Measles Vaccines Cards Flashcards
Describe the genetic material/structure/family of measlesvirus
Paramyxovirus family, RNA genome, enveloped
How contagious is measles?
90% transmission after exposure
What are the antiviral treatments for measles?
There are no effective treatments.
Name the most important measles glycoproteins
H protein (hemagglutinin) and F protein (fusion)
How is measles transmitted?
Respiratory droplets and aerosolized small droplet nuclei enter at the respiratory tract
Measles fuses with what cells?
In the lung: Dendritic cells of respiratory tract and alveolar macrophages. In the lymph: T and B lymphocytes.
Where does measles disseminate to?
Lymph nodes; secondary lymph organs; intestine (endothelial cells); skin and brain (epithelial cells)
How does measles inhibit innate immunity?
Inhibit TLR signaling and interferon synthesis/signaling; interferes with T cell activation. Additionally, it’s associated with transient lymphopenia/immune suppression
How does measles enter an epithelial cell?
From the basal side through Nectin 4, a protein in the cell junction
How does measles exit a host?
It buds apically from an infected respiratory epithelium and is released into airway lumen
How long is measles incubation period?
10-14 days
When do the main clinical signs of measles appear, and what are they?
prodrome @ 14 days: low-grade fever and malaise; then cough, coryza, conjunctivitis
What are koplik spots?
White-blue specks on red mucosa, normally buccal and lower labial surfaces, appearing 2 days after prodrome symptoms; resolve when skin rash (exanthem) appears.
Describe the timing of the measles skin rash
4 days after prodrome symptoms, exanthem appears. Onset coincides with T-cell immunity activation and resolution of prodrone clinical symptoms. Fever peaks on day 2-3 of rash, resolves on day 3-4 of rash.
Describe the clinical appearance of the measles skin rash
Red maculopapular lesion, confluencing. Beginning at hairline and spreading to trunk, extremities, palms + soles. After 3-4 days turns copper/brown, resolving in same pattern after 7 days.
Describe clinical signs/symptoms of measles dissemination
Diarrhea, vomiting, abdominal pain; cervical lymphadenopathy/splenomegaly; pharyngitis; bronchiolitis/viral pneumonia; encephalitis
What are the common complications of measles?
Secondary pneumonia, otitis media, or other URI (source of morbidity in infants and developing countries)
What is SSPE?
Subacute sclerosing panencephalitis; slow, progressive CNS disease occuring 4-8 years after acute measles infection (usually at
How do you diagnose measles?
Measles IgM antibody; 4x rise in measles IgG; PCR and culture (slow, esp wild-type)
How do you treat measles?
Supportive care and Vitamin A (decrease mortality in developing countries)
Describe the measles vaccine
Live attenuated vaccine, 95% efficacy (99% efficacy with 2 doses), combined in MMR
What is the protective vaccination rate for measles?
93% to avoid community circulation/outbreak
What was the rate of death of measles in 2013?
14 deaths per hour
Define vaccine antigen
Molecule that an antibody response is generated against
Define adjuvant
Substance that nonspecifically activates the immune system, added to vaccine to enhance immune response
Define vaccine titer
A measure of the amount of antibody made to a vaccine antigen
Give three examples of inactivated killed vaccines
Polio (injected), hepatitis A, rabies
Give two examples of inactivated toxin vaccines
Tetanus (tetanospasmin neurotoxin), diptheria
What are toxoid vaccines?
Toxin inactivated by heat or chemical (formalin) treatment, typically requiring boosters
Give examples of subunit vaccines
Hep B, HPV, Pertussis, influenxa (IM), pneumococcal polysaccharide, meningococcal polysaccharide
What does the Hep B vaccine contain?
Hep B surface antigen (recombinant from yeast)
What does the pneumococcal polysaccharide vaccine contain?
Mixed carbohydrates isolated from the outer capsule of 23 different streptococcus pneumoniae serotypes
Give examples of conjugated vaccines
HiB, pneumococcal conjugate, meningococcal conjugate; often conjugated with diptheria or tetanus toxoid
Give examples of live attenuated vaccines
Measles, mumps, rubella, varicella, rotavirus, influenza (nasal spray), oral polio vaccine, yellow fever, BCG
What is the significant risk of OPV?
OPV may revert back to wild-type, fully pathogenic form. It repiclicates in gut mucosa, and reverts within weeks of vaccination.
What is the risk of BCG vaccine?
Causes disseminated, TB-like disease in immunocompromised patients.
What antigens are T cell dependent?
Protein antigens
What antigens are T cell independent?
Carbohydrate antigens
What do T cells secrete to aid in T-cell dependent immune response?
Secrete IL2, IL4, IL5 which helps promote B cell class switching
Define secondary immune response
Memory B cells proliferate and result in a higher IgG response to an antigen upon second exposure
How do protein antigens cause an immune response?
T-cell dependent; presented by APC and recognized by T and B cells in germinal centers of local lymph nodes; T cells promote B cell class switching
How do carbohydrate antigens cause an immune response?
Antigens directly cross-link B-cell receptors on B cells in marginal zones of spleen/lymph nodes; B cells class switch or differentiate into plasma cells, persisting in spleen
What type of immune response produces memory B cells?
T cell dependent (protein antigens)
What types of patients cannot respond to carbohydrate antigens? How do vaccines work around this?
Children under 2; requires conjugating carbohydrate to diptheria or tetanus toxoid to provoke T cell dependent response
Where do T cell dependent responses take place?
Germinal center of lymph
Where do T cell independent responses take place?
Marginal Zone, outside of the germinal center, of lymph and spleen
