Mycoplasma gallisepticum field strain and ts-11 vaccine DIVA PCR tests

Dear Kristina, I agree with you. We found this when I was in Budapest with Miklos. The definition of a field strain by being negative in a test is a real problem. Most strain specific PCRs are less sensitive than pan Species PCRs so it is easy to get a Pan positive/strain negative result on direct swabs. Miklos group have published MG vaccine PCRs (MAMAs) and we have a CAST PCR here. One of the big problems is that ts-11 populations initially appear to peak (about 40% of vaccinated birds on individual PCRs) about 4 weeks after eyedrop vaccination and then decrease to being nearly undetectable until the onset of lay. After peak of lay (40 weeks) nearly 100% ts-11 are positive - and as this happens they often seroconvert. No field strains have been found in these flocks (Zavala and others 2015). It adds to the myth that ts-11 protection only lasts to 40 weeks. This is not the pattern of MSH (but I think it is probably the pattern of 6/85). Anyhow one things for sure - Serology is useless in Vaccinated animals. We will be publishing on this soon and presenting at the AAAP meeting this year.

can you please email me chris.morrow@bioproperties.com.au

if the mg and ms pcr test give + ve results for vaccinated live and killed mg breeders but no signs off infection appear on birds or post mortem or production and eggs quality or hatchability what i can do to make accurate tests or what will be the reasons of +ve results ?