GENOMIC CHARACTERIZATION OF TYPE-1 SABIN-RELATED POLIOVIRUSES ISOLATED IN BRAZIL

Eight strains of P1/Sabin-derived polioviruses isolated in Brazil from paralysis cases were analyzed. The serotypes of the viral isolates we re identified by neutralization test with hyperimmune equine sera. The relationship of the isolates to the P1/Sabin strain was demonstrated by molecular hybridization and PCR. The isolates were partially sequen ced with the objective of finding mutations at nucleotides (nt) 480 an d 525 of the 5'-noncoding region (5'NCR) and at nt 6203 of the 3Dpol c oding region (3Dpol), which are important for reversion towards neurov irulence. Four isolates from paralysis cases classified as Guillain Ba rre Syndrome (GBS; three with sequels) were analyzed; one presented G- ->A (480) and C-->U (6203) mutations, one G-->A (480) mutation, one G- ->A (480) and U-->C (525) mutations, and one did not mutate at the ana lyzed positions. Two isolates from transient facial paralysis cases we re analyzed; one presented U-->C (525) mutation and the other G-->A (4 80) mutation. One isolate from a transient paralysis case classified a s a neuroviral disease and one isolate from a paralysis case with sequ els were analyzed and none mutated at the analyzed positions. Although the isolates may not be the causative agent of the disease, a tempora l association between the isolation of the P1/Sabin-derived isolates a nd the disease was observed. The possibility that GBS and the facial p aralysis were caused by these isolates could not be excluded.