Why is there no staph vaccine?

Staph bacteria are mostly feared for drug-resistant strains, which are becoming a serious threat to public health because they are the leading cause of potentially dangerous skin diseases. Attempts to establish a Staphylococcus aureus methicillin-resistant vaccine (MRSA) did not outsize the ubiquity and antibiotic adaptability of the superbug.

Research from 'Washington University School of Medicine' in St. Louis may help to explain why past vaccination attempts failed, as well as proposing a new approach to vaccine design. This strategy concentrates on the stimulation, during or within the first few days after birth, of untapped immune cells and the immunization against staphs.

The research, in mice, found that T cells (one of the body's major types of highly specific immune cells) play a critical role in protecting against staph bacteria. Most vaccines rely solely on stimulating the other main type of immune cells, the B cells, which produce antibodies to attack disease-causing microorganisms such as bacteria.

The findings are published in the 'Journal of Clinical Investigation.'

A senior author Juliane Bubeck Wardenburg, MD, PhD, Director of University's Division of Pediatric Critical Care said: "Across the globe, staph infections have become a pervasive health threat because of increasing antibiotic resistance. Despite the medical community's best efforts, the superbug has shown a consistent ability to elude treatment. Our findings indicate that a robust T cell response is absolutely essential for protection against staph infections."

Highly contagious staph survives and thrives on human skin and can be spread through skin-to-skin contact or exposure via contaminated surfaces.

In total, about one-third of the population lives in harmless and unseen environments. Bacteria can cause red, pus-filled sores from their skin residence.

Staphs may enter the bloodstream, bones or liver and cause hundreds of thousands of people to contract pneumonia, major organs failure and other serious complications each year. More than 10,000 individuals in the US die each year from prescription staph infections.

"The focus in the vaccine field for Staphylococcus aureus during the past 20 years has been on generating antibody responses, not on specific T cell responses," Bubeck Wardenburg said.

For nearly 15 years, Wardenburg has studied a single toxin called 'Alpha Toxin' which plays a role in tissue damage in multiple forms of infection. "An important thing about the alpha-toxin is that it is found in all staph strains, meaning those that are and are not antibiotic-resistant," she said.

Wardenburg further mentioned that the study helped to improve research on the impact of alpha-toxin on immune response in minor skin infections and on more severe blood-stream infections.

The researchers found that the immune cells did not protect mice that had minor staph infections on their skin. However, mice that were exposed to life-threatening staph infections in the bloodstream did develop protection.

"We discovered a robust T cell response targeting staph in the bloodstream," Bubeck Wardenburg said.

In terms of the big picture, Bubeck Wardenburg said blocking the toxin in skin infections may yield a healthy T cell response.

Further, protecting the T cell response from the time of birth may reprogram the bacteria's overall effect on the immune system.

"This bug is deliberate and acts in a sinister way early on. The bug appears to be using the toxin to shape the T cell response in a way that's favourable for the bug but not for humans," said Bubeck.

Previous vaccine development efforts have focused on adults. However, Bubeck Wardenburg said, a vaccine may be more likely to succeed if administered before infants first encounter staph.

Therefore, immunization should happen before initial exposure to staph, to block the toxin and generate a vigorous T cell response.

Bubeck Wardenburg said, "We're planning two approaches. "One of these steps involves immunizing pregnant women in the presence of antibodies to shield babies against birth contaminants. The second is to immunize children two or two days after birth. Neither of these strategies has been considered for staph vaccines to date.