Greig A S, Girard A
Can J Comp Med. 1969 Jan;33(1):25-8.
Examination by the HI test of 20 representative HEV isolates reveals that only one of them, HEV-18 differs quantitatively from the others. The difference is confirmed qualitatively by the SN test. Both the HI and SN tests demonstrated that all the other HE viruses, though isolated from oubreaks of disease in widely separated areas of Canada over a period of eight years, represent a single strain.