Table 1.

Comparison of transduction inhibition and total antibody assays

Assay	TI assay	TAb assay
Principle	•Cell-based assay that uses rAAV vector encoding a reporter gene49	•Immunoassay (e.g., ELISA or ECLA) capture-based method48
	•Measures the ability of plasma or serum samples containing NAbs and non-antibody neutralizing factors to reduce the transduction of cells49	•Measures the presence of anti-AAV antibodies (regardless of their neutralizing activity)48
Advantages	•Directly measures TI by detecting both NAbs and non-antibody neutralizing factors that may impact transduction48,49	•Less complex to implement and automate than a TI assay,48 and potentially could be developed into test kits for implementation across multiple clinical laboratories48
	•Common design using the same rAAV capsid as GTx with choice of reporter genes and cell lines49	•Antigen-capture format can be used to detect specific immunoglobulin isotypes48
Potential disadvantages	•Requires specialist laboratories and expertise	•Does not specifically predict TI48
	•More challenging to be developed into commercialized test kits	•Variety of platforms and format options makes standardization challenging48
		•Potential detection of low-avidity cross-reactive Abs that may not have relevance for successful GTx48

AAV, adeno-associated virus; ECLA, electrochemiluminescence assay; ELISA, enzyme-linked immunosorbent assay; GTx, gene therapy; NAb, neutralizing antibody; rAAV, recombinant AAV; TAb, total antibody; TI, transduction inhibition.