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COVID-19 vaccines are being developed urgently worldwide. Here, we constructed two adenovirus vectored COVID-19 vaccine candidates of Sad23L-nCoV-S and Ad49L-nCoV-S carrying the full-length gene of SARS-CoV-2 spike protein. The immunogenicity of two vaccines was individually evaluated in mice. Specific immune responses were observed by priming in a dose-dependent manner, and stronger responses were obtained by boosting. Furthermore, five rhesus macaques were primed with 5 × 10 9 PFU Sad23L-nCoV-S, followed by boosting with 5 × 10 9 PFU Ad49L-nCoV-S at 4-week interval. Both mice and macaques well tolerated the vaccine inoculations without detectable clinical or pathologic changes. In macaques, prime-boost regimen induced high titers of 10 3.16 anti-S, 10 2.75 anti-RBD binding antibody and 10 2.38 pseudovirus neutralizing antibody (pNAb) at 2 months, while pNAb decreased gradually to 10 1.45 at 7 months post-priming. Robust T-cell response of IFN-γ (712.6 SFCs/10 6 cells), IL-2 (334 SFCs/10 6 cells) and intracellular IFN-γ in CD4 + /CD8 + T cell (0.39%/0.55%) to S peptides were detected in vaccinated macaques. It was concluded that prime-boost immunization with Sad23L-nCoV-S and Ad49L-nCoV-S can safely elicit strong immunity in animals in preparation of clinical phase 1/2 trials.

The clinical value of 131 I-MIBG for targeted imaging and targeted radiotherapy is limited to neural crest-derived tumors expressing human norepinephrine transporters (hNET) protein. To extend 131 I-MIBG-targeted therapy to other nonexpressed hNET tumors, this study investigated the hNET expression in vitro and in vivo in HepG2 hepatoma mediated by recombinant adenovirus encoding the hNET gene (Ad- hNET ). For this purpose, the HepG2 cells showed a 4.87-fold increase in 125 I-MIBG uptake after infection with Ad- hNET , and the uptake of 125 I-MIBG could be specifically inhibited by maprotiline. Immunohistological analysis, in vivo biological study and 131 I-MIBG scintigraphic imaging also revealed the high expression of hNET protein in hepatoma. This in vitro and in vivo studies demonstrate the feasibility of hNET gene transfer, meditated by adenovirus vector, could extend to tumors other than those derived from the neural crest, which provides a sound foundation for further investigation of hepatocellular carcinoma-targeted radiotherapy mediated by adenovirus transfection with hNET gene.