There is now a wealth of information about the structure and function of retroviral RTs. Much of this information has been obtained by studying the RT of HIV-1. This is an appropriate emphasis considering the fact that HIV-1 is an important human pathogen and that the RT of HIV-1 is an important therapeutic target. Additional information about specific inhibitors of HIV-1 RT (some of which are important anti-AIDS drugs) is presented in Chapter 12 Chapter 12 also presents information about how mutations in HIV-1 RT lead to drug resistance. Resistance is an important consideration in any attempt to develop an effective therapy.

A reasonably clear notion exists of the role(s) RT has in the retroviral life cycle; the general form of the standard model for the copying of the RNA genome into DNA has not changed significantly in the past 15 years. However, neither the solid foundation provided by our understanding of the process of reverse transcription and its role in the retroviral life cycle nor the more recent progress in understanding the enzyme(s) that carries out this process represents tasks that are complete.

There is still much to learn: For example, a better understanding of HIV-1 RT might lead to the development of more effective AIDS therapies. The genomes of other important human pathogens (e.g., hepatitis B virus) are replicated via an RNA intermediate; relatively little is known about the RT of the hepatitis B virus. In addition to the questions that still exist for retroviral RTs, some of which have been discussed in this chapter, a number of odd (and fascinating) RTs are involved in the replication of the diverse families of retrotransposons (see Chapter 8. We can also look forward to learning more about the cellular DNA polymerase, telomerase, which creates the ends of the chromosomes in selected eukaryotic cells by copying an RNA template it carries with it.

In the end, we would hope that our understanding of reverse transcription would be an integral part of the global understanding of the ways in which genetic information is passed from parent to offspring in succeeding generations.