The world's first artificial virus was synthesized in late 2003 by a research team led by Craig Venter, who was also responsible for the first sequencing of the human genome. The virus was a Phi-X174 bacteriophage (bacteria-eater) whose genome has 5,000 base pairs, or nucleotides. In comparison, the human genome has around 3 billion base pairs.
The polio virus, with 7,500 base pairs, has also been synthesized from scratch. Synthesizing the Phi-X174 virus was a rapid task -- with contemporary technology, it only took two weeks. Synthesizing other virii has taken months.
The process begins with the synthesis of oligonucleotides, which are small lengths of nucleotide (DNA or RNA) with around twenty or fewer base pairs each. Because biologists have already been synthesizing oligonucleotides for years, DNA synthesis machines exist that are capable of manufacturing them automatically. Designing the oligonucleotides for the Phi-X174 virus only took about eight hours, followed by a four-day synthesis process.
The next step is the purification of the oligonucleotides by gel electrophoresis. The purified oligos are then tagged with special chemicals and assembled sequentially, one by one, in a process called PCA (polymerase cycling assembly). After 35 to 70 cycles, a full chromosome made out of the artificial oligos has been synthesized. Using PCR (polymerase chain reaction), many copies of the original chromosome are then created, the best of which are selected using another cycle of gel purification. These nucleotide chains are then circularized from their linear chromosomal forms, becoming infectious.
The infectious chromosomes (virii) are then transplanted to an agar plate containing bacteria for consumption. Within a day, telltale remnants of viral activity and self-replication can already be found, showing that the synthesis was a success.
The synthesis of artificial viruses has been discussed for such applications as pollution reduction and advanced filtering. Specialized microbes can be created to consume almost anything. On the other hand, there is always the risk that a malicious party would use this technology to create a virus engineered for high virulence or lethality against human hosts.
