32 



MASS. EXPERIxMENT STATION BULLETIN 273 



Fowls I lool and I ISli had laryngitis and I 1698 did not show any 

 symptoms or lesions of disease. From these results it was concluded that 

 tlie virulence of the Granby infectious trachitis virus had attenuated dur- 

 ing the third transfer and the resistance of the fowls may have been a 

 factor in the process. 



Rhode Island Red fowl MC 60840 contracted the disease from an acci- 

 dental infection and died December 30, 1929. This made it possible to 

 check up the experiments on the filtration of the Granby virus. Also, a 

 fourth transfer of the Granby virus was made from this fowl, demonstrat- 

 ing that the resistance of fowls I 1551, I 1514, and I 1698 was largely re- 

 sponsible for the attenuation of the Granby virus. 



The Fourth Transfer of the Granby Virus 



Three Rhode Island Red fowls were treated intratracheally with virus 

 fiom MC 60840 on January 2, 1930. The results of this transfer of the 

 Granby virus are given in Table 3. 



Table 3. — The fourth transfer of the Granby virus. 



Date 



Fowl No. I 2132 



Temp. History 



Fowl No. I 2567 



Temp. History 



Fowl No. I 2106 



Temp. History 



°F 



1/2/30 



1/3/30 



1/4/30 



1/5/30 



1/6/30 



1/7/30 



1/9/30 



1/10/30 



1/11/30 109.5 



1/12/30 106.4 



1/13/30 



1/14/30 



1/16/30 



1/17/30 



1/18/30 



107.2 Inoculated 

 107.4 

 107.3 

 107.4 

 107.5 



107.4 Symptoms of 

 infectious 



109.0 



110.0+ trachitis 



Dead 

 ( Lesions typical of 

 infectious trachitis) 



°F 



107.3 Inoculated 

 107.2 



107.1 

 107.3 

 107.3 

 107.4 

 107.2 



108.5 Symptoms of 



109.4 infectious 

 108.2 trachitis 

 107.4 



107.6 Improved 

 107.4 



107.2 



107.0 Recovered 



107.1 Inoculated 

 107.2 



107.1 

 107.2 

 107.2 

 107.1 

 107.0 



109.2 Symptoms of 



108.3 infectious 

 108.6 trachitis 

 109.2 



107.2 Dead 



( Lesions typical of 

 infectious trachitis) 



In this experiment the Granby virus was found to be of sufficient viru- 

 lence to infect all three of the fowls inoculated. Two of the fowls died 

 and one recovered. This experiment demonstrated that the Granby virus 

 had retained its potency in fowl MC 60840. Like all viruses which cause 

 disease in animals, the Granby virus evidently retains its potency as long 

 a? it is transmitted in susceptible birds, but tends to lose its virulence in 

 resistant fowls. The fowls reported under the third transfer of the 

 Graaby virus were apparently resistant to the disease. 



