The role of interleukin (IL)-2 and IL-4 in herpes simplex virus type 1 ocular replication and eye disease

To assess the relative effect of interleukin (IL)-2- and IL-4-dependent imm une responses on herpes simplex virus (HSV)-1 infection, naive, vaccinated, and mock-vaccinated IL-20(0/0) and IL-4(0/0) knockout mice were challenged ocularly with HSV-1, Naive IL-20(/0) mice were significantly more suscepti ble to lethal infection than IL-4(0/0) or parental BALB/c mice. Vaccinated, IL-2(0/0), IL-4(0/0), and BALB/c mice induced similar neutralizing antibod y titers and were completely protected against HSV-l-induced death and corn eal scarring. Vaccinated and mock-vaccinated IL-2(0/0) mice had significant ly higher HSV-1 titers in their eyes than BALB/c mice, while vaccinated and mock-vaccinated IL-4(0/0) mice had significantly lower HSV-1 titers in the ir eyes than BALB/c mice. Recombinant (r) IL-2 treatment of the IL-2(0/0) m ice significantly reduced ocular HSV-1 replications, but rIL-4 treatment of IL-4(0/0) mice significantly increased ocular HSV-1 replications. Th1 (IL- 2) cytokine responses may help protect mice against ocular HSV-1 challenge and reduce ocular HSV-1 replication.