The genome of swinepox virus

Abstract

Swinepox virus (SWPV), the sole member of the Suipoxvirus genus of the Poxviridae, is the etiologic agent of a worldwide disease specific for swine. Here we report the genomic sequence of SWPV. The 146-kbp SWPV genome consists of a central coding region bounded by identical 3.7-kbp inverted terminal repeats and contains 150 putative genes. Comparison of SWPV with chordopoxviruses reveals 146 conserved genes encoding proteins involved in basic replicative functions, viral virulence, host range, and immune evasion. Notably, these include genes with similarity to genes for gamma interferon (IFN-gamma) receptor, IFN resistance protein, interleukin-18 binding protein, IFN-alpha/beta binding protein, extracellular enveloped virus host range protein, dUTPase, hydroxysteroid dehydrogenase, superoxide dismutase, serpin, herpesvirus major histocompatibility complex inhibitor, ectromelia virus macrophage host range protein, myxoma virus M011L, variola virus B22R, four ankyrin repeat proteins, three kelch-like proteins, five vaccinia virus (VV) A52R-like family proteins, and two G protein-coupled receptors. The most conserved genomic region is centrally located and corresponds to the VV region located between genes F9L and A38L. Within the terminal 13 kbp, colinearity is disrupted and multiple poxvirus gene homologues are absent or share a lower percentage of amino acid identity. Most of these differences involve genes and gene families with likely functions involving viral virulence and host range. Three open reading frames (SPV018, SPV019. and SPV020) are unique for SWPV. Phylogenetic analysis, genome organization, and amino acid identity indicate that SWPV is most closely related to the capripoxvirus lumpy skin disease virus, followed by the yatapoxvirus yaba-like disease virus and the leporipoxviruses. The gene complement of SWPV better defines Suipoxvirus within the Chordopoxvirinae subfamily and provides a basis for future genetic comparisons.

FIG. 1.

Linear map of the SWPV genome. ORFs are numbered from left to right based on the position of the methionine initiation codon. ORFs transcribed to the right are located above the horizontal line; ORFs transcribed to the left are below. Genes with similar functions and members of gene families are colored as indicated. ITRs are represented as black bars below the ORF map.

FIG. 2.

Comparison of SPV068 to ChPV RNA polymerase subunit RPO147. Proteins were aligned with ClustalW. Complete amino acid sequences were used to generate the unrooted tree with Melanoplus sanguinipes entomopoxvirus RPO147 as the outgroup. The neighbor-joining algorithm with Poisson correction for multiple substitution and 1,000 bootstraps was used as implemented by the Phylip package (15). The figure represents the ChPV subtree. Bootstrap values greater than 80% are in boldface. The bar indicates changes per 100 amino acids. Similar results were obtaining using maximum-likelihood and maximum-parsimony analysis (data not shown).