AFP Acute flaccid paralysis. AFP surveillance Characterization of enteroviruses in stool samples from all AFP cases especially in individuals under 15 years of age to rule in or rule out etiology by polioviruses. AFR or AFRO The African Health Region of the WHO. AGG A PID with agammaglobulinemia. AMR or AMRO The American Health Region of the WHO. aVDPV A vaccine-derived poliovirus isolate whose evolutionary path is unknown or ambiguous. bOPV Bivalent oral polio vaccine (containing serotypes 1 and 3). BSL Biosafety standard level. CAG Containment Advisory Group. C-antigens Refers to the epitopes after poliovirus interacts with CD155 host cell receptor and transitions into a 135S particle. Capsid The protein shell that surrounds a virus particle. Capsomere One of the individual morphological units that makes up the viral capsid. It contains a single copy of viral capsid proteins VP1, VP| 2, VP3, and VP4. CAV Coxsackie A virus. CCID 50 The cell culture infectious dose of a virus that will cause cell death in 50% of replicate cell cultures. CDC US Centers for Disease Control and Prevention. CD155 or PVr The human encoded cell receptor for poliovirus, a member of the immunoglobulin superfamily. cDNA Complimentary DNA (DNA synthesized from RNA by a reverse transcriptase enzyme). CNS Central nervous system. Codon A sequence of three adjacent nucleotides on a strand of DNA or RNA that specifies which specific amino acid will be incorporated into a protein. Codon bias Unequal usage of synonymous codons (different codons that specify the same amino acid). CPE Cytopathic effect. CRE Cis-acting replication element. CVID Common variable immune deficiencya type of primary immune deficiency cVDPV A circulating vaccine-derived poliovirus, that is, a poliovirus that has evolved from vaccine during person-to-person transmission. D-antigens Refers to epitopes on native 150S virions. Lester M. Shulman has retired.