This Stage 2 ends with immune exhaustion and a restart of rapid virus replication.
The B cell supply becomes exhausted by uncontrolled polyclonal antibody production.
The T cells become anergic. T cell anergy is associated with an overexpression of IL10 from CD4 cells. IL10 causes a blockade of T cell activation via the CD28 pathway.

Stage 3. Death. High levels of virus kill CD4, CD8 and Bcell at 4m or later.
Nonregenerative anaemia, leucopoenia, neutropoenia, chronic immunosuppression. Secondary infections eg gingivitis, rhinitis.
B cell lymphomas. One such tumour contained FIV provirus (ref Molecular and immunophenotypical characterization of a feline immunodeficiency virus (FIV)-associated lymphoma: a direct role for FIV in B-lymphocyte transformation byBeatty JA, et al, in J Virol 1998 72,767-71).