Viral Immunology and Vaccines Flashcards
What are the 2 barriers discussed in regards to infection?
- physical barriers (skin, mucus, stomach acidity)
- antimicrobial products
What are the first innate immune responses?
- interferons first to tell body that infection is occurring
- NK cells to kill infected cells stopping viral spread
How are interferons activated?
- pattern recognition receptors recognize viral RNA/DNA in an infected cell and stimulate type 1 interferon
T/F: Viruses have evolved and reduced type 1 interferon response.
True!
These viruses that inhibit the IFN response are typically the ones that make you the sickest
What do interferons do?
- activate anti-viral genes/proteins
T/F: interferon can act as an antiviral treatment.
True!
- they can make you very sick though
- only about 30% effective
What happens with MHC 1 in regards to viruses?
- some viruses can down regulate MHC 1 to avoid killing from cytotoxic T cells
T/F: Macrophages and DC are important for innate immunity only.
False!
They’re important for both innate and adaptive immunity and bridging them together
What do DC do?
- sample virus and induce type 1 interferon
- produce cytokines
- traffic to lymph node and start adaptive arm of immune response
What are CTL’s important for?
- important in viral infection for infected cell killing
What are B cells important for in the adaptive immune response?
- neutralizing antibody response
What do neutralizing antibodies do?
- bind to surface of virus; specifically envelope glycoprotein in enveloped viruses or viral capsid protein in naked viruses
- can not infect a cell but binds to surface of virus preventing virus from infecting a cell
What do viral antigens encountered in mucosa primary produce?
dimeric IgA
What do viral antigens encountered in blood primary produce?
IgG
What are ways viruses subvert the immune system?
- escape neutralizing antibodies by antigenic drift
- blocking type 1 INF response
- down regulating MHC 1
- killing immune cells like killing CD4 cells
- staying latent/hiding
What happens if you encounter the same strain of virus again?
- generally protected from reinfection due to long lived plasma cells and secreted antibodies
- neutralizing antibodies are already present in mucosa and blood before re-encounter and they can actually go through another round of affinity maturation and end up with a better antibodies and higher levels
If you encounter a different strain of the virus, what will happen?
- usually have cross-protection meaning the new strain is recognized well by antibodies from previous strain with no new sickness
- can also have partial cross-protection. antibodies will bind with lower affinity so can’t stop infection but get less sick
- if no cross protection… likely a new infection to your body
What is required for an effective vaccine?
- neutralizing antibodies that respond to the virus
- stimulate an immune response to prevent virus from infecting (attenuated virus or whole killed/inactivated virus or adjuvant that activates the immune system)
What do adjuvants do?
- you can add with a vaccine so you don’t have to add so much virus to the person to stimulate a response
What types of vaccine need an adjuvant to stimulate the immune system?
subunit vaccine and inactivated
Why do attenuated and whole killed viruses not require an adjuvant?
- attenuated viruses replicate just enough to activate the immune system but not too much so the immune system can clear the virus before you get sick
How is passive immunization with antibodies natural in babies?
- IgG (from blood) is transferred to baby in third trimester and IgA (from mucosa) in colostrum and breast milk
Why do babies have to wait a year to get MMR vaccine?
- maternal antibodies can interfere with vaccination
What viruses have attenuated live vaccines?
- MMR
- Varicella Zoster (chickenpox)
- Rotavirus
- Nasal Influenza Vaccine
- Yellow fever vaccine
- smallpox/mpox (vaccinia)
- oral polio
- military only-adeno type 4 and 7
- adenovirus modified vaccines for coronavirus
What viruses have inactivated vaccines?
- polio vaccine
- hep A vaccine
- rabies vaccine
- influenza vaccine
What viruses have subunit vaccines?
- HA only influenza vaccine
- Hep B vaccine
- human papilloma vaccine
- new shingles vaccine
- mRNA vaccines producing one or two viral proteins
What viruses do we use immunoglobulin from healthy blood donors?
- Hep A
- measles
What viruses do we use hyperimmune IgG from people with a high titer to a specific infection?
- Hep B
- rabies
- chickenpox
- CMV
- vaccinia
What do we use from monoclonal antibodies to which specific viruses?
- RSV
- SARS-CoV-2
What are some viruses that it is possible to prevent infection after exposure by vaccination if done quickly?
- Rabies vaccine with rabies immune globulin
- Hep A vaccine
- Hep B vaccine with Hep b immune globulin
- smallpox
What is herd immunity?
- referring that spread requires contact between a non-immune/susceptible person and an infected person
- lower # of non immune people= less chance of infection spreading
- ultimately benefits non-immune people
What antibody is found in mucosa?
dimeric IgA
