L20B cells simplify culture of polioviruses from clinical samples

Culture of polioviruses from clinical samples is the gold-standard method f or virological surveillance in the world-wide initiative to eradicate wild- type polioviruses. Two poliovirus-sensitive cell lines of human origin were used originally by the laboratories of the World Health Organisation (WHO) global poliovirus network. However, the cell lines used, Hep2 and RD, also support cytopathic growth of a variety of non-poliovirus enteroviruses. Th is can make detection of polioviruses in samples with mixtures of viruses d ifficult and time consuming. The development of mouse cell lines that expre ss the gene for the human cellular receptor for polioviruses allows selecti ve poliovirus culture, because very few non-poliovirus enteroviruses grow i n these murine cells. A WHO Collaborative Study was initiated to test one s uch cell line, L20B, and to compare under routine conditions the sensitivit y and selectivity of L20B cells against RD and Hep2 cells. Five laboratorie s in countries endemic or recently endemic for wild polioviruses participat ed. A total of 425 samples were tested prospectively in all three cell line s and there was a clear and consistent trend for greater sensitivity for po lioviruses in L20B cells. Overall, 148/160 polioviruses were detected in L2 0B cells compared with 89/160 in RD and 98/ 160 in Hep2. In part, this find ing was due to detection in L20B cells of polioviruses from samples that al so contained non-poliovirus enteroviruses in which the poliovirus was maske d in RD or Hep2 cells. However, L20B cells were also significantly more sen sitive for poliovirus than either RD or Hep2 cells in three of the five stu dy laboratories. The L20B cells were completely selective for polioviruses, as 0/89 wild type non-poliovirus enteroviruses produced cytopathic effect in L20B cells. Finally, L20B cells provided a diagnosis of poliovirus infec tion in the same time as RD and Hepa cells from samples that contained poli ovirus only, but substantially more quickly for samples that contained anot her enterovirus. Taken together, these data indicate that L20B cells simpli fy primary diagnosis of poliovirus from clinical samples and as a result th ey have been introduced for routine use by laboratories of the WHO global p oliovirus network. J. Med. Virol. 58:188-192, 1999. (C) 1999 Wiley-Liss, In c.