Experimental Materials 



Newcastle Disease Virus 



I'he strain oi Xewcastle disease virus used was the Wi or Blacksburg 

 strain. In the field trials (with one exception, in which a commercial vaccine 

 was used), the avian embryo titre of this virus was 10 "''-^''. This strain was 

 obtained directly from llitclmer in 1951. 



Infectious Bronchitis Virus 



From observations of held outbreaks of infectious l>ronchitis, it was 

 quite ap])arent that variations in strains occurred. 



In 1951, fifteen strains of infectious l)ronchitis were isc^lated, and for 

 the remainder of that year and up to 'the fall of 1952, repeated screenings 

 of these strains were carried out. This work resulted in tlie selection of one 

 strain which appeared to be adaptable to mass imnuuiization procedures. 

 This strain was found to have high antigenic properties. 



Screenings of embryo passages were carried out and it was found that 

 the twentv-fourth and twenty-fifth embryo passages were desirable for the 

 field trials. The avian enil)ryo titre was 10 ■'•^. using one tenth ml. of 

 inocuhun per embryo. 



Sprayers 



Four different s]M"ayer> were used in the field trials. 



1. Binks power spra}er (electric) 



2. Aerosol hand sprayer 



3. Common hand fly sprayer 



4. Z & \\' hand spraxer 



The type of sprayer first mentioned was used in tlie application of the 

 commercially dehydrated Xewcastle vaccine and, later, in the application of 

 the experimental combination of Newcastle and infectious bronchitis viruses 

 under the direction of a commercial concern. 



The three latter types oi sprayers were used in conjunction with the 

 experimental vaccine prepared in the University of New Hampshire lab- 

 oratories. 



Diluents 



The diluents used in the experiments were modified l)uffered saline 

 solutions. 



Chicks 



The chicks u.^ed in the experimental lal)oratory trials were obtained 

 from the poultry department at the University of New Hampshire. 



The chicks used in tlie field trials were provided 1)y cooperating 



pouhrynien in the state of Xew llam]xshire. 



Experimental Procedures 



Field Trial Procedure 



Due to the fact that the University of Xew Hami)shire did not have 

 sufficient facilities for Ivophili/.ation of the viruses involved, the vaccines 



