Your genome is all of the hereditary information encoded in your DNA. In 2003, scientists in the U.S. completed the Human Genome Project. This was an incredible feat given that the DNA of the 24 different human chromosomes contains about three billion chemical building blocks. The researchers undertook this massive investigation in order to reveal the 25,000 odd human genes within our DNA.
The DNA sequence maps are now being used to study human health and biology to better develop preventions and treatments for disease. And gene sequencing might help us make vaccines more effective, too. When we talk about the genome of a virus, all of its hereditary information is encoded in its DNA as well. By sequencing the genome of a virus, just like in the Human Genome Project, scientists get a much better picture of the way the virus lives and functions. And these details, in turn, are leading to a better understanding of how to develop vaccines that can outsmart viruses and kill them off. Genome sequencing can show a scientist, for example, how a virus reacts in the presence of a vaccine.
This is exactly what happened in a recent clinical trial that used genome sequencing technology to see what changes a population of pneumococcal bacteria went through after being exposed to a vaccine. Pneumococcal bacteria typically cause respiratory problems including coughing, sneezing, and congestion. When this bacterium colonizes in the lungs, it can cause pneumonia. It can also spread to the blood where it can trigger septic shock and life-threatening low blood pressure. When scientists at the Wellcome Trust Sanger Institute in the U.K. used genome sequencing to study a sample of pneumococci, they determined that some of the bacteria were wiped out when exposed to a certain vaccine. Into this void grew pre-existing bacteria with a slight genetic variation and this variation was likely responsible for a drop in the pneumococcal disease.
The scientists hope to be able to follow the changes a bacteria goes through in order to flag the sudden emergence of a disease-causing strain. It’s this ability of being able to quickly and precisely investigate a disease outbreak that has got the medical community excited. However, there’s one snag: some infections are caused by two different strains of the same bacteria. If only one strain is sequenced, then the ability of genome sequencing to help is limited. Scientists are working on this problem right now.
Another way to utilize genome sequencing in the fight against viruses is to use whole genome sequences to build vaccine candidates. Mathematical formulas can be used to determine the best antigens and these, in turn, can be developed into a vaccine. However, this process will not be as easy as it sounds. Scientists will have to choose from hundreds of identified antigens, the ones which can best be combined to form an effective vaccine. The research does look promising, and I’m excited to see what scientists discover next.
Source(s) for Today’s Article:
Croucher, N.J., “Population genomics of post-vaccine changes in pneumococcal epidemiology,” Nat Genet. May 5, 2013.
Eyre, D.W., et al., “Detection of Mixed Infection from Bacterial Whole Genome Sequence Data Allows Assessment of Its Role in Clostridium difficile Transmission,” PLoS Comput Biol. May 2013; 9(5): e1003059.
Schubert-Unkmeir, A., et al., “Genome-Based Bacterial Vaccines: Current State and Future Outlook,” BioDrugs. April 16, 2013