Skip to main content

LUP Student Papers

LUND UNIVERSITY LIBRARIES

Mycobacteriophages: isolation and mycobacterial killing

Kassaliete, Jana (2022) MOBN03 20212
Degree Projects in Molecular Biology
Popular Abstract
Isolation of mycobacteriophages for tuberculosis treatment

Tuberculosis (TB) is the second deadliest infectious disease after Covid-19. Due to the recent rise in antibiotic resistance, new avenues for TB treatment need to be explored. Bacteriophages are viruses that can infect bacteria and kill them. Mycobacteriophages consist of a phage head containing dsDNA and tail fibres that are used to attach to the bacteria. Advantages of phages are their ability to self-replicate and high host selectivity. Additionally, phages can be engineered to improve their properties.

There are two types of phages: lytic, that infect and kill the bacteria and lysogenic, that can integrate into the bacterial genome and co-exist with the host for many... (More)
Isolation of mycobacteriophages for tuberculosis treatment

Tuberculosis (TB) is the second deadliest infectious disease after Covid-19. Due to the recent rise in antibiotic resistance, new avenues for TB treatment need to be explored. Bacteriophages are viruses that can infect bacteria and kill them. Mycobacteriophages consist of a phage head containing dsDNA and tail fibres that are used to attach to the bacteria. Advantages of phages are their ability to self-replicate and high host selectivity. Additionally, phages can be engineered to improve their properties.

There are two types of phages: lytic, that infect and kill the bacteria and lysogenic, that can integrate into the bacterial genome and co-exist with the host for many generations. Environmental stress or damage to the bacteria can cause a lysogenic phage to exit the genome and become lytic. Mitomycin C is a chemotherapeutic that causes a specific type of DNA damage in the bacteria that forces the phage to exit bacteria. We induced four strains of non-virulent M. smegmatis and one strain of M. abscessus with mitomycin C to isolate lysogenic phages.

After the induction with mitomycin C the phages were purified, characterised, and tested for their killing capacity of M. smegmatis and M. bovis BCG. We optimised a method for isolating phages that involves precipitation of phage proteins and purification of phages using a density gradient. Phages were imaged in transmission electron microscopy and the entire genome of one sample was sequenced to characterise it. Preliminary analysis of the phage DNA revealed that we isolated a lysogenic phage with high similarity to a previously sequenced phage. The phages did not show the capacity to kill bacteria, possibly due to their lysogenic origin or the damage sustained during handling and processing.

Additionally, isolated phages were tested on human immune cells - monocytes. Phages are known to only harm the bacteria, which makes them a favourable candidate for future TB treatments. However, we observed slight inhibition of monocyte survival as well as an inflammatory response from the monocytes. This could be due to contamination from bacterial debris in the samples. Another possibility is that the lysogenic phages picked up a bacterial gene when induced by mitomycin C. While this is a cause of concern, the genome of a phage can be easily edited to suit the scientist's needs. Phage engineering allows the possibility of removing undesirable genes, such as the ones picked up from bacteria, or addition of new features. An exciting future application of phages could be as a vaccine or drug delivery system.




Master’s Degree Project in Molecular Biology 60 credits 2022
Department of Biology, Lund University

Advisors: Gabriela Godaly and Camilla Davids
Medical Microbiology, Division of Microbiology, Immunology and Glycobiology (Less)
Please use this url to cite or link to this publication:
author
Kassaliete, Jana
supervisor
organization
course
MOBN03 20212
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9103288
date added to LUP
2022-11-17 11:00:28
date last changed
2022-11-17 11:00:28
@misc{9103288,
  author       = {{Kassaliete, Jana}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Mycobacteriophages: isolation and mycobacterial killing}},
  year         = {{2022}},
}