Haipeng Lu

A duck adenovirus type 3 strain, SD2019, was isolated from sick Muscovy ducks in our laboratory in 2019. To study the biological properties of the virus, an infectious clone of the SD2019 strain was successfully established. The plasmid containing the whole genome of DAdV-3 was digested with Pac I and the linearized DNAs were electortransfected into LMH cells; the cells showed cytopathic effects (CPEs) at 96 h post transfection and the rescued virus (rSD2019) was identified by PCR and indirect immunofluorescence assays (IFAs). The biological characteristics of strain rSD2019 were studied in vitro and in vivo and the results show that rSD2019 grew to similar titers as compared with the wild-type SD2019 strain in LMH cells, as well as showing similar replication and virulence in Muscovy ducks. The establishment of a reliable reverse genetics system for DAdV-3 provides a foundation for future studies of DAdV-3.

A duck adenovirus type 3 strain SD2019 was isolated from sick Muscovy ducks in our laboratory in 2019. To study the biological properties of the virus, an infectious clone of the SD2019 strain was successfully established. The plasmid containing whole genome of DAdV-3 was digested with Pac I and the linearized DNAs were electortransfected into LMH cells, the cells showed cytopathic effects (CPEs) at 96 hours post transfection and the rescuded virus (rSD2019) was identified by PCR and indirect immunofluorescence assays (IFA). The biological characteristics of strain rSD2019 were studied in vitro and in vivo and the results showed that the rSD2019 grew to similar titers as compared with the wild-type SD2019 strain in LMH cells, and showed similar replication and virulence in Muscovy ducks. The establishment of a reliable reverse genetics system for DAdV-3 provides a foundation for future studies of DAdV-3.

Infectious laryngotracheitis virus (ILTV) causes severe respiratory disease in chickens and results in huge economic losses in the poultry industry worldwide. To correlate the genomic difference with the replication and pathogenicity, phenotypes of three ILTVs isolated from chickens in China from 2016 to 2018 were sequenced by high-throughput sequencing. Based on the entire genome, the isolates GD2018 and SH2017 shared 99.9% nucleotide homology, while the isolate SH2016 shared 99.7% nucleotide homology with GD2018 and SH2017, respectively. Each virus genome contained 82 ORFs encoding 77 kinds of protein, 31 of which share the same amino acid sequence in the three viruses. GD2018 and SH2017 shared 57 proteins with the same amino acid sequence, while SH2016 shared 42 and 41 proteins with the amino acid sequences of GD2018 and SH2017, respectively. SH2016 propagated efficiently in allantoic fluid and on chorioallantoic membranes (CAMs) of SPF chicken embryo eggs, while GD2018 and SH2017 proliferated well only on CAMs. GD2018 propagated most efficiently on CAMs and LMH cells among three isolates. SH2016 caused serious clinical symptoms, while GD2018 and SH2017 caused mild and moderate clinical symptoms in chickens, although the sero of the chickens infected with those three isolates were all positive for anti-ILTV antibody at 14 and 21 days after challenge. Three ILTVs with high genetic homology showed significant differences in the replication in different culture systems and the pathogenicity of chickens, providing basic materials for studying the key determinants of pathogenicity of ILTV.