Alcamí A, Smith G L
Sir William Dunn School of Pathology, University of Oxford, United Kingdom.
J Virol. 1995 Aug;69(8):4633-9. doi: 10.1128/JVI.69.8.4633-4639.1995.
Soluble receptors for gamma interferon (IFN-gamma) are secreted from cells infected by 17 orthopoxviruses, including vaccinia, cowpox, rabbitpox, buffalopox, elephantpox, and camelpox viruses, representing three species (vaccinia, cowpox, and campelpox viruses). The B8R open reading frame of vaccinia virus strain Western Reserve, which has sequence similarity to the extracellular binding domain of cellular IFN-gamma receptors (IFN-gamma Rs), is shown to encode an IFN-gamma binding activity by expression in recombinant baculovirus. The soluble virus IFN-gamma Rs bind IFN-gamma and, by preventing its interaction with the cellular receptor, interfere with the antiviral effects induced by this cytokine. Interestingly, in contrast to cellular IFN-gamma Rs, which are highly species specific, the vaccinia, cowpox, and camelpox virus IFN-gamma Rs bind and inhibit the biological activity of human, bovine, and rat IFN-gamma but not mouse IFN-gamma. This unique broad species specificity of the IFN-gamma R would aid virus replication in different species and suggests that vaccinia, cowpox, and camelpox viruses may have evolved in several species, possibly including humans but excluding mice. Last, the conservation of an IFN-gamma R in orthopoxviruses emphasizes the importance of IFN-gamma in defense against poxvirus infections.
γ干扰素（IFN-γ）的可溶性受体由感染17种正痘病毒的细胞分泌，这些正痘病毒包括痘苗病毒、牛痘病毒、兔痘病毒、水牛痘病毒、象痘病毒和骆驼痘病毒，分属于三个种（痘苗病毒、牛痘病毒和骆驼痘病毒）。痘苗病毒株Western Reserve的B8R开放阅读框与细胞IFN-γ受体（IFN-γR）的细胞外结合域具有序列相似性，通过在重组杆状病毒中表达，显示其编码IFN-γ结合活性。可溶性病毒IFN-γR结合IFN-γ，并通过阻止其与细胞受体相互作用，干扰该细胞因子诱导的抗病毒效应。有趣的是，与具有高度种属特异性的细胞IFN-γR不同，痘苗病毒、牛痘病毒和骆驼痘病毒的IFN-γR能结合并抑制人、牛和大鼠IFN-γ的生物学活性，但不能抑制小鼠IFN-γ的生物学活性。IFN-γR这种独特的广泛种属特异性有助于病毒在不同物种中复制，这表明痘苗病毒、牛痘病毒和骆驼痘病毒可能在包括人类但不包括小鼠的多个物种中进化。最后，正痘病毒中IFN-γR的保守性强调了IFN-γ在抵抗痘病毒感染中的重要性。
