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2008 National DNA Day Online Chatroom Transcript

This is just one question from an archive of the National DNA Day Moderated Chat held in April 2008. The NHGRI Director and many genomics experts from across NHGRI took questions from students, teachers and the general public on topics ranging from basic genomic research, to the genetic basis of disease, to ethical questions about genetic privacy.

How do viruses replicate without having DNA?
     Pam Schwartzberg, M.D., Ph.D.: We study mouse models of primary immunodeficiencies (genetic diseases that impair the ability of the immune system to fight infections) and how specific disorders affect responses to infectious diseases. There are many different types of viruses, some of which are encoded by RNA, not DNA. Thus, RNA is their genetic material. RNA viruses replicate using their own RNA polymerases. One fascinating set of viruses are the retroviruses and lentiviruses, which have an RNA genome in the virion, but are copied into a DNA copy via an enzyme called reverse transcriptase. The DNA copy is inserted into the host genome, which can cause cancer in some cases by integrating near "oncogenes". The "proviral" DNA is then copied like any other gene by cellular enzymes. The fascinating thing about viruses is that they have evolved all sorts of mechanisms to replicate. They have been around alot longer than us and will outlast and outbeat us.
Abbeville High School in SC (12th grade student)

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