Hepatitis B virus infects liver cells.
But this virus has a secret weapon.
Along with new whole virus particles,
the virus also generates a huge number 
of excess surface proteins.
These extra proteins don’t cause disease,
but they do attract antibodies.
As many as five hundred quadrillion 
of these proteins flood the bloodstream,
distracting antibodies designed 
to neutralize the whole virus.
But instead of directly attacking the whole virus,
antibodies are diverted
by the overwhelming number of surface particles,
often allowing the whole virus to escape
and go on to infect other liver cells.
It’s a cunning defense.
But Maurice Hilleman saw these excess particles
as the virus’s Achilles heel,
and the basis for the world’s first vaccine 
against hepatitis B.
