Biomedical Engineering Reference
In-Depth Information
*Epstein
Barr virus
*Herpes simplex virus type 1
*Herpes simplex virus type 2
*Herpes virus varicella-zoster virus
*Herpesvirus simiae, also known as B virus
*Human herpesvirus type 6, HHV6
*Human herpesvirus type 7, HHV7
*Human herpesvirus type 8, HHV8
*Cytomegalovirus
Members of Class Herpesviridae are commonly known as herpesviruses.
These viruses produce acute disease characterized by lytic (i.e. cytopathic)
effects in infected cells; and latent disease, characterized by recurrences of
disease, sometimes spanning the life of the host. After cells are infected by
virus particles, the viral genome migrates to the host nucleus, where replica-
tion and transcription of the viral genes occurs. During the latent phase,
viruses may trigger a lytic phase, manifesting as clinical disease. The recur-
ring disease may be clinically distinct from the initial infection (e.g. chicken
pox, the initial varicella virus infection, is followed decades later by shin-
gles). Some of the herpesviruses are DNA-transforming viruses.
The human herpesviruses are: Epstein
Barr virus, herpes simplex viruses,
varicella virus, and human herpesviruses 6, 7, and 8, and cytomegalovirus.
Epstein
Barr virus infects almost all adults. Its persistence makes it one of
the most prevalent human pathogens. It manifests acutely as mononucleosis, a
pharyngitis accompanied by lymphocytosis (increased lymphocytes in the
peripheral blood) and with morphologic alterations in infected lymphoctyes.
Splenomegaly and hepatomegaly may occur. The generalized symptoms of the
disease, particularly fatigue, may extend for months or longer, and some cases
of mononucleosis recur. Epstein
Barr virus is a DNA-transforming virus and
accounts for several cancers, including Hodgkin's lymphoma, Burkitt's lym-
phoma, nasopharyngeal carcinoma, and central nervous system lymphoma. A
role for the virus in several autoimmune diseases has been suggested.
Herpes simplex type 1 causes cold sores, and herpes simplex types 2
causes genital herpes. Both diseases may recur after initial infection.
Herpes virus varicella-zoster causes chickenpox on first infection and her-
pes zoster, also known as shingles, on re-activation.
Herpesvirus simiae, also known as B virus, infects macaque monkeys,
without causing severe disease. In rare circumstances, humans may become
infected with this virus, from the monkey reservoir. Human infection typi-
cally results in a severe encephalopathy.
Human herpesvirus type 6 (HHV6) and type 7 (HHV7) produce exan-
them subitum, also known as roseola infantum and sixth disease. Readers
should not confuse sixth disease with fifth disease. Fifth disease, also known
as erythema infectiosum and slapped face disease, is caused by Parvovirus
