Eaves Le

An evaluation of inactivated infectious coryza vaccines containing a double-emulsion adjuvant system.

The efficacy of experimental inactivated infectious coryza vaccines produced by a commercial vaccine manufacturer was evaluated. The vaccines, containing as the adjuvant phase either a double-emulsion mineral oil system or aluminum-hydroxide gel, were administered to 6-week-old chickens as a single dose. Some vaccines were a monovalent product containing a Page serovar C Haemophilus paragallinarum strain, and others were a bivalent product containing both Page serovar A and serovar C strains. After 3 weeks, all chickens were challenged by infraorbital sinus inoculation of virulent H. paragallinarum, either Page serovar C (strain HP31) or Page serovar A (strain HP14). The monovalent serovar C double-emulsion-based vaccines gave significant protection against a serovar C challenge, with the level of protection varying from 60% to 100%. The monovalent serovar C aluminum-hydroxide-gel vaccine also gave significant protection (94%) against a serovar C challenge. The bivalent double-emulsion vaccine gave significant protection against challenge from both serovars (100% for serovar C and 83% for serovar A). Although no major adverse reactions were detected, some chickens receiving both the double-emulsion vaccines and the aluminum-hydroxide vaccine developed relatively minor granulomatous reactions at the site of injection.

Biotyping of Haemophilus paragallinarum isolates using hemagglutinin serotyping, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns.

Three techniques, a hemagglutinin (HA) serotyping scheme, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns, were used to examine 92 isolates of Haemophilus paragallinarum. The results were used to create biotyping schemes. The carbohydrate fermentation and antimicrobial drug resistance patterns each resulted in the identification of five biovars. With both of these techniques, a large majority of the isolates fell into one biovar: 81% were biochemical biovar I and 73% were antimicrobial biovar I. However, by combining the results of these techniques with those of the HA serotyping, a much greater discrimination could be achieved. The combined use of hemagglutinin serotyping, biochemical biotyping and antimicrobial biotyping appears to provide a suitable approach for epizootiological studies on infectious coryza.