Two new strains of horsesickness virus were isolated m suckling mice by the
intracerebral route. These strains were identified as horsesickness by:-
(a) Demonstration of fixation of complement by the group specific complement
(b) Non-inactivation by sodium desoxycholate and diethyl ether under
(c) Preliminary screen serum virus neutralisation tests.
Detailed serum virus cross neutralisation tests showed that these virus strains
belong to two new antigenic types, which have been designated Groups 8 and 9.
The two strains were isolated from widely separated geographical regions and
are regarded as the prototypes of the two new groups which have been shown to
include other strains of virus. The significance of the finding is discussed in relation of control of horsesickness by mass immunisation.