Monitoring Neurovirulent Polioviruses in the Americas

Worldwide polio eradication depends on high vaccine coverage. When vaccination decreases, oral polio vaccine can revert to neurovirulent poliovirus and cause outbreaks, as was recently demonstrated on Hispaniola. In this study, we monitored for polio virus in water samples obtained from Texas, Haiti and Ecuador by cell culture on RD and L20B cells. Positive polio virus isolates were genetically characterized for presumed neurovirulence markers including an amino acid substitution at position 143 in VP1 and a nucleotide substitution at position 481 in the 5'-UTR. Poliovirus was detected in samples from Haiti and Ecuador, but not in samples from Texas. All serotype 2 (n=7) and serotype 3 (n=1) isolates grew at 40°C and in the presence of Sabin-neutralizing monoclonal antibodies, and had mutations in the 5'UTR and VP1 associated with neurovirulence. By sequencing, the complete VP1 gene of all strains demonstrated >99% identity to Sabin strains. Four serotype 2 strains from Ecuador were shown to be neurovirulence in transgenic mice expressing the poliovirus receptor.Master of Science in Public Healt