LysGH15, a Novel Bacteriophage Lysin, Protects a Murine Bacteremia Model Efficiently against Lethal Methicillin-Resistant Staphylococcus aureus Infection

Abstract

Phage-coded lysin is an enzyme that destroys the cell walls of bacteria. Phage lysin could be an alternative to conventional antibiotic therapy against pathogens that are resistant to multiple antibiotics. In this study, a novel staphylococcal phage, GH15, was isolated, and the endogenous lytic enzyme (LysGH15) was expressed and purified. The lysin LysGH15 displayed a broad lytic spectrum; in vitro treatment killed a number of Staphylococcus aureus strains rapidly and completely, including methicillinresistant S. aureus (MRSA). In animal experiments, a single intraperitoneal injection of LysGH15 (50 g) administered 1 h after MRSA injections at double the minimum lethal dose was sufficient to protect mice (P < 0.01). Bacteremia in unprotected mice reached colony counts of about 10 7 CFU/ml within 3.5 h after challenge, whereas the mean colony count in lysin-protected mice was less than 10 4 CFU/ml (and ultimately became undetectable). These results indicate that LysGH15 can kill S. aureus in vitro and can protect mice efficiently from bacteremia in vivo. The phage lysin LysGH15 might be an alternative treatment strategy for infections caused by MRSA.Staphylococcus aureus is a common and dangerous pathogen that causes various infectious diseases, including skin abscesses, wound infections, endocarditis, osteomyelitis, pneumonia, and toxic shock syndrome (2, 23). Treatment of these infections has become ever more difficult due to the emergence of multidrug-resistant strains, especially methicillin-resistant S. aureus (MRSA) (15,25,26,36,37). Vancomycin was effective against MRSA, but certain MRSA strains have already acquired resistance to vancomycin as well (vancomycin-resistant S. aureus [VRSA]), raising serious concerns within the medical community (17,18,37). Therefore, there is an urgent need for novel therapeutic agents directed against this formidable pathogen (2, 9).The phage lysin is encoded by the bacteriophage genome and is synthesized at the end of the phage lytic life cycle to lyse the host cell (30). Lysins belong to the family of mureolytic enzymes that directly destroy peptidoglycans in the bacterial cell wall. Previous studies have suggested that lysins from certain phages were highly efficient in lysing bacteria, especially when applied exogenously (11,14,21,22,29,35). As a potential antibacterial agent, lysins possess several promising features, namely, a distinct mode of action, species or type specificity, and bactericidal activity independent of the antibiotic susceptibility pattern (1). Indeed, there is a low probability that bacteria will develop resistance against lysin (12, 21).Some Staphylococcus phage lysins have been isolated and studied, including LysK, ClyS, MV-L, LysWMY, and ⌽H5; however, only MV-L and ClyS have been studied in in vivo assays (6, 33). In this study, a novel myovirus phage infecting S. aureus was isolated. The lysin derived from this phage, LysGH15, was expressed and refined. The lysin LysGH15 demonstrated a very broad host range and strong lytic activity. We evaluate...

Antimicrobial bacteriophage-derived proteins and therapeutic applications

“…76 Using a more potent staphylococcal endolysin (LysGH15) at the same concentration of~2 mg/kg offered the same level of protection from fatal bacteremia, but treatment could be extended up to an hour after MRSA challenge. 79 However, increasing potency was still unable to eliminate all bacterial burden. The added benefit of using LysGH15 over MV-L was its exceptional staphylolytic activity specifically toward MRSA strains.…”

“…Gu et al suggested that the increased MRSA specific potency could be a result of greater binding by LysGH15 to cell wall moieties present only on methicillin-resistant strains. 79 In an attempt to show this, a LysGH15 CBD fused to GFP (LysGH15B-GFP) was constructed and tested on both methicillin-resistant and methicillin-sensitive S. aureus strains. Unfortunately, this methodology was unable to show different binding affinities between the 2 strain types.…”

Identification and characterization of HolGH15: the holin of Staphylococcus aureus bacteriophage GH15

“…We have previously described the staphylococcal phage GH15 (Gu et al, 2011). The complete genome (GenBank accession number JQ686190.1) was sequenced and analysed , revealing that a putative lysis module exists in the GH15 phage genome (Gu et al, 2013).…”

“…The complete genome (GenBank accession number JQ686190.1) was sequenced and analysed , revealing that a putative lysis module exists in the GH15 phage genome (Gu et al, 2013). The lysin of GH15 (LysGH15) has been identified and the molecular mechanism of its lytic activity has been elucidated in previous studies (Gu et al, 2011(Gu et al, , 2014. However, the putative holin of GH15, as well as other homologous staphylococcal phage holins, has not been characterized.…”

Endolysins of Bacteriophages as an Anti-Methicillin Resistant Staphylococcus aureus Infection in Children: A Narrative Review

“…The results showed that 80a, phi 11, LysK, lysostaphin, 2638A, WMY, and vancomycin protected 100% of the animals from death, and Twort-or phiSH2-treated mice had less protection from systemic infection (50% -60% survivors), and P68 (administered in 20%) (55). the best time and dose of endolysin were 1h after post infection by injected intraperitoneally of GH15 lysin (56). A synergistic effect of Endolysins was also reported by Schuch et al in 2016, in an investigation of combination therapy with lysin CF-301 and daptomycin, vancomycin, oxacillin antibiotics for treating MRSA1 (29).…”