New technologies
Advancements in science and technology have given researchers new tools to try against the coronavirus. Scientists can deliver genetic material into the body’s cells, turning them into vaccine factories and skipping time-consuming steps such as manufacturing viral proteins or growing the whole virus in chicken eggs.
Technology used:
The core of the coronavirus SARS-CoV-2 is a single strip of ribonucleic acid (RNA) surrounded by a protein shell. The virus is named for the iconic spikes that project from its center like a crown, or “corona” in Latin. These spike proteins aren’t just decoration. They are critical for the virus to get inside cells and make copies of itself.
Vaccines work by teaching the body’s immune system to recognize and block viruses, and each category of vaccine works under this basic principle. Vaccine technology aims to activate the immune system’s T-helper cells, which are responsible for detecting the presence of a virus. They instruct B-cells to create antibodies that block the virus from being able to replicate and T-killer cells to destroy infected cells. Some vaccines may activate only part of this immune response.
Coronavirus
SARS-CoV-2
Spike protein
M Protein
SARS-CoV-2
copies
RNA
ACE2
receptor
RNA
Proteins
SARS-CoV-2 uses
its spike to bind to
the ACE2 receptor,
allowing access
into the cell.
The virus’s RNA is
released into the
cell. The cell reads
the RNA and
makes proteins.
The viral
proteins are
then assembled
into new copies
of the virus.
The copies
are released
and go on to
infect more
cells.
Here is a look at how different vaccine technologies being developed around the world would ideally elicit an immune response to prevent SARS-CoV-2 in humans. Each vaccine may vary somewhat in how it works, but each would generally follow these steps.
Vaccines using nucleic acid (DNA and RNA)
DNA vaccines contain genetic material that carries the blueprint for the spike protein. To get the DNA into cells, researchers use an electrical pulse to disrupt the cell membrane. Once inside, the DNA is used as a template to create spike protein.
RNA vaccines contain a strip of genetic material within a fat bubble. Once inside the cell, the RNA generates a protein found on the surface of the virus. The immune system, presented with the protein, learns to recognize the virus.
These vaccines have the advantage of speed — they can be quickly designed and manufactured. But they have never been approved for use outside of medical research and will likely require two doses.
An electric pulse allows DNA into the cell’s nucleus where it forms mRNA, then creates spike proteins
Antigen-presenting cells (APCs) consume the viral proteins and pass viral peptides to T-helper cells
Cytotoxic
T cells may eliminate virus-infected cells
DNA vaccine
Spike gene
on DNA
Cytotoxic
T cell
Spike protein
Viral
peptide
Cell
T-helper
cell
APC
B-cell
A lipid shell delivers mRNA into the cell, where it is used to produce proteins
Antibodies from B-cells may block the virus
mRNA in
lipid shell
RNA vaccine
Nucleic acid vaccines, developed by...
Viral-vectored vaccines
Some vaccines use a virus that has been engineered to be harmless to ferry a gene from the coronavirus into cells. The gene codes for a distinctive part of the coronavirus, and the immune system learns to recognize it.
Viral-vectored vaccines can be designed quickly. One concern is that people can develop immunity to the viral vector, making this approach potentially less useful if booster shots need to be given.
Replicating
viral vector
Replicating viral vector infects cell, produces SARS-CoV-2 antigen and additional vectors
SARS-CoV-2 gene
in a different virus
Cytotoxic
T cell
Vectors
Cell
Viral
peptide
Antigen
T-helper
cell
APC
B-cell
SARS-CoV-2 gene
in a different virus
Non-replicating viral vector infects cells, produces SARS-CoV-2 antigen
Non-replicating
viral vector
Viral-vectored vaccines, developed by...
Subunit vaccines
Some traditional vaccines work by delivering viral proteins to cells. The technologies to manufacture those protein fragments vary, but companies are using insect cells and yeast. The hepatitis B vaccine relies on a viral protein created by genetically engineered yeast.
Empty viral shells look like the virus but are not harmful because they have no genetic material
Virus-like
particles
Empty viral shell
Cytotoxic
T cell
Viral
peptide
T-helper
cell
APC
B-cell
SARS-CoV-2 proteins
Specific protein subunits, such as the spike protein, enter the body
Protein
subunits
Subunit vaccines, developed by...
Weakened or inactivated virus vaccines
In a more old-fashioned approach, the virus is weakened so that it does not cause disease, but still triggers the immune system’s defenses. The vaccine for measles, mumps and rubella uses this approach.
Inactivated virus vaccines contain dead virus, incapable of infecting people but still able to instruct the immune system how to mount a defensive reaction against an infection. The polio vaccine invented by Jonas Salk used this approach, and flu vaccines use this technology.
These vaccines typically take longer to manufacture.
Weakened
virus
Weakened virus replicates in human cells.
Weakened virus
Replicated
virus
Cytotoxic
T cell
Viral
peptide
Cell
T-helper
cell
APC
B-cell
Dead virus from the vaccine enters the body
Dead virus
Inactivated
virus
Weakened and inactivated virus vaccines, developed by...
Other vaccines
Information on the technology platform being used was not available for all the experimental vaccines. Some vaccines being tested do not specifically target the coronavirus, but aim to increase the body’s first line of immune defenses.
