CD4 and infection: Although phages for the mouse model in this study were only filtered and not purified, remnant Salmonella debris in phage lysates induced the immune system to a certain extent; our results showed that when Salmonella continued to proliferate at 6 days post-infection, CD4+ T cells, macrophages, and granulocytes all participated to promote the reduction of bacterial load together in response to phage therapy.