The primary objective of the Viral Biochemistry Section (VBCS) is to gain insights into innate host defense mechanisms and to decipher the molecular mechanisms governing the functional neutralization of innate restriction factors by HIV- or SIV-encoded proteins. The ultimate goal is to identify possible points of interference that could lead to the development of novel treatment strategies. Over the last few years, our work on Vif has focused on characterizing mechanisms of dominant-negative interference by defective Vif variants. We also performed a comparative characterization of Vif proteins from HIV-1 versus HIV-2 and observed an interesting difference in how the two viruses deal with APOBEC3B (A3B) restriction.