Stem Cell Transplant in Immune-deficiency-associated Vaccine-derived Poliovirus

Area of Science:

• Immunology
• Virology
• Pediatrics

Background:

• Severe primary immunodeficiency (PID) increases susceptibility to live-attenuated vaccine complications.
• Severe combined immunodeficiency (SCID) is a critical condition impairing immune responses.
• Recombinant activating gene 1 (RAG1) deficiency is a cause of SCID.

Purpose of the Study:

• To report a case of vaccine-associated paralytic poliomyelitis and Bacille Calmette-Guérin (BCG) disease in an infant with SCID.
• To describe the treatment and outcomes of these infections in an immunocompromised patient.
• To investigate poliovirus evolution within the central nervous system (CNS) despite antiviral treatment.

Main Methods:

• Case report of a 6-month-old female infant with homozygous RAG1 deficiency.
• Treatment involved intravenous immunoglobulins (IVIG), oral pocapavir for poliovirus, and antimycobacterial therapy for BCG disease.
• Poliovirus detection and sequencing from cerebrospinal fluid (CSF) and stool before and after stem cell transplantation (SCT).

Main Results:

• The patient experienced vaccine-associated paralytic polio and regional BCG disease.
• Successful treatment with IVIG, pocapavir, and antimycobacterial therapy enabled SCT.
• Poliovirus type 3 with 13 mutations was detected in CSF post-SCT, indicating CNS viral evolution despite pocapavir.
• Clinical improvement and immune reconstitution were achieved post-transplant, with no further poliovirus detection.

Conclusions:

• Early diagnosis and combined therapeutic strategies are crucial for managing vaccine-induced complications in SCID patients.
• Antiviral treatment may not fully eradicate poliovirus from the CNS, allowing for in-situ viral evolution.
• Successful SCT can lead to immune reconstitution and resolution of infections, but long-term monitoring for viral evolution is warranted.