Bacteriophage biodistribution and infectivity from honeybee to bee larvae using a T7 phage model

Bacteriophages (phages) or viruses that specifically infect bacteria have widely been studied as biocontrol agents against animal and plant bacterial diseases. They offer many advantages compared to antibiotics. The American Foulbrood (AFB) is a bacterial disease affecting honeybee larvae caused by Paenibacillus larvae. Phages can be very significant in fighting it mostly due to European restrictions to the use of antibiotics in beekeeping. New phages able to control P. larvae in hives have already been reported with satisfactory results. However, the efficacy and feasibility of administering phages indirectly to larvae through their adult workers only by providing phages in bees feeders has never been evaluated. This strategy is considered herein the most feasible as far as hive management is concerned. This in vivo study investigated the ability of a phage to reach larvae in an infective state after oral administration to honeybees. The screening (by direct PFU count) and quantification (by quantitative PCR) of the phage in bee organs and in larvae after ingestion allowed us to conclude that despite 104 phages reaching larvae only an average of 32 were available to control the spread of the disease. The fast inactivation of many phages in royal jelly could compromise this therapeutic approach. The protection of phages from hive-derived conditions should be thus considered in further developments for AFB treatment.This study was supported by the project APILYSE, PTDC/CVT-EPI/4008/2014 - POCI-01-0145-FEDER-016598, - funded by FEDER through COMPETE 2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds trough FCT - Fundação para a Ciência e a Tecnologia, I.P. The work was also supported by the strategic funding of UID/BIO/04469/2013 unit, COMPETE 2020 (POCI-01-0145FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004), funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. HR was supported by FCT through the grant SFRH/BD/128859/2017. RC was founded by FCT and FEDER (POCI-010145-FEDER-007274).info:eu-repo/semantics/publishedVersio

Characterization of a new podovirus infecting Paenibacillus larvae

The Paenibacillus larvae infecting phage API480 (vB_PlaP_API480) is the first reported podovirus for this bacterial species, with an 58nm icosahedral capsid and a 12×8nm short, non-contractile tail. API480 encodes 77 coding sequences (CDSs) on its 45,026bp dsDNA genome, of which 47 were confirmed using mass spectrometry. This phage has got very limited genomic and proteomic similarity to any other known ones registered in public databases, including P. larvae phages. Comparative genomics indicates API480 is a new species as its a singleton with 28 unique proteins. Interestingly, the lysis module is highly conserved among P. larvae phages, containing a predicted endolysin and two putative holins. The well kept overall genomic organisation (from the structural and morphogenetic modules to the host lysis, DNA replication and metabolism related proteins) confirms a common evolutionary ancestor among P. larvae infecting phages. API480 is able to infect 69% of the 61 field strains with an ERIC I genotype, as well as ERIC II strains. Furthermore, this phage is very stable when exposed to high glucose concentrations and to larval gastrointestinal conditions. This highly-specific phage, with its broad lytic activity and stability in hive conditions, might potentially be used in the biocontrol of American Foulbrood (AFB).Te authors would like to aknowledge Dr. Mariano Higes Pascual from Laboratorio de Patología Apícola del Centro de Investigación Apícola y Agroambiental de Marchamalo (CIAPA-IRIAF) for gently providing us P. larvae isolates and the soil sample from which API480 was isolated. Tis study, carried out under the scope of the project APILYSE, PTDC/CVT-EPI/4008/2014 - POCI-01–0145-FEDER-016598, was supported by FCT - Fundação para a Ciência e a Tecnologia, under the scope of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020- Programa Operacional Regional do Norte. HR was supported by FCT through the grant SFRH/BD/128859/2017. MB and RL were supported by KU Leuven through a GOA grant [3E140356].info:eu-repo/semantics/publishedVersio