22
ANNUAL REPORT OF THE IMPL. INST. OF VETY. RESEARCH,
4. Viability of virus in blood.—Following previous work upon this
subject at this Institute it has been noted that the pH of the blood at
the time of withdrawal, which was found to vary considerably in indi-
vidual animals, appeared to have a considerable influence on the dura-
tion of viability. In general the indication was that the higher the
pH at the time of withdrawal the greater the duration of virulence.
In support of this observation it was found that the pH of goat's blood
was on the average lower than that of ox blood, in which viability
usually persists longer, and also that the addition of buffer salts of
known pH tended to the prolongation of viability. A similar experi-
ment with spleen tissue gave similar results, and it was noted that,
while at a low pH the virus appeared in the surrounding fluid, at the
pH of normal blood or higher it remained in the tissues.
An attempt was made to prepare rinderpest virus as free as possible
from portein by absorption on alumina and subsequent elution in the
manner claimed to be effective for poliomyelitis virus by Sabin in
America. It was found that the virus could be absorbed and subse-
quently eluted in a viable condition, but the separation or the virus from
accompanying body proteins has not so far been attained.
5. Dosage of serum.—The experiments initiated by the Military
Department at certain dairy farms upon the reduction of serum dosage
to 75 per cent. and 50 per cent. of the usual doses were reported to be
entirely successful, and these results have been confirmed by serum tests
at Muktesar. It is hoped now that a further extension of this work
will take place in the provinces and will by the economy so effected lead
to a wider application of active immunisation.
6. Dosage of virus.—The comparative evaluation of the potencies of
different sera has received considerable attention during the year, and
it has been shown that within certain limits the dose of virus is of con-
siderable importance, not only in relation to the dose of serum given
but also in relation to the size of the test animal.
7. Curative powers of serum.—A few cases of rinderpest treated
with serum responded promptly, even after the appearance of clinical
symptoms, and these results were later confirmed by Mr. Taylor, Prin-
cipal, Punjab Veterinary College, in an outbreak in Lahore. In order
to obtain results in advanced cases it is apparently essential to use an
exceptionally potent serum.
8. Fractionisation and Concentration of serum.—Work upon this
subject was continued by Dr. Sen and the fractions mentioned in last
year's report were tested more extensively. In general the results
obtained confirmed those already reported, with the notable exception of
the relative potencies of the water insoluble Felton fraction and the
euglobulin fraction obtained by ammonium sulphate precipitation.
These fractions, however, received least attention as the work developed
because, while it was found that quite a high percentage of antibodies
could be recovered with these fractions, on the other hand practically
100 per cent. of the original antibody content could be obtained in
the total globulin fraction. Following upon the work of Felton, pre-
cipitation with alcohol at low temperatures was attempted, and a very