Viruses Varieties Viral death Commentary

Martinus Beijerinck virology

Viruses

• Smaller than a bacterium,
• immune to heat,
• immune to chemicals,
• not a toxin,
• and able to grow
• only in living cells,
• Martinus Beijerinck realized
• it was a soluable living germ,
• and named it virus.

Varieties

• Beijerinck studied the tobacco mosaic virus.
• Friedrich Loeffler and Frosch found aphthovirus
• which causes foot-and-mouth disease.
• Frederick Twort discovered bacteriophages—
• viruses that infect bacteria.
• Scientists figured out how to grow viruses in the lab,
• which helped Jonas Salk create a vaccine for the poliovirus.
• Viruses are the most abundant biological entity on Earth,
• although many do not consider them to be a form of life
• because they do not have cells or their own metabolism.
• The smallpox virus has been eradicated,
• but yellow fever, measles, mumps and rubella,
• the herpes viruses, the Epstein-Barr virus, HIV,
• ebola, marburg,
• West Nile virus,
• hepatitis viruses,
• papillomaviruses,
• various influenza viruses
• and many others
• continue to plague us.

Viral death

• Phocine distemper virus kills harbor seals;
• canine parvovirus kills puppies;
• foot-and-mouth disease virus kills cattle;
• classical swine fever virus kills pigs;
• lactate dehydrogenase elevating virus kills mice;
• simian haemorrhagic fever virus kills monkeys;
• bluetongue virus kills sheep, goats, buffalo, deer, camels, and antelope;
• deformed-wing virus kills honeybees.
• Even though they do not live as we do;
• we talk of killing viruses.
• Vaccines for viruses stimulate our immune systems;
• whose killer cells use enzymes to disassemble viruses.