LIVE POLIO IRUS VACCINES

DISCUSSION
CHAIRMAN GEAR: The last three papers are
now open for discussion, that is, the papers by
Dr. Prem, Dr. Vonka, and by Dr. Voroshilova.
DR. HODES: The Chairman stated that he would
grant me a few minutes to speak about a new
method for determining antibody. This method
has been described to a number of my North
American colleagues, but it has not been seen
by others since the results of this are in press at
the moment. We believe the method to be simple
enough to be used for antibody testing on a mass
basis. We believe also that it is more sensitive
than any antibody method now in use.
The method which I shall describe very briefly
is based on the fact that a specific antibody retards
the spread of a radioactive virus up a strip
of filter paper. We think the test may have
practical importance because it requires only
0.1 ml. of serum. This can be obtained by finger
puncture, which is the way we have done it. The
test can be completed in a few hours. Moreover,
the materials required, cost approximately
five cents.
I do not think that we have time to go into it,
but believe we can make this a very sensitive test,
perhaps more so than any now available. In conducting
the test hundreds of times, and in comparing
it with standard neutralization tests, we
have obtained a very high degree of correlation,
something over 95 per cent.
The present method we use is described in
Fig. 1. A strip of filter paper is used. Although
the figure shows only the first 23 centimeters, we
actually have it 29 centimeters long, ruled off in
centimeter spaces. This piece of filter paper is
then suspended from a cork, and put into a test
tube. At the bottom of the test tube there is 0.5
cc. of radioactive poliovirus suspension.
The particular virus in this test was Type 2
with a titer of 15,000 TCD 50 per 0.1 ml. and radioactivity
of 15,000 counts per minute. One tenth
of 1 ml. of the serum to be tested is spread across
space 3. The bottom part of the filter paper
STRIP WITH
ANTIBODY-
NEG. SERUM
3.....ZONE 28 ...
STRIP WITH
ANTIBODY-
-POS. SERUM
1.65 N 15
19
~17~9 ~ 31
E1:~8$ 41
¡92 .54
i19a 66
17? 70
7..... ZONE 18 ...... 7
225 EX96
41..... ZONELIOVIR .... 22
245 [78
249 227
247 207
261 .205
261 2:'55
293 3,45
23 F. 1 75
323 467*
ZONEI .
-POLIOVIRUS;.
RESERVOIR
Fi. 1
..
(space 1) is dipped into the virus, the paper
being allowed to become wet.
When the paper is wet all the way up to the
top, it is taken out and put into an oven at
140' C.; this renders it non-infectious and makes
the radioactive phosphorus stick to the paper.
The paper strip is then fed into an automatic
scanning device which plots the distribution of
radioactivity on a graph.
266