VIRAL INFECTIONS Flashcards
Viral Hepatitis
HIV
Dengue
Herpes Virus infections: infectious mononucleosis, Epstein Barr Virus, Cytomegalovirus
Submicroscopic particle (size is measured in nanometers)
VIRUSES
VIRUSES
Demonstrated using (?) (compound for bacteria)
electron microscope
VIRUSES Basic Structure:
core of DNA or RNA
DNA or RNA is packed in (?) and some virus’s capsid is surrounded by outer envelope such as (?)
protein coat or capsid
glycolipids and proteins.
Intracellular pathogens
VIRUSES
They are going to rely on (?) for replication and survival.
host cells
No host =
dormant
First line of protection (nonspecific immunity)
INNATE IMMUNITY
(virus-infected cells; produced in the recognition of TLRs)
Interferon-a and Interferon-b
Inhibits viral replication
INNATE IMMUNITY
Inhibits viral replication
INNATE IMMUNITY
HUMORAL DEFENSE
– primary cells involved
B cells and plasma cells
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
produce proteins and proteases
Cytotoxic T cells (CTL)
proteases
Perforinm
Granzymes
- pore forming protein; create a pore in the membrane of the host cell
Perforin
- they will now enter the pore and will activate apoptosis
Granzymes
CELLULAR DEFENSE
Increase (?) its original number
50,000 times
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
– not recognized immediately by initial immune response
Produces new viral antigens
LABORATORY TESTING FOR VIRAL INFECTION
Virus specific IgM antibodies
IgG antibodies to the virus
Indicates current or recent infection or acute infection
Virus specific IgM antibodies
Specific IgM antibody in newborns indicates (?) with virus
congenital infection
Indicates current or past infection and in most cases immunity
IgG antibodies to the virus
IgG antibodies in newborns are mainly (?)
maternal antibodies
can cross the placenta; thus normal
IgG
infects the host cell by attaching to specific receptors in their target cells
Virion
It penetrates the
cell membrane
Release of
nucleic acid (RNA or DNA)
directs the host cell machinery to produce more viral nucleic acid and proteins
nucleic acid (RNA or DNA)
assemble inside the cell to form the intact virus, which is released thru (?) of the cell surface
cell lysis or budding
Viruses destroy the cells leading to
decreased cell count
Target cell:
CD4 T cells
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
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
antibodies neutralize viruses in the mucosal surfaces
Secretory IgA
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)
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
Some viruses can evade actions of the component of the immune response
can block the degradation of viral RNA that is induced by interferons.
Hepatitis C virus (HCV)
Viruses can evade the hosts defense by suppressing the immune system
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
cytomegalovirus and human immunodeficiency virus
LABORATORY TESTING FOR VIRAL INFECTION
Serologic testing
Molecular assays
– monitors the course of infection, detects past infection, can assess immune status
Serologic testing
