Use of chemokine receptors by poxviruses

Chemokine receptors serve as portals of entry for certain intracellular pat hogens, most notably human immunodeficiency virus (HIV). Myxoma virus is a member of the poxvirus family that induces a Lethal systemic disease in rab bits, but no poxvirus receptor has ever been defined. Rodent fibroblasts (3 T3) that cannot be infected with myxoma virus could be made fully permissiv e for myxoma virus infection by expression of any one of several human chem okine receptors, including CCR1, CCR5, and CXCR4. Conversely, infection of 3T3-CCR5; cells can be inhibited by RANTES, anti-CCR5 polyclonal antibody, or herbimycin A but not by monoclonal antibodies that block HIV-1 infection or by pertussis toxin. These findings suggest that poxviruses, Like HIV, a re able to use chemokine receptors to infect specific cell subtypes, notabl y migratory Leukocytes, but that their mechanisms of receptor interactions are distinct.