ABSTRACT
Posttranscriptional regulation is a key event in the expression of many cellular mRNAs, and it is also an essential mechanism for the expression of several retroviruses and DNA viruses. Studies of the human immunodeficiency virus type 1 and the human T-cell leukemia virus type 1 showed that these retroviruses depend on virally regulated posttranscriptional regulation for their expression. The chapter reviews the posttranscriptional mechanisms used by the different retroviruses. The type D simian retroviruses is a family of retroviruses consisting of simian retrovirus type 1 (SRV-1), type 2 (SRV-2), and type 3 or Mason-Pfizer monkey virus. Comparison of the gag/pol and env genes between SRV-1 and MPMV shows similarity of approximately 90–97%, whereas there is about a 72–80% similarity between SRV-1 to SRV-2. Avian leukosis-sarcoma viruses also belong to the simple retroviruses encoding gag/pol and env, a genomic organization that is similar to that of the type D simian retrovirus.
