| Abstract |
The IB-RS-2 cell line derived from swine kidney, after two years and a
half of continuous cultivation, is described. This cell line has shown to
be useful for titration and isolation of the foot-and-mouth disease
virus, types A, O and C. The results obtained in sera-neutralization test
in this cell line run parallel to the results obtained in sera-protection
test in unweaned mice. It is also reported here that some batches of
primary cultures of bovine kidney "resistant" to several samples of the
types A, O and C may occur; this observation seems to limit the use of
this system. From several samples of the three types of virus tested in
IB-RS-2 cell line, one, type C, was an exception and showed to be unable to
induce CPE, in first passage, in this cell line. However, after the third
passage, it became "adapted". On the other hand, another sample, also
typed as C, to which the IB-RS-2 cell line was as susceptible as swine
kidney primary cultures, was not able to induce CPE, nor could it be
isolated In "normal" bovine kidney primary cultures which were
susceptible to other samples. Evidence was observed that a virus sample
with a high number of passages in IB-RS-2 cell line, became modified, as
far as pathogenicity to unweaned mice and 'capacity to induce CPE in
"normal" bovine primary cultures are concerned. The advantages of the use
of the IB-RS-2 cell line are: it grows actively in a relatively simple
and unexpensive medium, It is apparently free of contaminants, and
replicates can be prepared easily for experimental purposes at any time
desired.
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