Lecture on Rabies and Its History

Introduction

In the 1970s, thousands of vaccinated chicken heads were dropped over Europe.
- Purpose: To combat the rabies virus.
- Result: Confusion and happiness in wildlife.

Rabies, named after Lyssa, the spirit of mad rage, has been a threat for over 4,000 years.
Effects on hosts:
- Turns animals aggressive.
- Causes humans to fear water.
Remarkable ability to evade the immune system.

Viruses exist between life and death, requiring living cells to multiply.
Lyssa virus specifics:
- Composed of only 5 genes.
- Efficiently solves complex problems like infecting mammals, avoiding immune detection, and spreading to new hosts.

Entry and Targeting
- Begins with a bite from an infected animal, often a dog.
- Targets neurons (nerve cells) using receptors for entry.
Hijacking Cellular Machinery
- Utilizes microtubules and dynein motors to travel within cells.
- Avoidance of immune response mechanisms, specifically interferons.
Immunity Evasion
- Interferons usually alert immune systems and reduce protein production.
- Lyssa prevents neurons from producing interferons, staying hidden from the immune system.

Lyssa travels neuron to neuron, reaching the brainstem slowly (weeks to months).
Once in the brain, immune response becomes ineffective.
- Killer T-cells are misled and ordered to self-destruct by infected neurons.

Rabies vaccine is effective even post-exposure due to slow virus progression.
Early vaccination is crucial after exposure, especially from small bites (e.g., bats).

Rabies continues to be a significant threat, killing about 60,000 people annually, many of whom are children.
The importance of vaccination in controlling rabies is emphasized.
Long-term goal: Eradicate rabies and prevent resurgence.