Directed attenuation to enhance vaccine immunity
Fig 4
Comparison of immunity-pathology tradeoffs generated by changing single parameters.
Wild-type values are given at the intersection of the curves, so viable attenuation strategies would lie to the left. As the goal is to attenuate and to increase the immune response, the desirable attenuation strategies lie in the upper left quadrant. The tradeoff for the classic mode of attenuation—lowering growth rate r (black line)—has the undesirable effect of lowering immunity, a pattern mimicked by changes in several other parameters. In contrast, decreasing the rate of loss of innate immunity (dZ↓ (brown)), or increasing the rate of proliferation or sensitivity of adaptive immunity (sX↑ (red), ϕZ↓ (blue)) leads to lower pathology and increased immunity.