VIRAL INFECTIONS CONT. & HEPATITIS Flashcards
Viral Hepatitis
HIV
Dengue
Herpes Virus infections: infectious mononucleosis, Epstein Barr Virus, Cytomegalovirus
Submicroscopic particle (size is measured in nanometers)
VIRUSES
VIRUSES Basic Structure:
core of DNA or RNA
Intracellular pathogens
VIRUSES
First line of protection (nonspecific immunity)
INNATE IMMUNITY AGAINST VIRUSES
Interferon-a and Interferon-b
INNATE IMMUNITY AGAINST VIRUSES
Inhibits viral replication
Interferon-a and Interferon-b
Enhances activity of NK cells
Interferon-a and Interferon-b
B cells and plasma cells
HUMORAL DEFENSE
Produces virus specific antibodies
HUMORAL DEFENSE
Ab prevents spread of viral replication through neutralization
HUMORAL DEFENSE
: promotes phagocytosis thru opsonization
IgG
: Agglutinates viral particles
IgM
Upon activation of [?], CD8+ Cytotoxic T cells (CTL) become programmed to expand in number and attack the virus-infected cells.
CD4+ T helper cells and cytokines
Cytotoxic T cells (CTL) produce
proteins and proteases
- pore forming protein, bubutasan nila ung host cell. It will create a pore in the membrane of the host cell.
Perforin
- they will now enter the pore and will activate apoptosis
Granzymes
Increase [?] its original number
50,000 times out of
Produces new viral antigens – not recognized immediately by initial immune response
They undergo frequent genetic mutations
Ex. Covid-19
Frequently undergo genetic mutation due to presence of nucleic acids
Production of new viral antigens that are not recognized immediately by the innate immune response
They undergo frequent genetic mutations
For example, the Hepatitis C virus (HCV) can block the degradation of viral RNA that is induced by interferons.
Some viruses can evade actions of the component of the immune response
For example, cytomegalovirus and human immunodeficiency virus can reduce the expression of major histocompatibility complex molecule on the surface of virus infected cells making them less likely to be recognized by B cells
Viruses can evade the hosts defense by suppressing the immune system
STRATEGIES ON HOW VIRUSES ESCAPES IMMUNE MECHANISMS
They undergo frequent genetic mutations
Some viruses can evade actions of the component of the immune response
Viruses can evade the hosts defense by suppressing the immune system
LABORATORY TESTING FOR VIRAL INFECTION
Serologic testing
Molecular assays
– monitors the course of infection, detects past infection, can assess immune status
Serologic testing
Indicates current or recent infection or acute infection
Specific IgM antibody
[?] in newborns indicates congenital infection with virus
Specific IgM antibody
Indicates current or past infection and in most cases immunity
IgG antibodies
[?] in newborns are mainly maternal antibodies
IgG antibodies
can cross the placenta; thus normal
IgG
Demonstrated using [?] (compound for bacteria)
electron microscope
DNA or RNA is packed in [?] and some virus’s capsid is surrounded by outer envelope such as glycolipids and proteins.
protein coat or capsid
They are going to rely on host cells for replication and survival.
Intracellular pathogens
No host =
dormant
[?]infects the host cell by attaching to specific receptors in their target cells
Virion
It penetrates the cell membrane
Virion
directs the host cell machinery to produce more viral nucleic acid and proteins
Release of nucleic acid (RNA or DNA)
assemble inside the cell to form the intact virus, which is released thru cell lysis or budding of the cell surface
Release of nucleic acid (RNA or DNA)
Viruses destroy the cells leading to [?]
decreased cell count
Target cell:
CD4 T cells
(virus-infected cells; produced in the recognition of TLRs)
Interferon-a and Interferon-b
By inducing transcription of several genes that will code for proteins w/ antiviral activity
Inhibits viral replication
Binds virus-infected cells and release cytotoxic proteins like perforin (substance that create pores) and granzymes
Enhances activity of NK cells
– primary cells involved of humoral defense
B cells and plasma cells
antibodies specific for a component of the virus that binds to a receptor on the host cell membrane will bind to the virus and prevent it from attaching to and penetrating the cell
Produces virus specific antibodies
neutralize viruses in the mucosal surfaces
Secretory IgA antibodies
can bind to viruses in the bloodstream and inhibit dissemination of the infection.
IgM and IgG antibodies
promote phagocytosis of viruses through their opsonizing activity
IgG antibodies
can also inactivate viral particles by agglutinating them.
IgM antibodies
also activate complement
IgG and IgM antibodies
leading to elimination of intracellular viruses required for replication
Cytotoxic T cells (CTL)
General term for inflammation of the liver
HEPATITIS
([?]– liver,[?] – inflammation)
hepa; itis
T or F
Most people though that the cause of hepatitis is virus but there are also other causes
T
HEPATITIS Causes:
viral infection, chemicals, ionizing radiation and autoimmune process
HEPATITIS TWO STAGES
Acute stage
Progressive/Chronic stage
: General flu like symptoms
Acute stage
Hepatomegaly (enlargement of the liver)
Progressive/Chronic stage
jaundice (yellowish discoloration of the skin)
Progressive/Chronic stage
dark urine (due to increase of urobilinogen passing through urine)
Progressive/Chronic stage
light feces (due to increase of stercobilin)
Progressive/Chronic stage
(enlargement of the liver)
Hepatomegaly
(yellowish discoloration of the skin)
jaundice
dark urine (due to increase of [?] passing through urine)
urobilinogen