15 research outputs found
Morphological effects of Pasteurella multocida Type-D dermonecrotoxin on rat osteosarcoma cells in a nude mouse model
Capsular serotype, toxA gene, and antimicrobial susceptibility profiles of Pasteurella multocida isolated from pigs with pneumonia in Korea
Cross-protection conferred by immunization with an rOmpH-based intranasal fowl cholera vaccine
Vaccines against infectious coryza
The paper reviews the literature on vaccines against infectious coryza of chickens. Our knowledge of natural immunity, antigens involved in protection and the degree of cross-serovar protection provided by vaccines is summarized. The effect of variables such as antigen dose, inactivating agent and adjuvant type on vaccine efficacy is reviewed. The protective ability of a new generation infectious coryza vaccine based on a live attenuated strain of Haemophilus paragallinarum is discussed
Identification of New Major Histocompatibility Complex Class II Restriction Fragment Length Polymorphisms in a Closed Experimental Line of Beltsville Small White Turkeys
The vaccination-challenge trial: The gold standard test to evaluate the protective efficacy of infectious coryza vaccines
Infectious coryza is an upper respiratory tract disease of chickens with the major impact occurring in multi-age flocks. We investigated the relationship between the level of antibodies, as detected by a haemagglutination-inhibition (HI) assay, in infectious coryza-vaccinated chickens and the protection against challenge in those chickens. In one experiment, chickens given a single dose of either of two infectious coryza vaccines lacked a detectable HI response to vaccination but showed significant levels of protection 11 weeks after vaccination. In contrast, in chickens given two doses of an infectious coryza vaccine and challenged 3 weeks after the second vaccine dose, there was a strong serological response with 36/40 birds having a HI titre of 1/20 or greater. In this trial there was an apparent relationship between titre and subsequent protection, with none of the 32 chickens with a titre of 1/40 or 1/80 showing any clinical signs and only one of the same group yielding the challenge organism on culture. In contrast, three of the four vaccinated chickens with a HI titre less than 1/5 developed the typical clinical signs of coryza and yielded the challenge organism on culture. Overall, our results suggest that HI titres cannot be regarded as a definitive predictor of vaccine efficacy. We suggest that the vaccination-challenge trial is the gold standard for the evaluation of the immune response to infectious coryza vaccines