New vaccine to protect against Strep A could be on the horizon

By Jim Leffman via SWNS

A new vaccine to protect against strep A could be on the horizon after scientists made a breakthrough in understanding how the body fights the infection.

The bacteria can cause both common throat infections, scarlet fever, sepsis, and swine pox skin infections, which has recently caused the deaths of several schoolchildren.

At the moment, the infection can be treated by antibiotics but potential vaccines have failed and if antibiotic resistance increases then there could be no treatment for it.

But researchers from Lund University in Sweden have found an antibody that attaches to the strep A bacteria in two places, flagging it up to the body's defense systems.

Writing in the journal EMBO Molecular Medicine, the researchers say this type of double attachment is very rare and is probably why previous vaccine attempts have failed.

Pontus Nordenfelt, a study author and an associate professor, said: "There is an unexpected way that antibodies interact with group A streptococci and, more specifically, how they hook onto the probably most important bacterial protein, the M protein, on the cell surface.

“We found that it happens in a way that has never been described before.

"Normally, an antibody binds via one of its two Y arms to its target protein at a single site, regardless of which of the two arms is used for binding.

"But what we have seen– and this is vital information – is that the two Y arms can recognize and hook on to two different places on the same target protein.

"This means that the two arms of the antibody – which are identical – can bind to two different sites on a target protein.

"It turns out that it is precisely this type of binding that is required for effective protection, and since it is probably rare, it could explain why so many vaccine attempts have been unsuccessful.

"It could also be a reason why the bacteria manage to escape the immune system."

The researchers focused on examining antibodies in patients who had recovered from group A streptococcal infection.

They managed to identify three so-called monoclonal antibodies from a patient who recovered from a Strep A infection.

Monoclonal antibodies are identical copies of each other, and in this case target a single protein, the M protein, of the group A streptococci.

It turned out that the antibody with the newly discovered binding mechanism produced a strong immune response against the bacteria.

The researchers have now applied for a patent based on the findings in the article, and will continue to study the antibody.

Another study author, Dr. Wael Bahnan, added: “This opens up possibilities where previous vaccine attempts have failed and means that the monoclonal antibody we used has the potential to protect against infection."