7.1.1.1 The retroviral genome

The genome consists of the genes essential for viral replication (Varmus, 1988). The genome can be divided into three transcriptions units namely gag, pol, and env. The gag region encodes genes for capsid proteins, the pol region encodes for the reverse transcriptase and integrase proteins, and the env region encodes the proteins for receptor recognition and envelop, glycoprotein.  In addition to these regions, there are other regions found at each end, they are composed of large number of nucleotide repeats known as long-terminal repeats LTR. The LTR are responsible for viral integration and regulating the transcription of the viral genome. (Fig.10).

Figure 10 : Retrovirus genome

The packing of the viral genome and its protein to form new virus occurs by the help of a sequence known as psi (packing signal), located at he 5/ end of the viral genome (Fig. 11)

Figure 11 : Construction of recombinant retrovirus