- Pre-existing immunity in humans may dampen efficacy of the adenoviral vector


Syracuse University

- Contains replication-defective Ad5 vectors expressing the full-length spike gene (S) based on Wuhan-Hu-1 (YP_009724390)
- Phase 2 Trials show vaccine dosage at 5 x 10^10 viral particles is safe and effective in inducing significant immune responses after a single immunization. 
- Completed phase 2 trials and planning on phase 3

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From our Literary Review:

Adenoviral vectors, armed with forgien genetic material, are already widely used in vaccines and cancer treatments (Zhang & Zhou, 2016). Ad5-nCoV, or Cansino, is a vaccine for COVID-19 that was developed in China by CanSino Biologics. Cansino was one of the first coronavirus vaccines to be tested in humans, beginning March of 202 and ending May of the same year. April 11, 2020 was the start of a randomized, double blind, placebo controlled phase II clinical trial. The middle and low doses tested exhibited a significant neutralizing antibody response with seroconversion of neutralizing antibodies of 59% and 47% respectively and seroconversion of binding antibody of 96% and 97% respectively. At 28 days post vaccination 95% of the middle and 91% of the low dosage groups showed cellular or humoral immune responses.
Ad5-nCoV uses replication defective mutant adenovirus type 5 as a viral vector to express the SARS-CoV-2 spike protein, the main antigen component responsible for entry into the cell. The purpose of this structure is to have the common cold virus mimic coronavirus. 

Adenovirus based viral vector technology appears to be a preferred strategy for prevention of newer infectious diseases. Adenovirus vector based vaccine candidates for prevention of infectious disease are being tested more often in order to protect humans from infectious diseases. It has been seen to be one of the most effective vectors to deliver antigens to the host cells of mammals. In addition, it can also induce strong innate and adaptive immune responses, is easily manipulated, and has a reduced risk for insertional mutagenesis of the viral gene. Ultimately, Ad vectored vaccines have shown great potential as candidates in infectious disease prevention.


Ad5-nCov vectored COVID-19 Vaccine by CanSino Biologics

Shin, M.D., Shukla, S., Chung, Y.H. et al. COVID-19 vaccine development and a potential nanomaterial path forward. Nat. Nanotechnol. 15, 646–655 (2020). doi: 10.1038/s41565-020-0737-y

https://doi.org/10.1038/s41565-020-0737-y

COVID-19 vaccine development and a potential
nanomaterial path forward

The vaccine is composed of an adenovirus vector that codes for the S protein. Phase 1 trial of the vaccine over three dose groups using a dose-escalation, sample. Ad5 had shown tolerable and immunogenic results 4 weeks after vaccinations.

Ad5-nCoV from CanSino Phase 1

- broad tissue tropism
- adjuvant qualities
- scalability


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