THE VIRULENCE OF PNEUMOCOCCAL STRAINS T4, ST124, ST138 AND ST306 IN ZEBRAFISH EMBRYOS
KAUPPINEN, KAI (2012)
KAUPPINEN, KAI
2012
Lääketiede - Medicine
Lääketieteen yksikkö - School of Medicine
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2012-04-27
Julkaisun pysyvä osoite on
https://urn.fi/urn:nbn:fi:uta-1-22354
https://urn.fi/urn:nbn:fi:uta-1-22354
Tiivistelmä
Streptococcus pneumoniae (pneumococcus) is one of the most important human pathogens worldwide. The development of new effective protein based vaccines against the bacterium has long been goal of scientists.
The objective of this study was to gain information about the virulence of pneumococcal strains ST124, ST138 and ST306 in zebrafish embryos. These strains have known invasive disease potential in humans but the strains have not been tested in zebrafish embryos before. The T4 strain, with known survival rate in zebrafish embryos, served as a control strain to validate the results. This study gave information for future projects dealing with the development of pneumococcal vaccines and also explored further the zebrafish embryo as a model of disease.
Each bacterial strain was injected into blood circulation of zebrafish embryo. The survival of the embryos was followed daily and after 72 hours the final survival rates were calculated for each strain. The combined survival rate for ST124 was 25 %, for ST138 92% and for ST306 11 % (P<0.0001). The most striking result was the high survival rate of embryos infected with ST138. In humans and mice this strain and serotype (6B) is associated with high mortality.
There might be several reasons for the different behavior of the bacteria in zebrafish embryos. The somewhat lower temperature of the embryos might have an impact on pneumococcal virulence. Also, infection route was different in these experiments than in earlier mouse experiments where bacteria were inoculated into nasal cavity. Moreover, the lack of acquired immunity in zebrafish embryos might have an effect on the course of infection. It can also be that the capsule expression of ST138 is somehow altered in zebrafish embryos leading to the lower mortality observed.
As a conclusion, this study demonstrated that even though zebrafish embryos can be used as a model of disease, the differences in host environment might affect the virulence of the bacterium and must be recognized when using this model.
Asiasanat:Streptococcus pneumoniae, host-pathogen interactions, Danio rerio, experimental immunology
The objective of this study was to gain information about the virulence of pneumococcal strains ST124, ST138 and ST306 in zebrafish embryos. These strains have known invasive disease potential in humans but the strains have not been tested in zebrafish embryos before. The T4 strain, with known survival rate in zebrafish embryos, served as a control strain to validate the results. This study gave information for future projects dealing with the development of pneumococcal vaccines and also explored further the zebrafish embryo as a model of disease.
Each bacterial strain was injected into blood circulation of zebrafish embryo. The survival of the embryos was followed daily and after 72 hours the final survival rates were calculated for each strain. The combined survival rate for ST124 was 25 %, for ST138 92% and for ST306 11 % (P<0.0001). The most striking result was the high survival rate of embryos infected with ST138. In humans and mice this strain and serotype (6B) is associated with high mortality.
There might be several reasons for the different behavior of the bacteria in zebrafish embryos. The somewhat lower temperature of the embryos might have an impact on pneumococcal virulence. Also, infection route was different in these experiments than in earlier mouse experiments where bacteria were inoculated into nasal cavity. Moreover, the lack of acquired immunity in zebrafish embryos might have an effect on the course of infection. It can also be that the capsule expression of ST138 is somehow altered in zebrafish embryos leading to the lower mortality observed.
As a conclusion, this study demonstrated that even though zebrafish embryos can be used as a model of disease, the differences in host environment might affect the virulence of the bacterium and must be recognized when using this model.
Asiasanat:Streptococcus pneumoniae, host-pathogen interactions, Danio rerio, experimental immunology