V–W

virus An infectious PATHOGENthat must invade a
host cell to replicate, technically called an obligate
intracellular PARASITE. A virus is a particle of living
material that contains an inner core of nucleic
acid (DNAor RNA), called the genome, encased in
an outer shell of protein, called a capsid. Some
viruses contain a third layer composed of lipids,
called an envelope, that further protects and nour-
ishes the virus. These components, collectively
called a virion, cannot themselves support a full
life cycle, which obligates the virus to find a host
to maintain its survival. A virus can attach only to

the type of cell capable of supporting it, binding to

specific protein molecules on the surface of the

cell membrane.

ANTIBIOTIC MEDICATIONSare not effective

in treating illnesses that result from

viral infections, such as COLDS and

INFLUENZA.

After invading a host cell, a virus hijacks the

cell’s structures and functions to serve its own

needs and to replicate itself. DNA viruses produce

361

COMMON VIRUSES AND THE ILLNESSES THEY CAUSE

Virus or Viral Family Genetic Configuration Illness
ADENOVIRUS DNA PHARYNGITIS, PNEUMONIA, acute respiratory disease, cervicitis,
URETHRITIS, CYSTITIS, GASTROENTERITIS

CYTOMEGALOVIRUS(CMV) DNA CMV INFECTION

EPSTEIN-BARR VIRUS DNA infectious mononucleosis, Burkitt’s lymphoma, Hodgkin’s
lymphoma

HEPATITISA virus (HAV), RNA HEPATITIS
hepatitis C virus (HBV)

HERPES SIMPLEXvirus 1 (HSV-1) DNA COLD SORE

herpes simplex virus 2 (HSV-2) DNA GENITAL HERPES

human herpesvirus 8 (HHV-8) DNA KAPOSI’S SARCOMA

human immunodeficiency RNA retrovirus AIDS
virus 1 (HIV-1), human
immunodeficiency virus 2
(HIV-2)