L12 RNA virus and the disease they cause Flashcards
Influenza Virus family
Orthomyxoviridae
Influenza Virus characteristics
- ss - sense RNA
- RNA segmentaed
- Each segment will code for 1 or 2 proteins
- Enveloped gp: hemagglutinin and Neuraminidase (NA) needed for entry and egress of virus to host
Influenza is caused by
Orthomyxoviridae
Myxo meaning
Greek for mucous
What does the “myxo” in orthomyxoviridae mean for influenza
IV attach to mucoproteins on cell surface
3 Gernera of influenza that infect humans
- IV A (H1-18)
- IV 2 (B/yamagata)
- IV 3 (Mild, inapparent)
Influenza A Characteristics
- undergo a genetic shift
- cause pandemics
Minus sense ssRNA undergo mutations and can cause what?
Reassortment: high rates of antigenic variation
Reassortment:
high rates of antigenic variation
How often does swine flu circulate in pigs
Throughout the year
Does swine flu infect humans
No normally but sporadic human infections can happen if exposed to an infected pig
Can vaccines against human IV protect against swine flu
No
Pathogenesis of Influenza
- Infect upper respiratory tract
- Virus replicates in epthelial cells in nose killing them
- Production of IFN and cytokines -> severe malaise
- Can infect lower repiratory tract and cause pneumonia bc virus replicates in alveolar pethelial cells
- IV infection also enhance stroke and heart disease
Avian IV dominates preference for what?
Alpha-2,3 sialic acid
or alpha 2,6 in humans
Genetic reassortment is the mixing of RNA via what and results in what?
Co-infections of host cells by > 1 IV that results in the formation of IV with new genomes (to human immune systems)
Genetic reassortment has severe disease and high death rates (T/F)
True
Influence antigenic changes
The structure of hemagglutinin and neuraminidase periodically change
Influence antigenic change: Shift (pandemic)
- Major change, new subtype
- Exchange gene segments (reassort): virus is immunologically distinct from the previous IV so there is no existing immunity.
Influence antigenic change: Drift (Epidemic)
- Minor change, same subtype
- Point mutations in HA/NA genes and can’t control replication.
Epidemics are an antigenic ____
Drift
Pandemics are an antigenic _____
Shift
Season Influenza
Respiratory illness transmitted person to person
- Vaccines and immunity
Avain Influenza
- Occur naturally in wild birds
- No human immunity or vaccine
Swine Influenza
- Respiratory disease of pigs by IV-A and cause outbreaks
_ Not infect human normally but can happen sporadically as H1N1v
Pandemic Influenza
- Virulent human Influenza that cause global outbreak
- Little natural immunity
- Easily transmittable between humans
Coronavirus RNA characteristics
- +pos sense
- enveloped
- non-segmented RNA with large genome
MERS-CoV
Middle East Respiratory Syndrome Coronavirus
MERS-CoV information
- in camels
- Camels don’t show signs of infection but can spread the disease in fluids
- 35% mortality
Human immunodeficiency virus family and genus
Retroviridae and lentivirus
Human immunodeficiency virus shape and characteristics simple
- Icosahedral
- Enveloped
- ss(+) RNA
Human immunodeficiency virus Infects what
CD4+ cells with gp120
Human immunodeficiency virus replication
- By conversion of vRNA to complementary DNA (vRT)
- Integrates into host with (v)Integrase
- Known as a provirus at this stage and ramians integrated for cell’s life
- HIV is a quasispecies
HIV-1 and HIV-2 both arose from what
Non-human primates in West Africa
HIV-1 came from
Chimpanzees and is the cause of almost all human infection
HIV-2 is related to
Simian immunodeficiency virus and is a less aggressive disease progression
Which group is the main circulating recombinant form of HIV-1
group M
HIV transmission
Percutaneous
- Injection
- Transfusion from donors
- Occupational - nurses
Permucosal
- Perinatal in-delivery or breast milk
- Sexual transmission across mucosal membranes in urogenital tract and rectal mucosa
What happens to the CD$ t-cell count after HIV infection without antivirals
CD4+ T-cell count gradually and consistently declines
Diagnosis of AIDS
Low CD$+ t-cell count of <200 cells
Pneumocystis jiroveci or one illness
Long term non-progression
- had stable CD4+ counts after given blood from infected donor
- Attenuation of the HIV-1 genome, the nef gene, interferes with viral replication and can influence disease outcome
Resistance to infection with HIV-1: CCR5-∆32
- HIV target T-cells via CD$ and coreceptors
- Slow progressors were homozygous for 32bp deletion in CCR5 gene
- More freq in north europe
[Resistence to HIV-1] CCR5 432 mutation expressed on what cells?
- receptor molecule expressed on T-cells, macrophages, dendritic cells, and microglia
microglia - Ligands are MPI1a, MPI1B, RANTES
*32 base pair deletion within coding region results in a frameshift and generates a non-function receptor for HIV-1
