Cómo funciona la vacuna contra la COVID-19 de Johnson & Johnson

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Cómo funciona la vacuna de Moderna

Johnson & Johnson is testing a coronavirus vaccine called JNJ-78436735 or Ad26.COV2.S. Clinical studies showed that a single dose of the vaccine had an efficacy rate of up to 72 percent. The vaccine has been approved for emergencies in the United States and Bahrain.

Janssen Pharmaceutica, a division of Johnson & Johnson based in Belgium, is developing the vaccine in collaboration with the Beth Israel Deaconess Medical Center.

A fragment of the coronavirus

The SARS-CoV-2 virus is filled with proteins that it uses to enter human cells. These proteins, called spikes, are tempting targets for potential vaccines and treatments.

Gene of

Protein from

the summit

Gene of

Protein from

the summit

The Johnson & Johnson vaccine relies on the virus' genetic instructions to build the spike protein. Unlike the Pfizer-BioNTech and Moderna vaccines, which store instructions in single-stranded or single-stranded RNA, the Johnson & Johnson vaccine uses double-stranded DNA.

DNA within an adenovirus

The researchers added the coronavirus spike protein gene to another virus called adenovirus 26. Adenoviruses are common viruses that often cause colds or flu-like symptoms. The Johnson & Johnson team used a modified adenovirus that can enter cells but cannot replicate internally or cause disease.

DNA inside

an adenovirus

DNA inside

an adenovirus

The Johnson & Johnson vaccine is the result of decades of research into adenovirus-based vaccines. The first was approved for general use in July: an Ebola vaccine, also manufactured by Johnson & Johnson. The company is also testing adenovirus-based vaccines for other diseases such as AIDS and Zika. Some other coronavirus vaccines are also based on adenoviruses, like the one developed by the University of Oxford and AstraZeneca using a chimpanzee adenovirus.

Adenovirus-based COVID-19 vaccines are more resistant than mRNA vaccines from Pfizer and Moderna. DNA is not as fragile as RNA, and the adenovirus' hard protein shell helps protect the genetic material it contains. As a result, the Johnson & Johnson vaccine can be refrigerated at 2-8 ° C (36-46 ° F) for up to three months.

Cell entry

After the vaccine is injected into a person's arm, adenoviruses collide with cells and cling to proteins on their surface. The cell wraps the virus in a bubble and pulls it inside. Inside, the adenovirus escapes from the bladder and migrates to the nucleus, the chamber in which the cell's DNA is stored.

Enveloped virus

in a bubble

Enveloped virus

in a bubble

Enveloped virus

in a bubble

virus

packed in

a bubble

virus

packed in

a bubble

virus

packed in

a bubble

virus

wrapped up

in one

bladder

virus

wrapped up

in one

bladder

The adenovirus introduces its DNA into the nucleus. The adenovirus is designed so that it cannot make copies of itself, but the coronavirus spike protein gene can be read by the cell and copied into a molecule called messenger RNA or mRNA.

Spike protein construction

The mRNA leaves the nucleus and the cell's molecules read their sequence and begin assembling the spike proteins.

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Combine three

Spike proteins

Fragments

of spikes

and proteins

The gifts

Fragments

top

Some of the spike proteins produced by the cell form spikes that migrate to the surface and spread their tips. The inoculated cells also separate into fragments some of the proteins that they present on their surface. The immune system can then recognize these protruding spikes and spike protein fragments.

Adenovirus also triggers the immune system by activating the cell's alarm systems. The cell sends out warning signals to activate nearby immune cells. By activating this alarm, the Johnson & Johnson vaccine makes the immune system more responsive to spike proteins.

Intruder detection

When a vaccinated cell dies, its remains contain many spike proteins and protein fragments that can then take up a type of immune cell called an antigen-presenting cell.

Remains of a

dead cell

CELL

MODERATOR

OF ANTIGENS

Digestion of

Proteins

The gifts

a fragment of

Spike protein

Remains of a

dead cell

CELL

MODERATOR

OF ANTIGENS

Digestion of

Proteins

The gifts

a fragment of

Spike protein

Remains of a

dead cell

CELL

MODERATOR

OF ANTIGENS

Digestion of

Proteins

The gifts

a fragment of

Spike protein

The cell has fragments of the spike protein on its surface. When other cells called helper T lymphocytes recognize these fragments, the helper T lymphocytes can sound the alarm and prompt other immune cells to fight infection.

Formation of antibodies

Other immune cells called B lymphocytes could collide with coronavirus spikes on the surface of vaccinated cells or with floating spike protein fragments. Some B lymphocytes may be able to adhere to the spike proteins. Later, when helper T cells activate these B cells, they begin to multiply and secrete antibodies that attack the spike protein.

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

protein

corresponding

on the surface

Activation of

B lymphocytes

Corresponding proteins

on the surface

Activation of

B lymphocytes

Corresponding proteins

on the surface

Activation of

B lymphocytes

Corresponding proteins

on the surface

Stop the virus

Antibodies can attach to coronavirus spikes, marking the virus for destruction, and blocking infection by preventing the spikes from attaching to other cells.

Suppression of infected cells

Antigen presenting cells can also activate another type of immune cell called a cytotoxic T lymphocyte to search for and destroy coronavirus infected cells that present spike protein fragments on their surface.

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

CELL

MODERATOR

OF ANTIGENS

Presentation of

a fragment of

Spike protein

LYMPHOCYTE T.

CYTOTOXIC

ACTIVATED

Begins to suppress

to the infected cell

Virus store

The Johnson & Johnson vaccine is given as a single dose, unlike the two-dose vaccines from Pfizer, Moderna and AstraZeneca.

The researchers don't yet know how long protection from the vaccine can last. Antibody and cytotoxic T lymphocyte counts may decrease in the months following vaccination. However, the immune system also contains special cells called memory B and T cells that can hold information about the coronavirus for years or even decades.


Sources: National Center for Information on Biotechnology; Nature; Lynda Coughlan, University of Maryland Medical School.

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