(A) The Baltimore classification divides all viruses into seven groups based on how the viral mRNA is produced. DNA strands are denoted in red (+ssDNA in darker shade of red than -ssDNA). Similarly RNA strands are denoted in green (+ssRNA in darker shade of green than -ssRNA). In the case of Baltimore groups 1,2,6, and 7, the genome either is or is converted to dsDNA, which is then converted to mRNA through the action of DNA-dependent RNA polymerase. In the case of Baltimore groups 3, 4 and 5, the genome is or is converted to +ssRNA, which is mRNA, through the action of RNA-dependent RNA polymerase. (B) Nucleotide type classification divides viruses based on their genomic material into DNA and RNA viruses. Baltimore viral groups 1, 2, and 7 are all considered DNA viruses, and the remaining viral groups are considered RNA viruses. (C) Host Domain classification groups viruses based on the host domain that they infect. Three groups are formed: eukaryotic, bacterial and archaeal viruses.