I nf luenza
Viruses pictured clockwise from top:
Adenovirus (causes the common
cold), Influenza A (causes the flu),
and Hepadnavirus (causes hepatitis
Chlorella viruses attached to an algal cell.
Marker in the left panel is 1.5 µm; in the right panel it is 0.33
The polio virus, left, once crippled
millions. Courtesy of the
MicrobeLibrary.org; © Jean-Yves
Sgro, University of Wisconsin. The T4
bacteriophage, middle, is a virus
that invades bacterial cells. Courtesy
of the MicrobeLibrary.org; © Dennis
Kunkel. Gold clusters bound to the
knob protein of Adenovirus, right.
Courtesy of Brookhaven National
Viruses come in many shapes. Left, an illustration
of the influenza virus. Right, an illustration of
Human Immunodeficiency Virus (HIV). Courtesy of
the National Institute of Allergies and Infectious
Diseases (NIAID), National Institutes of Health.
REPLICATION OF VIRUSES
(THE LYTIC CYCLE)