28th October 2013
by Ana Toribio
The newly isolated Vibrio cholerae phages have been classified as members of the Myovirideae family because of their typical icosahedral heads and a long and contractile tails.
I still remember the informal chat after a seminar given by Dr Sam Kariuki, Wellcome Trust International Fellow and Head of Department at the Centre for Microbiology Research at the Kenya Medical Research Institute (KEMRI), where we discussed the possibility of including bacteriophage (viruses that kill bacteria) analysis within the exciting Vibrio cholerae program that Sam has in Kenya. Alice Nyambura, a student at Nairobi University, was interested in pursuing this project as well, so we all jumped on board to isolate and characterise Vibrio phages.
Why use Vibrio cholerae phages and what for? Two short answers for two short questions: because cholera is endemic in parts of Kenya and the region and because, ‘the enemy of my enemy is my friend’. Bacteriophage scientists often use this phrase to describe the ability of phages to kill bacteria and it explains their eventual application as bio-control agents in the environment or as antimicrobial agents to treat infections (this is called phage therapy). For example, in 2006, the US Food and Drug Administration approved the use of phages for the control of Listeria monocytogenes (a food contaminant) in some types of meat. Phages are also interesting entities from a microbiology point of view, mainly due to the genetic mechanisms involved in the relationship with their respective bacterial hosts.
When, in 1917, Felix d’Herelle discovered bacteriophages and described them as ultraviruses that were antagonist microbes to bacteria, he had a strong feeling that they would be a potential treatment for infectious diseases. Even before d’Herelle and fellow scientist Frederick Twort (independently) discovered the bacteriophages, it was reported that environmental waters had antibacterial activity against many types of bacteria such us the cholera vibrio. Thus, Vibrio cholerae has been linked to the use of phage to treat infections from the early stages of the story of the bacteriology.
In the very early stages of our project, the aim was to isolate and characterise Vibrio cholerae phages from environmental waters of the Lake Victoria region of Kenya. Alice focused her research on virulent phages, which are able to produce in vitro lysis of the bacterial cell. Meanwhile, as usual, David Goulding from the Sanger Institute was in charge of the electronic microscopy pictures of the new isolated phages. The morphological details discovered through this have allowed for the classification of the new isolated Vibrio cholerae phages. Because these phages have a typical icosahedral head and a long and contractile tail (notice the difference of the tail lengths in the two pictures of the same phage), they have been classified as members of the Myovirideae family.
The communications between scientists at the Sanger Institute in Cambridge and Alice and Sam in Kenya were so strong during the realisation of this project that it is hard to believe that I have never met Alice in person. Working so closely yet from such a vast geographical distance serves as further proof that science does break frontiers!
Ana Luisa Toribio did her PhD in the Microbial Pathogenesis group under the supervision of Professor Gordon Dougan working with phages. She is currently at the European Bioinformatics Institute working in the European Nucleotide Archive project.
References
- Alice Nyambura Maina, Francis B. Mwaura, Julius Oyugi, David Goulding, Ana L. Toribio, Samuel Kariuki (2013) Characterization of Vibrio cholerae Bacteriophages Isolated from the Environmental Waters of the Lake Victoria Region of Kenya. Current Microbiology.
PMID:23982202
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