Adeno-associated virus mediated delivery of an engineered protein that combines the complement inhibitory properties of CD46, CD55 and CD59.
BACKGROUND
A variety of disorders are associated with the activation of complement. CD46, CD55 and CD59 are the major membrane associated regulators of complement on human cells. Previously, we have found that independent expression of CD55, CD46 or CD59 through gene transfer protects murine tissues against human complement mediated attack. In the present study, we investigated the potential of combining the complement regulatory properties of CD46, CD55 and CD59 into single gene products expressed from an adeno-associated virus (AAV) vector in a soluble non-membrane anchored form.


METHODS
Minigenes encoding the complement regulatory domains from CD46, CD55 and CD59 (SACT) or CD55 and CD59 (DTAC) were cloned into an AAV vector. The specific regulatory activity of each component of SACT and DTAC was measured in vitro. The recombinant AAV vectors were injected into the peritoneum of mice and the efficacy of the transgene products for being able to protect murine liver vasculature against human complement, specifically the membrane attack complex (MAC), was measured.


RESULTS
SACT and DTAC exhibited properties similar to CD46, CD55 and CD59 or CD55 and CD59, respectively, in vitro. AAV mediated delivery of SACT or DTAC protected murine liver vasculature from human MAC deposition by 63.2% and 56.7%, respectively.


CONCLUSIONS
When delivered to mice in vivo via an AAV vector, SACT and DTAC are capable of limiting human complement mediated damage. SACT and DTAC merit further study as potential therapies for complement mediated disorders when delivered via a gene therapy approach.
Department of Developmental, Molecular and Chemical Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA.
Derek
D
Leaderer
Department of Developmental, Molecular and Chemical Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA.
Siobhan M
SM
Cashman
Department of Developmental, Molecular and Chemical Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA.
Rajendra
R
Kumar-Singh
D000818:Animals; D018958:CD55 Antigens / Q000737:chemistry / Q000235:genetics*; D018957:CD59 Antigens / Q000737:chemistry / Q000235:genetics*; D003167:Complement Activation / Q000235:genetics*; D051056:Complement Inactivating Agents / Q000008:administration & dosage / Q000737:chemistry; D000229:Dependovirus; D005822:Genetic Vectors; D006801:Humans; D051916:Membrane Cofactor Protein / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D017434:Protein Structure, Tertiary / Q000235:genetics; D019076:Transgenes
D018958:CD55 Antigens; D018957:CD59 Antigens; D051056:Complement Inactivating Agents; D051916:Membrane Cofactor Protein
AAV; CD46; CD55; CD59; complement system; gene therapy