Figure 1 Genome organization of representative members of the Metaviridae family. The integrated genome of each virus contains Long Terminal Repeats (LTRs) flanking a central sequence. Black boxes within the LTRs depict sequences repeated at the 5′ and 3′ ends of the virus transcripts (R regions). Open boxes below the viruses indicate gag, pol and env ORFs. Not all viruses within the genera Metavirus and Semotivirus encode an Env-like protein. Arrows indicate sites of ribosomal frameshifting. Conserved aa sequences in pol that identify protease (PR), integrase (IN) and reverse transcriptase/RNAse H (RT-RH) are labeled. Individual mRNAs are depicted below the ORF diagrams as arrows. Transcription of the DmeBelV and AluTasV has not been studied.
Figure 2 Phylogeny of the family Metaviridae and related groups based on their reverse transcriptase domain. The portion of the reverse transcriptase domain used in this analysis spans approximately 250 aa and includes the most conserved residues found in all retroelements. The phylogram is a 50% consensus tree of the viruses based on neighbor-joining distance algorithms and was rooted using sequences of members of the family Pseudoviridae. Bootstrap values (percentage of the time all elements are located on that branch) are shown for the major branches only. Viruses that are included in the various divisions of Metaviridae are indicated by the vertical lines to the right of each systematic name. Each group of viruses that are not part of the family Metaviridae is represented by a box with the length of the box related to the sequence diversity within that group. DIRS retrotransposons are mobile elements that utilize a reverse transcriptase closely related to that of the family Metaviridae but lack many structural features of this group and integrate by a different mechanism. The bar at the bottom represents divergence per site.