Genetic Characterizations Of Type3Olioviruses In Mainland China In2011

ObjectiveTo analyze the molecular characterizations of type3vaccine-related poliovirusesisolated from patients with acute flaccid paralysis in2011in mainland China, and providescientific evidence for “maintaining polio free” status in China.MethodsStool sample were treated and inoculated onto RD and L20B cell lines for viralisolation. Positive virus isolates were serotyped by neutralization test. Then viral RNA wasextacted, Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was performed toamplify VP1region of the polioviruses. Nucleotide sequencing was performed with thePCR amplicons. Neurovirulence determinant sites and mutation hot spots were analyzedand phylogenetic trees were constructed for analysising evolution relationship among thetype3polioviruses.ResultsOne handred and fifty nine type3polioviruses were isolated from AFP casesurveillance system in2011in mainland China, which included149vaccine-like isolatesand10immunodeficient vaccine-derived polioviruses (iVDPVs). All the polioviruses wereidentified as vaccine related, and no wild polioviruses were found. All159polioviruseshave a nucleotide substitution in known nt2493neurovirulence determinate site.ConclusionsNucleotide substitutions in VP1region was not randomly distributed because of theexist of hot spots of mutation; and the hot spots of mutation in VP1region may have somecorrelation to some of their biological characterizations. The epidemiological survey andlaboratory results showed that ten iVDPVs were newly discovered, based on there is no genetic correlation between Ningxia iVDPVs and other iVDPVs in the world. The researchon the genetic characterizations of type3polioviruses provided labotarory information formaintaining polio free status in mainland China.