306           A Study on Desiccated Goat Spleen Vaccine

well as vaccine kept at room temperature for one to seven days was tried.
The temperature of the room varied from 92.6° to 101.8°F. Further, to
serve as control for the material used in the preparation of the vaccine, two
buffalo-calves were each injected with 1 c.c. of one per cent emulsion, in normal
saline, of the pooled spleen pulp, taken just before putting it in the desiccator.
In all, 18 calves were used for this batch of experiments. The dose of
the desiccated vaccine given was 0.0025 gram in 1 c.c. of normal saline, and
all the calves were retested with virulent bull virus.

It was found from this experiment that:—

     (a) the spleen pulp used was infective;
     (b) the fresh desiccated vaccine, as also the vaccine exposed to room
           temperature for one day, provoked good rinderpest reaction ;
     (c) the vaccine exposed to room temperature for two days produced a
           mild reaction;
     (d) the vaccine exposed to room temperature for three to seven days
           produced no reaction;
     (e) all the calves used in (a), (6) and (c) withstood the retest with
          5 c.c. of virulent bull virus, while in (d) no protection could be
          detected.

There was no mortality among the calves (Table I).

It was considered that the potency of the vaccine fell off after two days'
exposure to room temperature, as spleens of different strains—with the
possibility of varying viral content—were used in this experiment. Further,
this was the first time that a satisfactory desiccated vaccine was prepared
at this Institute and it was possible that the technique might not have been
as perfect as it was in later work. However, studies were continued with
pooled spleens of a single strain of virus and yielded better results.

Experiments with the second batch of vaccine

The second batch of vaccine was prepared on 18 July 1939, using
pooled spleen pulp from three goats of the 329th passage of Mukteswar strain
No. 1. In order to test the utility of the product for field use, the vaccine
was kept under conditions simulating those under which it is despatched to
the field and then tested on buffalo-calves at varying periods of exposure
to room temperature. For this purpose, the tube of vaccine, was placed for
three days in a thermos jar with ice; it was now removed and exposed to
room temperature, which varied from 96.6°F. to 97.8°F. Trials were con-
ducted with the freshly prepared vaccine, vaccine just removed from the
thermos jar and vaccine exposed to room temperature for one to four days.
Twelve calves, in all, were used for this experiment.

It was observed that the fresh vaccine, as well as the vaccine just removed
from thermos jar and the vaccine kept exposed to room temperature for one
to four days, produced moderate reactions. The immunity value was satis-
factory, as there was no reaction in any of the calves after retest. There
was no mortality in the calves (Table II).

Experiments with the third batch of vaccine

The third batch of vaccine was prepared on 1 August 1939, from the
pooled spleen pulp of three goats of the 386th passage of the Madras strain