Welcome back to know more about viruses!
Viruses only have a core genome consisting of
a single kind of nucleic acid (RNA or DNA)
contained within a protein shell / coat called the
capsid made of protein subunits called capsomeres
which is in many cases surrounded by a lipid –
containing membrane. They cannot grow or divide
by themselves. They must take over a living cell,
and force the cell to create copies of the virus.
The cell often dies in the process. The new viral
copies then invade other cells. When enough
cells are killed, the victim becomes sick and
Viruses were first discovered by a Russian botanist,
Dmitri Iosifovich Ivanovsky (1864-1920) in 1892 in
Tobacco Plant Disease. The Dutch microbiologist and
botanist, Martinus Willem Beijerinck (March 16, 1851
– January 1, 1931) independently replicated Dmitri
Ivanovsky’s experiments in 1898, gracefully
acknowledged Ivanovsky’s priority of discovery,
asserted that the newly found infective agent was
somewhat liquid in nature, and first called it
“contagium vivum fluidum” (contagious living fluid).
The name “virus” was later coined by
Beijerinck himself deriving it from the Latin word
“virus” referring to poison and other noxious
substances, first used in English in 1392. Virulent,
from Latin “virulentus” means “poisonous”.
The adjective viral dates to 1948. The term virion
(plural virions), which dates from 1959, is also used
to refer to a single, stable infective viral particle
that is released from the cell and is fully capable of
infecting other cells of the same type.
Unlike bacteria, viruses cannot stay on
inanimate objects, called fomites, contacted
by infected organisms and thence get into
other organisms coming into contact with such
The term “fomite” gained popularity after being
used in the 2011 film Contagion, although its use
led people to believe that the term referred to
germs spread through touching such objects,
instead of the objects themselves.
Seen the 2011 Sci-Fi / Medical Thriller / Disaster /
Pandemic movie, Contagion, by James Cameron,
which ran houseful for months in 3222 Screens in
the U.S. and world over – starred The Titanic (1997
– highest Box Office Grosser of the time, beaten
later by Avatar 2009, also by James Cameron) movie
– famed Kate Winslet as Dr. Erin Mears, an Epidemic
Intelligence Service Officer, who herself falls a
victim to the virus? Remember Kate won the
Academy (Oscar) Award for Best Actress for playing
Hanna Shmitz, the illiterate but book – loving Tram
Conductor, later turned Nazi Schutzstaffel SS agent,
and still later tried for Nazi War Crimes and
sentenced to life imprisonment and ultimately
killed herself in the prison, in the 2008 Stephen
Daldry directed movie, The Reader?
The word Fomite comes from the Latin “tinder,”
– a fomite is an object, such as a toilet seat, flush
handle, soap dispensers, tissue papers, stall
doors, bathroom exit handles,
cutting boards, sponges, and sink handles, cups,
books or items of clothing ) that, in themselves are
not harmful, but are able to harbor pathogenic
micro – organisms and thus may serve as agents
of transmission of infection.
Viruses were probably the earliest inhabitants
of our earth. Our Universe started in a rapid
expansion about 13.7 billion years ago –
The Big Bang – of everything, the building blocks
of all life and has evolved since that time. It is
thought that all of space was created in this first
moment. Viruses, the earliest inhabitants of our
earth started more than 6 billion years ago. Virus
self-assembly within host cells has implications
for the study of the origin of life, as it may support
the hypothesis that life could have started as
self-assembling organic molecules like the viruses.
The Bacteria arrived next about 4 billion years ago.
Anatomically modern humans arose in Africa only
about 200,000 years ago, and reached today’s
behavioral modernity barely 50,000 years ago!
More on viruses in the next page!