eCAPs, the next cool thing to fight antibiotic resistant infection?

CyrilCrodius

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Through the serendipity of science, researchers at the University of Pittsburgh have discovered a potential treatment for deadly, drug-resistant bacterial infections that uses the same approach that HIV uses to infect cells. The National Institutes of Health-supported discovery will be described in the June issue of the journal Antimicrobial Agents and Chemotherapy. It is especially promising in the development of a potential treatment for lung infections in people with cystic fibrosis.


"The discovery of this new antibiotic was an unexpected result of basic research on HIV proteins," said senior author Ronald Montelaro, Ph.D., professor and co-director of Pitt's Center for Vaccine Research (CVR). "As a result of studying these proteins, we discovered novel structures that turn out to work very well against bacterial infections, including the complicated bacterial populations in lung infections in cystic fibrosis patients."


Dr. Montelaro and his colleagues found that a particular sequence of amino acids on the tail end of HIV allow the virus to "punch into" and infect cells. The team manufactured a synthetic and more efficient version of this sequence -- called engineered cationic antimicrobial peptides, or "eCAPs" -- that laboratory tests have shown to rapidly destroy bacteria that are otherwise resistant to most standard antibiotics.


The eCAPs can be assembled in a laboratory setting from the amino acids arginine and tryptophan and manufactured to the shortest effective length, giving the resulting antibiotic treatment maximum potency while reducing costs.

The discovery was featured in April at two gatherings intended to put scientists in touch with business developers -- the BIO International Convention in Chicago, and the University Research & Entrepreneurship Symposium (URES) in Boston.


"At both symposia, we received a lot of interest from pharmaceutical-related companies," said co-author Jonathan Steckbeck, Ph.D., M.B.A., post-doctoral associate at CVR. "It was a particular honor to be recognized at URES as one of the year's 10 breakthroughs in life sciences."


Pitt has taken out several U.S. and international patents on this discovery.


"We have an unmet clinical need for treatment of hospital-acquired infections where the bacteria are extremely resistant to antibiotics," said co-author Yohei Doi, M.D., Ph.D., assistant professor of medicine in Pitt's School of Medicine. "We have patients with no treatment options left. The fact that these eCAPs are completely engineered puts them at an advantage because they can be manufactured easily, and they give us some hope for a quick-acting treatment in these dire circumstances."


Traditional antibiotics typically work by poisoning important metabolic processes after being taken up by the target bacteria, a process that may take hours, or days, to clear a bacterial infection. In contrast, the eCAPs are specifically attracted to the surface of target bacteria where they disrupt the bacterial membrane, causing death within seconds, or minutes.


Laboratory tests indicate that the eCAPs work well against biofilms, which are bacterial communities that develop very high levels of resistance to antibiotics by working together to protect the film's inner bacteria from traditional treatments. The eCAPs seem to push through the outer layers of biofilms to destroy the entire bacterial community.


"It's like a pin bursting a balloon; it's a very rapid action," said Dr. Montelaro. "While cystic fibrosis patients are our initial target and a very high-priority target, we also could look at infections associated with burns or indwelling medical devices, such as venous catheters. We could even look to the biodefense realm, in terms of a rapid, handheld nebulizer treatment that soldiers could use in the case of exposure to a bioterrorism agent."


Additional co-authors are Berthony Deslouches, M.D., Ph.D., and Jodi Craigo, Ph.D., both of Pitt's Center for Vaccine Research; and Timothy A. Mietzner, Ph.D., of the Lake Erie College of Osteopathic Medicine at Seton Hill.




Source : http://www.sciencedaily.com/releases/2013/05/130507155033.htm

P.S. I love that website.
 

CyrilCrodius

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http://aac.asm.org/content/57/6/2511.abstract
The emergence of multidrug-resistant (MDR) pathogens underscores the need for new antimicrobial agents to overcome the resistance mechanisms of these organisms. Cationic antimicrobial peptides (CAPs) provide a potential source of new antimicrobial therapeutics. We previously characterized a lytic base unit (LBU) series of engineered CAPs (eCAPs) of 12 to 48 residues demonstrating maximum antibacterial selectivity at 24 residues. Further, Trp substitution in LBU sequences increased activity against both P. aeruginosa and S. aureus under challenging conditions (e.g., saline, divalent cations, and serum). Based on these findings, we hypothesized that the optimal length and, therefore, the cost for maximum eCAP activity under physiologically relevant conditions could be significantly reduced using only Arg and Trp arranged to form idealized amphipathic helices. Hence, we developed a novel peptide series, composed only of Arg and Trp, in a sequence predicted and verified by circular dichroism to fold into optimized amphipathic helices. The most effective antimicrobial activity was achieved at 12 residues in length (WR12) against a panel of both Gram-negative and Gram-positive clinical isolates, including extensively drug-resistant strains, in saline and broth culture and at various pH values. The results demonstrate that the rational design of CAPs can lead to a significant reduction in the length and the number of amino acids used in peptide design to achieve optimal potency and selectivity against specific pathogens.

Emphasis mine. What is in bold is very important. Scientists have previously tried to use peptides to kill bacteria, but they faced a problem where the efficiency of the peptides depended greatly on the environment's pH, levels of salt and the presence of other ions. You can read about it here. Now what they have done is find a peptide that is effective in all kinds of difficult environments.

Bacterial killing kinetic assays in serum revealed that WLBU2 achieved complete bacterial killing in 20 min.

I think this was worth quoting.
 
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