Following initial exposure, the virus begins replication in the oropharynx, infiltrating the local lymphatic tissues including the tonsils and pharyngeal lymph nodes3, 7, 18. At this stage of the infection, immunocompetent animals (also known as “regressor cats”) may be able to mount an effective cell-mediated immune response resulting in complete clearance of the infection prior to systemic spread (and thus subsequent stages of the infection) 7. This initial cell-mediated immune response is largely independent of the high levels of neutralizing antibody in the blood7. If the viral infection is cleared at this stage, the animal tends to develop a strong, long-lasting immunity, and is at low-risk of developing the disease with subsequent exposure to the virus7. If an initial pre-parturient immune response fails, the infection becomes disseminated, resulting is systemic spread of the virus in circulating B-lymphocytes and macrophages at which point the animal will have the disease for the rest of its life 3, 7.