BSc/MSc project on characterisation of astrithrvirus, a novel group of tiny phages at Københavns Universitet

The aim of this project is to perform a thorough characterization of a small group of so far undescribed Salmonella phages (virus of bacteria). Recently one of the isolates, Salmonella phage astrithr, gave rise to a new genera Astrithrvirus Astrithr. This genus has been posed by the International Committee on Taxonomy of Viruses (ICTV) to receive a higher taxonomic rank in future ratifications. But apart from the isolation host, isolation source and genomic sequence we know very little about these tiny viruses which can attack and completely take over and ultimately kill bacteria to produce their own progeny, all with just 15 genes.

Background: The group consists of three phages, Astrid, assan and astrithr, though Astrid and assan are considered strains of Salmonella virus Astrithr. They were all isolated from wastewater from Estbjerg and Skovlund using Salmonella enterica subsp. enterica serovar Enteritidis PT1 as propagation host. Phages with small genomes (16-20 kb with 20-29 CDS) are usually characterized by their special tail structure, inverted terminal repeats (ITR) and a rare protein primed polymerase (type B).The astrithrviruses have even smaller genomes (11.6-11.7 kb) and encode only 15 potential genes and even though they also have ITR and encode type B polymerases, they have very low DNA sequence similarity (39%) with all other published phage genomes. One of the project aims is to obtain TEM images of these phages and another is to investigate its infection effectivity and range.

Techniques: Microbiology; phage characterisation, imaging (transmission electron microscopy TEM), host range analysis, adsorption, burst size and latency period assays, investigations of the effect of co-infection with other phages (Jerseyvirus) or phage therapy related assays. Possibly also DNA work; primer design, PCR, sequencing, bioinformatics.The obtained results are expected to be included in a scientific publication presenting the Astrithrvirusgenus.

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Contact information:

Postdoc Nikoline S. Olsen (sno@plen.ku.dk) or Professor Lars H. Hansen (lhha@plen.ku.dk)

Microbial Ecology and Biotechnology
Section of Plant and Environmental Sciences
Thorvaldsensvej 40, 1871 Frederiksberg C

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