List five mechanims by which virus can cause damage to animal cell? Draw the rea
ID: 260589 • Letter: L
Question
List five mechanims by which virus can cause damage to animal cell?
Draw the reactions of Kreb's cycle (enzyme names are required)
The most commonly accepted hypothesis for the production of ATP that results from electron transport system is called the ____ hypothesis.( Is it chemoismotic?)
Production of ATP using the energy liberated whn electrons from reduced chemical bonds are pass through the electron transport system is generally referred to as ______
a. chemiosmotic
b. respiration
c. subsrate level
d. conformational change
Explanation / Answer
1. Humoral Immunity
(a) In animal model systems the Moloney leukemia virus, Friend leukemia virus, Ranscher leukemia virus and the avian leukosis virus all cause a depression of the synthesis of immunoglobulins of the IgM and IgG classes. Although human leukemia has not yet been shown to be of viral etiology, the analogy with animal systems is strengthened by the fact that human leukemia victims do have a reduced ability to synthesize immunoglobulins.
(b) Viruses which do not produce leukemia but infect lymphoid tissue also decrease the immune response of the host. Again in animal model systems, the lymphocytic choriomeningitis virus, the Argentinian hemorrhagic fever virus and the Aleutian mink disease virus all cause a lessened antibody (IgM and IgG) response to a variety of antigens. Depression of the immune response is greatest in adults, temporary in neonates and absent in chronic virus infections.
(c) Both leukemia and lymphoma viruses also decrease the ability of an animal to undergo anaphylaxis. This is thought to be due to a reduced synthesis of IgE.
Many theories have been proposed to explain how viruses depress immune function. Since these are only theories at the present, only the more common ones are worth mentioning.
(a) Viruses alter the uptake and processing of antigens.
(b) Viruses depress cellular protein (antibody) synthesis.
(c) Viruses destroy antibody-producing cells.
(d) Viruses increase immunoglobulin catabolism.
2. Cellular immunity
(a) Again, in animal systems, it has been shown that both leukemia viruses and non-leukemia viruses can either prevent or ameliorate homograft rejection across weak histocompatibility barriers.
(b) Many viruses promote the growth of tumors which would normally be rejected by the host's cellular immune mechanisms.
(c) More relevant to human medicine is the fact that infection with measles virus, influenza virus, chickenpox virus, polio virus or rubella virus causes a depression of delayed hypersensitivity as measured by skin reaction to tuberculin.
The major theory explaining these phenomena relates the reduced cellular immunity to a depressed ability to undergo lymphocyte blast transformation.
3. Reticuloendothelial system and phagocytosis
(a) In animal studies, infection with either lactic dehydrogenase virus, ectromelia virus, hepatitis virus or lymphocytic choriomeningitis virus causes a slower clearance of carbon particles from the circulatory system.
(b) Infection of animals with Venezuelan equine encephalitis virus, Friend leukemia virus or Moloney leukemia virus augments clearance of carbon particles.
(c) Infection of human polymorphonuclear leukocytes with mumps virus, influenza virus or Coxsackie virus decreases the ability of these cells to engulf bacteria.
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