• Age ≥14 years old, male or female;

• Symptoms of autoimmune encephalitis (AE) ≤ 9 months prior to enrollment;

• Diagnosed as autoimmune encephalitis, diagnostic criteria as follows:

‣ Rapid onset (\<3 months) of at least four of the following six major symptoms:

• Abnormal (mental) behavior or cognitive dysfunction

∙ Speech dysfunction (verbal urgency, hypospeech, mutism)

∙ Seizures

∙ Movement disorders, dyskinesias, or postural rigidity/abnormalities

∙ Decreased level of consciousness

∙ Autonomic dysfunction or central hypoventilation in the presence of one or more of the six major symptoms;

⁃ Positive anti-NMDAR (GluN1) IgG antibody detected in CSF or positive serum and/or cerebrospinal fluid LGI1 antibody; c．Reasonable exclusion of other etiologies and other well-defined encephalitis syndromes (e.g., Bickerstaff brainstem encephalitis, acute disseminated encephalomyelitis, Hashimoto encephalopathy, primary CNS vasculitis, Rasmussen encephalitis);

• Refractory AE: ineffective treatment with steroids and rituximab or other immunosuppressants, post-treatment mRS score≥2 (stable for at least 24 hours）;Recurrent AE: at least 2 months after 1st or 2nd line treatment, new symptoms or worsening of existing symptoms (mRS increase\>1); 5）Doses of steroids and other immunosuppressants (e.g. azathioprine, mycophenolate mofetil, cyclophosphamide) should be stabilised for 4 weeks prior to enrolment; 6）Ability to obtain patient or proxy consent; 7）Women of childbearing potential should use effective contraception during treatment or avoid heterosexual intercourse for at least 3 months after the last dose of talitacicept;