Poliovirus non-permissive CD155 knockout cells derived from RD cell line for handling poliovirus potentially infectious materials in virology laboratories

STATEMENTS OF THE PROBLEM

Destruction of all poliovirus containing materials, safe and secure handling of retained polioviruses for vaccine production and research will be obligatory to eliminate facility-associated risks. Polioviruses and poliovirus potentially infectious materials (PIM) include fecal or respiratory samples requiring containment have been defined in WHO-GAPIII documents. Non-polio laboratories culturing viruses from PIM are most affected as cell cultures of human and monkey origin are also poliovirus permissive.

METHOD OF STUDY

CRISPR gene-editing technology was used to knockout the poliovirus receptor (PVR/CD155) gene in RD cell line. PVR knockout RD cell susceptibility was tested using known non-polio enterovirus types. A selected clone (RD-SJ40) was field evaluated for virus isolation from 626 stool samples of AFP cases.

RESULTS

Poliovirus non-permissive cells derived from RD cell line did not show CD155-specific cell-surface immunofluorescence. CD155 gene sequencing confirmed nucleotide base pair deletions within exon2 and exon3. The CD155 knockout RD-SJ40 cells did not support the growth of poliovirus from positive stool samples. All NPEV types were isolated in RD and RD-SJ40 cells.

CONCLUSION

CRISPR correctly edited CD155 gene of RD cells to render them poliovirus non-permissive while susceptibility to NPEV remained unchanged. RD-SJ40 cells are safe for NPEV isolation from poliovirus PIM without derogating GAPIII containment requirements. This article is protected by copyright. All rights reserved.

Detection and distribution of culturable Human Enteroviruses through environmental surveillance in Milan, Italy

AIMS

Human Enteroviruses (HEVs) infections have a significant impact on public health, being implicated in outbreaks of meningitis, encephalitis, hand-foot-mouth disease and other acute and chronic manifestation. In the strategic plan for poliomyelitis eradication, the environmental surveillance of poliovirus (PV) has been identified by the World Health Organization (WHO) as an activity that can complement the surveillance of polio. Having wastewater samples available for PV surveillance allows us to study nonpolio enteroviruses (NPEVs) circulating in the study population, which are widely spread.

METHODS AND RESULTS

This study was carried out according to the WHO guidelines for environmental surveillance of PV and analysed the circulation of PV and NPEVs through the isolation of viruses in cell cultures in Milan area; from 2006 to 2010, 321 wastewater samples were collected, regularly over time, at the inlet of three diverse waste water treatment plants (WWTPs). Culturable HEVs were isolated in 80% of sewage samples: all isolates belonged to the HEV-B group and those circulating more intensely were CVB5 and Echo 6, while CVB4 was the predominant serotype found in 2010. In this study, two type 2 PVs were isolated, both characterized as Sabin like.

CONCLUSION

Environmental monitoring of HEVs in Milan has proved to be an interesting tool to investigate the circulation and distribution of viruses.

SIGNIFICANCE AND IMPACT OF THE STUDY

The detection of PV and other NPEV could be predictive of possible re-emergence of these viruses with an impact on public health. NPEV monitoring could also be a powerful public health tool to investigate the possible role of NPEV in different clinical manifestations.