Molecular analysis of poliovirus 3 isolated from an aerosol generated by a waste water treatment plant

We examined three samples of lysates from cell cultures that had previously been infected by the aerosol generated by a waste water treatment plant near Pisa. We first attempted to confirm that we were dealing with one of the enterovirus family, using an inverse PCR analysis of the RNA extracted from the cell lysates. This identified a single genome sequences in all the samples, which corresponded to poliovirus 3. Sequence analyses revealed that the genotyping of poliovirus 3 was accurate for the species, irrespective of the genomic region sequenced. Subspecies genotyping is only possible for the translated region, and in this case, it identified the Poliovirus type 3 Leon 12a1b strain as ancestor of the virus isolated. Molecular analyses were then carried out on the wild virus in the regions VP2 (9623 bp), VP3 (922 bp) and VP1 (1128 bp) and found various nucleotide mutations (e.g. 472T→C; 970G→C, Cys→Ser; 1319G→T, Val→Leu; 1743T→C, Val→Ala; 1817C→T, Hys→Tyr). Thermosensitivity tests at 34°C and 44°C showed a slight reversion to the heat resistant phenotype. The need for adequate protective measures for plant staff, together with the frequent use of treated water for irrigation, means that effective methods of aerosol borne pathogen detection and risk determination must be adopted.