The Story of How the Deadliest Virus to Humans Was Revived

Subject :Science and Technology

Section: Health

Introduction

From a two-part story on the virus that caused the Great Influenza epidemic (1918 Spanish flu).
Johan Hultin‘s request to exhume a mass grave in Brevig Mission, Alaska.
Objective: To retrieve preserved genetic material of the deadliest virus for revival.

Recreating Viruses in the Lab

Scientists engineer viruses by altering the genetic material (DNA/RNA) of existing viruses.
Purpose: Understand virus properties, effects of mutations, and implications.
Viruses cannot be created from scratch; reliance on natural samples.

The Hunt for the Deadliest Strain

Jeffery Taubenberger’s work on the influenza virus.
Goal: Understand why some influenza strains cause pandemics.
Focus on the genetic makeup of the 1918 influenza virus (Spanish flu).
The 1918 virus (RNA Virus) infected 500 million people, causing severe disease and 50 million deaths.
After 1920, the virus vanished; subsequent outbreaks were less deadly.
Designation using “H” (haemagglutinin) and “N” (neuraminidase) genes (e.g., H1N1).

Importance of ‘H’ and ‘N’

Influenza strains are classified by haemagglutinin (H) and neuraminidase (N) subtypes.
18 subtypes of H (H1-H18) and 11 subtypes of N (N1-N11).
Strains are determined by the combination of H and N subtypes.
Different sub-variations influence virus properties and severity.

Genetic Sequence Unveiled

Hultin’s samples allowed sequencing of the virus’s full genetic code.
Virus’s origins were traced to avian ancestors with adaptation to mammals.
Evolution of virus from avian to human/swine infection.
Recurrence as a deadly pathogen after circulating and evolving.

Recreating Influenza Viruses

Influenza viruses exhibit annual genetic changes, leading to the need for updated vaccines.
Vaccination effectiveness depends on predicting viral mutations.
Influenza viruses can infect various animals like birds, pigs, and horses.
Inter-species infections can create new viral variants, complicating vaccine strategies.
The United States Centers for Disease Control and Prevention (CDC) is the apex organization in the U.S. on matters of public health and safety.
In 2005, the CDC received an application to study a very old infectious agent.

Investigating Virulence

Terrence Tumpey‘s approach involved creating “recombinant” viruses.
Recombinant viruses contain H1 and N1 gene segments from the 1918 strain.
The remaining genetic material originated from a laboratory strain that caused mild disease.
The experiment aimed to identify which gene segments contributed to the 1918 virus’s severity.
Initial tests indicated increased disease severity in mice with the 1918 H1N1 genes.

Uncovering Viral Impact

Autopsy results revealed extensive lung damage in mice infected with the 1918 virus.
Focus on understanding the role of specific genes, particularly haemagglutinin (access to cells) and RNA polymerase (making copies).
Both genes played a significant role in virulence, especially when interacting with other segments.

Recreation of the Full Virus

Tumpey’s research required recreating the entire 1918 H1N1 influenza virus.
The process involved mixing the genetic material of all eight virus gene segments.
The revived virus was successfully brought back from extinction after nearly a century.
The recreated virus demonstrated an unparalleled level of pathogenicity compared to other influenza variants.
The research paved the way for developing improved therapeutics and preventive measures.