Isolation and characterisation of KP34—a novel φKMV-like bacteriophage for Klebsiella pneumoniae

Bacteriophage KP34 is a novel virus belonging to the subfamily Autographivirinae lytic for extended-spectrum β-lactamase-producing Klebsiella pneumoniae strains. Its biological features, morphology, susceptibility to chemical and physical agents, burst size, host specificity and activity spectrum were determined. As a potential antibacterial agent used in therapy, KP34 molecular features including genome sequence and protein composition were examined. Phylogenetic analyses and clustering of KP34 phage genome sequences revealed its clear relationships with “phiKMV-like viruses”. Simultaneously, whole-genome analyses permitted clustering and classification of all phages, with completely sequenced genomes, belonging to the Podoviridae

The structure and function of human IgA subclasses

An unusual structural feature of human immunoglobulin A (IgA) is the heterogeneity of the molecular forms, with a characteristic distribution in various body fluids. Serum IgA is largely monomeric, but in external secretions it exists as S-IgA - a dimer consisting of two IgA molecules bound together by J chain and attached to secretory piece (SC). Both in serum and secretions IgA occurs in two isotypic forms, IgA1 and IgA2. IgA2 exists as two known allotypes, namely IgA2m(1) and IgA2m(2), with a form IgA2(n) possibly representing a third allotype. The major difference between the IgA subclasses is an absence of 13-aminoacid segment in the hinge region of IgA2 that is found in IgA1 molecules. This truncated hinge region in IgA2 molecules renders them resistant to at least two families of IgA1-specific bacterial proteases, which presumably is advantageous to IgA2 antibody function at mucosal surfaces. Further and profound structural difference between the iα1 and α2 chains concerns the distribution and composition of the oligosaccharide side chains. The IgA1 contains two N-linked glycosylation sites (Asn263 in the CH2 domain and Asn459 in the tail piece) as well as nine potential O-linked glycosylation sites in the hinge region. All three IgA2 variants lack these O-linked sugars, but they have two extra N-linked glycosylation sites (Asn166 in the CH1 and Asn337 in the CH2). The IgA2m(2) and IgA2(n) allotypes have a fifth potential N-linked side in the CH1 (Asn211) domain. The variations in the glycosylation structure of the different form of IgA play a significant role in determining antibodies conformation and assembly, receptors (TCR, ASGP-R) binding and t1/2. Here we review current knowledge concerning the relationship of the structure of human IgA1 to the IgA2 isotype, the polymeric IgA and secretory IgA structures, and IgA function

Learning from Bacteriophages - Advantages and Limitations of Phage and Phage-Encoded Protein Applications

The emergence of bacteria resistance to most of the currently available antibiotics has become a critical therapeutic problem. The bacteria causing both hospital and community-acquired infections are most often multidrug resistant. In view of the alarming level of antibiotic resistance between bacterial species and difficulties with treatment, alternative or supportive antibacterial cure has to be developed. The presented review focuses on the major characteristics of bacteriophages and phage-encoded proteins affecting their usefulness as antimicrobial agents. We discuss several issues such as mode of action, pharmacodynamics, pharmacokinetics, resistance and manufacturing aspects of bacteriophages and phage-encoded proteins application.status: publishe