes across a 'species barrier' represents an example of horizontal or lateral gene transfer, as shown in this accompanying diagram illustrating Horizontal Gene Transfers in Early Evolution. When this gene transfer is conducted by a virus, it is known as transduction, a process 1st discovered & characterized in bacteria. A similar mode of genetic transduction has also since been discovered & characterized in viruses capable of infecting human, notably the retroviruses. The observed outcome of retroviral gene transduction is typically referred to as oncogene capture. During this genetic transduction from 1 individual organism to another, a normally functioning gene, known as a 'proto-oncogene', is altered to become a mutated, cancer-causing oncogene, as illustrated in this Model for Retroviral Transduction of a Cellular Proto-oncogene to Form an Acute Transforming Virus.

With this background in mind, it should be noted that while "horizontal gene transfers occur much more frequently between different species of procaryotes [e.g bacteria]....horizontal transfers of genes between eucaryotic cells of different species [e.g. humans] are very rare, and they do not seem to have played a significant part in eucaryote evolution", as discussed in the section of the Molecular Biology of the Cell online textbook explaining how Genes Can Be Transferred Between Organisms, Both in the Laboratory and in Nature.

So although it might theoretically be possible for a virus to transduce the 'green glow gene' that you mention, which is probably either the firefly luciferase or jellyfish green fluorescent protein gene, from transgenic animal cells into a human host, it would appear to be a highly unlikely event in nature. While there are examples of viruses infecting humans from more distant species, as you also correctly mention, the capacity for transduction is limited to very few types of eucaryotic viruses, probably because most viruses cannot afford to carry additional genetic material in their comparatively compact genomes.

Thanks for the great question,

Jeff Buzby, Ph.D.
CHOC Research Institute
MadSci Genetics Network

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