CUTANEOUS VACCINE FOR FOWL POX 249 



Unit 3. 



This group consisted of 22 cockerels confined in a small house and large 

 run adjacent to units 1 and 2. Upon examination five of the birds showed 

 moderately severe pox lesions. They were vaccinated cutaneously on Septem- 

 ber 26. The vaccine did not "take" on the infected birds. The others showed 

 the typical follicular reactions which appeared in units 1 and 2. No addi- 

 tional infection appeared in this unit. 



Interpretation of Results. — Since it was im.possible to use controls in this 

 flock no conclusions can be drawn from the results. In carrying out the work 

 it was hoped that some indication of the efficiency of the cutaneous vaccine, 

 when used in this way, could be obtained. The results appear to indicate that 

 cutaneous vaccination prevented further spread of the infection, and that the 

 vaccination should be used immediately after the appearance of the natural 

 infection in a flock. 



The Duration of Cutaneous Immunity Against Fowl Pox 



It has been definitely established that after recovery from an attack of 

 fowl pox, either spontaneous in nature or artificially induced, a bird is im- 

 miune to subsequent attacks for an indefinite period of time. Few and excep- 

 tional cases have occurred where birds have succumbed to a second attacli of 

 the disease. This acquired immunity is of long duration and in the majority 

 of cases probably lasts throughout the remainder of life. 



Cutaneous vaccination results in the development of a complete immunity 

 in those cases; where the treatment is followed by the typical follicular swell- 

 ing and scab formation. This has been repeatedly demonstrated by all in- 

 vestigators who have worked with this problem. This cutaneous immunity is 

 apparently, also, of long duration. Sawyer (5) states that the birds are pro- 

 tected for at least two years and probably during life. Edgington and 

 Broemian (4) report that, when young fowls are vaccinated during the sum- 

 mer or fall, they will be protected against fowl pox during the following 

 winter and spring. Johnson (2) found tlie duration of immunity to be sliglit- 

 ly less than 11 months, at least. 



Early in November, 1927, a groujj of 100 trapnested, pedigreed Rhode 

 Island Red pullets was vaccinated cutaneously at the College poultry plant 

 of this institution. The report of that work is found in a previous bulletin 

 (3). No opportunity was afforded to check the immunity produced in these 

 birds by virus inoculation of the comb until they had completed their pullet 

 year. Tlie results of the check immunity tests on birds from this group are 

 contained in Table 3. 



For the complement-fixation studies in relation to cutaneous imjnunity 

 (3) several Rhode Island Red cockerels had been vaccinated cutaneously dur- 

 ing December, 1927, and January, 1928. Representative members of this 

 group were found to be completely inunune to fowl pox after check inocula- 

 tion on the comb with a virulent virus suspension. The remainder were bled 

 periodically for serologic tests and thereafter held over for the duration of 

 immunity tesits recorded in Table 3. 



The unvaccinated controls used in this experiment were of the same age 

 and breed as those vaccinated. They had never been subjected to the infec- 

 tion. All birds used in this experiment were kept in individual experimental 

 cages and quarantined from any source of contamination with fow^l pox in- 

 fection. 



