Figure 1 The arterivirus particle: (Left) A diagram of the Porcine respiratory and reproductive syndrome virus (PRRSV) particle. The diameter of the virion is ~ 55 nm. Although the proteins encoded by each of the 3 ORFs (ORFs 2 to 7) of PRRSV have been shown to be components of the virion, the glycoproteins encoded by ORFs 3 and 4 have not yet been identified as structural components of the other arteriviruses. The ORF5 protein is the major virion glycoprotein and forms heterodimers with M. The ORF 2, 3, and 4 glycoproteins are minor components. (Right) A negatively stained electron micrograph of extracellular virions of Lactate dehydrogenase-elevating virus (LDV). Surface patterns observed on virions are indicated by the arrow. Bar represents 50 nm.
Figure 2 Arterivirus genome organization. (A) The genome organization of Equine arteritis virus (EAV) is shown at the top. Approximate positions of insertions in other arteriviruses are indicated below. (B) The viral protease cleavage sites in the ORF1a and ORF1ab polyproteins are indicated. (Snijder and Meulenberg, 1998.)
Figure 3 Phylogenetic analysis of the RNA-dependent-RNA polymerase motifs of the members of the family Arteriviridae. The analysis was done using the neighbor-joining method. Bootstrap confidence limits are indicated at the branch points. The bootstrap values were generated with 1000 replications. The root position was inferred using the polymerase region of the torovirus Berne virus (BEV), as an outgroup (S. Weaver, unpublished data).
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