When the animal is challenged intranasaly or intratracheally will there be any clinical signs in animal? I challenged calves intranasally with 5ml of inoculum containing 109 cfu/ml but observed no clinical signs. Also no clinical signs were produced when the calves were challenged intratracheally with 109 cfu. So in such case will there be any immune response?
Pasteurella is an opportunistic organism that inhabits the upper respiratory tract of most animals. So, it is important to exclude the presence of Pasteurella before starting experimental infection experiment. Moreover, Pasteurella will cause no thing to an animal of normal immune response because it is opportunistic and unable to cause a disease except if there is a stress condition that is lowering the animal's immunity. Additionally, systemic immune response to pasteurella will not be evident except after systemic disease such as pneumonic pasteurellosis, otherwise immune response to Pasteurella will be local immunity in the upper respiratory system mucous membranes.
I agree with dr Atef answer. It is important to exclude the presence of Pasteurella before starting experimental infection experiment. You may observe some respiratory signs if the animals are free of Pasteurella. If they are natural carrier of some strains and you use a laboratory strain immune response could be unsignifiant, since natural strains of Pasteurella may inhibit growing of laboratory strains
Thank you for the question. In fact, I have no observation made, usually injections are the right route for incolum to challenge, but parasitic larvae can be exercised as intranasal and tracheal challenge. So I advice to inoculate P.multocida antigen via injection at the right anatomical site of trachea for your experimental observation. Thank you.
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