Introduction

Pathogens evolve sophisticated adaptations to enter hosts, secure nutrients, and evade immune defences. Hosts, in turn, develop their own countermeasures, creating an ongoing evolutionary struggle.

Mechanisms of Entry and Evasion

Influenza viruses alter surface proteins to evade immune responses, explaining the need for annual vaccine updates. HIV targets specific receptors on immune cells, while SARS-CoV-2 exploits ACE2 receptors. Bacteria may utilise secretion systems to breach cell membranes. Each strategy reflects finely tuned adaptations honed over time.

Examples of Pathogen Strategies:

Nutrient Acquisition and Environmental Survival

Pathogens like the malaria parasite digest haemoglobin inside red blood cells. Outside the host, durable forms like anthrax spores endure harsh conditions. Prions resist standard sterilisation, underscoring the resilience some pathogens possess.

Immune Evasion and Modern Implications

Trypanosomes periodically change their surface antigens to evade immune recognition. Understanding such tactics informs treatment design, improving current therapies and guiding vaccine development. Preparing for emerging pathogens requires a thorough grasp of these evolving mechanisms.