Abstract
Currently, a fatal disease of hepatitis-hydropericardium syndrome (HHS) caused by serotype 4 fowl adenovirus (FAdV-4) has spread worldwide and resulted in tremendous economic losses to the poultry industry. Various vaccines against FAdV-4 were developed to control the disease; however, few live-attenuated vaccines were available. In this study, we targeted the N-terminal of fiber-1 and rescued a recombinant virus FAdV4-RFP_F1 expressing the fusion protein of RFP and Fiber-1 based on the CRISPR/Cas9 technique. In vitro studies showed that FAdV4-RFP_F1 replicated slower than the wild type FAdV-4, but the peak viral titer of FAdV4-RFP_F1 could still reach 107.0 TCID50/ml with high stability in LMH cells. Animal studies found that FAdV4-RFP_F1 not only was highly attenuated to the 2-week-old SPF chickens, but could also provide efficient protection against lethal challenge of FAdV-4. All these demonstrate that the recombinant virus FAdV4-RFP_F1 could be as an efficient live-attenuated vaccine candidate for FAdV-4, and the N-terminal of fiber-1 could be as a potential insertion site for expressing foreign genes to develop FAdV-4-based vaccine.
Highlights
Fowl adenovirus (FAdV) belongs to genus Aviadenovirus, family Adenoviridae [1]
RFP could be efficiently found in LMH cells transfected with sgRNA and donor plasmid, but no RFP could be found in LMH cells without infection (Figure 1B), indicating that the recombinant virus, designated as FAdV4-RFP_F1, was successfully generated
Hepatitis-hydropericardium syndrome caused by the highly pathogenic FAdV-4 has resulted in substantial economic losses to poultry industry globally
Summary
Fowl adenovirus (FAdV) belongs to genus Aviadenovirus, family Adenoviridae [1]. FAdV is a kind of non-enveloped viruses with a double-stranded DNA genome, clustered into 5 species (FAdV-A to FAdV-E) with 12 serotypes (FAdV-1 to FAdV-8a, FAdV-8b, and FAdV-9 to FAdV-11) based on the restriction enzyme digestion profile and sera cross-neutralization assay [2]. FAdV can infect chickens through both vertical propagation and horizontal transmission. Of these 12 serotypes of FAdV, FAdV-4 is thought to be a highly pathogenic pathogen for poultry. The infection of FAdV-4 mainly results in hepatitis-hydropericardium syndrome (HHS) with a short latency, sudden onset, and high mortality. The disease caused by FAdV-4 has spread globally and lead to substantial economic losses to the poultry industry [3].
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