Bacterial immune evasion

Published on September 29, 2021   36 min

Other Talks in the Series: The Immune System - Key Concepts and Questions

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Welcome to this lecture on bacterial immune evasion. My name is Christoph Tang, I work on the interaction between bacteria and their host, and I am based at the Sir William Dunn School of Pathology at the University of Oxford. My talk will be about the way bacteria can evade the immune system. This is quite different to many of the lectures which you've had in this course, which is about the organisation and function of the immune system. I'll be talking about how bacteria can subvert immunity to survive within the host.
Why should we be interested in bacteria at all? Critically, bacteria are a leading cause of death globally. This pie chart shows data, from the WHO, of the causes of death worldwide. You can see that infectious diseases - which includes bacteria, parasitic, and viral diseases - cause a significant proportion of deaths every year. Additionally, bacteria such as tuberculosis and pneumococcus account for the vast majority of deaths from respiratory tract disease. Infections such as Helicobacter pylori make a significant contribution to cancer as an important cause of gastric cancer, and bacterial infection is the leading cause of perinatal death, particularly in low- and middle-income countries where organisms such as E. coli and group B streptococcus are important causes of neonatal sepsis and meningitis.
Aside from the deaths which are caused by bacterial infection, we now know that bacteria contribute to health and disease, by being part of our microbiome. Sequencing analysis is beginning to reveal just how complex the microbiome is, there are more and more studies coming out on a daily basis, showing how the microbiome influences development of the immune system, and influences important conditions such as obesity and neurological diseases. Another important feature is that by studying bacteria, we've now got important tools for molecular biology. CRISPR-Cas, which is now being widely used, is a system of bacterial immune defence against phage attack, and likewise, restriction modification systems (which are involved in bacterial immunity against phages) have led to the development of restriction enzymes, which allowed modern molecular biology. More recently we know that we are facing an increasing problem, an alarming problem, with the emergence of antimicrobial resistance, which will only increase over the next decades. It's important we understand bacteria for a variety of reasons.