Lec 1 Influenza Flashcards
Orthomyxoviruses:types and structure
Influenza A B C
1)RNA enveloped viruses
2)has RNA dependant RNA polymerase (important for infectivity)
3) -ssRNA with 8 segments in type A and B
Haemagglutinin of Orthomyxoviruses:
17 subtypes
-allows virus to adhere into endothelium of respiratory tract
-main determinant of immunity
Neuraminidase of Orthomyxoviruses: 9 serotypes
(not in type C)
-allows release of newly formed viruses within the host.
-determines how severe a disease is
M protiens and ribonucleoproteins in Orthomyxoviruses:
M proteins (1&2): between capsid and envelop, only in type A
Act as ion channel to change endosomal pH (M2 mainly)
RBP’s: Distinguish between types A B C
Antigenic shift of Orthomyxoviruses: (type A)
(the cause of pandemics)
-reassortment and swapping in the genomic RNA
-pre existing antibodies DO NOT protect
Antigenic drift (all types) of Orthmyxoviruses:
-HA and NA accumulate mutations
-immune response no longer protects you fully
Orthomyxovirus life cycle
1)Adhesion of virus
2)fusion
3)uncoating by M2(pH changes)
4)RNA replication
5)packaging and budding
6)release of progeny virus, By NA
summed up
-HA binds to receptor, then undergoes pH change by M2,then released from recepteor by NA
Host response and recovery:
Orthomyxo
-Interferon production, stops virus replication
-gives flu like symptoms
Orthomyxovirus I.P and symptoms
I.P 1-4 days
3-7 days symptoms last
Orthomyxoviruses clinically:
type A B C
1)-Fever hedache cough Rhinitis
-type B milder
-Type C has no fever
Pulmonary complications caused by orthomyxo:
-CROUP (children)
-secondary bacterial infection: strep pneumonia, staph influenza , hemophilus influenza.
Non pulmonary complications caused by Orthomyxo:
1)Reye’s syndrome (encephalopathy + liver degeneration)
-isnt affected by aspirin
2) Guilliane barre syndrome, Affect PNS, AI disease
3) Cardiac: myositis
diagnosis by PCR
Treatment of orthomyxoviruses:
1)symptomatic:
fluids and analgesics
2)Drugs
-amantadine, inhibit M2 but not used anymore
-Neuroaminidase inhibitors: Zanamavir, Oseltamivir, Permivir—– inhbit viral release
-Cap dependant endonuclease inhibitors:
* Baloxavir and marboxil
* inhbit viral replication
drugs effective against Types A and B
prevention vaccines of Orthomyxo;
Vaccine types:
1)inactivated
2)Life attenuated; nasally
avoid in:
-anaphylactic shock and GBS history
-Acute fever
-immunosupressed and pregnant; dont give life attenuated
Parainfluenza:
-ss RNA enveloped
-RNA dependant RNA polymerase
-can be asymptomatic but still infective
