A captured viral interleukin 10 gene with cellular exon structure.

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Gammaherpesviruses are known to capture host genes, including those encoding cytokines like interleukin-10 (IL-10).
• Viral IL-10 (vIL-10) homologues often exhibit sequence divergence from their cellular counterparts.
• Understanding the structure and function of vIL-10 provides insights into viral immune evasion strategies.

Purpose of the Study:

• To characterize a novel vIL-10 homologue ((OvHV)IL-10) from ovine herpesvirus 2.
• To investigate the gene structure and protein characteristics of (OvHV)IL-10.
• To determine the functional activity of (OvHV)IL-10 in immune modulation.

Main Methods:

• Sequence analysis of the (OvHV)IL-10 gene and peptide.
• Protein characterization including glycosylation status and molecular weight.
• Functional assays to assess mast cell proliferation and macrophage chemokine production.

Main Results:

• The (OvHV)IL-10 peptide sequence was highly divergent from ovine IL-10.
• The (OvHV)IL-10 gene retained the original five-exon cellular structure with reduced intron sizes.
• The secreted (OvHV)IL-10 protein stimulated mast cell proliferation and inhibited macrophage chemokine production, similar to ovine IL-10.
• This represents the first instance of a captured herpesvirus gene maintaining its complete cellular exon structure.

Conclusions:

• Ovine herpesvirus 2 has captured a functional IL-10 gene that retains its cellular exon structure.
• (OvHV)IL-10 possesses immunosuppressive functions comparable to its host homologue.
• The precise retention of gene structure is a unique feature among known virus-captured genes.