CCR5 and infection: However, the critical role of CCR5 in flavivirus pathogenesis appears to be unique in other neurotropic viruses, because infections of Ccr5−/− mice with several neurotropic viruses, such as LCMV [49], retrovirus FR98 [50], and mouse hepatitis virus (MHV) [51], resulted in viral burdens in the CNS similar to those of Ccr5+/+ mice.