Acclimation of suspension LMH cell line for high-efficient inactivated FAdV-4 vaccine production

Fowl adenovirus serotype 4 (FAdV-4) is the main pathogen of hepatitis-hydropericardium syndrome (HHS) and mainly prevented and controlled through inactivated vaccine vaccination. In this study, to improve manufacturing efficiency and quality of inactivated virus vaccine, adherent Leghorn Male Hepatoma cell line (LMH-TB) was adapted to suspension growth by continuously passaging and optimizing culture parameters in serum-free medium, finally two suspended cell lines namely LMH-MB adapted in SF003/Celer-S101S (v/v = 1:1) medium and LMH-ME adapted in SF003/50 %Tac-S101S (v/v = 1:1) medium were obtained. The serum-free suspended cell lines LMH-MB/LMH-ME kept stable growth performance during 35-62 passages. The replication of FAV-C4 in LMH-MB and LMH-ME is 10 folds of adherent cells, and the expression level of coxsackie-adenovirus receptor (CAR) in suspended cells is also significantly higher than that in adherent cells, indicating that the suspension LMH is suitable for FAdV-4 replication. Furthermore, the LMH-MB-derived activated FAdV-4 as vaccine could protect 100 % immunized SPF chicken from virulent FAdV-4 challenge, and other avian viruses such as ARV, AIV, DTMUV, AIV and GoAstV also replicated well in LMH-MB cell line. Overall, this study established the highly efficient LMH cell-based production platform for FAdV-4 inactivated vaccine manufacturing.