Viral DNA carried by human immunodeficiency virus type 1 virions.

A fundamental step in the replication of retroviruses is the reverse transcription of the viral RNA genome into a double-stranded DNA provirus. Retroviruses are believed to carry genomic information only as RNA, and synthesis of DNA is thought to start only after virus entry into the infected cell. We report here that infectious mature human immunodeficiency virus type 1 virions contain viral DNA of heterogeneous size. This heterogeneity seems to result from random stops of reverse transcription during minus- and plus-strand synthesis. The DNA carried by human immunodeficiency virus type 1 virions presumably originates from reverse transcription which takes place prior to or during formation of the mature virus particle.