PROLONGED REPLICATION OF A TYPE-1 VACCINE-DERIVED POLIOVIRUS IN AN IMMUNODEFICIENT PATIENT

VP1 sequences were determined for poliovirus type 1 isolates obtained over a 189-day period from a poliomyelitis patient with common variabl e immunodeficiency syndrome (a defect in antibody formation), The isol ate from the first sample, taken 11 days after onset of paralysis, con tained two poliovirus populations, differing from the Sabin 1 vaccine strain by similar to 10%, differing from diverse type 1 wild polioviru ses by 19 to 24%, and differing from each other by 5.5% of nucleotides . Specimens taken after day Il appeared to contain only one major poli ovirus population. Evolution of YP1 sequences at synonymous third-codo n positions occurred at an overall rate of similar to 3.4% per year ov er the 189-day period. Assuming this rate to be constant throughout th e period of infection, the infection was calculated to have started si milar to 9.3 years earlier. This estimate is about the time (6.9 years earlier) the patient received his last oral poliovirus vaccine dose, approximately 2 years before the diagnosis of immunodeficiency, These findings may have important implications for the strategy to eliminate poliovirus immunization after global polio eradication.