Chronological study of cytokine transcription in the spleen and lung of chickens after vaccination with serotype 1 Marek's disease vaccines

Transcription of cytokine genes was evaluated in the lung and spleen of chickens vaccinated with various serotype 1 Marek's disease (MD) vaccines. Three vaccine pairs/series, each consisting of one or two high protective (HP) and one low protective (LP) vaccine, were used. Vaccinated chickens had increased transcripts of IFN-γ in the lung and spleen at 3, 5, and 10 days post vaccination (dpv) compared to unvaccinated control chickens. In addition, transient increase of cytokine transcripts (iNOS, IL-1β, IL-18, IL-8, and IL-6 in the lung and iNOS, IL-18, and IL-6 in the spleen) was detected. Compared to chickens vaccinated with LP vaccines, HP vaccinated chickens had increased transcripts of iNOS at 5 dpv but decreased transcripts of IL-6, IL-8, and IL-18 at 10 dpv in the lung. HP vaccinated chickens had increased IFN-γ in the spleen at 3 and at 10 dpv. This study demonstrated that MD vaccines administered subcutaneously elicit a pulmonary immune response and identified differences in the cytokine gene expression between HP and LP vaccinated chickens.