An Evaluation of Inactivated Infectious Coryza Vaccines Containing a Double-Emulsion Adjuvant System

Abstract

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.

Evaluation of inactivated infectious coryza vaccines in chickens challenged by serovar B strains ofHaemophilus paragallinarum

“…In comparing the results of these trials with those performed by a similar method (Blackall, 1988s Blackall & Reid, 1987Blackall et al, 1992;Jacobs et al, 1992;Reid & Blackall, 1984), we achieved an apparently lower protection rate. As well, unlike these previous studies, we often failed to recover H. paragallinarum from chickens with frank clinical signs.…”

“…Clearance of the challenge organisms may have occurred, in some chickens, before that time. Another difference between our trials and the previous work was the age at challenge; in this work the chickens were older than the ones used by Blackall and colleagues (Blackall, 1988;Blackall et al, 1992;Reid & Blackall, 1984. When experimentally challenged, older chickens (13 weeks old) have been shown to produce greater signs of infectious coryza than younger birds (4 to 8 weeks old) along with a shorter incubation period (Yamamoto, 1991).…”

“…The same three serovars can also be recognized using a haemagglutination inhibition test that is more reliable than the former plate agglutination test Jacobs et al, 1992). Several studies established that inactivated infectious coryza vaccines either manufactured with aluminium hydroxide gel (Davis et al, 1976;Kume et al, 1980a;Matsumoto & Yamamoto, 1971; or mineral oil (Blackall et al, 1992;Coetzee et al, 1982;Jacobs et al, 1992) can protect chickens against the disease. Such vaccines provide typespecific immunity within Page serovars, but no cross-protection across serovars Kume et al, 1980b;.…”

Vaccines against infectious coryza

“…Blackall and Reid (1987) found that the use of two commercial brands of aluminium hydroxide gel resulted in equally effective vaccines. All the studies that have evaluated aluminium hydroxide gel vaccines for adverse reactions have reported either no such reactions or only minor reactions at the vaccination site (Matsumoto and Yamamoto, 1971;Boycott et al, 1977;Blackall and Reid, 1987;Reid and Blackalt 1987;Blackall et al, 1992).…”

“…Double emulsion vaccines produced by an Australian manufacturer, experienced in the production of this type of vaccine, have been very effective and have given high levels of protection (Blackall et al, 1992). They have also caused very few adverse reactions at the site of inoculation (breast muscle).…”