Isolation of a type 3 vaccine-derived poliovirus (VDPV) from an Iranian child with X-linked agammaglobulinemia

Type 3 immunodeficiency-associated vaccine-derived polioviruses (iVDPVs) were isolated from a 15-month-old Iranian boy with acute flaccid paralysis (AFP) who was subsequently diagnosed with X-linked agammaglobulinemia (XLA). VP1 nucleotide sequences of the two isolates differed from Sabin 3 by 2.0% and 2.1% and from each other by 0.6%. Although the key determinant of attenuation and temperature sensitivity in the 5′-untranslated region (U472 → C) had reverted, a second capsid-region determinant (VP3:Phe091) was unchanged, but a presumptive suppressor (VP1:Ala054 → Val) was found. The isolates were Sabin 3/Sabin 1 recombinants, sharing a single recombination breakpoint in the 2C region. Although the two isolates were antigenically distinct from Sabin 3, only one amino acid replacement was found in the neutralizing antigenic sites (VP3:Ser059 → Asn in site 3). The patient was placed on intravenous immunoglobulin (IVIG) therapy within 9 days of onset of AFP, and iVDPV excretion ceased thereafter, but the patient remained severely paralyzed until his death ∼11 months after paralysis. No secondary AFP cases were found, and none of the seven tested contacts of the patient were found to be infected with poliovirus.