HIV Spike density

Antibody (immune) response to viral infection:

Viral spikes are keys to binding receptors on target cells:

Spike density of some viruses:

Why is HIV spike density two orders of magnitude lower than other viruses?

Is evading potent antibody response an evolutionary force in setting viral spike densities?

If so, why is HIV different from other viruses?  

HIV disrupts the process of affinity maturation by depleting the helper T cell population:

The competition for reduced helper T cell signal negates the loss of competition at high spike densities:

Note that there is no structural reason preventing higher spike density on SIV, and mutant viruses with higher density have been created:

However, once injected into host the spike density goes down in subsequent generations.

Next (Affinity Maturation) Outline Adaptive Immunity Thymic Selection Quorum sensing Affinity Maturation HIV spike density Broadly neutralizing Abs EMF dynamics Summary