Single chain variable fragment antibodies block aggregation and toxicity induced by familial ALS-linked mutant forms of SOD1

• We screened a phage display library to identify scFvs that bind wild type and/or mutant SOD1.
• We isolated scFvs that bind wild type and mutant SOD1.
• Two of the scFvs interfere with aggregation and toxicity of mtSOD1 in a motor neuron cell line.

Approximately 10% of amyotrophic lateral sclerosis (ALS) cases are familial (known as FALS) with an autosomal dominant inheritance pattern, and ~ 25% of FALS cases are caused by mutations in Cu/Zn superoxide dismutase (SOD1). There is convincing evidence that mutant SOD1 (mtSOD1) kills motor neurons (MNs) because of a gain-of-function toxicity, most likely related to aggregation of mtSOD1. A number of recent reports have suggested that antibodies can be used to treat mtSOD1-induced FALS. To follow up on the use of antibodies as potential therapeutics, we generated single chain fragments of variable region antibodies (scFvs) against SOD1, and then expressed them as ‘intrabodies’ within a motor neuron cell line. In the present study, we describe isolation of human scFvs that interfere with mtSOD1 in vitro aggregation and toxicity. These scFvs may have therapeutic potential in sporadic ALS, as well as FALS, given that sporadic ALS may also involve abnormalities in the SOD1 protein or activity.