 Disease*vaccination was not carried out. 
During the last few years, the inactivated vaccine, using 
the lapinized Footeand-Mouth Disease virus, was utilized for 
the purpose of vaccination. However, in some cases, in areas where 
this disease had flared up, the FooteandeMouth infections were 
' observed among the immunized heads of cattle, 
The studies have shown that the poorly fed, physically 
under-developed (younger cattle, 4 to 6 months old) animals, as 
_ well as, lengthy transportation, driving of cattle, sharp 
changes in the weather have a negative influence on the 
immunological changes of the organisms and the development of 
immunity. 
We asnlied the stress on the immunity in the immunized 
animals ry 
. fhe strength of the immunolegical effect after vaccination 
was determined by the condition of the immunized animals in 
areas affected by the Footeand-Mouth Disease and by the level 
of the virus neutralizing anti-bodies in the blood serum. 
While studying the degree of immunity, after the large 
tattle were vaccinated using the sapenin vaccine, it has been 
established that on the 20th day, the virus neutralizing 
activity of the blood serum increased by 43 times. A repeated 
vaccination after 20 days increased the activity of the blood 
serum by 3900 times, as compared with the’ activity of the serum 
before the vaccination and by 90 times after a single vaccination. 
| At the highest level, the humoral immunity is retained for 
a period of 116 days, then on the 180th day it comes down to a 
level, which is only 10 times more than the initial. However, 
'Yeevaccination of such animals again established a high humoral 
immunity. 
If we accept the view established by the international 
actice that 10 thousand infection dozes of the Footeand-Mouth 
wirus can cause a generalized type of infection in the immunized 
animals, then on the 20th day after a single dose of vaccine has 
been introduced into 1 ml of the sheep bleod serum, such a number 
of anti-bodies are formed that are capable to neutralize more 
than one doze of the virus infection. After the two-ephased 
(6) 
