Yes and No. HIV and HCV are both RNA viruses. That is both use RNA to carry
their genetic code until they find a yummy host! However, these viruses
belong to two entirely different families. Sort of like whales and humans
are both mammals, but boy what a difference. They have completely
different strategies for replication and for survival.
HIV is a retrovirus, and once the virus is in a human cell it copies itself to
DNA and migrates into the cell nucleus and integrates into the host
genome and is then copied every time the cell copies its own DNA. Retro
means that the virus reverts to a DNA virus once it is in the cell. Other
retro viruses are HTLV viruses like some types of leukemia.
HCV is a flavivirus. It is related to yellow fever and dengue fever viruses. It
replicates by making positive and negative RNA strands and does not make
DNA or integrate into the host genome.
There are lots of other structural and envelope differences between these two, but the main point is that HIV and HCV are NOT very similar at all—except they both completely screw up the immune system and there is no known cure. (See Double Jeopardy: The HIV/HCV Co-Infection Handbook, which we have appended to the printed version of this FAQ). See also Appendix F: “The Double Challenge of HIV/HCV Co-infection.”