Influence of Caudovirales Phages on Humoral Immunity in Mice

Abstract

Bacteriophages are promising antibacterial agents. Although they have been recognized as bacterial viruses and are considered to be non-interacting with eukaryotic cells, there is growing evidence that phages may have a significant impact on the immune system via interactions with macrophages, neutrophils, and T-cell polarization. In this study, the influence of phages of podovirus, siphovirus, and myovirus morphotypes on humoral immunity of CD-1 mice was investigated. In addition, tissue distribution of the phages was tested in these mice. No common patterns were found either in the distribution of phages in mice or in changes in the levels of cytokines in the sera of mice once injected with phages. Importantly, pre-existing IgM-class antibodies directed against capsid proteins of phages with myovirus and siphovirus morphotypes were identified in mice before immunization. After triple immunization of CD1-mice with phages without any adjuvant, levels of anti-phage serum polyclonal IgG antibodies increased. Immunogenic phage proteins recognized by IgM and/or IgG antibodies were identified using Western blot analysis and mass spectrometry. In addition, mice serum collected after immunization demonstrated neutralizing properties, leading to a substantial decrease in infectivity of investigated phages with myovirus and siphovirus morphotypes. Moreover, serum samples collected before administration of these phages exhibited some ability to reduce the phage infectivity. Furthermore, Proteus phage PM16 with podovirus morphotype did not elicit IgM or IgG antibodies in immunized mice, and no neutralizing activities against PM16 were revealed in mouse serum samples before and after immunization.

Repetitive Exposure to Bacteriophage Cocktails against Pseudomonas aeruginosa or Escherichia coli Provokes Marginal Humoral Immunity in Naïve Mice

“…However, although the presence of phage-specific antibodies with neutralizing capacity, in particular IgG2a and IgG2b, was detected after repeated intraperitoneal applications of an A. baumannii -specific phage cocktail in naïve mice, this did in fact not negatively affect the efficiency of the phages in a wound infection model [ 60 ]. Antibody formation and neutralizing capacity depend on the phage type, especially the capsid and tail protein composition; therefore, phages vary in immunogenicity and can induce different antibody responses [ 58 , 59 , 67 ]. In a murine study, Chechushkov et al [ 67 ] found that phages with podovirus morphotype were non-immunogenic.…”

“…Antibody formation and neutralizing capacity depend on the phage type, especially the capsid and tail protein composition; therefore, phages vary in immunogenicity and can induce different antibody responses [ 58 , 59 , 67 ]. In a murine study, Chechushkov et al [ 67 ] found that phages with podovirus morphotype were non-immunogenic. In contrast, they observed an increase in neutralizing antibodies after triple immunization with phages of myovirus and siphovirus morphotypes [ 67 ].…”

“…In a murine study, Chechushkov et al [ 67 ] found that phages with podovirus morphotype were non-immunogenic. In contrast, they observed an increase in neutralizing antibodies after triple immunization with phages of myovirus and siphovirus morphotypes [ 67 ]. Additionally, Majewska et al identified multicopy proteins of phages [ 33 ], the T4 phage proteins Hoc, Soc and gp12 [ 37 , 68 ], as well as the conserved structural proteins gp22 and gp29 of Pseudomonas phages [ 69 ] as highly immunogenic.…”

“…However, they had only a low neutralizing capacity. A rapid increase in IgG levels after initial immunization may indicate the previous contact of experimental mice with the applied phages [ 67 ]. Conversely, naturally present phages in the gut may lead to immunological tolerance [ 59 ].…”

Potential application of a newly isolated phage BUCT609 infecting Stenotrophomonas maltophilia

“…In vivo experiments demonstrated that phages can reduce the bacterial load and weight of abscesses ( Capparelli et al, 2007 ). At the same time, increasing evidence suggests that phages may have a major impact on the immune system by interacting with macrophages, neutrophils, and T-cell polarization ( Chechushkov et al, 2021 ). Phage therapy as a potential regimen against drug-resistant bacteria still requires adequate clinical trials.…”