LGI1 and viral encephalitis: Polyclonal LGI1 autoantibodies were obtained from the serum of 3 patients with LGI1 encephalitis and high titer of LGI1 antibodies and used as a pooled IgG fraction.27 Cultures were incubated with patient-derived polyclonal serum LGI1 autoantibodies included in the growth medium for 7 days (LGI1-7d; with a second dose applied 1 day before recordings), with LGI1 autoantibodies for 1 day only (LGI1-1d), or with patient control antibodies without antineuronal reactivity.