HK2 and infection: When spirochetes migrate from ticks to the mammalian host, the Hk2-Rrp2 pathway is activated during tick feeding, leading to the production of OspC, DbpA/B, BBK32 BBA64 and many factors that are important for B. burgdorferi to establish infection in the mammalian host [81], [82], [83], [84], [85], [86].