Caulimoviruses achieve entry into plant cells via damaged tissues, transmission via an animal vector (aphid insects) and seeds passed down to generations. Plant cells do not possess receptors like animal cells that would allow the virus to enter and since plant cells are thick, viruses achieve entry as aforementioned. Once inside the plant, the virus spreads using
plasmodesmata, a membrane channel found in plants connecting one plant cell to another. Caulimoviruses are para-retroviruses with a DNA genome; thus, part of their viral replication takes place in the nucleus, where the host replication machinery is utilized. The rest of its life cycle takes place in the cytoplasm. Replication follows, where initially the dsDNA enters the nucleus and is transcribed into RNA using the host RNA polymerase. Then, the RNA is reverse transcribed to viral DNA using the host reverse transcriptase in the cytoplasm. The viral product is made and assembled in the cytoplasm, which then spreads to other parts of the plant cell using plasmodesmata. Translation takes place by
ribosomal shunting. For most Caulimoviruses, their genome is not integrated into the host cell; however, some viruses, such as Dahlia mosaic virus (genus Caulimovirus), have been identified as having integrated their genome into the host. Transmission routes are mechanical. ==Application: Plant Biotechnology==