Table 2. Neutralization assay with LLcMk2 cells*.

Virus	Antiserum			Viral controls
	a-HPeV1 (Harris)	a-HPeV2 (Williamson)	a-HPeV3 (A308-99)
HPeV1 Harris	–	++++	++++	++++
HPeV2 Williamson	++++	–	++++	++++
K251181-02 (HPeV3)	++++	++++	–	++++
K251176-02	++++	++++	++++	++++

*Culture isolates of K251176-02, human parechovirus 1 (HPeV1, echovirus 22) and HPeV2 (echovirus 23) from a reference panel (National Institute for Public Health and the Environment, Bilthoven, the Netherlands) and K251181-02 that was previously genotyped as HPeV3 (12) were incubated with antisera (20 U/mL in Eagle minimal essential medium) directed against HPeV1 Harris, HPeV2 Williamson, and HPeV3 A308-99. The antisera to HPeV1 and HPeV2 were raised in horses. The antiserum to HPeV3 was raised in guinea pigs. Neutralization is done on a 96-microtiter plate containing a monolayer of LLcMk2 cells that have been incubated for 3 days. The assay was determined after viral controls (no antisera used) of the 4 culture isolates showed cytopathic effects >50% (++++).