Effects of the In ovo vaccination of the ts-11 strain of mycoplasma gallisepticum in layer embryos and posthatch chicks

Authors: ALQHTANI, A - Mississippi State University; FATEMI, S - Mississippi State University; Collins Elliott, Katie; BRANTON, S - Retired ARS Employee; Evans, Jeffrey - Jeff; Leigh, Spencer; GERARD, P - Clemson University; PEEBLES, E - Mississippi State University

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2022
Publication Date: 4/27/2022
Citation: Alqhtani, A.H., Fatemi, S.A., Collins Elliott, K.E., Branton, S.L., Evans, J.D., Leigh, S.A., Gerard, P.D., Peebles, E.D. 2022. Effects of the In ovo vaccination of the ts-11 strain of mycoplasma gallisepticum in layer embryos and posthatch chicks. Animals. 12(9):1120. https://doi.org/10.3390/ani12091120.
DOI: https://doi.org/10.3390/ani12091120

Interpretive Summary: Vaccination represents an important barrier to disease in animal production. Among commercial egg laying chickens, live vaccines may be used to protect against Mycoplasma gallisepticum, a respiratory pathogen. These vaccines may be delivered to the bird by eye-drop, spray, or drinking water, but each of these methods has its disadvantages. Vaccines delivered prior to hatch or in ovo may overcome disadvantages associated with other delivery methods and result in an efficient, effective, and timely means of delivery. To test in ovo delivery of an M. gallisepticum vaccine, embryos were vaccinated with the vaccine at 18 days of incubation. After hatch, impacts of the in ovo vaccine delivery were assessed.

Technical Abstract: Effects of the in ovo injection of the ts-11 strain of Mycoplasma gallisepticum (MG) vaccine (ts-11MGV) and its transmission between incubated eggs and between hatchlings, and their subsequent posthatch performance were evaluated. Marek’s disease diluent alone (sham-injected) or containing either 3.63 x 101, 102, 103, or 104 cfu of ts-11MGV was manually in ovo-injected into the amnion on 18 days of incubation. All 5 treatments were randomly represented in each of 12 replicate blocks of a single-stage incubator. One group of sham-injected eggs were transferred on day of injection to a separate identical incubator to represent ts-11MGV unexposed control (UC) eggs, while those that remained represented ts-11MGV exposed control (EC) eggs. In the incubator containing UC eggs, 30 eggs were set in each of 3 flats on 2 tray levels and 2 tray columns. Egg residue analysis, percentage incubational egg weight loss, hatchability of viable injected eggs, and hatchling body weight (BW) were assessed. One hatchling from each of the 12 replicate groups in each treatment were swabbed in the choanal cleft for MG DNA detection. Twenty female chicks were randomly placed in each of 3 replicate biological isolation units in the EC, and the 3.63 x 102, 103, and 104 cfu treatment groups for assessment of performance through to 21 days of posthatch age. Five male sentinel chicks from the UC treatment were allocated to each biological isolation unit to assess horizontal transmission. Birds were swabbed and bled respectively, for detection of MG DNA and IgM production at 21 days posthatch. In all birds, no MG DNA was detected and SPA tests for IgM were negative. There were no significant treatment differences for any of the hatch variables examined, and only 0 to 21 day BW gain in the 3.63 x 104 ts-11 MGV treatment was significantly lower in comparison to all the other treatments. Because ts-11MGV does not exhibit vertical or horizontal transmission capabilities under commercial conditions, it may not be a good candidate for in ovo injection.