Describe the phage lambda bacteriophage.
binds only to e.coli and injects DNA into cytoplasm
What life cycle does the lambda phage use?
both the lytic and the lysogenic cycle
Why type of virus is the influenza virus?
a negative strand RNA virus
Why is H7N9 a large concern influenza?
it is very serious but is only transmitted from bird-person, however if it mutates it could be transmitted person to person
Describe the structure of the influenza virus.
- no geometric capsid
- has a shell of matrix proteins surrounding 8 linear RNA each coated with nucleocapsid protein
- two major envelope proteins: Hemagglutinin and Neuraminidase
What is one of the most dangerous aspects of influenza?
It can continually change its antigenic determinants
What is the function of the H protein of influenza?
it forms a trimer complex with an N-terminal fusion peptide to allow fusion of the viral membrane with the host cell membrane
What is the mechanism of the fusion that the H protein facilitates?
- HA binds to host cell glycoprotein receptors
- binds triggers endocytosis
- endocytosis changes the HA fusion peptide
- fusion of host and viral membrane takes place
Explain the replication of the influenza virus.
- HA is endocytosed
- RNA is uncoated and enters nucleus
- RNA polymerase synthesizes + RNA strand
- mRNA is translated and segmented genome is reassortment
- virus over takes host machinery so host produces viral proteins
- neuraminidase enzyme is activated to allow the virion to be cleaved to go outside the cell
- host protease activates viron so it can infect other cells
Describe the N proteins of influenza.
neuraminidase, cuts virion loose from host cell to release it to the extracellular space
What determines if a host is susceptible to influenza?
presence of glycoproteins for HA binding and host protease to activate virion
Why do we need a flu shot every year?
due to drifting - the ability of the virus to slightly change from RNA replication errors (the body doesn’t recognize the change)
or shifting - a big change in the virus caused by new virus species or reassortment
