Briefly, to calculate ELISA models (EU), 10 points of standard serum dilutions were determined on each plate, and the dilution giving an optical density at 450 nm (OD450) of 1 1 was assigned as 1000 EU

Briefly, to calculate ELISA models (EU), 10 points of standard serum dilutions were determined on each plate, and the dilution giving an optical density at 450 nm (OD450) of 1 1 was assigned as 1000 EU. antagonized gut transit of active phage. Phage resistantE. colidominated gut flora very late, on day 92. Thus, the immunological response emerges as a major factor determining phage survival in the gut. Phage proteins Hoc and gp12 were identified as highly immunogenic. A low response to exemplary foreign antigens (from Ebola computer virus) offered on Hoc was observed, which suggests that phage platforms can be used in oral vaccine design. Keywords:T4 phage, EBOV, Ebola virus, oral administration, vaccine, phage display, capsid proteins, antibodies, phage resistance == 1. Introduction == Bacteriophages deliver a few important medical solutions. One of them is antibacterial therapy, which makes use of the natural ability ASP8273 (Naquotinib) of bacteriophages to kill bacteria. Currently, we are observing renewed interest in phage therapy as a promising alternative to antibiotics, mostly due to the problem of antibiotic resistance in bacteria. This inspires both recapitulation of previous experience and testing for an up-to-date methodology and approach [1,2,3,4,5,6,7]. Special regard is given to various aspects of phage interactions with organisms of treated individuals, since these interactions determine safety issues, phage pharmacokinetics, bioavailability and resulting outcomes of antibacterial treatment. The other popular phage solution is the technological approach to phages as nanocarriers that are able to deliver biologically active elements. Nanocarriers may deliver various kinds of drugs, but they can also constitute ASP8273 (Naquotinib) a platform that allows for exposure of selected antigens. Such bacteriophage-based platforms are proposed as a new generation of safe (non-pathogenic) and effective vaccines. T4 phage capsid has been experimentally used to expose antigens of difficult pathogens, ASP8273 (Naquotinib) e.g.,Neisseria meningitidis[8], anthrax [9,10] and HIV [11,12]. All medical applications of bacteriophages, including antibacterial therapy, vaccines and others, share a common feature: phages make direct contact with the mammalian organism and thus challenge the mammalian immunological system. One of the major consequences is a humoral response to a phage [13,14,15]. The humoral response, however, does not follow a simple schema of induction. It appears to depend on the route of phage administration and on individual features of a phage. It also depends on the dose and application schedule and possibly on other features, not yet specified [15,16,17,18]. As a consequence, it is not easy to draw a general conclusion about the effects that anti-phage antibodies have on the outcomes of therapeutic use of bacteriophages. Some authors found that the effect of the humoral response can be devastating [19], but others reported that anti-phage activity of serum does not exclude a favorable result of phage therapy in humans [17]. The first safety study of T4 phage application on humans revealed no antibody induction in phage-treated volunteers at all [2]. Difficulties with joint conclusions from different studies are related to the multi-factor nature of the immune system and its interactions with potential antigens. Probably one of the most complex systems that can be considered in terms of therapeutic phage application is the gut, with its dynamic balance of symbiotic and sometimes pathogenic bacteria, natural and possibly therapeutic bacteriophages, as well as a variety of mammalian host-related factors. New technologies for sequencing and the metagenomics approach have revealed extreme microbiological diversity of the natural gut ecosystem, including bacteriophages [20,21]. This microbial balance, and especially its impact on human health, has been recently reviewed by Dalmassoet al.[22]. In spite of emerging interest in the topic, little is known about the humoral response to therapeutic bacteriophages if they are applied orally, even though it is generally expected that phages present in the gut may induce specific antibodies [16,23]. Here we present a long-term study (240 days) of specific antibody induction by T4 phage appliedper osin a murine model: 100 days of phage treatment followed by 112 days without the phage, and then repeated treatment with the same phage up to day 240. The purpose of these studies was to provide immunological data Rabbit polyclonal to AKR1E2 useful for medical applications of bacteriophages, both those employing phages as antibacterials and those making use of phages as nanocarriers. In this work, the assessment comprised serum and gut antibodies (IgM, IgG, IgA) in relation to microbiological status of the animals: phage survival in gut and occurrence of phage-resistant bacteria. Immune response emerged as a major factor determining phage survival in the gut. The analysis concerned the individual impact of structural proteins on induction of the humoral response. Selected proteins were those exposed on the surface of phage head (gp23*, gp24*, Hoc, Soc) and the protein responsible for phage ability to infect bacteria (gp12). This allowed for the identification of highly immunogenic structural proteins and for further testing of the immune response to foreign antigen presented.