INTRODUCTION: The first plant virus shown to have a DNA genome and the first shown to replicate by reverse transcription. Worldwide but only causes significantly losses locally. It is transmitted by aphids . Type member of the Caulimovirus genus, contains 11 species and 6 possible members. significantly impact on plant virology and plant molecular biology. The virus is an important source of gene regulatory elements, used exclusively in the genetic manipulation of plants. STRUCTURE:Icosachedral with a diameter of 52Â nm built from 420 capsid protein subunits. It contains a circular double-stranded DNA molecule of about 8.0 kB . Dna is interrupted by sitespecific discontinuties resulting from its replication by reverse transcription. After entering the host, the single stranded nicks in the viral DNA are repaired, forming a supercoiled molecule that binds to histones. DNA is transcriped into a full length . Replication Risk Factors:The Cauliflower mosaic virus promoter (CaMV 35S) is used in most transgenic crops to activate foreign genes which have been artificially inserted into the host plant. It is inserted into transgenic plants in a form which is different from that found when it is present in its natural Brassica plant hosts. This enables it to operate in a wide range of host-organism environments which would otherwise not be possible.