Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) open reading frame 4 protein (kaposica) is a functional homolog of complement control proteins.
The genome analysis of Kaposi's sarcoma-associated herpesvirus (KSHV) has revealed the presence of an open reading frame (ORF 4) with sequence homology to complement control proteins. To assign a function to this protein, we have now expressed this ORF using the Pichia expression system and shown that the purified protein inhibited human complement-mediated lysis of erythrocytes, blocked cell surface deposition of C3b (the proteolytically activated form of C3), and served as a cofactor for factor I-mediated inactivation of complement proteins C3b and C4b (the subunits of C3 convertases). Thus, our data indicate that this KSHV inhibitor of complement activation (kaposica) provides a mechanism by which KSHV can subvert complement attack by the host.
Mullick
Jayati
J
National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India.
Bernet
John
J
Singh
Akhilesh K
AK
Lambris
John D
JD
Sahu
Arvind
A
D003001:Cloning, Molecular; D003167:Complement Activation; D003169:Complement Inactivator Proteins / Q000494:pharmacology; D005786:Gene Expression Regulation; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016366:Open Reading Frames; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
D003169:Complement Inactivator Proteins; D014764:Viral Proteins