For some, Streptococcus means a sore throat. But for others, the bacteria’s associated danger makes a vaccine critical.

For most patients, it starts with a raw, scratchy throat. After a day or two, a fever develops and it hurts to swallow. Even sips of cold water become painful.

Strep throat: we’ve all had it.

Typically, the infection interrupts our daily lives and causes discomfort. For most patients, antibiotics easily combat the infection. Many feel better in 24 hours. Although some patients spread the bacteria for months, even after therapy.

But in some cases, the bacteria pose a greater threat.  Now, one University of Minnesota expert aims to tackle Streptococcus once and for all. His vaccine is designed to cripple the bacteria’s ability to infect humans.

For years, University of Minnesota microbiologist Dr. Patrick Cleary has worked to put the spotlight on the infection. Since 1972, Dr. Cleary has investigated the molecular basis of StrepA infections and immunology. He also recently developed a vaccine to prevent sore throats and potentially serious medical complications.

It’s just strep throat. No big deal. Right?

Well, not always. In some cases, Streptococcus can cause a number of associated complications:

• Pharyngitis and tonsillitis (inflammation of the throat and tonsils)
• Impetigo (blistering skin infection)
• Toxic shock (fever, shock and death)
• Necrotizing fasciitis (flesh-eating disease)
• Rheumatic fever (the immune system attacks the heart, brain, joints and skin)

Because of these associated risks, Group A Streptococcus (StrepA) is a substantial public health problem, particularly in underdeveloped countries where access to health care is in short supply.

Not only are Streptococci masters of immune avoidance, current prevention measures are often inadequate or ineffective, as evidenced by significant morbidity and mortality rates associated with the bacteria. In fact, nearly five percent of children under the age of 15 in parts of Africa, Cambodia and South America have damaged heart valves as a result of StrepA-induced rheumatic fever.

Cleary discovered that the C5a peptidase on the surface of StrepA (an enzyme which breaks down sentinels of immune recognition) is a prime vaccine candidate. The peptidase destroys the C5a signal, which prevents detection of the bacteria by white blood cells.

“The peptidase we discovered essentially covers the tracks of Streptococcus, so the bacteria can hide from the body’s protective white blood cells. When left alone, the bacteria expand their number and cause damage,” explained Cleary.

“The vaccine I developed neutralizes the peptidase, allowing white blood cells to follow the C5a signal to streptococci. Once there, the white cells ingest and kill the streptococci before an infection is established.”

The results of trials in the animal model suggest that the vaccine will provide protection against StrepA infections. Human clinical trials are expected to begin in the upcoming years.

Cleary still faces many obstacles associated with the process of vaccine development.

“The biggest issue to tackle is education,” he said. “Public resistance and skepticism toward vaccines has increased dramatically over the past few years. Misinformation and fear about vaccines means the health science community must work hard to inform the public about their benefits.”

Universal use of the vaccine could potentially save hundreds of thousands of trips to the doctor and many lives each year. It is Cleary’s hope that, with the right educational approach combined with greater access to health care, the vaccine will make a positive impact on global public health.

--- Sarah Hamman