While CD8+ T cell responses detected after viral infection are generally protective, several studies from us and others show that this is not always the case for CD8+ T cell responses detected against more complex pathogens such as intracellular bacteria, including Listeria (53), or parasites such as Plasmodium berghei (60) or Toxoplasma gondii (61). The gene discussed is CD8A; the disease is viral infectious disease.