A novel recombinant serotype 4 fowl adenovirus efficiently protects both serotype 4 and 11 fowl adenovirus.

Recently, the diseases caused by the infection of multiple serotypes of fowl adenoviruses (FAdVs) have spread worldwide and resulted in huge economic losses to the poultry industry. However, the commercial multivalent or bivalent vaccines against different serotypes of FAdV are not available. In this study, a novel recombinant FAdV-4, designated FAdV-4-F11, expressing the Fiber of FAdV-11, was generated using the template virus FA4-EGFP through the CRISPR-Cas9 and Cre-LoxP system. The recombinant virus FAdV-4-F11 could efficiently replicate in LMH cells with a high yield of 109.6 TCID50/mL. Moreover, the inoculation of inactivated FAdV-4-F11 could induce high neutralizing antibodies against both FAdV-4 and FAdV-11, providing efficient protection against both viruses. All these data demonstrate that the recombinant virus FAdV-4-F11 generated here can be a novel bivalent vaccine candidate against both FAdV-4 and FAdV-11.