Newcastle disease virus TS09-C strain provides long-lasting protection against virulent strain after in-ovo immunization.

Newcastle disease (ND) is an important infectious disease in poultry, causing substantial economic losses in many countries. Vaccination with live vaccines is a common strategy for ND control, and farmers generally vaccinate multiple times each year because the current ND vaccines have a relatively short protection period. Here, we report that the NDV strain TS09-C, as an in ovo vaccine, provided long-lasting protection for at least 12 months against virulent NDV. TS09-C significantly reduced the tissue viral titer, alleviated histopathological lesions, and induced proliferation of CD8+ T cells after challenge. TS09-C in ovo group vs PBS group, 142 immune-related DEGs were screened based on RNA-Seq, including 18 up-regulated DEGs and 124 down-regulated DEGs. The innate immune pathways of these genes, as NOD-like, Toll-like, RIG-I-like, Cytokine-cytokine receptor interaction, and all genes (including pro-inflammatory cytokines IL-1B, IL-6, IL-18, etc) in these pathways were significantly downregulated. These results indicate that NDV strain TS09-C is a long-lasting protection vaccine candidate against ND, and the protection might be due to the reason that TS09-C induces the proliferation of CD8+ T cells and inhibits the inflammatory response.