I would be grateful if somebody tell me if I vaccinated a flock with ts-11at 10 week old if at 26 week -old found the mean titer of Mycoplasma gallisepticum 1454 is that a titer of the vaccine or field challenge . When does the antibody titer following vaccination at 10 week -old with ts-11 wane to negative titer t
Hi there,
We have seen birds respond differently to the ts-11 vaccine recently especially when it comes to serological-based tests for diagnoses in vaccinated flocks. Recent observations from a longitudinal field study on commercial layers in Australia are showing increasing serology titers in vaccinated birds correlating with increasing detection of the ts-11 and MS-H vaccine strain genomes in the absence of a field challenge (Graph). These birds were vaccinated with MGts-11 and MS-H vaccines at 6 weeks of age. The best possible way to get an answer quickly will be to collect some choanal cleft swabs and run a DIVA PCR assay on them. The other most important assessment will be to check for any production deviations or disease syndrome presentations in these birds or their progeny that would be consistent with Avian Mycoplasmosis to help decide. If there are no deviations or issues, then the serology is most likely to be due to vaccines. Similar reports have been published by Moronato et al., 2018 (Italy), Zavala et al., 2015 (USA) and Whithear & Scott, 2002 (Australia).
Have a look at http://www.bioproperties.com.au/!Pages/Publications/Documents/DOC-Bulletin-2015-02.pdf
there are at least three different responses by flocks to vaccination especially to ts-11 and they are all normal. Perhaps as Robin Achari says it is very dependant on the time after vaccination what you see but serology is useless after vaccination is my conclusion from 25 years experience. If you want to know what is happening use a recent (last 5 years) DIVA PCR.
Every ELISA supplier will tell you that their ELISA can differentiate vacoinated from field challenge but it has not been my experience.
Chris Morrow , Good discussion on Immune response to Mycoplasma.
Would anyone be able to say which immune response is more reliable and consistent--'HUMORAL/CELL-MEDIATED/COMPETITIVE EXCLUSION--- in response to either vaccination or field challenge ?
If it is Humoral, how long will it be protective after single exposure of Live MG(Vaccine/Field) or Killed MG antigen?
Dr. Jignesh Barot
(AVIAN DISEASES)
POULTRY DISEASE DIAGNOSTIC LABORATORY
VENKY'S INDIA LIMITED
jignesh barot Killed vaccines make humoral antibody and little else. Humoral antibody might not be totally beneficial - It is thought to increase the efficacy of vertical transmission by preventing the MG from killing the embryo (see diseases of poultry). It also gives vets a warm and fuzzy feeling that they can follow this on ELISAs and RSAs.
Live vaccines make mucosal immunity and variable amounts of humoral antibody. Birds with no antibody from live vaccination can still be protected.
Most of the pathology in avian mycoplasmosis (respiratory) is from the host response. Toxins seem lacking but the host response with cellular infiltration makes the purulent exudates etc. The cat and mouse game between the mycoplasma and chicken immune response finishes up as inconclusive with the mycoplasma devoting massive resources to staying ahead of the response (antigen switching, mimicry, auto immune tricks (Fc receptors), etc). Antibody and systemic immune response are consuming immence resources that then limit chicken production.
Killed vaccines may interfere with live vaccine efficacy (Glisson and Kleven 1984) experience in Japan suggest killed MG vaccines on provide modest benefits for half the production period.
Anyhow in birds vaccinated with live or killed mycoplasma vaccines ELISAs are not predictive and you need to do DIVA PCRs to work out what is going on. The live vaccines colonize the bird for life if they are going to provide ongoing protection. This is very similar to the coccidiosis vaccines (trickle infection needed to maintain immunity).
Dear Dr.Jignesh Barot.
Please allow me to attempt an answer for you. I am Dr. Chris Morrow's off-sider.
As you may know already, the local immunity generated by Live vaccines is far better than humoral immunity generated by killed vaccines. The only thing killed mycoplasma vaccines are good at is producing nice serology reports for vets to action antibiotic use. I have seen (and from experience) ts-11 and MS-H produce lifelong immunity in a properly managed farm operation without the need for antimycoplasma antibiotics. I was able to detect ts-11 and MS-H from breeders of 59 weeks of age in well-managed farms. The fact that antibiotics are prescribed post a killed vaccine program, in many places, is self-explanatory on humoral antibody efficiency. In a recent study in Australia, we have seen an increase in serological response in a ts-11+MS-H vaccinated flock that was correlated with an increase in detection of these vaccine strain DNA in the absence of a field challenge. This shows the confusion a serological-based test result would cause for a vet looking after a flock that is vaccinated with these live vaccines. Therefore, we continuously say that a DIVA-PCR based monitoring is the best for flocks vaccinated with ts-11+MSH. And, remember a complete mycoplasma control program should include MG and MS protection both together + Biosecurity. Hope this helps.
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