mRNA to code for proteins
Virus genome to pack in virus particles
The negative strand of RNA has a sequence complementary to the coding strand. Therefore, viruses that use this type of genome must synthesize the complementary plus strand upon entry into the host cell. The plus RNA strand can then be used as a template to manufacture more viral genomes (right side). The negative RNA strand is then free to manufacture more copies of the plus strand (left side). These act as mRNA and direct viral protein synthesis.
Retroviruses carry RNA in the particle but make a DNA copy after entering the host cell.
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