{"id":2241372,"date":"2019-12-26T12:01:53","date_gmt":"2019-12-26T17:01:53","guid":{"rendered":"https:\/\/www.futurity.org\/?p=2241372"},"modified":"2019-12-26T12:01:53","modified_gmt":"2019-12-26T17:01:53","slug":"staph-bacteria-vaccine-2241372","status":"publish","type":"post","link":"https:\/\/www.futurity.org\/staph-bacteria-vaccine-2241372\/","title":{"rendered":"2 new vaccine strategies may outsmart staph bacteria"},"content":{"rendered":"
New research in mice may explain why previous attempts to develop a staph vaccine have failed, while also suggesting a new approach to vaccine design.<\/p>\n
This approach focuses on activating an untapped set of immune cells, as well as immunizing against staph in utero or within the first few days after birth.<\/p>\n
Staph bacteria, the leading cause of potentially dangerous skin infections, are most feared for the drug-resistant strains that have become a serious threat to public health. Attempts to develop a vaccine against methicillin-resistant Staphylococcus aureus<\/em> (MRSA) have failed to outsmart the superbug’s ubiquity and adaptability to antibiotics.<\/p>\n The research, in mice, found that T cells\u2014one of the body’s major types of highly specific immune cells\u2014play 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.<\/p>\n “Across the globe, staph infections have become a pervasive health threat because of increasing antibiotic resistance<\/a>,” says senior author Juliane Bubeck Wardenburg, director of the Division of Pediatric Critical Care at Washington University in St. Louis. “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.”<\/p>\n Highly contagious, staph survives and thrives on human skin and can be spread through skin-to-skin contact or exposure via contaminated surfaces. Generally, the bacteria live harmlessly and invisibly in about one-third of the population. From their residence on the skin, the bacteria can cause red, pus-filled sores. Ever persistent, the superbug will deliver recurrent infections in about half of its victims.<\/p>\n Staph strains can enter the bloodstream, bones, or organs and lead to pneumonia<\/a>, severe organ damage, and other serious complications in hundreds of thousands of people each year. More than 10,000 people die in the US from drug-resistant staph infections annually.<\/p>\n “The focus in the vaccine field for Staphylococcus aureus<\/em> during the past 20 years has been on generating antibody responses, not on specific T cell responses,” Bubeck Wardenburg says. “This new approach shows promise.”<\/p>\n For nearly 15 years, Bubeck Wardenburg has studied a single toxin\u2014called alpha-toxin\u2014made by staph. This toxin 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 says.<\/p>\n “Understanding this allowed us to devise studies in mice that examined the effect of alpha-toxin on the immune response in minor skin infections as well as in more serious infections that spread in the bloodstream.”<\/p>\n 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.<\/p>\n “We discovered a robust T cell response targeting staph in the bloodstream,” Bubeck Wardenburg says. “By contrast, T cells were diminished in skin infections as a result of the toxin. Because skin infection is very common, we think that staph uses alpha-toxin to prevent the body from activating a T cell response that affords protection against the bacteria.”<\/p>\n In terms of the big picture, Bubeck Wardenburg says blocking the toxin in skin infections may yield a healthy T cell response.<\/p>\n 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,” she says. “The bug appears to be using the toxin to shape the T cell response in a way that’s favorable for the bug but not for humans.”<\/p>\n Previous vaccine development efforts have focused on adults. However, Bubeck Wardenburg says, 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.<\/p>\n “We envision two strategies,” Bubeck Wardenburg says. “One is immunizing pregnant women so they can transfer antibodies that protect infants against the toxin at birth. The second involves immunizing infants within a day or two after birth. Neither of these strategies has been considered for staph vaccines to date.”<\/p>\n The findings appear in the Journal of Clinical Investigation<\/em><\/a>.<\/p>\n