An antibody therapy can treat an infection caused by a dangerous strain of bacteria that most antibiotics cannot kill. Although the treatment has not yet been tested in humans, it has been shown to be effective in mice.
methicillin resistant Staphylococcus aureus (MRSA) is one of the deadliest bacteria. It killed more than 100,000 people worldwide in 2019 and has evolved to avoid all but seven antibiotics.
“One of the challenges in treating [MRSA] is that the organism is very good at evading various immune responses,” says Victor Torres at NYU Langone Health in New York. It involves the body’s deployment of proteins known as antibodies, which identify and attack pathogens.
Torres and his team developed a treatment by introducing a genetic mutation into human antibodies that attack MRSA. They modeled small proteins called sentirins on the surface of the molecule – these prevent bacteria from burrowing into immune cells. Engineered antibody targets 10 disease-causing mechanisms of MRSA.
To test its efficacy, the researchers injected 20 mice with the antibody 4 hours after being infected with MRSA. Half of the mice received infection with the new antibody treatment while the other half received ineffective antibodies against the bacteria.
After three days, skin lesions in mice treated with the engineered antibodies were, on average, 95 percent smaller than those seen in the control group. They had an average of 98 percent fewer bacteria in their infected tissues than untreated animals, indicating that the treatment can ward off MRSA infections that progress to other organ systems.
The team conducted a separate experiment in 54 mice with MRSA-induced kidney infections and found that antibody treatment enhanced the efficacy of vancomycin, one of the so-called “last resort” antibiotics. The mice on the combination therapy had 99 percent fewer bacteria in their kidney tissue than mice treated with vancomycin alone.
“even though [this] products had failed to reach efficacy endpoints in human clinical trials, this is an important step,” says jim cassatt at Vanderbilt University Medical Center in Tennessee. That’s because it offers a new blueprint for designing antibody therapeutics, he says.
“number of [effective] Antibiotics are shrinking and shrinking and shrinking, says Torres. “Therefore, the importance of this research is to provide a new alternative or at least a new route by which we can generate new treatments to prevent death and infection.”