Analysis host-recognition mechanism of staphylococcal kayvirus phiSA039 reveals a novel strategy that protects Staphylococcus aureus against infection by Staphylococcus pseudintermedius Siphoviridae phages

Following the emergence of antibiotic resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), phage therapy has attracted significant attention as an alternative to antibiotic treatment. Bacteriophages belonging to kayvirus (previously known as Twort-like phages) have broad host range and are strictly lytic in Staphylococcus spp. Previous work revealed that kayvirus {phi}SA039 has a host-recognition mechanism distinct from those of other known kayviruses: most of kayviruses use the backbone of wall teichoic acid (WTA) as their receptor; by contrast, {phi}SA039 uses the {beta}-N-acetylglucosamine ({beta}-GlcNAc) residue in WTA. In this study, we found that {phi}SA039 could switch its receptor to be able to infect S. aureus lacking the {beta}-GlcNAc residue by acquiring a spontaneous mutation in open reading frame (ORF) 100 and ORF102. Moreover, {phi}SA039 could infect S. pseudintermedius, which has a different WTA structure than S. aureus. By comparison with newly isolated S. pseudintermedius-specific phage (SP phages), we determined that glycosylation in WTA of S. pseudintermedius is essential for adsorption of SP phages, but not {phi}SA039. Finally, we describe a novel strategy of S. aureus which protects the bacteria from infection of SP phages. Notably, glycosylation of ribitol phosphate (RboP) WTA by TarM or/and TarS prevents infection of S. aureus by SP phages. These findings could help to establish a new strategy for treatment of S. aureus and S. pseudintermedius infection, as well as provide valuable insights into the biology of phage-host interactions.