CD44 and viral infectious disease: In our study, there was no significant difference in the number of CXCR3+CD8+T cells and CXCR3+CD4+T, CD44+CD8+T, and KLRG1+CD8+T between pregnant and non-pregnant mice, but the proportion of CD69+CD8+ T cells, increasing mainly at the early infection, and CX3CR1+ CD8+ T cells acted as an antiviral defender, was significantly downregulated, which emphasizes the deficiency of pregnancy in defending viral infections in females.