Three siblings are exposed to Parvovirus B19, a virus that commonly infects children, infecting and destroying erythrocytes (RBCs) and in rare cases causes a transient anemia but usually is cleared with no long term affects. They responded as follows:
-Brother #1, age 14, develops a high fever and general malaise 8 days after exposure, lasting for 4 days, and recover completely with no further complications.
-Sister, age 9, was also infected with the virus but developed no acute clinical symptoms. However, she developed a post-infection arthritis that was transient in nature, resolving after a few weeks with no permanent damage to any joints.
-Brother #2, age 6, also develops a high fever and general malaise 10 days after exposure to the virus lasting for 4 days, and recovers completely. Two weeks later he develops a rash covering his entire body, which gradually subsided over the next several days. He had elevated serum levels of IgG.
Explain the outcome of the infection and the subsequent clinical manifestations immunologically for each sibling and speculate on potential reasons for the different disease outcome in each