HIV1 Reverse Transcriptase is an RNA-dependent DNA polymerase of HIV1 (AIDS virus), subtype B origin. It is responsible for the production of a double stranded DNA copy of the single stranded RNA genome that is contained in the HIV1 virus particle and primed by the host cell lysine-tRNA which partly unfolds and anneals to the 5' end of the viral genomic RNA. This is extended by the polymerase function of RT to give a DNA-RNA hybrid. It also has RNaseH activity which degrades the RNA component of this hybrid once it has been copied.