Koi herpesvirus encodes and expresses a functional interleukin-10.
Koi herpesvirus (KHV) (species Cyprinid herpesvirus 3) ORF134 was shown to transcribe a spliced transcript encoding a 179-amino-acid (aa) interleukin-10 (IL-10) homolog (khvIL-10) in koi fin (KF-1) cells. Pairwise sequence alignment indicated that the expressed product shares 25% identity with carp IL-10, 22 to 24% identity with mammalian (including primate) IL-10s, and 19.1% identity with European eel herpesvirus IL-10 (ahvIL-10). In phylogenetic analyses, khvIL-10 fell in a divergent position from all host IL-10 sequences, indicating extensive structural divergence following capture from the host. In KHV-infected fish, khvIL-10 transcripts were observed to be highly expressed during the acute and reactivation phases but to be expressed at very low levels during low-temperature-induced persistence. Similarly, KHV early (helicase [Hel] and DNA polymerase [DNAP]) and late (intercapsomeric triplex protein [ITP] and major capsid protein [MCP]) genes were also expressed at high levels during the acute and reactivation phases, but only low-level expression of the ITP gene was detected during the persistent phase. Injection of khvIL-10 mRNA into zebrafish (Danio rerio) embryos increased the number of lysozyme-positive cells to a similar degree as zebrafish IL-10. Downregulation of the IL-10 receptor long chain (IL-10R1) using a specific morpholino abrogated the response to both khvIL-10 and zebrafish IL-10 transcripts, indicating that, despite the structural divergence, khvIL-10 functions via this receptor. This is the first report describing the characteristics of a functional viral IL-10 gene in the Alloherpesviridae.
CSIRO Livestock Industries, Australian Animal Health Laboratory, Geelong, Victoria, Australia.
Agus
A
Sunarto
Clifford
C
Liongue
Kenneth A
KA
McColl
Mathew M
MM
Adams
Dieter
D
Bulach
Mark St J
MS
Crane
Karel A
KA
Schat
Barry
B
Slobedman
Andrew C
AC
Barnes
Alister C
AC
Ward
Peter J
PJ
Walker
D000818:Animals; D002347:Carps; D002478:Cells, Cultured; D016000:Cluster Analysis; D005393:Fish Diseases / Q000821:virology; D020869:Gene Expression Profiling; D015967:Gene Expression Regulation, Viral; D006564:Herpesviridae / Q000235:genetics* / Q000472:pathogenicity; D006566:Herpesviridae Infections / Q000662:veterinary / Q000821:virology; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000235:genetics*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000096:biosynthesis* / Q000235:genetics*
D014764:Viral Proteins; D016753:Interleukin-10