Answer:
The answer to this question would be: antiviral agents that block any of the steps in the transcription process, since without newly produced RNA, or DNA for the new virions, it would be impossible for the virus to replicate itself and thus spread out to infect further. An example of such a drug is aciclovir, and what they do is inhibit, or prevent, the transcription process, either of DNA, or RNA depending on the invading virus, so that viral proteins cannot be coded for and the new virions cannot be assembled.
These agents usually are nucleotide analogues that mimick the DNA, or RNA, that the virus will need in order to replicate its genetic material for the new viruses. However, since they are not the correct material, these analogues will inhibit correct replication, or further coding, of the genetic material. This in turn will ensure that either no proteins, or weak proteins, will be produced and the virus will be left weakened for the attack of the immune system.