Unraveling Capsular Switching in Indian Streptococcus pneumoniae Isolates (ISPPD conference poster)
- 1 minBangalore, India 2024
I presented this project as a poster in the 13th meeting of the International Society of Pneumonia and Pneumococcal Diseases (ISPPD) held in Cape Town, South Africa
Introduction
Streptococcus pneumoniae, a common respiratory pathogen, employs a clever strategy to evade the host immune system: capsular switching. By exchanging capsule biosynthesis loci, this bacterium can change its appearance, making it harder for the immune system to recognize and attack. This study aimed to investigate capsular switching events among Indian S. pneumoniae isolates and explore the genetic mechanisms driving this phenomenon.
Methods
We analyzed a collection of 630 S. pneumoniae isolates collected from various regions in India. These isolates were subjected to whole-genome sequencing to obtain their genetic information. To further analyse the data I employed the GPS pipeline which is built on Nextflow and integrated with the Seroba pipeline for in-silico serotyping, we reconstructed the evolutionary history of these isolates and analyzed their capsular types by using the Gubbins software to predict recombination events potentially leading to Capsular switching. I also employed Phandango to visualise the recombination regions on the genome and Microreact for the epidemiological visualisation.
Results
Through our analysis, we identified four distinct instances of capsular switching. This means that these bacteria changed their capsular type during their evolution. Interestingly, these switches occurred between serotypes that are typically closely related, such as 9V to 9A and 6A to 6B.
Furthermore, we found strong genetic evidence supporting these capsular switching events. By examining the genetic makeup of the capsule genes, we identified recombination events, which are molecular processes that can lead to the exchange of genetic material. These recombinations provide compelling evidence for the occurrence of capsular switching in these isolates.
Poster
Srikanth Srinivas
Bioinformatics graduate student at University of Bristol | Former Bioinformatics Intern at Global Health Research Unit, CRL, KIMS