A duplicate sample of the RV 11 vaccine used in the field against the SAT1
epizootic in South West Africa in 1960-1961 retained its infectivity after storage for
three years at -20° C. When inoculated intramuscularly into sheep 15 to 18 months
old, it stimulated an antibody response. The site of multiplication of the modified
virus appeared to be the muscle tissue into which the vaccine was inoculated. A
viraemia was detected in a few sheep three to four days after vaccination, but no other
clinical signs or macroscopic lesions were observed on post mortem.
Attempts to induce involvement of the central nervous system by simultaneous
intracerebral inoculation of starch, or by intranasal or intraspinal inoculation of the
vaccine diluted hundredfold, were unsuccessful. No evidence of abnormal behaviour
was detected over a 15 week period of observation.