Elsevier established a COVID-19 resource centre in January 2020, offering free English and Mandarin information on the virus. The centre is hosted on Elsevier Connect, and Elsevier grants permission for free access to all COVID-19-related research in PubMed Central and other repositories. The article discusses RNA virus genome structure and evolution, highlighting advances in understanding viral replication strategies and genome organization. It explores how genomic sequence comparisons, direct mRNA sequencing, and replication intermediates have provided new insights into viral evolution. The study reveals that certain viruses are closely related despite lacking sequence homology, and that specific amino acid motifs indicate protein function and evolutionary relationships. The article also discusses the coding strategy of the V/P genes in paramyxoviruses, noting a new mechanism for translational frame-shifting that aids in virus classification. It describes how different paramyxoviruses use varying numbers of non-templated G residues to shift reading frames, leading to the production of multiple proteins from a single gene. This has led to suggestions for reclassifying the Paramyxoviridae family. The article also covers new aspects of coronavirus replication, including the production of subgenomic mRNAs and the role of the coronavirus replicase in genome organization. It discusses the structure and function of coronavirus proteins, including the nucleocapsid protein, membrane glycoproteins, and the additional envelope glycoprotein with homology to influenza C virus. The article highlights the discovery that many plant viruses have animal virus counterparts, suggesting a common evolutionary origin. It discusses the relationships between animal and plant viruses, including similarities in genome organization and amino acid sequence homology. The study also explores the replication strategies of viruses such as Sindbis virus and tobacco mosaic virus, noting similarities in their genome structure and replication mechanisms. The article concludes that RNA viruses have evolved from a small number of ancestral viruses, with recombination playing a significant role in their evolution. It emphasizes the importance of genomic sequence analysis in understanding viral phylogeny and the modular evolution of viral genes. The study also highlights the efficiency of RNA viruses in expanding their coding capacity through various mechanisms, including frame-shifting, differential splicing, and the production of multiple mRNAs.Elsevier established a COVID-19 resource centre in January 2020, offering free English and Mandarin information on the virus. The centre is hosted on Elsevier Connect, and Elsevier grants permission for free access to all COVID-19-related research in PubMed Central and other repositories. The article discusses RNA virus genome structure and evolution, highlighting advances in understanding viral replication strategies and genome organization. It explores how genomic sequence comparisons, direct mRNA sequencing, and replication intermediates have provided new insights into viral evolution. The study reveals that certain viruses are closely related despite lacking sequence homology, and that specific amino acid motifs indicate protein function and evolutionary relationships. The article also discusses the coding strategy of the V/P genes in paramyxoviruses, noting a new mechanism for translational frame-shifting that aids in virus classification. It describes how different paramyxoviruses use varying numbers of non-templated G residues to shift reading frames, leading to the production of multiple proteins from a single gene. This has led to suggestions for reclassifying the Paramyxoviridae family. The article also covers new aspects of coronavirus replication, including the production of subgenomic mRNAs and the role of the coronavirus replicase in genome organization. It discusses the structure and function of coronavirus proteins, including the nucleocapsid protein, membrane glycoproteins, and the additional envelope glycoprotein with homology to influenza C virus. The article highlights the discovery that many plant viruses have animal virus counterparts, suggesting a common evolutionary origin. It discusses the relationships between animal and plant viruses, including similarities in genome organization and amino acid sequence homology. The study also explores the replication strategies of viruses such as Sindbis virus and tobacco mosaic virus, noting similarities in their genome structure and replication mechanisms. The article concludes that RNA viruses have evolved from a small number of ancestral viruses, with recombination playing a significant role in their evolution. It emphasizes the importance of genomic sequence analysis in understanding viral phylogeny and the modular evolution of viral genes. The study also highlights the efficiency of RNA viruses in expanding their coding capacity through various mechanisms, including frame-shifting, differential splicing, and the production of multiple mRNAs.