Polar flagella rotation in Vibrio parahaemolyticus confers resistance to bacteriophage infection

Abstract

Bacteriophage has been recognized as a novel approach to treat bacterial infectious diseases. However, phage resistance may reduce the efficacy of phage therapy. Here, we described a mechanism of bacterial resistance to phage infections. In Gram-negative enteric pathogen Vibrio parahaemolyticus, we found that polar flagella can reduce the phage infectivity. Deletion of polar flagella, but not the lateral flagella, can dramatically promote the adsorption of phage to the bacteria and enhances the phage infectivity to V. parahaemolyticus, indicating that polar flagella play an inhibitory role in the phage infection. Notably, it is the rotation, not the physical presence, of polar flagella that inhibits the phage infection of V. parahaemolyticus. Strikingly, phage dramatically reduces the virulence of V. parahaemolyticus only when polar flagella were absent both in vitro and in vivo. These results indicated that polar flagella rotation is a previously unidentified mechanism that confers bacteriophage resistance.Vibrio parahaemolyticus is the leading cause of diarrhea linked to the consumption of contaminated seafood worldwide 1 . Currently, the most common treatment for V. parahaemolyticus infection is antibiotics. However, increasing prevalence of antimicrobial resistance in V. parahaemolyticus, presumably due to the extensive use of antimicrobials in clinical treatment and aquaculture systems, was recently reported 2-4 . For instance, recent studies have shown that all isolates of V. parahaemolyticus are resistant to ampicillin and cephazolin and 50% of the clinical and environmental isolates are multi-drug resistant [2][3][4] . Particularly, recent isolates of V. parahaemolyticus have been shown to be resistant to new front-line antibiotics, e.g., fluoroquinolones and extended-spectrum cephalosporins 5 . Emergence of Vibrio species that are resistant to multiple antibiotics is a serious global problem and suggests that alternative treatment and prevention strategies are needed.Lytic bacteriophages (phages) that are widespread in nature are a group of viruses that can invade various bacterial species and eventually lyse the bacterial cells 6 . Studies have demonstrated that phages have the potential to alleviate infectious diseases caused by various bacterial pathogens 7 . One of the key advantages for phage therapy is that phages are active against antibiotic-resistant bacteria and they usually do not disturb beneficial microbiota 7,8 . The initial step for phages to invade their hosts is adsorption 9 . Adsorption is one the most intricate steps for the entire lytic cycle because phages must recognize specific bacterial components 10 . The primary receptors that are recognized by phages include bacterial surface-located proteins (e.g., outer membrane protein) [11][12][13][14] , lipopolysaccharide 15 and teichoic acids 16 . Resistance to phage adsorption occurs when these receptors are altered or masked by extracellular matrix or other structures 17 . Recent studies have shown that lateral flagella are required fo...

Hydrodynamics of bacteriophage migration along bacterial flagella

“…While all phages need to find themselves on the surface of the cell body for infection to take place, there is a class of phages, called flagellotropic phages, that first attach to the flagellar filaments of bacteria. Examples include the χ-phage infecting Escherichia coli (E. coli) and Salmonella typhimurium (Salmonella), the phage PBS1 infecting Bacillus subtilis (B. subtilis) and the recently discovered phage vB VpaS OWB (for short OWB) infecting Vibrio parahaemolyticus (V. parahaemolyticus) [19], illustrated in Fig. 2.…”

Natural Transformation in Vibrio parahaemolyticus: a Rapid Method To Create Genetic Deletions

“…Investigating the various mechanisms involved in bacterial pathogenesis at the genetic level most commonly involves genetic engineering. The standard and most widely used technique for achieving genetic modifications in V. parahaemolyticus employs a multistep process, including cloning of a gene-flanking region into a nonreplicating suicide vector, such as pDM4, electroporation into an S17-1 (pir) Escherichia coli strain for propagation, transfer of the plasmid into V. parahaemolyticus by conjugation, mutant selection in antibiotics, and final curing of plasmid (1,(9)(10)(11)(12)(13)(14). This process is laborious and can take up to 2 to 3 weeks before mutant strains are validated and useful for downstream applications.…”

Identification of a novel bacterial receptor that binds tail tubular proteins and mediates phage infection of Vibrio parahaemolyticus

“…The primers used in this study are listed in Table S2. Phage OWB-infected V. parahaemolyticus cultures were centrifuged (13,000×g at 4°C for 10 min), and the supernatants containing phage OWB were used in this study after filtration with a 0.22 μm filter [26]. Expression of phage OWB genes in DH5α was performed using the expression plasmid pGEX-4T-1 as described previously [27].…”

“…DNA of phage OWB was extracted as previously described [26]. Briefly, after polyethylene glycol (PEG) precipitation, the phage pellet was resuspended in sodium chloride magnesium sulfate (SM) buffer.…”

“…A phage drop assay was performed as previously described [26]. Briefly, freshly cultured V. parahaemolyticus strains were dropped on LB plates (approximately 10 4 CFU/ drop).…”