1.What organism is the most likely etiology of this illness?
Organism most likely for this infection: Haemophilus influenzae type B(HIB)
Haemophilus influenzae B(hib) can cause respiratory tract infections including pneumonia, otitis media, epiglottitis (swelling in the throat), eye infections and bloodstream infection, meningitis. It can also cause cellulitis (skin infection) and infectious arthritis.
2.What component of this organism is the target of vaccine-induced immunity?
ANS -The target of vaccine-induced immunity in organism: Purified polyribitol phosphate, a component of the H. Influenzae type B polysaccharide capsule.
Anti-PRP antibodies have a protective effect against Hib infections. Thus, purified PRP was considered a good candidate for a vaccine. However, the antibody response to PRP diminished rapidly after administration. This problem was due to recognition of the PRP antigen by B cells, but not T cells. In other words, even though B cell recognition was taking place, T cell recruitment (via MHC class II) was not, which compromised the immune response. This interaction with only B cells is termed T-independent (TI). This process also inhibits the formation of memory B cells, thus compromising long term immune system memory.
