The SARS-CoV-2 coronavirus pandemic, which causes the COVID-19 disease, has caused a global health and economic crisis. For this reason, laboratories are abuzz with data and clinical tests with the aim of providing, as soon as possible, an effective vaccine or viral treatment. Several vaccine prototypes have already started the first phases to test their efficacy.
Here’s another one, this time, by scientists from the University of Iowa and the University of Georgia. With a nuance: the prototype is not exactly a vaccine against COVID-19, but a vaccine against MERS, another coronavirus that causes a respiratory disease , and that could be considered a first cousin of the coronavirus that causes the current pandemic. Because the viruses are so close together, researchers believe this vaccine may show promise for developing vaccines against other diseases caused by a coronavirus, including COVID-19. This MERS vaccine is also the most effective against this disease to date.
MERS (Middle East respiratory syndrome) and COVID-19 are caused by a coronavirus. MERS is more deadly and fatal in about a third of known cases, but there have only been 2,494 cases since 2012, when the first case appeared. In contrast, the coronavirus that causes COVID-19 has a much faster and more efficient spread , accounting (at the time of writing) more than 1.3 million confirmed cases since the end of 2019.
How does the vaccine work?
The vaccine in question uses another type of virus, a harmless one, as a vehicle to deliver a MERS coronavirus protein into cells to generate an immune response.
Explained in more detail, the vaccine consists of a harmless parainfluenza virus (PIV5), which carries the spike protein of MERS, which this coronavirus uses to infect cells (the SARS-CoV-2 coronavirus also uses a similar procedure to infect). The results are very promising, given that all vaccinated mice survived a lethal dose of the MERS coronavirus, as described in a paper published April 7 in the journal mBio . The application consisted of only a relatively low dose of the vaccine administered to the mice intranasally (inhaled through the nose).
The same strategy, for COVID-19
Not only do scientists have in mind to use the same method to make a vaccine against COVID-19, but they already have several candidate compounds to be the next vaccine.
As the researchers write: “Our new study indicates that PIV5 may be a useful vaccine platform for emerging coronavirus diseases, including SARS-CoV-2, the virus that causes the COVID-19 pandemic. Using the same strategy, they are have generated PIV5-based vaccine candidates expressing the SARS-CoV-2 spike protein We are planning further animal studies to evaluate the ability of PIV5-based vaccines to prevent SARS-CoV-2 disease.
More details on the immunity generated by the mice: When the researchers analyzed the immune responses generated by the vaccine, they found that both antibodies and protective T cells were produced. However, the antibody response was quite weak and it seems highly likely that the protective effect of the vaccine is due to the T-cell response in the lungs of the mice.
The advantages of using a harmless virus as ‘transport’
As we have explained, the vaccine uses a harmless virus as a vehicle to transport the spike proteins of the coronavirus. This virus, PIV5, has many advantages as a transport: first, because it can infect many different mammals, including humans, without causing disease (since it is a harmless virus). On the other hand, PIV5 is also being investigated as a means of a vaccine for other respiratory diseases, including respiratory syncytial virus (RSV) and the common flu.
Furthermore, the fact that a low dose of the vaccine was sufficient to protect the mice could be beneficial in creating enough vaccine to cause mass immunization in the population , to vaccinate many people.
