Week 1: How the body recognises a viral infection

Introduction

This week, you will be introduced to a range of acute and chronic viral infections, focusing on acute viral infections. You will take a close look at influenza-A and SARS-CoV2, the causative agent of COVID-19, as key examples – not just because of the recent pandemic but also because they are very informative. The role of antibodies in protection against viral disease and reinfection is an important component of immunity. This area, and vaccine development, will be discussed later in the course, but for now you will start with an overview of viruses and then move on to see how the innate immune system recognises and responds to an acute viral infection.

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Transcript: Video 1 Introduction to Week 1

DAVID MALE:

The COVID-19 pandemic swept across the world in 2020–2022, with waves of infection in different countries, produced by successive variants of the SARS-CoV2 virus. The rapid spread was made possible by the high infectivity of the virus and the fact that a substantial proportion of infected individuals had no symptoms. But, why should the course of this novel infection be so variable in different individuals? It is partly due to the differences in the immune systems of each person, but it also relates to the dose and variant of virus encountered.

The genome of the SARS-CoV2 virus was sequenced within days of the initial virus isolation and the importance of the viral spike protein which allows attachment to target cells, was immediately recognised. There followed an enormous research effort to produce vaccines which would induce antibodies against the spike protein. The production and distribution of millions of doses of vaccine followed on rapidly, and this required equally heroic efforts in biotechnology and logistics.

Understanding how the immune system protects against viruses and how this knowledge can be applied to vaccine development and the control of a pandemic disease is one of the great stories of modern science.

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Video 1 Introduction to Week 1

By the end of this week, you should be able to:

• outline the range of different viral infections
• describe the structure and genomes of influenza-A and SARS-CoV2 viruses
• identify intracellular receptors of the innate system that recognise viruses
• understand how interferons delay the spread of an acute virus infection.

The Open University would really appreciate a few minutes of your time to tell us about yourself and your expectations for the course before you begin, in our optional start-of-course survey [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] . Participation will be completely confidential and we will not pass on your details to others.