HIV and AIDS (AQA A-level Biology)

This fully-resourced lesson describes the structure of HIV, its replication inside helper T cells and EXPLAINS how it causes the symptoms of AIDS. The PowerPoint and accompanying resources are part of the 5th lesson in a series of 7 that cover the details of point 2.4 of the AQA A-level Biology specification.

The structure of viruses was covered during the lessons in topic 2.1, so this lesson starts by challenging the students to recall the capsid, genetic material in the form of viral RNA and the lipid envelope. At this point, the students are introduced to gp120, the glycoprotein which is exposed on the surface of the lipid envelope, as this structure is critical for the entry of the virus into host cells. Students will annotate a basic diagram of HIV with these four structures which also has gp41 labelled. A quick quiz competition introduces the names of the enzymes found inside the capsid and the students will learn that integrase allows the viral DNA to be integrated into the host’s genome whilst reverse transcriptase catalyses the reaction to form DNA from RNA. A prior knowledge check challenges the students to identify the helper T cells from a description of their function and they are informed that these immune cells have the CD4 glycoprotein on their surface.

Moving forwards, the main part of the lesson describes how HIV binds to the helper T cells, injects its capsid and integrates its DNA into the host’s genome in order to replicate to form virus particles (virions). Students are guided through the formation of a detailed answer about the mechanism of HIV and have to input key terms and structures where information is missing. Students will learn that the increase in the number of virus particles and a decrease in helper T cells and other immune cells results in infections like TB and by opportunistic pathogens and that this stage is recognised as AIDS

The final part of the lesson challenges the students to explain why antibiotics are ineffective against viruses through a series of exam-style questions and the final task gets them to work as a class where they have to study the replication process once more to suggest drug actions that might be used to treat HIV