Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
COLLEGE OF VETERINARY MEDICINE
Non Technical Summary
Live and inactivated MG vaccines protect well against clinical signs and lesions. However in order to be useful for eradication and control, vaccines must either protect against wild-type infection or significantly reduce populations of wild-type organism in the upper respiratory tract. Our current project concerns the ability of live vaccines to prevent or reduce infection; in this proposal we will determine the ability of inactivated MG bacterin and an MG-vectored fowl pox vaccine to prevent or reduce infection by contact challenge. We also propose to determine whether a combination of bacterin and live F strain vaccine is more efficacious than either product alone in preventing or reducing infection from contact challenge at peak egg production and at mid-production. To evaluate the ability of Mycoplasma gallisepticum bacterin and pox vectored vaccine, alone or in combination with live vaccine, to protect against infection.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
a. Utilize quantitative real-time PCR to evaluate the ability of a commercially available inactivated bacterin and a commercially available recombinant fowl pox vaccine against Mycoplasma gallisepticum to prevent colonization from a contact challenge with the virulent R strain. b. If the above-vaccinated birds do become infected by contact challenge, determine if they have reduced the M. gallisepticum populations in the upper respiratory tract. c. Utilize strain-specific quantitative PCR to determine if a commercially available inactivated bacterin and live F strain vaccine, alone or in combination, have an enhanced ability to prevent colonization from a contact challenge with the R strain.
Project Methods
Experiment 1. Effect of bacterin and recombinant fowl pox MG vaccine: Three groups of about 20 mycoplasma-free commercial leghorn-type pullets will be vaccinated at about 12 weeks of age with commercially available MG bacterin (Fort Dodge Laboratories) given subcutaneously, a recombinant fowl pox vaccine containing 2 MG genes (Biomune) given by wing web, or left as unvaccinated controls. All groups will also be vaccinated with a conventional fowl pox vaccine. Approximately 6 weeks post vaccination 10 birds/group will be tested by agglutination and HI and two birds previously challenged with R strain of MG will be placed in each pen. Five birds/group will be removed at 1, 2, 4, and 8 weeks post challenge and tracheas will be tested by agglutination and HI, cultured and quantitatively tested by real-time PCR specific for the challenge R strain. Experiment 2. F strain vaccine and bacterin, alone or in combination: Four groups of fifty mycoplasma-free commercial leghorn
type pullets will be vaccinated with bacterin (12 weeks), live F strain vaccine (16 weeks), both, or left unvaccinated. These birds will be managed and lit in order to come into egg production normally. At approximately peak egg production (about 25 weeks) 25 birds per group will be bled and tested by agglutination and HI and exposed to 2 seeder birds which had been earlier infected with the R strain of MG. At mid-production (about 55 weeks of age) the remaining hens will be bled and challenged in a similar manner. At 1, 2, 4, and 8 weeks post challenge 5 birds/group will be removed, bled for agglutination and HI tests, cultured, and tracheas quantitatively evaluated for the presence of both the F vaccine strain and the R challenge strain. Data will be evaluated to determine whether the R challenge strain has infected the vaccinated birds, and if so, whether the population of the R challenge strain has been reduced in vaccinated groups versus unvaccinated, challenged groups. Note: We
have chosen to utilize a contact exposure type of challenge in these experiments. We know that challenge of any vaccine with a high-titer, virulent challenge strain will overwhelm any vaccine. We think that a contact challenge is more appropriate for the type of challenge that birds in the field will face. The purpose is to determine whether the birds become infected with the challenge strain, and if the copy number is reduced, in vaccinated birds. We do not expect to reproduce any signs or lesions with this type of challenge.