Armstrong – Table of Contents

groups. He reasoned that a strain of virus adapted to the cotton rat might be pathogenic
for other rodent species; he, therefore, decided to try adapting the Lansing strain to white
mice. He was able to adapt the Lansing strain to white mice with considerably more ease
than he was able to adapt the strain initially to the cotton rat (25). At the time of the initial
reporting, he had carried the strain through 12 successful mouse transfers. Using brain
and spinal cord from the fourth mouse transfer, he was able to transmit poliomyelitis to
monkeys. He was able, at this point, to transfer the Lansing strain successfully back and
forth among mice, monkeys and cotton rats most of which developed the characteristic
clinical signs and the definitive microscopic pathologic features of poliomyelitis. The
Lansing strains derived from mice, monkeys and cotton rats, originally isolated by
Armstrong from a single source, had immunologic identity.
Armstrong finally had found a utilitarian laboratory host to promote and extend
further poliomyelitis research (24, 25) and to bypass the cumbersome, incompletely
accurate techniques using expensive, difficult monkeys. Armstrong’s opinion was that
from the standpoint of availability, cost, expense of maintenance, care, safety of handling
and resistance to naturally acquired infections (e.g., Theiler’s mouse virus, MM, and
encephalomyocarditis viruses), the cotton rat compared favorably with the white mouse
as a laboratory animal with the exception that it was somewhat more timid; he noted that
it propagated slowly or not at all during the colder seasons which limited its availability
in the laboratory. The white mouse, on the other hand, was readily available at all times,
and its employment was familiar to most investigators.
Armstrong began his initial studies using mice to test for the presence of
antibodies in human serums capable of neutralizing the Lansing strain of poliomyelitis.