High-Sensitivity Monoclonal Antibodies Specific for Homoserine Lactones Protect Mice from Lethal Pseudomonas aeruginosa Infections

Abstract

cA number of bacteria, including pathogens like Pseudomonas aeruginosa, utilize homoserine lactones (HSLs) as quorum sensing (QS) signaling compounds and engage in cell-to-cell communication to coordinate their behavior. Blocking this bacterial communication may be an attractive strategy for infection control as QS takes a central role in P. aeruginosa biology. In this study, immunomodulation of HSL molecules by monoclonal antibodies (MAbs) was used as a novel approach to prevent P. aeruginosa infections and as tools to detect HSLs in bodily fluids as a possible first clue to an undiagnosed Gram-negative infection. Using sheep immunization and recombinant antibody technology, a panel of sheep-mouse chimeric MAbs were generated which recognized HSL compounds with high sensitivity (nanomolar range) and cross-reactivity. These MAbs retained their nanomolar sensitivity in complex matrices and were able to recognize HSLs in P. aeruginosa cultures grown in the presence of urine. In a nematode slow-killing assay, HSL MAbs significantly increased the survival of worms fed on the antibiotic-resistant strain PA058. The therapeutic benefit of these MAbs was further studied using a mouse model of Pseudomonas infection in which groups of mice treated with HSL-2 and HSL-4 MAbs survived, 7 days after pathogen challenge, in significantly greater numbers (83 and 67%, respectively) compared with the control groups. This body of work has provided early proof-of-concept data to demonstrate the potential of HSL-specific, monoclonal antibodies as theranostic clinical leads suitable for the diagnosis, prevention, and treatment of life-threatening bacterial infections.

Alternatives to antibiotics—a pipeline portfolio review

“…Thus an antibody targeting a virulence factor or quorum sensing would be included but a compound targeting these processes would not. 4,5 Biologicals or compounds targeting the host were included. This review focused on therapies that could be developed to treat systemic/invasive rather than superficial infections and is therefore limited to therapies that are administered orally, by inhalation or by injection.…”

Monoclonal Antibodies and Antibody Like Fragments Derived from Immunised Phage Display Libraries

“…Infection control using high affinity monoclonal antibodies specifically targeting the quorum sensing (QS) molecules of Pseudomonas aerugi-nosa has been reported from our laboratory [78]. A number of Gram negative bacteria, including pathogens like P. aeruginosa, utilise homoserine lactones (HSLs) as QS signalling compounds and engage in cell-to-cell communication to coordinate their behaviour.…”

“…This characteristic feature makes sheep library construction simpler, as the entire heavy and light chain gene repertoire can be amplified using a small number of primers. Much of the antibody diversity is achieved through antigen-independent post-rearrangement somatic hypermutation, which diversifies all CDRs as compared to the sole variability of just CDR3 in humans and mice [17,62,78,84]. Comparison of chicken and sheep responses by hyperimmunisation with the same immunogen revealed the ability of the sheep immune system to produce higher specificity antibodies than chicken [109].…”

In vitro gene expression‐coupled bacterial cell chip for screening species‐specific antimicrobial enzymes

“…Recent studies report that altering the gut microbiome by overuse of antibiotics increases risks of asthma (Korpela et al, 2016) and other allergies (Reynolds and Finlay, 2013), obesity (Cox et al, 2014), and vulnerability to many diseases due to an altered immune system (Modi et al, 2014). To that end, alternatives to antibiotics are being developed, including antibodies (Hua et al, 2014;Palliyil et al, 2014), probiotics (Goldenberg et al, 2013;Kotzampassi and Giamarellos-Bourboulis, 2012;Villena and Kitazawa, 2014), bacteriophages (Abedon et al, 2011;Kutter et al, 2010;Lu and Collins, 2007), vaccines (Andrade et al, 2016;Hampton et al, 2012;Palmu et al, 2014), and lysins (Briers et al, 2014;Jun et al, 2014;Schuch et al, 2014;Yang et al, 2014) some of which are currently in phase 2 and 3 clinical trials (Czaplewski et al, 2016). To that end, alternatives to antibiotics are being developed, including antibodies (Hua et al, 2014;Palliyil et al, 2014), probiotics (Goldenberg et al, 2013;Kotzampassi and Giamarellos-Bourboulis, 2012;Villena and Kitazawa, 2014), bacteriophages (Abedon et al, 2011;Kutter et al, 2010;Lu and Collins, 2007), vaccines (Andrade et al, 2016;Hampton et al, 2012;Palmu et al, 2014), and lysins (Briers et al, 2014;Jun et al, 2014;Schuch et al, 2014;Yang et al, 2014) some of which are currently in phase 2 and 3 clinical trials …”