Adenoviral Vector Vaccines for COVID-19: A New Hope?

The global war against the coronavirus that causes COVID-19 rages on, spearheaded by efforts to develop effective and safe vaccines. At the time of writing, over 100 COVID-19 vaccine clinical trials were listed in the database. Recent attention has focused on mRNA vaccines developed by Pfizer/BioNTech and Moderna. If licensed, they would become the first mRNA vaccines for human use.

Other vaccine development efforts are relying on more conventional techniques—using an adenoviral vector to deliver a DNA molecule that encodes the SARS-CoV-2 spike (S) protein. Examples of these adenoviral vector vaccines include the vaccines from Oxford University/AstraZeneca (the UK), Cansino Biologics (China), Sputnik V (Russia) and Janssen Pharmaceuticals/Johnson & Johnson (the Netherlands and USA).

sars-cov-2 coronavirus covid-19 infection with antibodies from a vaccine attacking the virus; several vaccines are in development including adenoviral vector vaccines
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mRNA Vaccines for COVID-19: The Promise and Pitfalls

Multiple battles are being fought in the war against the SARS-CoV-2 coronavirus that causes COVID-19. Currently, there are nearly 3,000 clinical trials listed in the World Health Organization (WHO) database, either underway or in the recruiting stage, for vaccines and antiviral drugs. Two recent announcements of data from phase 3 vaccine trials, by Pfizer/BioNTech and Moderna, have offered some hope for global efforts to fight the pandemic. At the time of writing, Pfizer and BioNTech had submitted an application for emergency use authorization (EUA) to the Food and Drug Administration (FDA), and Moderna had planned to do so shortly.

mrna vaccines and coronavirus covid-19

Both vaccines are mRNA-based, as opposed to most conventional vaccines against established diseases that are protein-based. Typically, the key ingredient in viral vaccines is either part of an inactivated virus, or one or more expressed proteins (antigens) that are a part of the virus. These protein antigens are responsible for eliciting an immune response that will fight future infection by the actual virus. Another approach is to use a replication-deficient viral vector (such as adenovirus) to deliver the gene encoding the antigen into human cells. This method was used for the coronavirus vaccine developed by Oxford University in collaboration with AstraZeneca; phase 3 interim data were announced on the heels of the Pfizer/BioNTech and Moderna announcements. All three vaccines target the SARS-CoV-2 spike protein, because it is the key that unlocks a path of entry into the host cell.

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The Path Brightens for Vaccine Researchers: Luminescent Reporter Viruses Detect Neutralizing Antibodies

Developing a vaccine that is safe, effective, easily manufactured and distributed is a daunting task. Yet, that is exactly what is needed in response to the COVID-19 pandemic.

Vaccine development, safety and efficacy testing take time. The mumps vaccine is thought to be the quickest infectious disease vaccine ever produced, and its development required four years from sample collection to licensing (2). However, there are many reasons to anticipate quicker development for a COVID-19 vaccine: Researchers are collaborating in unprecedented ways, and most COVID-19 scientific publications are free for all to access and often available as preprints. As of August 11, 2020, researchers around the globe have more than 165 vaccine candidates in development, 30 of which are in some phase of human clinical trials (1). The range of vaccine formulations available to scientists has expanded to include RNA and DNA vaccines, replication-defective adenovirus vaccines, inactivated or killed vaccines and subunit protein vaccines. Equally important is that vaccine developers and researchers have greater access to powerful molecular biology tools like bioluminescent reporters that enable quicker testing and development.

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Antibody From Humanized Mice Blocks SARS-CoV-2 Infection in Cells

As the SARS-CoV-2 coronavirus continues to spread throughout the world, the race is on to produce antivirals and vaccines to treat and prevent COVID-19. One potential treatment is the use of human monoclonal antibodies, which are antibodies engineered to target and block specific antigens. A recent study by Wang, C. and colleagues published in Nature Communications showed that human monoclonal antibodies can be used to block SARS-CoV-2 from infecting cells.

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TB Vaccine News

Mycobacterium tuberculosis (Ziehl Neelsen stain). Photo credit: Centers for Disease Control and Prevention.
Mycobacterium tuberculosis (Ziehl Neelsen stain). Photo credit: Centers for Disease Control and Prevention.
A paper published last week in Science Translational Medicine describes promising results from a phase 1 clinical trial of a new anti-tuberculosis vaccine. The vaccine, composed of a human Adenoviral vector expressing a Mycobacterium tuberculosis antigen, generated an immune response in people with and without previous exposure to the current anti-tuberculosis (BCG) vaccine.

Mycobacterium tuberculosis, discovered by Robert Koch in 1882, is the organism that causes tuberculosis—commonly known as TB. After introduction of the BCG (Bacille Calmette-Guérin ) vaccine in 1919 and antibiotic treatment in the 1950s, the hope was that TB would be finally consigned to history—that Mycobacteruim tuberculosis would be a name only associated with the pre-antibiotic era and would not be a part of the 21st century world. However, over the last 30 years the emergence of multi-drug resistance and the worldwide HIV epidemic have led to the re-emergence of TB to the point where the following statements are true: Continue reading “TB Vaccine News”