Two Faces of Adenovirus — A Time to Kill, A Time to Heal
Viruses are a kind of non-cellular organisms that are tiny to the nanometer level, with a simple structure that only has a protein shell and a long nucleic acid chain as genetic material. It cannot be independently metabolized but must be parasitic in living cells and multiply in a replication mode. It is weak but also strong, and human beings have to face the two-sided nature of a kind.
Adenovirus is such a virus that can infect human body. They are widespread in nature and can cause infections of the respiratory tract, eyes, gastrointestinal tract, and urinary system. They can cause regional transmission in highly confined, crowded and humid environments. But the advancement of science and technology helps us discover that this type of virus can also be used to fight tumors and even the novel coronavirus disease, COVID-19, that has recently raged around the world.
· Adenovirus Infection Can Be Dangerous
Adenovirus infection will cause many uncomfortable symptoms, including symptoms of upper respiratory tract infection (fever, sore throat, nasal congestion and other common cold symptoms), conjunctivitis (such as pharyngeal conjunctivitis, conjunctivitis, epidemic keratoconjunctivitis), gastrointestinal infection (diarrhea, more common in children under 5 years old), urinary tract infections, hemorrhagic cystitis, etc.
Adenovirus infection is a contagious disease and should be actively prevented. Adenovirus transmission mainly includes contact transmissions of respiratory droplets, pollutants and excrement, and eye secretions.
· Adenovirus Help Fight Tumors
Oncolytic viruses are currently an important method in the field of tumor immunotherapy. At present, Adenoviruses are the most used type in clinical trials. Oncolytic adenovirus is a genetically engineered adenovirus that can selectively replicate and express in tumor cells, thereby lysing tumor cells.
In 1996, since the world’s first oncolytic adenovirus ONXY-015 was launched in clinical research, it has been widely used in scientific research, involving a variety of solid tumors. Oncolytic adenovirus combined with radiotherapy, chemotherapy, and targeted drug therapy are also proved to be more effective treatment options. Further clinical research will continue to explore the potential of oncolytic virus combined with other therapies.
· Adenovirus Vaccine for SARS-CoV-2
Adenovirus-vectored COVID-19 vaccines are one of the hot topics in global news. Johnson & Johnson’s JNJ-78436735, CanSino Biologics’ Convidicea (AD5-nCoV) and Russia’s Sputnik V, AZD1222 are all examples of this type. So what kind of vaccine is it? How does it work?
Like all vaccines, this method is designed to trick our body into getting infected. These homemade spike proteins will train our bodies to detect and terminate any actual SARS-CoV-2 infection before the virus causes severe damage. The adenovirus vector COVID-19 vaccine constructs the gene of S protein of SARS-CoV-2 into the adenovirus genome, and the shell is still the normal shell protein of the adenovirus. Therefore, when adenovirus infects host cells, the genes encoding the SARS-CoV-2 S protein are released to the host cell, and S protein is synthesized in the cytoplasm, which stimulates a series of immune responses.
The advantage of an adenovirus-based vaccine is that it can induce humoral and cellular immunity at the same time. Humoral immunity produces antibodies that bind to viruses, preventing viruses from entering human cells, that’s to say, viruses are recognized, swallowed, and degraded by macrophages outside the cells. For viruses that have been lucky enough to enter cells, they can be recognized by cellular immune mechanisms and cytokine secreted by killer T cells to lyse the infected cells.
